Merge branch 'x86/core' into x86/xsave
[linux-2.6] / drivers / serial / serial_core.c
1 /*
2  *  linux/drivers/char/core.c
3  *
4  *  Driver core for serial ports
5  *
6  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
7  *
8  *  Copyright 1999 ARM Limited
9  *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
24  */
25 #include <linux/module.h>
26 #include <linux/tty.h>
27 #include <linux/slab.h>
28 #include <linux/init.h>
29 #include <linux/console.h>
30 #include <linux/serial_core.h>
31 #include <linux/smp_lock.h>
32 #include <linux/device.h>
33 #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
34 #include <linux/delay.h>
35 #include <linux/mutex.h>
36
37 #include <asm/irq.h>
38 #include <asm/uaccess.h>
39
40 /*
41  * This is used to lock changes in serial line configuration.
42  */
43 static DEFINE_MUTEX(port_mutex);
44
45 /*
46  * lockdep: port->lock is initialized in two places, but we
47  *          want only one lock-class:
48  */
49 static struct lock_class_key port_lock_key;
50
51 #define HIGH_BITS_OFFSET        ((sizeof(long)-sizeof(int))*8)
52
53 #define uart_users(state)       ((state)->count + ((state)->info ? (state)->info->port.blocked_open : 0))
54
55 #ifdef CONFIG_SERIAL_CORE_CONSOLE
56 #define uart_console(port)      ((port)->cons && (port)->cons->index == (port)->line)
57 #else
58 #define uart_console(port)      (0)
59 #endif
60
61 static void uart_change_speed(struct uart_state *state,
62                                         struct ktermios *old_termios);
63 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
64 static void uart_change_pm(struct uart_state *state, int pm_state);
65
66 /*
67  * This routine is used by the interrupt handler to schedule processing in
68  * the software interrupt portion of the driver.
69  */
70 void uart_write_wakeup(struct uart_port *port)
71 {
72         struct uart_info *info = port->info;
73         /*
74          * This means you called this function _after_ the port was
75          * closed.  No cookie for you.
76          */
77         BUG_ON(!info);
78         tasklet_schedule(&info->tlet);
79 }
80
81 static void uart_stop(struct tty_struct *tty)
82 {
83         struct uart_state *state = tty->driver_data;
84         struct uart_port *port = state->port;
85         unsigned long flags;
86
87         spin_lock_irqsave(&port->lock, flags);
88         port->ops->stop_tx(port);
89         spin_unlock_irqrestore(&port->lock, flags);
90 }
91
92 static void __uart_start(struct tty_struct *tty)
93 {
94         struct uart_state *state = tty->driver_data;
95         struct uart_port *port = state->port;
96
97         if (!uart_circ_empty(&state->info->xmit) && state->info->xmit.buf &&
98             !tty->stopped && !tty->hw_stopped)
99                 port->ops->start_tx(port);
100 }
101
102 static void uart_start(struct tty_struct *tty)
103 {
104         struct uart_state *state = tty->driver_data;
105         struct uart_port *port = state->port;
106         unsigned long flags;
107
108         spin_lock_irqsave(&port->lock, flags);
109         __uart_start(tty);
110         spin_unlock_irqrestore(&port->lock, flags);
111 }
112
113 static void uart_tasklet_action(unsigned long data)
114 {
115         struct uart_state *state = (struct uart_state *)data;
116         tty_wakeup(state->info->port.tty);
117 }
118
119 static inline void
120 uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
121 {
122         unsigned long flags;
123         unsigned int old;
124
125         spin_lock_irqsave(&port->lock, flags);
126         old = port->mctrl;
127         port->mctrl = (old & ~clear) | set;
128         if (old != port->mctrl)
129                 port->ops->set_mctrl(port, port->mctrl);
130         spin_unlock_irqrestore(&port->lock, flags);
131 }
132
133 #define uart_set_mctrl(port, set)       uart_update_mctrl(port, set, 0)
134 #define uart_clear_mctrl(port, clear)   uart_update_mctrl(port, 0, clear)
135
136 /*
137  * Startup the port.  This will be called once per open.  All calls
138  * will be serialised by the per-port mutex.
139  */
140 static int uart_startup(struct uart_state *state, int init_hw)
141 {
142         struct uart_info *info = state->info;
143         struct uart_port *port = state->port;
144         unsigned long page;
145         int retval = 0;
146
147         if (info->flags & UIF_INITIALIZED)
148                 return 0;
149
150         /*
151          * Set the TTY IO error marker - we will only clear this
152          * once we have successfully opened the port.  Also set
153          * up the tty->alt_speed kludge
154          */
155         set_bit(TTY_IO_ERROR, &info->port.tty->flags);
156
157         if (port->type == PORT_UNKNOWN)
158                 return 0;
159
160         /*
161          * Initialise and allocate the transmit and temporary
162          * buffer.
163          */
164         if (!info->xmit.buf) {
165                 /* This is protected by the per port mutex */
166                 page = get_zeroed_page(GFP_KERNEL);
167                 if (!page)
168                         return -ENOMEM;
169
170                 info->xmit.buf = (unsigned char *) page;
171                 uart_circ_clear(&info->xmit);
172         }
173
174         retval = port->ops->startup(port);
175         if (retval == 0) {
176                 if (init_hw) {
177                         /*
178                          * Initialise the hardware port settings.
179                          */
180                         uart_change_speed(state, NULL);
181
182                         /*
183                          * Setup the RTS and DTR signals once the
184                          * port is open and ready to respond.
185                          */
186                         if (info->port.tty->termios->c_cflag & CBAUD)
187                                 uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
188                 }
189
190                 if (info->flags & UIF_CTS_FLOW) {
191                         spin_lock_irq(&port->lock);
192                         if (!(port->ops->get_mctrl(port) & TIOCM_CTS))
193                                 info->port.tty->hw_stopped = 1;
194                         spin_unlock_irq(&port->lock);
195                 }
196
197                 info->flags |= UIF_INITIALIZED;
198
199                 clear_bit(TTY_IO_ERROR, &info->port.tty->flags);
200         }
201
202         if (retval && capable(CAP_SYS_ADMIN))
203                 retval = 0;
204
205         return retval;
206 }
207
208 /*
209  * This routine will shutdown a serial port; interrupts are disabled, and
210  * DTR is dropped if the hangup on close termio flag is on.  Calls to
211  * uart_shutdown are serialised by the per-port semaphore.
212  */
213 static void uart_shutdown(struct uart_state *state)
214 {
215         struct uart_info *info = state->info;
216         struct uart_port *port = state->port;
217
218         /*
219          * Set the TTY IO error marker
220          */
221         if (info->port.tty)
222                 set_bit(TTY_IO_ERROR, &info->port.tty->flags);
223
224         if (info->flags & UIF_INITIALIZED) {
225                 info->flags &= ~UIF_INITIALIZED;
226
227                 /*
228                  * Turn off DTR and RTS early.
229                  */
230                 if (!info->port.tty || (info->port.tty->termios->c_cflag & HUPCL))
231                         uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
232
233                 /*
234                  * clear delta_msr_wait queue to avoid mem leaks: we may free
235                  * the irq here so the queue might never be woken up.  Note
236                  * that we won't end up waiting on delta_msr_wait again since
237                  * any outstanding file descriptors should be pointing at
238                  * hung_up_tty_fops now.
239                  */
240                 wake_up_interruptible(&info->delta_msr_wait);
241
242                 /*
243                  * Free the IRQ and disable the port.
244                  */
245                 port->ops->shutdown(port);
246
247                 /*
248                  * Ensure that the IRQ handler isn't running on another CPU.
249                  */
250                 synchronize_irq(port->irq);
251         }
252
253         /*
254          * kill off our tasklet
255          */
256         tasklet_kill(&info->tlet);
257
258         /*
259          * Free the transmit buffer page.
260          */
261         if (info->xmit.buf) {
262                 free_page((unsigned long)info->xmit.buf);
263                 info->xmit.buf = NULL;
264         }
265 }
266
267 /**
268  *      uart_update_timeout - update per-port FIFO timeout.
269  *      @port:  uart_port structure describing the port
270  *      @cflag: termios cflag value
271  *      @baud:  speed of the port
272  *
273  *      Set the port FIFO timeout value.  The @cflag value should
274  *      reflect the actual hardware settings.
275  */
276 void
277 uart_update_timeout(struct uart_port *port, unsigned int cflag,
278                     unsigned int baud)
279 {
280         unsigned int bits;
281
282         /* byte size and parity */
283         switch (cflag & CSIZE) {
284         case CS5:
285                 bits = 7;
286                 break;
287         case CS6:
288                 bits = 8;
289                 break;
290         case CS7:
291                 bits = 9;
292                 break;
293         default:
294                 bits = 10;
295                 break; /* CS8 */
296         }
297
298         if (cflag & CSTOPB)
299                 bits++;
300         if (cflag & PARENB)
301                 bits++;
302
303         /*
304          * The total number of bits to be transmitted in the fifo.
305          */
306         bits = bits * port->fifosize;
307
308         /*
309          * Figure the timeout to send the above number of bits.
310          * Add .02 seconds of slop
311          */
312         port->timeout = (HZ * bits) / baud + HZ/50;
313 }
314
315 EXPORT_SYMBOL(uart_update_timeout);
316
317 /**
318  *      uart_get_baud_rate - return baud rate for a particular port
319  *      @port: uart_port structure describing the port in question.
320  *      @termios: desired termios settings.
321  *      @old: old termios (or NULL)
322  *      @min: minimum acceptable baud rate
323  *      @max: maximum acceptable baud rate
324  *
325  *      Decode the termios structure into a numeric baud rate,
326  *      taking account of the magic 38400 baud rate (with spd_*
327  *      flags), and mapping the %B0 rate to 9600 baud.
328  *
329  *      If the new baud rate is invalid, try the old termios setting.
330  *      If it's still invalid, we try 9600 baud.
331  *
332  *      Update the @termios structure to reflect the baud rate
333  *      we're actually going to be using. Don't do this for the case
334  *      where B0 is requested ("hang up").
335  */
336 unsigned int
337 uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
338                    struct ktermios *old, unsigned int min, unsigned int max)
339 {
340         unsigned int try, baud, altbaud = 38400;
341         int hung_up = 0;
342         upf_t flags = port->flags & UPF_SPD_MASK;
343
344         if (flags == UPF_SPD_HI)
345                 altbaud = 57600;
346         if (flags == UPF_SPD_VHI)
347                 altbaud = 115200;
348         if (flags == UPF_SPD_SHI)
349                 altbaud = 230400;
350         if (flags == UPF_SPD_WARP)
351                 altbaud = 460800;
352
353         for (try = 0; try < 2; try++) {
354                 baud = tty_termios_baud_rate(termios);
355
356                 /*
357                  * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
358                  * Die! Die! Die!
