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   1 /* MN10300 On-chip serial driver for gdbstub I/O
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #include <linux/string.h>
  12 #include <linux/kernel.h>
  13 #include <linux/signal.h>
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/console.h>
  17 #include <linux/init.h>
  18 #include <linux/tty.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/system.h>
  21 #include <asm/gdb-stub.h>
  22 #include <asm/exceptions.h>
  23 #include <unit/clock.h>
  24 #include "mn10300-serial.h"
  25
  26 #if defined(CONFIG_GDBSTUB_ON_TTYSM0)
  27 struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif0;
  28 #elif defined(CONFIG_GDBSTUB_ON_TTYSM1)
  29 struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif1;
  30 #else
  31 struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif2;
  32 #endif
  33
  34
  35 /*
  36  * initialise the GDB stub I/O routines
  37  */
  38 void __init gdbstub_io_init(void)
  39 {
  40         uint16_t scxctr;
  41         int tmp;
  42
  43         switch (gdbstub_port->clock_src) {
  44         case MNSCx_CLOCK_SRC_IOCLK:
  45                 gdbstub_port->ioclk = MN10300_IOCLK;
  46                 break;
  47
  48 #ifdef MN10300_IOBCLK
  49         case MNSCx_CLOCK_SRC_IOBCLK:
  50                 gdbstub_port->ioclk = MN10300_IOBCLK;
  51                 break;
  52 #endif
  53         default:
  54                 BUG();
  55         }
  56
  57         /* set up the serial port */
  58         gdbstub_io_set_baud(115200);
  59
  60         /* we want to get serial receive interrupts */
  61         set_intr_level(gdbstub_port->rx_irq, GxICR_LEVEL_0);
  62         set_intr_level(gdbstub_port->tx_irq, GxICR_LEVEL_0);
  63         set_intr_stub(EXCEP_IRQ_LEVEL0, gdbstub_io_rx_handler);
  64
  65         *gdbstub_port->rx_icr |= GxICR_ENABLE;
  66         tmp = *gdbstub_port->rx_icr;
  67
  68         /* enable the device */
  69         scxctr = SC01CTR_CLN_8BIT;      /* 1N8 */
  70         switch (gdbstub_port->div_timer) {
  71         case MNSCx_DIV_TIMER_16BIT:
  72                 scxctr |= SC0CTR_CK_TM8UFLOW_8; /* == SC1CTR_CK_TM9UFLOW_8
  73                                                    == SC2CTR_CK_TM10UFLOW_8 */
  74                 break;
  75
  76         case MNSCx_DIV_TIMER_8BIT:
  77                 scxctr |= SC0CTR_CK_TM2UFLOW_8;
  78                 break;
  79         }
  80
  81         scxctr |= SC01CTR_TXE | SC01CTR_RXE;
  82
  83         *gdbstub_port->_control = scxctr;
  84         tmp = *gdbstub_port->_control;
  85
  86         /* permit level 0 IRQs only */
  87         asm volatile(
  88                 "       and %0,epsw     \n"
  89                 "       or %1,epsw      \n"
  90                 :
  91                 : "i"(~EPSW_IM), "i"(EPSW_IE|EPSW_IM_1)
  92                 );
  93 }
  94
  95 /*
  96  * set up the GDB stub serial port baud rate timers
  97  */
  98 void gdbstub_io_set_baud(unsigned baud)
  99 {
 100         const unsigned bits = 10; /* 1 [start] + 8 [data] + 0 [parity] +
 101                                    * 1 [stop] */
 102         unsigned long ioclk = gdbstub_port->ioclk;
 103         unsigned xdiv, tmp;
 104         uint16_t tmxbr;
 105         uint8_t tmxmd;
 106
 107         if (!baud) {
 108                 baud = 9600;
 109         } else if (baud == 134) {
 110                 baud = 269;     /* 134 is really 134.5 */
 111                 xdiv = 2;
 112         }
 113
 114 try_alternative:
 115         xdiv = 1;
 116
 117         switch (gdbstub_port->div_timer) {
 118         case MNSCx_DIV_TIMER_16BIT:
 119                 tmxmd = TM8MD_SRC_IOCLK;
 120                 tmxbr = tmp = (ioclk / (baud * xdiv) + 4) / 8 - 1;
 121                 if (tmp > 0 && tmp <= 65535)
 122                         goto timer_okay;
 123
 124                 tmxmd = TM8MD_SRC_IOCLK_8;
 125                 tmxbr = tmp = (ioclk / (baud * 8 * xdiv) + 4) / 8 - 1;
 126                 if (tmp > 0 && tmp <= 65535)
 127                         goto timer_okay;
 128
 129                 tmxmd = TM8MD_SRC_IOCLK_32;
 130                 tmxbr = tmp = (ioclk / (baud * 32 * xdiv) + 4) / 8 - 1;
 131                 if (tmp > 0 && tmp <= 65535)
 132                         goto timer_okay;
