2 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
3 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
4 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
5 * Copyright (C) 2004 IBM Corporation
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 #include <linux/config.h>
26 #include <linux/console.h>
27 #include <linux/cpumask.h>
28 #include <linux/init.h>
29 #include <linux/kbd_kern.h>
30 #include <linux/kernel.h>
31 #include <linux/kobject.h>
32 #include <linux/kthread.h>
33 #include <linux/list.h>
34 #include <linux/module.h>
35 #include <linux/major.h>
36 #include <linux/sysrq.h>
37 #include <linux/tty.h>
38 #include <linux/tty_flip.h>
39 #include <linux/sched.h>
40 #include <linux/spinlock.h>
41 #include <linux/delay.h>
42 #include <asm/uaccess.h>
43 #include <asm/hvconsole.h>
52 * Wait this long per iteration while trying to push buffered data to the
53 * hypervisor before allowing the tty to complete a close operation.
55 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
58 * The Linux TTY code does not support dynamic addition of tty derived devices
59 * so we need to know how many tty devices we might need when space is allocated
60 * for the tty device. Since this driver supports hotplug of vty adapters we
61 * need to make sure we have enough allocated.
63 #define HVC_ALLOC_TTY_ADAPTERS 8
68 #define __ALIGNED__ __attribute__((__aligned__(8)))
70 static struct tty_driver *hvc_driver;
71 static struct task_struct *hvc_task;
73 /* Picks up late kicks after list walk but before schedule() */
74 static int hvc_kicked;
76 #ifdef CONFIG_MAGIC_SYSRQ
77 static int sysrq_pressed;
83 struct tty_struct *tty;
86 char outbuf[N_OUTBUF] __ALIGNED__;
91 struct list_head next;
92 struct kobject kobj; /* ref count & hvc_struct lifetime */
96 /* dynamic list of hvc_struct instances */
97 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
100 * Protect the list of hvc_struct instances from inserts and removals during
103 static DEFINE_SPINLOCK(hvc_structs_lock);
106 * This value is used to assign a tty->index value to a hvc_struct based
107 * upon order of exposure via hvc_probe(), when we can not match it to
108 * a console canidate registered with hvc_instantiate().
110 static int last_hvc = -1;
113 * Do not call this function with either the hvc_strucst_lock or the hvc_struct
114 * lock held. If successful, this function increments the kobject reference
115 * count against the target hvc_struct so it should be released when finished.
117 struct hvc_struct *hvc_get_by_index(int index)
119 struct hvc_struct *hp;
122 spin_lock(&hvc_structs_lock);
124 list_for_each_entry(hp, &hvc_structs, next) {
125 spin_lock_irqsave(&hp->lock, flags);
126 if (hp->index == index) {
127 kobject_get(&hp->kobj);
128 spin_unlock_irqrestore(&hp->lock, flags);
129 spin_unlock(&hvc_structs_lock);
132 spin_unlock_irqrestore(&hp->lock, flags);
136 spin_unlock(&hvc_structs_lock);
142 * Initial console vtermnos for console API usage prior to full console
143 * initialization. Any vty adapter outside this range will not have usable
144 * console interfaces but can still be used as a tty device. This has to be
145 * static because kmalloc will not work during early console init.
147 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
148 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
151 * Console APIs, NOT TTY. These APIs are available immediately when
152 * hvc_console_setup() finds adapters.
155 void hvc_console_print(struct console *co, const char *b, unsigned count)
157 char c[16] __ALIGNED__;
158 unsigned i = 0, n = 0;
161 /* Console access attempt outside of acceptable console range. */
162 if (co->index >= MAX_NR_HVC_CONSOLES)
165 /* This console adapter was removed so it is not useable. */
166 if (vtermnos[co->index] < 0)
169 while (count > 0 || i > 0) {
170 if (count > 0 && i < sizeof(c)) {
171 if (b[n] == '\n' && !donecr) {
180 r = hvc_put_chars(vtermnos[co->index], c, i);
182 /* throw away chars on error */
193 static struct tty_driver *hvc_console_device(struct console *c, int *index)
195 if (vtermnos[c->index] == -1)
202 static int __init hvc_console_setup(struct console *co, char *options)
204 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
207 if (vtermnos[co->index] == -1)
213 struct console hvc_con_driver = {
215 .write = hvc_console_print,
216 .device = hvc_console_device,
217 .setup = hvc_console_setup,
218 .flags = CON_PRINTBUFFER,
223 * Early console initialization. Preceeds driver initialization.
225 * (1) we are first, and the user specified another driver
226 * -- index will remain -1
227 * (2) we are first and the user specified no driver
228 * -- index will be set to 0, then we will fail setup.