359                  */
360                 if (baud == 38400)
361                         baud = altbaud;
362
363                 /*
364                  * Special case: B0 rate.
365                  */
366                 if (baud == 0) {
367                         hung_up = 1;
368                         baud = 9600;
369                 }
370
371                 if (baud >= min && baud <= max)
372                         return baud;
373
374                 /*
375                  * Oops, the quotient was zero.  Try again with
376                  * the old baud rate if possible.
377                  */
378                 termios->c_cflag &= ~CBAUD;
379                 if (old) {
380                         baud = tty_termios_baud_rate(old);
381                         if (!hung_up)
382                                 tty_termios_encode_baud_rate(termios,
383                                                                 baud, baud);
384                         old = NULL;
385                         continue;
386                 }
387
388                 /*
389                  * As a last resort, if the quotient is zero,
390                  * default to 9600 bps
391                  */
392                 if (!hung_up)
393                         tty_termios_encode_baud_rate(termios, 9600, 9600);
394         }
395
396         return 0;
397 }
398
399 EXPORT_SYMBOL(uart_get_baud_rate);
400
401 /**
402  *      uart_get_divisor - return uart clock divisor
403  *      @port: uart_port structure describing the port.
404  *      @baud: desired baud rate
405  *
406  *      Calculate the uart clock divisor for the port.
407  */
408 unsigned int
409 uart_get_divisor(struct uart_port *port, unsigned int baud)
410 {
411         unsigned int quot;
412
413         /*
414          * Old custom speed handling.
415          */
416         if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
417                 quot = port->custom_divisor;
418         else
419                 quot = (port->uartclk + (8 * baud)) / (16 * baud);
420
421         return quot;
422 }
423
424 EXPORT_SYMBOL(uart_get_divisor);
425
426 /* FIXME: Consistent locking policy */
427 static void
428 uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
429 {
430         struct tty_struct *tty = state->info->port.tty;
431         struct uart_port *port = state->port;
432         struct ktermios *termios;
433
434         /*
435          * If we have no tty, termios, or the port does not exist,
436          * then we can't set the parameters for this port.
437          */
438         if (!tty || !tty->termios || port->type == PORT_UNKNOWN)
439                 return;
440
441         termios = tty->termios;
442
443         /*
444          * Set flags based on termios cflag
445          */
446         if (termios->c_cflag & CRTSCTS)
447                 state->info->flags |= UIF_CTS_FLOW;
448         else
449                 state->info->flags &= ~UIF_CTS_FLOW;
450
451         if (termios->c_cflag & CLOCAL)
452                 state->info->flags &= ~UIF_CHECK_CD;
453         else
454                 state->info->flags |= UIF_CHECK_CD;
455
456         port->ops->set_termios(port, termios, old_termios);
457 }
458
459 static inline int
460 __uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
461 {
462         unsigned long flags;
463         int ret = 0;
464
465         if (!circ->buf)
466                 return 0;
467
468         spin_lock_irqsave(&port->lock, flags);
469         if (uart_circ_chars_free(circ) != 0) {
470                 circ->buf[circ->head] = c;
471                 circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
472                 ret = 1;
473         }
474         spin_unlock_irqrestore(&port->lock, flags);
475         return ret;
476 }
477
478 static int uart_put_char(struct tty_struct *tty, unsigned char ch)
479 {
480         struct uart_state *state = tty->driver_data;
481
482         return __uart_put_char(state->port, &state->info->xmit, ch);
483 }
484
485 static void uart_flush_chars(struct tty_struct *tty)
486 {
487         uart_start(tty);
488 }
489
490 static int
491 uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
492 {
493         struct uart_state *state = tty->driver_data;
494         struct uart_port *port;
495         struct circ_buf *circ;
496         unsigned long flags;
497         int c, ret = 0;
498
499         /*
500          * This means you called this function _after_ the port was
501          * closed.  No cookie for you.
502          */
503         if (!state || !state->info) {
504                 WARN_ON(1);
505                 return -EL3HLT;
506         }
507
508         port = state->port;
509         circ = &state->info->xmit;
510
511         if (!circ->buf)
512                 return 0;
513
514         spin_lock_irqsave(&port->lock, flags);
515         while (1) {
516                 c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
517                 if (count < c)
518                         c = count;
519                 if (c <= 0)
520                         break;
521                 memcpy(circ->buf + circ->head, buf, c);
522                 circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
523                 buf += c;
524                 count -= c;
525                 ret += c;
526         }
527         spin_unlock_irqrestore(&port->lock, flags);
528
529         uart_start(tty);
530         return ret;
531 }
532
533 static int uart_write_room(struct tty_struct *tty)
534 {
535         struct uart_state *state = tty->driver_data;
536         unsigned long flags;
537         int ret;
538
539         spin_lock_irqsave(&state->port->lock, flags);
540         ret = uart_circ_chars_free(&state->info->xmit);
541         spin_unlock_irqrestore(&state->port->lock, flags);
542         return ret;
543 }
544
545 static int uart_chars_in_buffer(struct tty_struct *tty)
546 {
547         struct uart_state *state = tty->driver_data;
548         unsigned long flags;
549         int ret;
550
551         spin_lock_irqsave(&state->port->lock, flags);
552         ret = uart_circ_chars_pending(&state->info->xmit);
553         spin_unlock_irqrestore(&state->port->lock, flags);
554         return ret;
555 }
556
557 static void uart_flush_buffer(struct tty_struct *tty)
558 {
559         struct uart_state *state = tty->driver_data;
560         struct uart_port *port;
561         unsigned long flags;
562
563         /*
564          * This means you called this function _after_ the port was
565          * closed.  No cookie for you.
566          */
567         if (!state || !state->info) {
568                 WARN_ON(1);
569                 return;
570         }
571
572         port = state->port;
573         pr_debug("uart_flush_buffer(%d) called\n", tty->index);
574
575         spin_lock_irqsave(&port->lock, flags);
576         uart_circ_clear(&state->info->xmit);
577         if (port->ops->flush_buffer)
578                 port->ops->flush_buffer(port);
579         spin_unlock_irqrestore(&port->lock, flags);
580         tty_wakeup(tty);
581 }
582
583 /*
584  * This function is used to send a high-priority XON/XOFF character to
585  * the device
586  */
587 static void uart_send_xchar(struct tty_struct *tty, char ch)
588 {
589         struct uart_state *state = tty->driver_data;
590         struct uart_port *port = state->port;
591         unsigned long flags;
592
593         if (port->ops->send_xchar)
594                 port->ops->send_xchar(port, ch);
595         else {
596                 port->x_char = ch;
597                 if (ch) {
598                         spin_lock_irqsave(&port->lock, flags);
599                         port->ops->start_tx(port);
600                         spin_unlock_irqrestore(&port->lock, flags);
601                 }
602         }
603 }
604
605 static void uart_throttle(struct tty_struct *tty)
606 {
607         struct uart_state *state = tty->driver_data;
608
609         if (I_IXOFF(tty))
610                 uart_send_xchar(tty, STOP_CHAR(tty));
611
612         if (tty->termios->c_cflag & CRTSCTS)
613                 uart_clear_mctrl(state->port, TIOCM_RTS);
614 }
615
616 static void uart_unthrottle(struct tty_struct *tty)
617 {
618         struct uart_state *state = tty->driver_data;
619         struct uart_port *port = state->port;
620
621         if (I_IXOFF(tty)) {
622                 if (port->x_char)
623                         port->x_char = 0;
624                 else
625                         uart_send_xchar(tty, START_CHAR(tty));
626         }
627
628         if (tty->termios->c_cflag & CRTSCTS)
629                 uart_set_mctrl(port, TIOCM_RTS);
630 }
631
632 static int uart_get_info(struct uart_state *state,
633                          struct serial_struct __user *retinfo)
634 {
635         struct uart_port *port = state->port;
636         struct serial_struct tmp;
637
638         memset(&tmp, 0, sizeof(tmp));
639
640         /* Ensure the state we copy is consistent and no hardware changes
641            occur as we go */
642         mutex_lock(&state->mutex);
643
644         tmp.type            = port->type;
645         tmp.line            = port->line;
646         tmp.port            = port->iobase;
647         if (HIGH_BITS_OFFSET)
648                 tmp.port_high = (long) port->iobase >> HIGH_BITS_OFFSET;
649         tmp.irq             = port->irq;
650         tmp.flags           = port->flags;
651         tmp.xmit_fifo_size  = port->fifosize;
652         tmp.baud_base       = port->uartclk / 16;
653         tmp.close_delay     = state->close_delay / 10;
654         tmp.closing_wait    = state->closing_wait == USF_CLOSING_WAIT_NONE ?
655                                 ASYNC_CLOSING_WAIT_NONE :
656                                 state->closing_wait / 10;
657         tmp.custom_divisor  = port->custom_divisor;
658         tmp.hub6            = port->hub6;
659         tmp.io_type         = port->iotype;
660         tmp.iomem_reg_shift = port->regshift;
661         tmp.iomem_base      = (void *)(unsigned long)port->mapbase;
662
663         mutex_unlock(&state->mutex);
664
665         if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
666                 return -EFAULT;
667         return 0;
668 }
669
670 static int uart_set_info(struct uart_state *state,
671                          struct serial_struct __user *newinfo)
672 {
673         struct serial_struct new_serial;
674         struct uart_port *port = state->port;
675         unsigned long new_port;
676         unsigned int change_irq, change_port, closing_wait;
677         unsigned int old_custom_divisor, close_delay;
678         upf_t old_flags, new_flags;
679         int retval = 0;
680
681         if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
682                 return -EFAULT;
683
684         new_port = new_serial.port;
685         if (HIGH_BITS_OFFSET)
686                 new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;
687
688         new_serial.irq = irq_canonicalize(new_serial.irq);
689         close_delay = new_serial.close_delay * 10;
690         closing_wait = new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
691                         USF_CLOSING_WAIT_NONE : new_serial.closing_wait * 10;
692
693         /*
694          * This semaphore protects state->count.  It is also
695          * very useful to prevent opens.  Also, take the
696          * port configuration semaphore to make sure that a
697          * module insertion/removal doesn't change anything
698          * under us.
699          */
700         mutex_lock(&state->mutex);
701
702         change_irq  = !(port->flags & UPF_FIXED_PORT)
703                 && new_serial.irq != port->irq;
704
705         /*
706          * Since changing the 'type' of the port changes its resource
707          * allocations, we should treat type changes the same as
708          * IO port changes.
709          */
710         change_port = !(port->flags & UPF_FIXED_PORT)
711                 && (new_port != port->iobase ||
712                     (unsigned long)new_serial.iomem_base != port->mapbase ||
713                     new_serial.hub6 != port->hub6 ||
714                     new_serial.io_type != port->iotype ||
715                     new_serial.iomem_reg_shift != port->regshift ||
716                     new_serial.type != port->type);
717
718         old_flags = port->flags;
719         new_flags = new_serial.flags;
720         old_custom_divisor = port->custom_divisor;
721
722         if (!capable(CAP_SYS_ADMIN)) {
723                 retval = -EPERM;
724                 if (change_irq || change_port ||
725                     (new_serial.baud_base != port->uartclk / 16) ||
726                     (close_delay != state->close_delay) ||
727                     (closing_wait != state->closing_wait) ||
728                     (new_serial.xmit_fifo_size &&
729                      new_serial.xmit_fifo_size != port->fifosize) ||
730                     (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
731                         goto exit;
732                 port->flags = ((port->flags & ~UPF_USR_MASK) |
733                                (new_flags & UPF_USR_MASK));
734                 port->custom_divisor = new_serial.custom_divisor;
735                 goto check_and_exit;
736         }
737
738         /*
739          * Ask the low level driver to verify the settings.
740          */
741         if (port->ops->verify_port)
742                 retval = port->ops->verify_port(port, &new_serial);
743
744         if ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) ||
745             (new_serial.baud_base < 9600))
746                 retval = -EINVAL;
747
748         if (retval)
749                 goto exit;
750
751         if (change_port || change_irq) {
752                 retval = -EBUSY;
753
754                 /*
755                  * Make sure that we are the sole user of this port.
756                  */
757                 if (uart_users(state) > 1)
758                         goto exit;
759
760                 /*
761                  * We need to shutdown the serial port at the old
762                  * port/type/irq combination.
763                  */
764                 uart_shutdown(state);
765         }
766
767         if (change_port) {
768                 unsigned long old_iobase, old_mapbase;
769                 unsigned int old_type, old_iotype, old_hub6, old_shift;
770
771                 old_iobase = port->iobase;
772                 old_mapbase = port->mapbase;
773                 old_type = port->type;
774                 old_hub6 = port->hub6;
775                 old_iotype = port->iotype;
776                 old_shift = port->regshift;
777
778                 /*
779                  * Free and release old regions
780                  */
781                 if (old_type != PORT_UNKNOWN)
782                         port->ops->release_port(port);
783
784                 port->iobase = new_port;
785                 port->type = new_serial.type;
786                 port->hub6 = new_serial.hub6;
787                 port->iotype = new_serial.io_type;
788                 port->regshift = new_serial.iomem_reg_shift;
789                 port->mapbase = (unsigned long)new_serial.iomem_base;
790
791                 /*
792                  * Claim and map the new regions
793                  */
794                 if (port->type != PORT_UNKNOWN) {
795                         retval = port->ops->request_port(port);
796                 } else {
797                         /* Always success - Jean II */
798                         retval = 0;
799                 }
800
801                 /*
802                  * If we fail to request resources for the
803                  * new port, try to restore the old settings.
804                  */
805                 if (retval && old_type != PORT_UNKNOWN) {
806                         port->iobase = old_iobase;
807                         port->type = old_type;
808                         port->hub6 = old_hub6;
809                         port->iotype = old_iotype;
810                         port->regshift = old_shift;
811                         port->mapbase = old_mapbase;
812                         retval = port->ops->request_port(port);
813                         /*
814                          * If we failed to restore the old settings,
815                          * we fail like this.
816                          */
817                         if (retval)
818                                 port->type = PORT_UNKNOWN;
819
820                         /*
821                          * We failed anyway.
822                          */
823                         retval = -EBUSY;
824                         /* Added to return the correct error -Ram Gupta */
825                         goto exit;
826                 }
827         }
828
829         if (change_irq)
830                 port->irq      = new_serial.irq;
831         if (!(port->flags & UPF_FIXED_PORT))
832                 port->uartclk  = new_serial.baud_base * 16;
833         port->flags            = (port->flags & ~UPF_CHANGE_MASK) |
834                                  (new_flags & UPF_CHANGE_MASK);
835         port->custom_divisor   = new_serial.custom_divisor;
836         state->close_delay     = close_delay;
837         state->closing_wait    = closing_wait;
838         if (new_serial.xmit_fifo_size)
839                 port->fifosize = new_serial.xmit_fifo_size;
840         if (state->info->port.tty)
841                 state->info->port.tty->low_latency =
842                         (port->flags & UPF_LOW_LATENCY) ? 1 : 0;
843
844  check_and_exit:
845         retval = 0;
846         if (port->type == PORT_UNKNOWN)
847                 goto exit;
848         if (state->info->flags & UIF_INITIALIZED) {
849                 if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
850                     old_custom_divisor != port->custom_divisor) {
851                         /*
852                          * If they're setting up a custom divisor or speed,
853                          * instead of clearing it, then bitch about it. No
854                          * need to rate-limit; it's CAP_SYS_ADMIN only.
855                          */
856                         if (port->flags & UPF_SPD_MASK) {
857                                 char buf[64];
858                                 printk(KERN_NOTICE
859                                        "%s sets custom speed on %s. This "
860                                        "is deprecated.\n", current->comm,
861                                        tty_name(state->info->port.tty, buf));
862                         }
863                         uart_change_speed(state, NULL);
864                 }
865         } else
866                 retval = uart_startup(state, 1);
867  exit:
868         mutex_unlock(&state->mutex);
869         return retval;
870 }
871
872
873 /*
874  * uart_get_lsr_info - get line status register info.
875  * Note: uart_ioctl protects us against hangups.
876  */
877 static int uart_get_lsr_info(struct uart_state *state,
878                              unsigned int __user *value)
879 {
880         struct uart_port *port = state->port;
881         unsigned int result;
882
883         result = port->ops->tx_empty(port);
884
885         /*
886          * If we're about to load something into the transmit
887          * register, we'll pretend the transmitter isn't empty to
888          * avoid a race condition (depending on when the transmit
889          * interrupt happens).
890          */
891         if (port->x_char ||
892             ((uart_circ_chars_pending(&state->info->xmit) > 0) &&
893              !state->info->port.tty->stopped && !state->info->port.tty->hw_stopped))
894                 result &= ~TIOCSER_TEMT;
895
896         return put_user(result, value);
897 }
898
899 static int uart_tiocmget(struct tty_struct *tty, struct file *file)
900 {
901         struct uart_state *state = tty->driver_data;
902         struct uart_port *port = state->port;
903         int result = -EIO;
904
905         mutex_lock(&state->mutex);
906         if ((!file || !tty_hung_up_p(file)) &&
907             !(tty->flags & (1 << TTY_IO_ERROR))) {
908                 result = port->mctrl;
909
910                 spin_lock_irq(&port->lock);
911                 result |= port->ops->get_mctrl(port);
912                 spin_unlock_irq(&port->lock);
913         }
914         mutex_unlock(&state->mutex);
915
916         return result;
917 }
918
919 static int
920 uart_tiocmset(struct tty_struct *tty, struct file *file,
921               unsigned int set, unsigned int clear)
922 {
923         struct uart_state *state = tty->driver_data;
924         struct uart_port *port = state->port;
925         int ret = -EIO;
926
927         mutex_lock(&state->mutex);
928         if ((!file || !tty_hung_up_p(file)) &&
929             !(tty->flags & (1 << TTY_IO_ERROR))) {
930                 uart_update_mctrl(port, set, clear);
931                 ret = 0;
932         }
933         mutex_unlock(&state->mutex);
934         return ret;
935 }
936
937 static int uart_break_ctl(struct tty_struct *tty, int break_state)
938 {
939         struct uart_state *state = tty->driver_data;
940         struct uart_port *port = state->port;
941
942         mutex_lock(&state->mutex);
943
944         if (port->type != PORT_UNKNOWN)
945                 port->ops->break_ctl(port, break_state);
946
947         mutex_unlock(&state->mutex);
948         return 0;
949 }
950
951 static int uart_do_autoconfig(struct uart_state *state)
952 {
953         struct uart_port *port = state->port;
954         int flags, ret;
955
956         if (!capable(CAP_SYS_ADMIN))
957                 return -EPERM;
958
959         /*
960          * Take the per-port semaphore.  This prevents count from
961          * changing, and hence any extra opens of the port while
962          * we're auto-configuring.
963          */
964         if (mutex_lock_interruptible(&state->mutex))
965                 return -ERESTARTSYS;
966
967         ret = -EBUSY;
968         if (uart_users(state) == 1) {
969                 uart_shutdown(state);
970
971                 /*
972                  * If we already have a port type configured,
973                  * we must release its resources.
974                  */
975                 if (port->type != PORT_UNKNOWN)
976                         port->ops->release_port(port);
977
978                 flags = UART_CONFIG_TYPE;
979                 if (port->flags & UPF_AUTO_IRQ)
980                         flags |= UART_CONFIG_IRQ;
981
982                 /*
983                  * This will claim the ports resources if
984                  * a port is found.
985                  */
986                 port->ops->config_port(port, flags);
987
988                 ret = uart_startup(state, 1);
989         }
990         mutex_unlock(&state->mutex);
991         return ret;
992 }
993
994 /*
995  * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
996  * - mask passed in arg for lines of interest
997  *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
998  * Caller should use TIOCGICOUNT to see which one it was
999  */
1000 static int
1001 uart_wait_modem_status(struct uart_state *state, unsigned long arg)
1002 {
1003         struct uart_port *port = state->port;
1004         DECLARE_WAITQUEUE(wait, current);
1005         struct uart_icount cprev, cnow;
1006         int ret;
1007
1008         /*
1009          * note the counters on entry
1010          */
1011         spin_lock_irq(&port->lock);
1012         memcpy(&cprev, &port->icount, sizeof(struct uart_icount));
1013
1014         /*
1015          * Force modem status interrupts on
1016          */
1017         port->ops->enable_ms(port);
1018         spin_unlock_irq(&port->lock);
1019
1020         add_wait_queue(&state->info->delta_msr_wait, &wait);
1021         for (;;) {
1022                 spin_lock_irq(&port->lock);
1023                 memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
1024                 spin_unlock_irq(&port->lock);
1025
1026                 set_current_state(TASK_INTERRUPTIBLE);
1027
1028                 if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
1029                     ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
1030                     ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
1031                     ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
1032                         ret = 0;
1033                         break;
1034                 }
1035
1036                 schedule();
1037
1038                 /* see if a signal did it */
1039                 if (signal_pending(current)) {
1040                         ret = -ERESTARTSYS;
1041                         break;
1042                 }
1043
1044                 cprev = cnow;
1045         }
1046
1047         current->state = TASK_RUNNING;
1048         remove_wait_queue(&state->info->delta_msr_wait, &wait);
1049
1050         return ret;
1051 }
1052
1053 /*
1054  * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
1055  * Return: write counters to the user passed counter struct
1056  * NB: both 1->0 and 0->1 transitions are counted except for
1057  *     RI where only 0->1 is counted.