229 * (3) we are first and the user specified our driver
230 * -- index will be set to user specified driver, and we will fail
231 * (4) we are after driver, and this initcall will register us
232 * -- if the user didn't specify a driver then the console will match
234 * Note that for cases 2 and 3, we will match later when the io driver
235 * calls hvc_instantiate() and call register again.
237 static int __init hvc_console_init(void)
239 register_console(&hvc_con_driver);
242 console_initcall(hvc_console_init);
245 * hvc_instantiate() is an early console discovery method which locates
246 * consoles * prior to the vio subsystem discovering them. Hotplugged
247 * vty adapters do NOT get an hvc_instantiate() callback since they
248 * appear after early console init.
250 int hvc_instantiate(uint32_t vtermno, int index)
252 struct hvc_struct *hp;
254 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
257 if (vtermnos[index] != -1)
260 /* make sure no no tty has been registerd in this index */
261 hp = hvc_get_by_index(index);
263 kobject_put(&hp->kobj);
267 vtermnos[index] = vtermno;
269 /* reserve all indices upto and including this index */
270 if (last_hvc < index)
273 /* if this index is what the user requested, then register
274 * now (setup won't fail at this point). It's ok to just
275 * call register again if previously .setup failed.
277 if (index == hvc_con_driver.index)
278 register_console(&hvc_con_driver);
283 /* Wake the sleeping khvcd */
284 static void hvc_kick(void)
287 wake_up_process(hvc_task);
290 static int hvc_poll(struct hvc_struct *hp);
293 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
294 * In this case the console is poll driven.
296 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
298 /* if hvc_poll request a repoll, then kick the hvcd thread */
299 if (hvc_poll(dev_instance))
304 static void hvc_unthrottle(struct tty_struct *tty)
310 * The TTY interface won't be used until after the vio layer has exposed the vty
311 * adapter to the kernel.
313 static int hvc_open(struct tty_struct *tty, struct file * filp)
315 struct hvc_struct *hp;
319 struct kobject *kobjp;
321 /* Auto increments kobject reference if found. */
322 if (!(hp = hvc_get_by_index(tty->index))) {
323 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
327 spin_lock_irqsave(&hp->lock, flags);
328 /* Check and then increment for fast path open. */
329 if (hp->count++ > 0) {
330 spin_unlock_irqrestore(&hp->lock, flags);
333 } /* else count == 0 */
335 tty->driver_data = hp;
337 /* Save for request_irq outside of spin_lock. */
340 hp->irq_requested = 1;
344 spin_unlock_irqrestore(&hp->lock, flags);
345 /* check error, fallback to non-irq */
347 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
350 * If the request_irq() fails and we return an error. The tty layer
351 * will call hvc_close() after a failed open but we don't want to clean
352 * up there so we'll clean up here and clear out the previously set
353 * tty fields and return the kobject reference.
356 spin_lock_irqsave(&hp->lock, flags);
358 hp->irq_requested = 0;
359 spin_unlock_irqrestore(&hp->lock, flags);
360 tty->driver_data = NULL;
362 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
364 /* Force wakeup of the polling thread */
370 static void hvc_close(struct tty_struct *tty, struct file * filp)
372 struct hvc_struct *hp;
373 struct kobject *kobjp;
377 if (tty_hung_up_p(filp))
381 * No driver_data means that this close was issued after a failed
382 * hvc_open by the tty layer's release_dev() function and we can just
383 * exit cleanly because the kobject reference wasn't made.
385 if (!tty->driver_data)
388 hp = tty->driver_data;
389 spin_lock_irqsave(&hp->lock, flags);
392 if (--hp->count == 0) {
393 if (hp->irq_requested)
395 hp->irq_requested = 0;
397 /* We are done with the tty pointer now. */
399 spin_unlock_irqrestore(&hp->lock, flags);
402 * Chain calls chars_in_buffer() and returns immediately if
403 * there is no buffered data otherwise sleeps on a wait queue
404 * waking periodically to check chars_in_buffer().
406 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
413 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
414 hp->vtermno, hp->count);
415 spin_unlock_irqrestore(&hp->lock, flags);
421 static void hvc_hangup(struct tty_struct *tty)
423 struct hvc_struct *hp = tty->driver_data;
427 struct kobject *kobjp;
432 spin_lock_irqsave(&hp->lock, flags);
435 * The N_TTY line discipline has problems such that in a close vs
436 * open->hangup case this can be called after the final close so prevent
437 * that from happening for now.
439 if (hp->count <= 0) {
440 spin_unlock_irqrestore(&hp->lock, flags);
445 temp_open_count = hp->count;
449 if (hp->irq_requested)
450 /* Saved for use outside of spin_lock. */
452 hp->irq_requested = 0;
453 spin_unlock_irqrestore(&hp->lock, flags);
456 while(temp_open_count) {
463 * Push buffered characters whether they were just recently buffered or waiting
464 * on a blocked hypervisor. Call this function with hp->lock held.