1058  */
1059 static int uart_get_count(struct uart_state *state,
1060                           struct serial_icounter_struct __user *icnt)
1061 {
1062         struct serial_icounter_struct icount;
1063         struct uart_icount cnow;
1064         struct uart_port *port = state->port;
1065
1066         spin_lock_irq(&port->lock);
1067         memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
1068         spin_unlock_irq(&port->lock);
1069
1070         icount.cts         = cnow.cts;
1071         icount.dsr         = cnow.dsr;
1072         icount.rng         = cnow.rng;
1073         icount.dcd         = cnow.dcd;
1074         icount.rx          = cnow.rx;
1075         icount.tx          = cnow.tx;
1076         icount.frame       = cnow.frame;
1077         icount.overrun     = cnow.overrun;
1078         icount.parity      = cnow.parity;
1079         icount.brk         = cnow.brk;
1080         icount.buf_overrun = cnow.buf_overrun;
1081
1082         return copy_to_user(icnt, &icount, sizeof(icount)) ? -EFAULT : 0;
1083 }
1084
1085 /*
1086  * Called via sys_ioctl.  We can use spin_lock_irq() here.
1087  */
1088 static int
1089 uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
1090            unsigned long arg)
1091 {
1092         struct uart_state *state = tty->driver_data;
1093         void __user *uarg = (void __user *)arg;
1094         int ret = -ENOIOCTLCMD;
1095
1096
1097         /*
1098          * These ioctls don't rely on the hardware to be present.
1099          */
1100         switch (cmd) {
1101         case TIOCGSERIAL:
1102                 ret = uart_get_info(state, uarg);
1103                 break;
1104
1105         case TIOCSSERIAL:
1106                 ret = uart_set_info(state, uarg);
1107                 break;
1108
1109         case TIOCSERCONFIG:
1110                 ret = uart_do_autoconfig(state);
1111                 break;
1112
1113         case TIOCSERGWILD: /* obsolete */
1114         case TIOCSERSWILD: /* obsolete */
1115                 ret = 0;
1116                 break;
1117         }
1118
1119         if (ret != -ENOIOCTLCMD)
1120                 goto out;
1121
1122         if (tty->flags & (1 << TTY_IO_ERROR)) {
1123                 ret = -EIO;
1124                 goto out;
1125         }
1126
1127         /*
1128          * The following should only be used when hardware is present.
1129          */
1130         switch (cmd) {
1131         case TIOCMIWAIT:
1132                 ret = uart_wait_modem_status(state, arg);
1133                 break;
1134
1135         case TIOCGICOUNT:
1136                 ret = uart_get_count(state, uarg);
1137                 break;
1138         }
1139
1140         if (ret != -ENOIOCTLCMD)
1141                 goto out;
1142
1143         mutex_lock(&state->mutex);
1144
1145         if (tty_hung_up_p(filp)) {
1146                 ret = -EIO;
1147                 goto out_up;
1148         }
1149
1150         /*
1151          * All these rely on hardware being present and need to be
1152          * protected against the tty being hung up.
1153          */
1154         switch (cmd) {
1155         case TIOCSERGETLSR: /* Get line status register */
1156                 ret = uart_get_lsr_info(state, uarg);
1157                 break;
1158
1159         default: {
1160                 struct uart_port *port = state->port;
1161                 if (port->ops->ioctl)
1162                         ret = port->ops->ioctl(port, cmd, arg);
1163                 break;
1164         }
1165         }
1166 out_up:
1167         mutex_unlock(&state->mutex);
1168 out:
1169         return ret;
1170 }
1171
1172 static void uart_set_ldisc(struct tty_struct *tty)
1173 {
1174         struct uart_state *state = tty->driver_data;
1175         struct uart_port *port = state->port;
1176
1177         if (port->ops->set_ldisc)
1178                 port->ops->set_ldisc(port);
1179 }
1180
1181 static void uart_set_termios(struct tty_struct *tty,
1182                                                 struct ktermios *old_termios)
1183 {
1184         struct uart_state *state = tty->driver_data;
1185         unsigned long flags;
1186         unsigned int cflag = tty->termios->c_cflag;
1187
1188
1189         /*
1190          * These are the bits that are used to setup various
1191          * flags in the low level driver. We can ignore the Bfoo
1192          * bits in c_cflag; c_[io]speed will always be set
1193          * appropriately by set_termios() in tty_ioctl.c
1194          */
1195 #define RELEVANT_IFLAG(iflag)   ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
1196         if ((cflag ^ old_termios->c_cflag) == 0 &&
1197             tty->termios->c_ospeed == old_termios->c_ospeed &&
1198             tty->termios->c_ispeed == old_termios->c_ispeed &&
1199             RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0) {
1200                 return;
1201         }
1202
1203         uart_change_speed(state, old_termios);
1204
1205         /* Handle transition to B0 status */
1206         if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
1207                 uart_clear_mctrl(state->port, TIOCM_RTS | TIOCM_DTR);
1208
1209         /* Handle transition away from B0 status */
1210         if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
1211                 unsigned int mask = TIOCM_DTR;
1212                 if (!(cflag & CRTSCTS) ||
1213                     !test_bit(TTY_THROTTLED, &tty->flags))
1214                         mask |= TIOCM_RTS;
1215                 uart_set_mctrl(state->port, mask);
1216         }
1217
1218         /* Handle turning off CRTSCTS */
1219         if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
1220                 spin_lock_irqsave(&state->port->lock, flags);
1221                 tty->hw_stopped = 0;
1222                 __uart_start(tty);
1223                 spin_unlock_irqrestore(&state->port->lock, flags);
1224         }
1225
1226         /* Handle turning on CRTSCTS */
1227         if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
1228                 spin_lock_irqsave(&state->port->lock, flags);
1229                 if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
1230                         tty->hw_stopped = 1;
1231                         state->port->ops->stop_tx(state->port);
1232                 }
1233                 spin_unlock_irqrestore(&state->port->lock, flags);
1234         }
1235 #if 0
1236         /*
1237          * No need to wake up processes in open wait, since they
1238          * sample the CLOCAL flag once, and don't recheck it.
1239          * XXX  It's not clear whether the current behavior is correct
1240          * or not.  Hence, this may change.....
1241          */
1242         if (!(old_termios->c_cflag & CLOCAL) &&
1243             (tty->termios->c_cflag & CLOCAL))
1244                 wake_up_interruptible(&state->info->port.open_wait);
1245 #endif
1246 }
1247
1248 /*
1249  * In 2.4.5, calls to this will be serialized via the BKL in
1250  *  linux/drivers/char/tty_io.c:tty_release()
1251  *  linux/drivers/char/tty_io.c:do_tty_handup()
1252  */
1253 static void uart_close(struct tty_struct *tty, struct file *filp)
1254 {
1255         struct uart_state *state = tty->driver_data;
1256         struct uart_port *port;
1257
1258         BUG_ON(!kernel_locked());
1259
1260         if (!state || !state->port)
1261                 return;
1262
1263         port = state->port;
1264
1265         pr_debug("uart_close(%d) called\n", port->line);
1266
1267         mutex_lock(&state->mutex);
1268
1269         if (tty_hung_up_p(filp))
1270                 goto done;
1271
1272         if ((tty->count == 1) && (state->count != 1)) {
1273                 /*
1274                  * Uh, oh.  tty->count is 1, which means that the tty
1275                  * structure will be freed.  state->count should always
1276                  * be one in these conditions.  If it's greater than
1277                  * one, we've got real problems, since it means the
1278                  * serial port won't be shutdown.
1279                  */
1280                 printk(KERN_ERR "uart_close: bad serial port count; tty->count is 1, "
1281                        "state->count is %d\n", state->count);
1282                 state->count = 1;
1283         }
1284         if (--state->count < 0) {
1285                 printk(KERN_ERR "uart_close: bad serial port count for %s: %d\n",
1286                        tty->name, state->count);
1287                 state->count = 0;
1288         }
1289         if (state->count)
1290                 goto done;
1291
1292         /*
1293          * Now we wait for the transmit buffer to clear; and we notify
1294          * the line discipline to only process XON/XOFF characters by
1295          * setting tty->closing.
1296          */
1297         tty->closing = 1;
1298
1299         if (state->closing_wait != USF_CLOSING_WAIT_NONE)
1300                 tty_wait_until_sent(tty, msecs_to_jiffies(state->closing_wait));
1301
1302         /*
1303          * At this point, we stop accepting input.  To do this, we
1304          * disable the receive line status interrupts.
1305          */
1306         if (state->info->flags & UIF_INITIALIZED) {
1307                 unsigned long flags;
1308                 spin_lock_irqsave(&port->lock, flags);
1309                 port->ops->stop_rx(port);
1310                 spin_unlock_irqrestore(&port->lock, flags);
1311                 /*
1312                  * Before we drop DTR, make sure the UART transmitter
1313                  * has completely drained; this is especially
1314                  * important if there is a transmit FIFO!
1315                  */
1316                 uart_wait_until_sent(tty, port->timeout);
1317         }
1318
1319         uart_shutdown(state);
1320         uart_flush_buffer(tty);
1321
1322         tty_ldisc_flush(tty);
1323
1324         tty->closing = 0;
1325         state->info->port.tty = NULL;
1326
1327         if (state->info->port.blocked_open) {
1328                 if (state->close_delay)
1329                         msleep_interruptible(state->close_delay);
1330         } else if (!uart_console(port)) {
1331                 uart_change_pm(state, 3);
1332         }
1333
1334         /*
1335          * Wake up anyone trying to open this port.
1336          */
1337         state->info->flags &= ~UIF_NORMAL_ACTIVE;
1338         wake_up_interruptible(&state->info->port.open_wait);
1339
1340  done:
1341         mutex_unlock(&state->mutex);
1342 }
1343
1344 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1345 {
1346         struct uart_state *state = tty->driver_data;
1347         struct uart_port *port = state->port;
1348         unsigned long char_time, expire;
1349
1350         if (port->type == PORT_UNKNOWN || port->fifosize == 0)
1351                 return;
1352
1353         lock_kernel();
1354
1355         /*
1356          * Set the check interval to be 1/5 of the estimated time to
1357          * send a single character, and make it at least 1.  The check
1358          * interval should also be less than the timeout.
1359          *
1360          * Note: we have to use pretty tight timings here to satisfy
1361          * the NIST-PCTS.
1362          */
1363         char_time = (port->timeout - HZ/50) / port->fifosize;
1364         char_time = char_time / 5;
1365         if (char_time == 0)
1366                 char_time = 1;
1367         if (timeout && timeout < char_time)
1368                 char_time = timeout;
1369
1370         /*
1371          * If the transmitter hasn't cleared in twice the approximate
1372          * amount of time to send the entire FIFO, it probably won't
1373          * ever clear.  This assumes the UART isn't doing flow
1374          * control, which is currently the case.  Hence, if it ever
1375          * takes longer than port->timeout, this is probably due to a
1376          * UART bug of some kind.  So, we clamp the timeout parameter at
1377          * 2*port->timeout.
1378          */
1379         if (timeout == 0 || timeout > 2 * port->timeout)
1380                 timeout = 2 * port->timeout;
1381
1382         expire = jiffies + timeout;
1383
1384         pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
1385                 port->line, jiffies, expire);
1386
1387         /*
1388          * Check whether the transmitter is empty every 'char_time'.
1389          * 'timeout' / 'expire' give us the maximum amount of time
1390          * we wait.
1391          */
1392         while (!port->ops->tx_empty(port)) {
1393                 msleep_interruptible(jiffies_to_msecs(char_time));
1394                 if (signal_pending(current))
1395                         break;
1396                 if (time_after(jiffies, expire))
1397                         break;
1398         }
1399         set_current_state(TASK_RUNNING); /* might not be needed */
1400         unlock_kernel();
1401 }
1402
1403 /*
1404  * This is called with the BKL held in
1405  *  linux/drivers/char/tty_io.c:do_tty_hangup()
1406  * We're called from the eventd thread, so we can sleep for
1407  * a _short_ time only.
1408  */
1409 static void uart_hangup(struct tty_struct *tty)
1410 {
1411         struct uart_state *state = tty->driver_data;
1412
1413         BUG_ON(!kernel_locked());
1414         pr_debug("uart_hangup(%d)\n", state->port->line);
1415
1416         mutex_lock(&state->mutex);
1417         if (state->info && state->info->flags & UIF_NORMAL_ACTIVE) {
1418                 uart_flush_buffer(tty);
1419                 uart_shutdown(state);
1420                 state->count = 0;
1421                 state->info->flags &= ~UIF_NORMAL_ACTIVE;
1422                 state->info->port.tty = NULL;
1423                 wake_up_interruptible(&state->info->port.open_wait);
1424                 wake_up_interruptible(&state->info->delta_msr_wait);
1425         }
1426         mutex_unlock(&state->mutex);
1427 }
1428
1429 /*
1430  * Copy across the serial console cflag setting into the termios settings
1431  * for the initial open of the port.  This allows continuity between the
1432  * kernel settings, and the settings init adopts when it opens the port
1433  * for the first time.
1434  */
1435 static void uart_update_termios(struct uart_state *state)
1436 {
1437         struct tty_struct *tty = state->info->port.tty;
1438         struct uart_port *port = state->port;
1439
1440         if (uart_console(port) && port->cons->cflag) {
1441                 tty->termios->c_cflag = port->cons->cflag;
1442                 port->cons->cflag = 0;
1443         }
1444
1445         /*
1446          * If the device failed to grab its irq resources,
1447          * or some other error occurred, don't try to talk
1448          * to the port hardware.
1449          */
1450         if (!(tty->flags & (1 << TTY_IO_ERROR))) {
1451                 /*
1452                  * Make termios settings take effect.
1453                  */
1454                 uart_change_speed(state, NULL);
1455
1456                 /*
1457                  * And finally enable the RTS and DTR signals.
1458                  */
1459                 if (tty->termios->c_cflag & CBAUD)
1460                         uart_set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
1461         }
1462 }
1463
1464 /*
1465  * Block the open until the port is ready.  We must be called with
1466  * the per-port semaphore held.
1467  */
1468 static int
1469 uart_block_til_ready(struct file *filp, struct uart_state *state)
1470 {
1471         DECLARE_WAITQUEUE(wait, current);
1472         struct uart_info *info = state->info;
1473         struct uart_port *port = state->port;
1474         unsigned int mctrl;
1475
1476         info->port.blocked_open++;
1477         state->count--;
1478
1479         add_wait_queue(&info->port.open_wait, &wait);
1480         while (1) {
1481                 set_current_state(TASK_INTERRUPTIBLE);
1482
1483                 /*
1484                  * If we have been hung up, tell userspace/restart open.
1485                  */
1486                 if (tty_hung_up_p(filp) || info->port.tty == NULL)
1487                         break;
1488
1489                 /*
1490                  * If the port has been closed, tell userspace/restart open.
1491                  */
1492                 if (!(info->flags & UIF_INITIALIZED))
1493                         break;
1494
1495                 /*
1496                  * If non-blocking mode is set, or CLOCAL mode is set,
1497                  * we don't want to wait for the modem status lines to
1498                  * indicate that the port is ready.
1499                  *
1500                  * Also, if the port is not enabled/configured, we want
1501                  * to allow the open to succeed here.  Note that we will
1502                  * have set TTY_IO_ERROR for a non-existant port.
1503                  */
1504                 if ((filp->f_flags & O_NONBLOCK) ||
1505                     (info->port.tty->termios->c_cflag & CLOCAL) ||
1506                     (info->port.tty->flags & (1 << TTY_IO_ERROR)))
1507                         break;
1508
1509                 /*
1510                  * Set DTR to allow modem to know we're waiting.  Do
1511                  * not set RTS here - we want to make sure we catch
1512                  * the data from the modem.
1513                  */
1514                 if (info->port.tty->termios->c_cflag & CBAUD)
1515                         uart_set_mctrl(port, TIOCM_DTR);
1516
1517                 /*
1518                  * and wait for the carrier to indicate that the
1519                  * modem is ready for us.
1520                  */
1521                 spin_lock_irq(&port->lock);
1522                 port->ops->enable_ms(port);
1523                 mctrl = port->ops->get_mctrl(port);
1524                 spin_unlock_irq(&port->lock);
1525                 if (mctrl & TIOCM_CAR)
1526                         break;
1527
1528                 mutex_unlock(&state->mutex);
1529                 schedule();
1530                 mutex_lock(&state->mutex);
1531
1532                 if (signal_pending(current))
1533                         break;
1534         }
1535         set_current_state(TASK_RUNNING);
1536         remove_wait_queue(&info->port.open_wait, &wait);
1537
1538         state->count++;
1539         info->port.blocked_open--;
1540
1541         if (signal_pending(current))
1542                 return -ERESTARTSYS;
1543
1544         if (!info->port.tty || tty_hung_up_p(filp))
1545                 return -EAGAIN;
1546
1547         return 0;
1548 }
1549
1550 static struct uart_state *uart_get(struct uart_driver *drv, int line)
1551 {
1552         struct uart_state *state;
1553         int ret = 0;
1554
1555         state = drv->state + line;
1556         if (mutex_lock_interruptible(&state->mutex)) {
1557                 ret = -ERESTARTSYS;
1558                 goto err;
1559         }
1560
1561         state->count++;
1562         if (!state->port || state->port->flags & UPF_DEAD) {
1563                 ret = -ENXIO;
1564                 goto err_unlock;
1565         }
1566
1567         /* BKL: RACE HERE - LEAK */
1568         /* We should move this into the uart_state structure and kill off
1569            this whole complexity */
1570         if (!state->info) {
1571                 state->info = kzalloc(sizeof(struct uart_info), GFP_KERNEL);
1572                 if (state->info) {
1573                         init_waitqueue_head(&state->info->port.open_wait);
1574                         init_waitqueue_head(&state->info->delta_msr_wait);
1575
1576                         /*
1577                          * Link the info into the other structures.
1578                          */
1579                         state->port->info = state->info;
1580
1581                         tasklet_init(&state->info->tlet, uart_tasklet_action,
1582                                      (unsigned long)state);
1583                 } else {
1584                         ret = -ENOMEM;
1585                         goto err_unlock;
1586                 }
1587         }
1588         return state;
1589
1590  err_unlock:
1591         state->count--;
1592         mutex_unlock(&state->mutex);
1593  err:
1594         return ERR_PTR(ret);
1595 }
1596
1597 /*
1598  * calls to uart_open are serialised by the BKL in
1599  *   fs/char_dev.c:chrdev_open()
1600  * Note that if this fails, then uart_close() _will_ be called.
1601  *
1602  * In time, we want to scrap the "opening nonpresent ports"
1603  * behaviour and implement an alternative way for setserial
1604  * to set base addresses/ports/types.  This will allow us to
1605  * get rid of a certain amount of extra tests.
1606  */
1607 static int uart_open(struct tty_struct *tty, struct file *filp)
1608 {
1609         struct uart_driver *drv = (struct uart_driver *)tty->driver->driver_state;
1610         struct uart_state *state;
1611         int retval, line = tty->index;
1612
1613         BUG_ON(!kernel_locked());
1614         pr_debug("uart_open(%d) called\n", line);
1615
1616         /*
1617          * tty->driver->num won't change, so we won't fail here with
1618          * tty->driver_data set to something non-NULL (and therefore
1619          * we won't get caught by uart_close()).
1620          */
1621         retval = -ENODEV;
1622         if (line >= tty->driver->num)
1623                 goto fail;
1624
1625         /*
1626          * We take the semaphore inside uart_get to guarantee that we won't
1627          * be re-entered while allocating the info structure, or while we
1628          * request any IRQs that the driver may need.  This also has the nice
1629          * side-effect that it delays the action of uart_hangup, so we can
1630          * guarantee that info->port.tty will always contain something reasonable.
1631          */
1632         state = uart_get(drv, line);
1633         if (IS_ERR(state)) {
1634                 retval = PTR_ERR(state);
1635                 goto fail;
1636         }
1637
1638         /*
1639          * Once we set tty->driver_data here, we are guaranteed that
1640          * uart_close() will decrement the driver module use count.
1641          * Any failures from here onwards should not touch the count.
1642          */
1643         tty->driver_data = state;
1644         tty->low_latency = (state->port->flags & UPF_LOW_LATENCY) ? 1 : 0;
1645         tty->alt_speed = 0;
1646         state->info->port.tty = tty;
1647
1648         /*
1649          * If the port is in the middle of closing, bail out now.