466 static void hvc_push(struct hvc_struct *hp)
470 n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
474 /* throw away output on error; this happens when
475 there is no session connected to the vterm. */
479 if (hp->n_outbuf > 0)
480 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
485 static inline int __hvc_write_kernel(struct hvc_struct *hp,
486 const unsigned char *buf, int count)
489 int rsize, written = 0;
491 spin_lock_irqsave(&hp->lock, flags);
493 /* Push pending writes */
494 if (hp->n_outbuf > 0)
497 while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
500 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
503 hp->n_outbuf += rsize;
507 spin_unlock_irqrestore(&hp->lock, flags);
511 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
513 struct hvc_struct *hp = tty->driver_data;
516 /* This write was probably executed during a tty close. */
523 written = __hvc_write_kernel(hp, buf, count);
526 * Racy, but harmless, kick thread if there is still pending data.
527 * There really is nothing wrong with kicking the thread, even if there
528 * is no buffered data.
537 * This is actually a contract between the driver and the tty layer outlining
538 * how much write room the driver can guarentee will be sent OR BUFFERED. This
539 * driver MUST honor the return value.
541 static int hvc_write_room(struct tty_struct *tty)
543 struct hvc_struct *hp = tty->driver_data;
548 return N_OUTBUF - hp->n_outbuf;
551 static int hvc_chars_in_buffer(struct tty_struct *tty)
553 struct hvc_struct *hp = tty->driver_data;
560 #define HVC_POLL_READ 0x00000001
561 #define HVC_POLL_WRITE 0x00000002
562 #define HVC_POLL_QUICK 0x00000004
564 static int hvc_poll(struct hvc_struct *hp)
566 struct tty_struct *tty;
567 int i, n, poll_mask = 0;
568 char buf[N_INBUF] __ALIGNED__;
572 spin_lock_irqsave(&hp->lock, flags);
574 /* Push pending writes */
575 if (hp->n_outbuf > 0)
577 /* Reschedule us if still some write pending */
578 if (hp->n_outbuf > 0)
579 poll_mask |= HVC_POLL_WRITE;
581 /* No tty attached, just skip */
586 /* Now check if we can get data (are we throttled ?) */
587 if (test_bit(TTY_THROTTLED, &tty->flags))
590 /* If we aren't interrupt driven and aren't throttled, we always
591 * request a reschedule
593 if (hp->irq == NO_IRQ)
594 poll_mask |= HVC_POLL_READ;
596 /* Read data if any */
599 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
600 count = TTY_FLIPBUF_SIZE - tty->flip.count;
602 /* If flip is full, just reschedule a later read */
604 poll_mask |= HVC_POLL_READ;
608 n = hvc_get_chars(hp->vtermno, buf, count);
610 /* Hangup the tty when disconnected from host */
612 spin_unlock_irqrestore(&hp->lock, flags);
614 spin_lock_irqsave(&hp->lock, flags);
618 for (i = 0; i < n; ++i) {
619 #ifdef CONFIG_MAGIC_SYSRQ
620 if (hp->index == hvc_con_driver.index) {
621 /* Handle the SysRq Hack */
622 /* XXX should support a sequence */
623 if (buf[i] == '\x0f') { /* ^O */
626 } else if (sysrq_pressed) {
627 handle_sysrq(buf[i], NULL, tty);
632 #endif /* CONFIG_MAGIC_SYSRQ */
633 tty_insert_flip_char(tty, buf[i], 0);
637 tty_schedule_flip(tty);
640 * Account for the total amount read in one loop, and if above
641 * 64 bytes, we do a quick schedule loop to let the tty grok
642 * the data and eventually throttle us.