1650          */
1651         if (tty_hung_up_p(filp)) {
1652                 retval = -EAGAIN;
1653                 state->count--;
1654                 mutex_unlock(&state->mutex);
1655                 goto fail;
1656         }
1657
1658         /*
1659          * Make sure the device is in D0 state.
1660          */
1661         if (state->count == 1)
1662                 uart_change_pm(state, 0);
1663
1664         /*
1665          * Start up the serial port.
1666          */
1667         retval = uart_startup(state, 0);
1668
1669         /*
1670          * If we succeeded, wait until the port is ready.
1671          */
1672         if (retval == 0)
1673                 retval = uart_block_til_ready(filp, state);
1674         mutex_unlock(&state->mutex);
1675
1676         /*
1677          * If this is the first open to succeed, adjust things to suit.
1678          */
1679         if (retval == 0 && !(state->info->flags & UIF_NORMAL_ACTIVE)) {
1680                 state->info->flags |= UIF_NORMAL_ACTIVE;
1681
1682                 uart_update_termios(state);
1683         }
1684
1685  fail:
1686         return retval;
1687 }
1688
1689 static const char *uart_type(struct uart_port *port)
1690 {
1691         const char *str = NULL;
1692
1693         if (port->ops->type)
1694                 str = port->ops->type(port);
1695
1696         if (!str)
1697                 str = "unknown";
1698
1699         return str;
1700 }
1701
1702 #ifdef CONFIG_PROC_FS
1703
1704 static int uart_line_info(char *buf, struct uart_driver *drv, int i)
1705 {
1706         struct uart_state *state = drv->state + i;
1707         int pm_state;
1708         struct uart_port *port = state->port;
1709         char stat_buf[32];
1710         unsigned int status;
1711         int mmio, ret;
1712
1713         if (!port)
1714                 return 0;
1715
1716         mmio = port->iotype >= UPIO_MEM;
1717         ret = sprintf(buf, "%d: uart:%s %s%08llX irq:%d",
1718                         port->line, uart_type(port),
1719                         mmio ? "mmio:0x" : "port:",
1720                         mmio ? (unsigned long long)port->mapbase
1721                              : (unsigned long long) port->iobase,
1722                         port->irq);
1723
1724         if (port->type == PORT_UNKNOWN) {
1725                 strcat(buf, "\n");
1726                 return ret + 1;
1727         }
1728
1729         if (capable(CAP_SYS_ADMIN)) {
1730                 mutex_lock(&state->mutex);
1731                 pm_state = state->pm_state;
1732                 if (pm_state)
1733                         uart_change_pm(state, 0);
1734                 spin_lock_irq(&port->lock);
1735                 status = port->ops->get_mctrl(port);
1736                 spin_unlock_irq(&port->lock);
1737                 if (pm_state)
1738                         uart_change_pm(state, pm_state);
1739                 mutex_unlock(&state->mutex);
1740
1741                 ret += sprintf(buf + ret, " tx:%d rx:%d",
1742                                 port->icount.tx, port->icount.rx);
1743                 if (port->icount.frame)
1744                         ret += sprintf(buf + ret, " fe:%d",
1745                                 port->icount.frame);
1746                 if (port->icount.parity)
1747                         ret += sprintf(buf + ret, " pe:%d",
1748                                 port->icount.parity);
1749                 if (port->icount.brk)
1750                         ret += sprintf(buf + ret, " brk:%d",
1751                                 port->icount.brk);
1752                 if (port->icount.overrun)
1753                         ret += sprintf(buf + ret, " oe:%d",
1754                                 port->icount.overrun);
1755
1756 #define INFOBIT(bit, str) \
1757         if (port->mctrl & (bit)) \
1758                 strncat(stat_buf, (str), sizeof(stat_buf) - \
1759                         strlen(stat_buf) - 2)
1760 #define STATBIT(bit, str) \
1761         if (status & (bit)) \
1762                 strncat(stat_buf, (str), sizeof(stat_buf) - \
1763                        strlen(stat_buf) - 2)
1764
1765                 stat_buf[0] = '\0';
1766                 stat_buf[1] = '\0';
1767                 INFOBIT(TIOCM_RTS, "|RTS");
1768                 STATBIT(TIOCM_CTS, "|CTS");
1769                 INFOBIT(TIOCM_DTR, "|DTR");
1770                 STATBIT(TIOCM_DSR, "|DSR");
1771                 STATBIT(TIOCM_CAR, "|CD");
1772                 STATBIT(TIOCM_RNG, "|RI");
1773                 if (stat_buf[0])
1774                         stat_buf[0] = ' ';
1775                 strcat(stat_buf, "\n");
1776
1777                 ret += sprintf(buf + ret, stat_buf);
1778         } else {
1779                 strcat(buf, "\n");
1780                 ret++;
1781         }
1782 #undef STATBIT
1783 #undef INFOBIT
1784         return ret;
1785 }
1786
1787 static int uart_read_proc(char *page, char **start, off_t off,
1788                           int count, int *eof, void *data)
1789 {
1790         struct tty_driver *ttydrv = data;
1791         struct uart_driver *drv = ttydrv->driver_state;
1792         int i, len = 0, l;
1793         off_t begin = 0;
1794
1795         len += sprintf(page, "serinfo:1.0 driver%s%s revision:%s\n",
1796                         "", "", "");
1797         for (i = 0; i < drv->nr && len < PAGE_SIZE - 96; i++) {
1798                 l = uart_line_info(page + len, drv, i);
1799                 len += l;
1800                 if (len + begin > off + count)
1801                         goto done;
1802                 if (len + begin < off) {
1803                         begin += len;
1804                         len = 0;
1805                 }
1806         }
1807         *eof = 1;
1808  done:
1809         if (off >= len + begin)
1810                 return 0;
1811         *start = page + (off - begin);
1812         return (count < begin + len - off) ? count : (begin + len - off);
1813 }
1814 #endif
1815
1816 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
1817 /*
1818  *      uart_console_write - write a console message to a serial port
1819  *      @port: the port to write the message
1820  *      @s: array of characters
1821  *      @count: number of characters in string to write
1822  *      @write: function to write character to port
1823  */
1824 void uart_console_write(struct uart_port *port, const char *s,
1825                         unsigned int count,
1826                         void (*putchar)(struct uart_port *, int))
1827 {
1828         unsigned int i;
1829
1830         for (i = 0; i < count; i++, s++) {
1831                 if (*s == '\n')
1832                         putchar(port, '\r');
1833                 putchar(port, *s);
1834         }
1835 }
1836 EXPORT_SYMBOL_GPL(uart_console_write);
1837
1838 /*
1839  *      Check whether an invalid uart number has been specified, and
1840  *      if so, search for the first available port that does have
1841  *      console support.
1842  */
1843 struct uart_port * __init
1844 uart_get_console(struct uart_port *ports, int nr, struct console *co)
1845 {
1846         int idx = co->index;
1847
1848         if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
1849                                      ports[idx].membase == NULL))
1850                 for (idx = 0; idx < nr; idx++)
1851                         if (ports[idx].iobase != 0 ||
1852                             ports[idx].membase != NULL)
1853                                 break;
1854
1855         co->index = idx;
1856
1857         return ports + idx;
1858 }
1859
1860 /**
1861  *      uart_parse_options - Parse serial port baud/parity/bits/flow contro.
1862  *      @options: pointer to option string
1863  *      @baud: pointer to an 'int' variable for the baud rate.
1864  *      @parity: pointer to an 'int' variable for the parity.
1865  *      @bits: pointer to an 'int' variable for the number of data bits.
1866  *      @flow: pointer to an 'int' variable for the flow control character.
1867  *
1868  *      uart_parse_options decodes a string containing the serial console
1869  *      options.  The format of the string is <baud><parity><bits><flow>,
1870  *      eg: 115200n8r
1871  */
1872 void
1873 uart_parse_options(char *options, int *baud, int *parity, int *bits, int *flow)
1874 {
1875         char *s = options;
1876
1877         *baud = simple_strtoul(s, NULL, 10);
1878         while (*s >= '0' && *s <= '9')
1879                 s++;
1880         if (*s)
1881                 *parity = *s++;
1882         if (*s)
1883                 *bits = *s++ - '0';
1884         if (*s)
1885                 *flow = *s;
1886 }
1887 EXPORT_SYMBOL_GPL(uart_parse_options);
1888
1889 struct baud_rates {
1890         unsigned int rate;
1891         unsigned int cflag;
1892 };
1893
1894 static const struct baud_rates baud_rates[] = {
1895         { 921600, B921600 },
1896         { 460800, B460800 },
1897         { 230400, B230400 },
1898         { 115200, B115200 },
1899         {  57600, B57600  },
1900         {  38400, B38400  },
1901         {  19200, B19200  },
1902         {   9600, B9600   },
1903         {   4800, B4800   },
1904         {   2400, B2400   },
1905         {   1200, B1200   },
1906         {      0, B38400  }
1907 };
1908
1909 /**
1910  *      uart_set_options - setup the serial console parameters
1911  *      @port: pointer to the serial ports uart_port structure
1912  *      @co: console pointer
1913  *      @baud: baud rate
1914  *      @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
1915  *      @bits: number of data bits
1916  *      @flow: flow control character - 'r' (rts)
1917  */
1918 int
1919 uart_set_options(struct uart_port *port, struct console *co,
1920                  int baud, int parity, int bits, int flow)
1921 {
1922         struct ktermios termios;
1923         static struct ktermios dummy;
1924         int i;
1925
1926         /*
1927          * Ensure that the serial console lock is initialised
1928          * early.
1929          */
1930         spin_lock_init(&port->lock);
1931         lockdep_set_class(&port->lock, &port_lock_key);
1932
1933         memset(&termios, 0, sizeof(struct ktermios));
1934
1935         termios.c_cflag = CREAD | HUPCL | CLOCAL;
1936
1937         /*
1938          * Construct a cflag setting.
1939          */
1940         for (i = 0; baud_rates[i].rate; i++)
1941                 if (baud_rates[i].rate <= baud)
1942                         break;
1943
1944         termios.c_cflag |= baud_rates[i].cflag;
1945
1946         if (bits == 7)
1947                 termios.c_cflag |= CS7;
1948         else
1949                 termios.c_cflag |= CS8;
1950
1951         switch (parity) {
1952         case 'o': case 'O':
1953                 termios.c_cflag |= PARODD;
1954                 /*fall through*/
1955         case 'e': case 'E':
1956                 termios.c_cflag |= PARENB;
1957                 break;
1958         }
1959
1960         if (flow == 'r')
1961                 termios.c_cflag |= CRTSCTS;
1962
1963         /*
1964          * some uarts on other side don't support no flow control.