645 if (read_total >= 64) {
646 poll_mask |= HVC_POLL_QUICK;
651 /* Wakeup write queue if necessary */
657 spin_unlock_irqrestore(&hp->lock, flags);
662 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
663 extern cpumask_t cpus_in_xmon;
665 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
669 * This kthread is either polling or interrupt driven. This is determined by
670 * calling hvc_poll() who determines whether a console adapter support
673 int khvcd(void *unused)
676 struct hvc_struct *hp;
678 __set_current_state(TASK_RUNNING);
683 if (cpus_empty(cpus_in_xmon)) {
684 spin_lock(&hvc_structs_lock);
685 list_for_each_entry(hp, &hvc_structs, next) {
686 poll_mask |= hvc_poll(hp);
688 spin_unlock(&hvc_structs_lock);
690 poll_mask |= HVC_POLL_READ;
693 if (poll_mask & HVC_POLL_QUICK) {
697 set_current_state(TASK_INTERRUPTIBLE);
702 msleep_interruptible(TIMEOUT);
704 __set_current_state(TASK_RUNNING);
705 } while (!kthread_should_stop());
710 static struct tty_operations hvc_ops = {
714 .hangup = hvc_hangup,
715 .unthrottle = hvc_unthrottle,
716 .write_room = hvc_write_room,
717 .chars_in_buffer = hvc_chars_in_buffer,
720 /* callback when the kboject ref count reaches zero. */
721 static void destroy_hvc_struct(struct kobject *kobj)
723 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
726 spin_lock(&hvc_structs_lock);
728 spin_lock_irqsave(&hp->lock, flags);
729 list_del(&(hp->next));
730 spin_unlock_irqrestore(&hp->lock, flags);
732 spin_unlock(&hvc_structs_lock);
737 static struct kobj_type hvc_kobj_type = {
738 .release = destroy_hvc_struct,
741 static int __devinit hvc_probe(
743 const struct vio_device_id *id)
745 struct hvc_struct *hp;
748 /* probed with invalid parameters. */
752 hp = kmalloc(sizeof(*hp), GFP_KERNEL);
756 memset(hp, 0x00, sizeof(*hp));
757 hp->vtermno = dev->unit_address;
759 hp->vdev->dev.driver_data = hp;
762 kobject_init(&hp->kobj);
763 hp->kobj.ktype = &hvc_kobj_type;
765 spin_lock_init(&hp->lock);
766 spin_lock(&hvc_structs_lock);
770 * see if this vterm id matches one registered for console.
772 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
773 if (vtermnos[i] == hp->vtermno)
776 /* no matching slot, just use a counter */
777 if (i >= MAX_NR_HVC_CONSOLES)
782 list_add_tail(&(hp->next), &hvc_structs);
783 spin_unlock(&hvc_structs_lock);
788 static int __devexit hvc_remove(struct vio_dev *dev)
790 struct hvc_struct *hp = dev->dev.driver_data;
792 struct kobject *kobjp;
793 struct tty_struct *tty;
795 spin_lock_irqsave(&hp->lock, flags);
799 if (hp->index < MAX_NR_HVC_CONSOLES)
800 vtermnos[hp->index] = -1;
802 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
804 spin_unlock_irqrestore(&hp->lock, flags);
807 * We 'put' the instance that was grabbed when the kobject instance
808 * was intialized using kobject_init(). Let the last holder of this
809 * kobject cause it to be removed, which will probably be the tty_hangup
815 * This function call will auto chain call hvc_hangup. The tty should
816 * always be valid at this time unless a simultaneous tty close already
817 * cleaned up the hvc_struct.
824 char hvc_driver_name[] = "hvc_console";
826 static struct vio_device_id hvc_driver_table[] __devinitdata= {
827 {"serial", "hvterm1"},
830 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
832 static struct vio_driver hvc_vio_driver = {
833 .name = hvc_driver_name,
834 .id_table = hvc_driver_table,
836 .remove = hvc_remove,
839 /* Driver initialization. Follow console initialization. This is where the TTY
840 * interfaces start to become available. */
841 int __init hvc_init(void)
845 /* We need more than hvc_count adapters due to hotplug additions. */
846 hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
850 hvc_driver->owner = THIS_MODULE;
851 hvc_driver->devfs_name = "hvc/";
852 hvc_driver->driver_name = "hvc";
853 hvc_driver->name = "hvc";
854 hvc_driver->major = HVC_MAJOR;
855 hvc_driver->minor_start = HVC_MINOR;
856 hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
857 hvc_driver->init_termios = tty_std_termios;
858 hvc_driver->flags = TTY_DRIVER_REAL_RAW;
859 tty_set_operations(hvc_driver, &hvc_ops);
861 if (tty_register_driver(hvc_driver))
862 panic("Couldn't register hvc console driver\n");
864 /* Always start the kthread because there can be hotplug vty adapters
866 hvc_task = kthread_run(khvcd, NULL, "khvcd");
867 if (IS_ERR(hvc_task)) {
868 panic("Couldn't create kthread for console.\n");
869 put_tty_driver(hvc_driver);
873 /* Register as a vio device to receive callbacks */
874 rc = vio_register_driver(&hvc_vio_driver);
878 module_init(hvc_init);
880 /* This isn't particularily necessary due to this being a console driver
881 * but it is nice to be thorough.
883 static void __exit hvc_exit(void)
885 kthread_stop(hvc_task);
887 vio_unregister_driver(&hvc_vio_driver);
888 tty_unregister_driver(hvc_driver);
889 /* return tty_struct instances allocated in hvc_init(). */
890 put_tty_driver(hvc_driver);
891 unregister_console(&hvc_con_driver);
893 module_exit(hvc_exit);