1965          * So we set * DTR in host uart to make them happy
1966          */
1967         port->mctrl |= TIOCM_DTR;
1968
1969         port->ops->set_termios(port, &termios, &dummy);
1970         /*
1971          * Allow the setting of the UART parameters with a NULL console
1972          * too:
1973          */
1974         if (co)
1975                 co->cflag = termios.c_cflag;
1976
1977         return 0;
1978 }
1979 EXPORT_SYMBOL_GPL(uart_set_options);
1980 #endif /* CONFIG_SERIAL_CORE_CONSOLE */
1981
1982 static void uart_change_pm(struct uart_state *state, int pm_state)
1983 {
1984         struct uart_port *port = state->port;
1985
1986         if (state->pm_state != pm_state) {
1987                 if (port->ops->pm)
1988                         port->ops->pm(port, pm_state, state->pm_state);
1989                 state->pm_state = pm_state;
1990         }
1991 }
1992
1993 struct uart_match {
1994         struct uart_port *port;
1995         struct uart_driver *driver;
1996 };
1997
1998 static int serial_match_port(struct device *dev, void *data)
1999 {
2000         struct uart_match *match = data;
2001         struct tty_driver *tty_drv = match->driver->tty_driver;
2002         dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2003                 match->port->line;
2004
2005         return dev->devt == devt; /* Actually, only one tty per port */
2006 }
2007
2008 int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
2009 {
2010         struct uart_state *state = drv->state + port->line;
2011         struct device *tty_dev;
2012         struct uart_match match = {port, drv};
2013
2014         mutex_lock(&state->mutex);
2015
2016         if (!console_suspend_enabled && uart_console(port)) {
2017                 /* we're going to avoid suspending serial console */
2018                 mutex_unlock(&state->mutex);
2019                 return 0;
2020         }
2021
2022         tty_dev = device_find_child(port->dev, &match, serial_match_port);
2023         if (device_may_wakeup(tty_dev)) {
2024                 enable_irq_wake(port->irq);
2025                 put_device(tty_dev);
2026                 mutex_unlock(&state->mutex);
2027                 return 0;
2028         }
2029         port->suspended = 1;
2030
2031         if (state->info && state->info->flags & UIF_INITIALIZED) {
2032                 const struct uart_ops *ops = port->ops;
2033                 int tries;
2034
2035                 state->info->flags = (state->info->flags & ~UIF_INITIALIZED)
2036                                      | UIF_SUSPENDED;
2037
2038                 spin_lock_irq(&port->lock);
2039                 ops->stop_tx(port);
2040                 ops->set_mctrl(port, 0);
2041                 ops->stop_rx(port);
2042                 spin_unlock_irq(&port->lock);
2043
2044                 /*
2045                  * Wait for the transmitter to empty.
2046                  */
2047                 for (tries = 3; !ops->tx_empty(port) && tries; tries--)
2048                         msleep(10);
2049                 if (!tries)
2050                         printk(KERN_ERR "%s%s%s%d: Unable to drain "
2051                                         "transmitter\n",
2052                                port->dev ? port->dev->bus_id : "",
2053                                port->dev ? ": " : "",
2054                                drv->dev_name, port->line);
2055
2056                 ops->shutdown(port);
2057         }
2058
2059         /*
2060          * Disable the console device before suspending.
2061          */
2062         if (uart_console(port))
2063                 console_stop(port->cons);
2064
2065         uart_change_pm(state, 3);
2066
2067         mutex_unlock(&state->mutex);
2068
2069         return 0;
2070 }
2071
2072 int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
2073 {
2074         struct uart_state *state = drv->state + port->line;
2075         struct device *tty_dev;
2076         struct uart_match match = {port, drv};
2077
2078         mutex_lock(&state->mutex);
2079
2080         if (!console_suspend_enabled && uart_console(port)) {
2081                 /* no need to resume serial console, it wasn't suspended */
2082                 mutex_unlock(&state->mutex);
2083                 return 0;
2084         }
2085
2086         tty_dev = device_find_child(port->dev, &match, serial_match_port);
2087         if (!port->suspended && device_may_wakeup(tty_dev)) {
2088                 disable_irq_wake(port->irq);
2089                 mutex_unlock(&state->mutex);
2090                 return 0;
2091         }
2092         port->suspended = 0;
2093
2094         /*
2095          * Re-enable the console device after suspending.
2096          */
2097         if (uart_console(port)) {
2098                 struct ktermios termios;
2099
2100                 /*
2101                  * First try to use the console cflag setting.
2102                  */
2103                 memset(&termios, 0, sizeof(struct ktermios));
2104                 termios.c_cflag = port->cons->cflag;
2105
2106                 /*
2107                  * If that's unset, use the tty termios setting.
2108                  */
2109                 if (state->info && state->info->port.tty && termios.c_cflag == 0)
2110                         termios = *state->info->port.tty->termios;
2111
2112                 uart_change_pm(state, 0);
2113                 port->ops->set_termios(port, &termios, NULL);
2114                 console_start(port->cons);
2115         }
2116
2117         if (state->info && state->info->flags & UIF_SUSPENDED) {
2118                 const struct uart_ops *ops = port->ops;
2119                 int ret;
2120
2121                 uart_change_pm(state, 0);
2122                 spin_lock_irq(&port->lock);
2123                 ops->set_mctrl(port, 0);
2124                 spin_unlock_irq(&port->lock);
2125                 ret = ops->startup(port);
2126                 if (ret == 0) {
2127                         uart_change_speed(state, NULL);
2128                         spin_lock_irq(&port->lock);
2129                         ops->set_mctrl(port, port->mctrl);
2130                         ops->start_tx(port);
2131                         spin_unlock_irq(&port->lock);
2132                         state->info->flags |= UIF_INITIALIZED;
2133                 } else {
2134                         /*
2135                          * Failed to resume - maybe hardware went away?
2136                          * Clear the "initialized" flag so we won't try
2137                          * to call the low level drivers shutdown method.
2138                          */
2139                         uart_shutdown(state);
2140                 }
2141
2142                 state->info->flags &= ~UIF_SUSPENDED;
2143         }
2144
2145         mutex_unlock(&state->mutex);
2146
2147         return 0;
2148 }
2149
2150 static inline void
2151 uart_report_port(struct uart_driver *drv, struct uart_port *port)
2152 {
2153         char address[64];
2154
2155         switch (port->iotype) {
2156         case UPIO_PORT:
2157                 snprintf(address, sizeof(address),
2158                          "I/O 0x%x", port->iobase);
2159                 break;
2160         case UPIO_HUB6:
2161                 snprintf(address, sizeof(address),
2162                          "I/O 0x%x offset 0x%x", port->iobase, port->hub6);
2163                 break;
2164         case UPIO_MEM:
2165         case UPIO_MEM32:
2166         case UPIO_AU:
2167         case UPIO_TSI:
2168         case UPIO_DWAPB:
2169                 snprintf(address, sizeof(address),
2170                          "MMIO 0x%llx", (unsigned long long)port->mapbase);
2171                 break;
2172         default:
2173                 strlcpy(address, "*unknown*", sizeof(address));
2174                 break;
2175         }
2176
2177         printk(KERN_INFO "%s%s%s%d at %s (irq = %d) is a %s\n",
2178                port->dev ? port->dev->bus_id : "",
2179                port->dev ? ": " : "",
2180                drv->dev_name, port->line, address, port->irq, uart_type(port));
2181 }
2182
2183 static void
2184 uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2185                     struct uart_port *port)
2186 {
2187         unsigned int flags;
2188
2189         /*
2190          * If there isn't a port here, don't do anything further.
2191          */
2192         if (!port->iobase && !port->mapbase && !port->membase)
2193                 return;
2194
2195         /*
2196          * Now do the auto configuration stuff.  Note that config_port
2197          * is expected to claim the resources and map the port for us.
2198          */
2199         flags = UART_CONFIG_TYPE;
2200         if (port->flags & UPF_AUTO_IRQ)
2201                 flags |= UART_CONFIG_IRQ;
2202         if (port->flags & UPF_BOOT_AUTOCONF) {
2203                 port->type = PORT_UNKNOWN;
2204                 port->ops->config_port(port, flags);
2205         }
2206
2207         if (port->type != PORT_UNKNOWN) {
2208                 unsigned long flags;
2209
2210                 uart_report_port(drv, port);
2211
2212                 /* Power up port for set_mctrl() */
2213                 uart_change_pm(state, 0);
2214
2215                 /*
2216                  * Ensure that the modem control lines are de-activated.
2217                  * keep the DTR setting that is set in uart_set_options()
2218                  * We probably don't need a spinlock around this, but
2219                  */
2220                 spin_lock_irqsave(&port->lock, flags);
2221                 port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
2222                 spin_unlock_irqrestore(&port->lock, flags);
2223
2224                 /*
2225                  * If this driver supports console, and it hasn't been
2226                  * successfully registered yet, try to re-register it.
2227                  * It may be that the port was not available.
2228                  */
2229                 if (port->cons && !(port->cons->flags & CON_ENABLED))
2230                         register_console(port->cons);
2231
2232                 /*
2233                  * Power down all ports by default, except the
2234                  * console if we have one.
2235                  */
2236                 if (!uart_console(port))
2237                         uart_change_pm(state, 3);
2238         }
2239 }
2240
2241 #ifdef CONFIG_CONSOLE_POLL
2242
2243 static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2244 {
2245         struct uart_driver *drv = driver->driver_state;
2246         struct uart_state *state = drv->state + line;
2247         struct uart_port *port;
2248         int baud = 9600;
2249         int bits = 8;
2250         int parity = 'n';
2251         int flow = 'n';
2252
2253         if (!state || !state->port)
2254                 return -1;
2255
2256         port = state->port;
2257         if (!(port->ops->poll_get_char && port->ops->poll_put_char))
2258                 return -1;
2259
2260         if (options) {
2261                 uart_parse_options(options, &baud, &parity, &bits, &flow);
2262                 return uart_set_options(port, NULL, baud, parity, bits, flow);
2263         }
2264
2265         return 0;
2266 }
2267
2268 static int uart_poll_get_char(struct tty_driver *driver, int line)
2269 {
2270         struct uart_driver *drv = driver->driver_state;
2271         struct uart_state *state = drv->state + line;
2272         struct uart_port *port;
2273
2274         if (!state || !state->port)
2275                 return -1;
2276
2277         port = state->port;
2278         return port->ops->poll_get_char(port);
2279 }
2280
2281 static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2282 {
2283         struct uart_driver *drv = driver->driver_state;
2284         struct uart_state *state = drv->state + line;
2285         struct uart_port *port;
2286
2287         if (!state || !state->port)
2288                 return;
2289
2290         port = state->port;
2291         port->ops->poll_put_char(port, ch);
2292 }
2293 #endif
2294
2295 static const struct tty_operations uart_ops = {
2296         .open           = uart_open,
2297         .close          = uart_close,
2298         .write          = uart_write,
2299         .put_char       = uart_put_char,
2300         .flush_chars    = uart_flush_chars,
2301         .write_room     = uart_write_room,
2302         .chars_in_buffer= uart_chars_in_buffer,
2303         .flush_buffer   = uart_flush_buffer,
2304         .ioctl          = uart_ioctl,
2305         .throttle       = uart_throttle,
2306         .unthrottle     = uart_unthrottle,
2307         .send_xchar     = uart_send_xchar,
2308         .set_termios    = uart_set_termios,
2309         .set_ldisc      = uart_set_ldisc,
2310         .stop           = uart_stop,
2311         .start          = uart_start,
2312         .hangup         = uart_hangup,
2313         .break_ctl      = uart_break_ctl,
2314         .wait_until_sent= uart_wait_until_sent,
2315 #ifdef CONFIG_PROC_FS
2316         .read_proc      = uart_read_proc,
2317 #endif
2318         .tiocmget       = uart_tiocmget,
2319         .tiocmset       = uart_tiocmset,
2320 #ifdef CONFIG_CONSOLE_POLL
2321         .poll_init      = uart_poll_init,
2322         .poll_get_char  = uart_poll_get_char,
2323         .poll_put_char  = uart_poll_put_char,
2324 #endif
2325 };
2326
2327 /**
2328  *      uart_register_driver - register a driver with the uart core layer
2329  *      @drv: low level driver structure
2330  *
2331  *      Register a uart driver with the core driver.  We in turn register
2332  *      with the tty layer, and initialise the core driver per-port state.
2333  *
2334  *      We have a proc file in /proc/tty/driver which is named after the
2335  *      normal driver.
2336  *
2337  *      drv->port should be NULL, and the per-port structures should be
2338  *      registered using uart_add_one_port after this call has succeeded.
2339  */
2340 int uart_register_driver(struct uart_driver *drv)
2341 {
2342         struct tty_driver *normal = NULL;
2343         int i, retval;
2344
2345         BUG_ON(drv->state);
2346
2347         /*
2348          * Maybe we should be using a slab cache for this, especially if
2349          * we have a large number of ports to handle.
2350          */
2351         drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
2352         retval = -ENOMEM;
2353         if (!drv->state)
2354                 goto out;
2355
2356         normal  = alloc_tty_driver(drv->nr);
2357         if (!normal)
2358                 goto out;
2359
2360         drv->tty_driver = normal;
2361
2362         normal->owner           = drv->owner;
2363         normal->driver_name     = drv->driver_name;
2364         normal->name            = drv->dev_name;
2365         normal->major           = drv->major;
2366         normal->minor_start     = drv->minor;
2367         normal->type            = TTY_DRIVER_TYPE_SERIAL;
2368         normal->subtype         = SERIAL_TYPE_NORMAL;
2369         normal->init_termios    = tty_std_termios;
2370         normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2371         normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2372         normal->flags           = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
2373         normal->driver_state    = drv;
2374         tty_set_operations(normal, &uart_ops);
2375
2376         /*
2377          * Initialise the UART state(s).
2378          */
2379         for (i = 0; i < drv->nr; i++) {
2380                 struct uart_state *state = drv->state + i;
2381
2382                 state->close_delay     = 500;   /* .5 seconds */
2383                 state->closing_wait    = 30000; /* 30 seconds */
2384
2385                 mutex_init(&state->mutex);
2386         }
2387
2388         retval = tty_register_driver(normal);
2389  out:
2390         if (retval < 0) {
2391                 put_tty_driver(normal);
2392                 kfree(drv->state);
2393         }
2394         return retval;
2395 }
2396
2397 /**
2398  *      uart_unregister_driver - remove a driver from the uart core layer
2399  *      @drv: low level driver structure
2400  *
2401  *      Remove all references to a driver from the core driver.  The low
2402  *      level driver must have removed all its ports via the
2403  *      uart_remove_one_port() if it registered them with uart_add_one_port().
2404  *      (ie, drv->port == NULL)
2405  */
2406 void uart_unregister_driver(struct uart_driver *drv)
2407 {
2408         struct tty_driver *p = drv->tty_driver;
2409         tty_unregister_driver(p);
2410         put_tty_driver(p);
2411         kfree(drv->state);
2412         drv->tty_driver = NULL;
2413 }
2414
2415 struct tty_driver *uart_console_device(struct console *co, int *index)
2416 {
2417         struct uart_driver *p = co->data;
2418         *index = co->index;
2419         return p->tty_driver;
2420 }
2421
2422 /**
2423  *      uart_add_one_port - attach a driver-defined port structure
2424  *      @drv: pointer to the uart low level driver structure for this port
2425  *      @port: uart port structure to use for this port.
2426  *
2427  *      This allows the driver to register its own uart_port structure
2428  *      with the core driver.  The main purpose is to allow the low
2429  *      level uart drivers to expand uart_port, rather than having yet
2430  *      more levels of structures.
2431  */
2432 int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
2433 {
2434         struct uart_state *state;
2435         int ret = 0;
2436         struct device *tty_dev;
2437
2438         BUG_ON(in_interrupt());
2439
2440         if (port->line >= drv->nr)
2441                 return -EINVAL;
2442
2443         state = drv->state + port->line;
2444
2445         mutex_lock(&port_mutex);
2446         mutex_lock(&state->mutex);
2447         if (state->port) {
2448                 ret = -EINVAL;
2449                 goto out;
2450         }
2451
2452         state->port = port;
2453         state->pm_state = -1;
2454
2455         port->cons = drv->cons;
2456         port->info = state->info;
2457
2458         /*
2459          * If this port is a console, then the spinlock is already
2460          * initialised.
2461          */
2462         if (!(uart_console(port) && (port->cons->flags & CON_ENABLED))) {
2463                 spin_lock_init(&port->lock);
2464                 lockdep_set_class(&port->lock, &port_lock_key);
2465         }
2466
2467         uart_configure_port(drv, state, port);
2468
2469         /*
2470          * Register the port whether it's detected or not.  This allows
2471          * setserial to be used to alter this ports parameters.
2472          */
2473         tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);
2474         if (likely(!IS_ERR(tty_dev))) {
2475                 device_init_wakeup(tty_dev, 1);
2476                 device_set_wakeup_enable(tty_dev, 0);
2477         } else
2478                 printk(KERN_ERR "Cannot register tty device on line %d\n",
2479                        port->line);
2480
2481         /*
2482          * Ensure UPF_DEAD is not set.
2483          */
2484         port->flags &= ~UPF_DEAD;
2485
2486  out:
2487         mutex_unlock(&state->mutex);
2488         mutex_unlock(&port_mutex);
2489
2490         return ret;
2491 }
2492
2493 /**
2494  *      uart_remove_one_port - detach a driver defined port structure
2495  *      @drv: pointer to the uart low level driver structure for this port
2496  *      @port: uart port structure for this port
2497  *
2498  *      This unhooks (and hangs up) the specified port structure from the
2499  *      core driver.  No further calls will be made to the low-level code
2500  *      for this port.
2501  */
2502 int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
2503 {
2504         struct uart_state *state = drv->state + port->line;
2505         struct uart_info *info;
2506
2507         BUG_ON(in_interrupt());
2508
2509         if (state->port != port)
2510                 printk(KERN_ALERT "Removing wrong port: %p != %p\n",
2511                         state->port, port);
2512
2513         mutex_lock(&port_mutex);
2514
2515         /*
2516          * Mark the port "dead" - this prevents any opens from
2517          * succeeding while we shut down the port.
2518          */
2519         mutex_lock(&state->mutex);
2520         port->flags |= UPF_DEAD;
2521         mutex_unlock(&state->mutex);
2522
2523         /*
2524          * Remove the devices from the tty layer
2525          */
2526         tty_unregister_device(drv->tty_driver, port->line);
2527
2528         info = state->info;
2529         if (info && info->port.tty)
2530                 tty_vhangup(info->port.tty);
2531
2532         /*
2533          * All users of this port should now be disconnected from
2534          * this driver, and the port shut down.  We should be the
2535          * only thread fiddling with this port from now on.
2536          */
2537         state->info = NULL;
2538
2539         /*
2540          * Free the port IO and memory resources, if any.
2541          */
2542         if (port->type != PORT_UNKNOWN)
2543                 port->ops->release_port(port);
2544
2545         /*
2546          * Indicate that there isn't a port here anymore.
2547          */
2548         port->type = PORT_UNKNOWN;
2549
2550         /*
2551          * Kill the tasklet, and free resources.
2552          */
2553         if (info) {
2554                 tasklet_kill(&info->tlet);
2555                 kfree(info);
2556         }
2557
2558         state->port = NULL;
2559         mutex_unlock(&port_mutex);
2560
2561         return 0;
2562 }
2563
2564 /*
2565  *      Are the two ports equivalent?
2566  */
2567 int uart_match_port(struct uart_port *port1, struct uart_port *port2)
2568 {
2569         if (port1->iotype != port2->iotype)
2570                 return 0;
2571
2572         switch (port1->iotype) {
2573         case UPIO_PORT:
2574                 return (port1->iobase == port2->iobase);
2575         case UPIO_HUB6:
2576                 return (port1->iobase == port2->iobase) &&
2577                        (port1->hub6   == port2->hub6);
2578         case UPIO_MEM:
2579         case UPIO_MEM32:
2580         case UPIO_AU:
2581         case UPIO_TSI:
2582         case UPIO_DWAPB:
2583                 return (port1->mapbase == port2->mapbase);
2584         }
2585         return 0;
2586 }
2587 EXPORT_SYMBOL(uart_match_port);
2588
2589 EXPORT_SYMBOL(uart_write_wakeup);
2590 EXPORT_SYMBOL(uart_register_driver);
2591 EXPORT_SYMBOL(uart_unregister_driver);
2592 EXPORT_SYMBOL(uart_suspend_port);
2593 EXPORT_SYMBOL(uart_resume_port);
2594 EXPORT_SYMBOL(uart_add_one_port);
2595 EXPORT_SYMBOL(uart_remove_one_port);
2596
2597 MODULE_DESCRIPTION("Serial driver core");
2598 MODULE_LICENSE("GPL");