 133
 134                 break;
 135
 136         case MNSCx_DIV_TIMER_8BIT:
 137                 tmxmd = TM2MD_SRC_IOCLK;
 138                 tmxbr = tmp = (ioclk / (baud * xdiv) + 4) / 8 - 1;
 139                 if (tmp > 0 && tmp <= 255)
 140                         goto timer_okay;
 141
 142                 tmxmd = TM2MD_SRC_IOCLK_8;
 143                 tmxbr = tmp = (ioclk / (baud * 8 * xdiv) + 4) / 8 - 1;
 144                 if (tmp > 0 && tmp <= 255)
 145                         goto timer_okay;
 146
 147                 tmxmd = TM2MD_SRC_IOCLK_32;
 148                 tmxbr = tmp = (ioclk / (baud * 32 * xdiv) + 4) / 8 - 1;
 149                 if (tmp > 0 && tmp <= 255)
 150                         goto timer_okay;
 151                 break;
 152         }
 153
 154         /* as a last resort, if the quotient is zero, default to 9600 bps */
 155         baud = 9600;
 156         goto try_alternative;
 157
 158 timer_okay:
 159         gdbstub_port->uart.timeout = (2 * bits * HZ) / baud;
 160         gdbstub_port->uart.timeout += HZ / 50;
 161
 162         /* set the timer to produce the required baud rate */
 163         switch (gdbstub_port->div_timer) {
 164         case MNSCx_DIV_TIMER_16BIT:
 165                 *gdbstub_port->_tmxmd = 0;
 166                 *gdbstub_port->_tmxbr = tmxbr;
 167                 *gdbstub_port->_tmxmd = TM8MD_INIT_COUNTER;
 168                 *gdbstub_port->_tmxmd = tmxmd | TM8MD_COUNT_ENABLE;
 169                 break;
 170
 171         case MNSCx_DIV_TIMER_8BIT:
 172                 *gdbstub_port->_tmxmd = 0;
 173                 *(volatile u8 *) gdbstub_port->_tmxbr = (u8)tmxbr;
 174                 *gdbstub_port->_tmxmd = TM2MD_INIT_COUNTER;
 175                 *gdbstub_port->_tmxmd = tmxmd | TM2MD_COUNT_ENABLE;
 176                 break;
 177         }
 178 }
 179
 180 /*
 181  * wait for a character to come from the debugger
 182  */
 183 int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
 184 {
 185         unsigned ix;
 186         u8 ch, st;
 187
 188         *_ch = 0xff;
 189
 190         if (gdbstub_rx_unget) {
 191                 *_ch = gdbstub_rx_unget;
 192                 gdbstub_rx_unget = 0;
 193                 return 0;
 194         }
 195
 196 try_again:
 197         /* pull chars out of the buffer */
 198         ix = gdbstub_rx_outp;
 199         barrier();
 200         if (ix == gdbstub_rx_inp) {
 201                 if (nonblock)
 202                         return -EAGAIN;
 203 #ifdef CONFIG_MN10300_WD_TIMER
 204                 watchdog_alert_counter = 0;
 205 #endif /* CONFIG_MN10300_WD_TIMER */
 206                 goto try_again;
 207         }
 208
 209         ch = gdbstub_rx_buffer[ix++];
 210         st = gdbstub_rx_buffer[ix++];
 211         barrier();
 212         gdbstub_rx_outp = ix & (PAGE_SIZE - 1);
 213
 214         st &= SC01STR_RXF | SC01STR_RBF | SC01STR_FEF | SC01STR_PEF |
 215                 SC01STR_OEF;
 216
 217         /* deal with what we've got
 218          * - note that the UART doesn't do BREAK-detection for us
 219          */
 220         if (st & SC01STR_FEF && ch == 0) {
 221                 switch (gdbstub_port->rx_brk) {
 222                 case 0: gdbstub_port->rx_brk = 1;       goto try_again;
 223                 case 1: gdbstub_port->rx_brk = 2;       goto try_again;
 224                 case 2:
 225                         gdbstub_port->rx_brk = 3;
 226                         gdbstub_proto("### GDB MNSERIAL Rx Break Detected"
 227                                       " ###\n");
 228                         return -EINTR;
 229                 default:
 230                         goto try_again;
 231                 }
 232         } else if (st & SC01STR_FEF) {
 233                 if (gdbstub_port->rx_brk)
 234                         goto try_again;
 235
 236                 gdbstub_proto("### GDB MNSERIAL Framing Error ###\n");
 237                 return -EIO;
 238         } else if (st & SC01STR_OEF) {
 239                 if (gdbstub_port->rx_brk)
 240                         goto try_again;
 241
 242                 gdbstub_proto("### GDB MNSERIAL Overrun Error ###\n");
 243                 return -EIO;
 244         } else if (st & SC01STR_PEF) {
 245                 if (gdbstub_port->rx_brk)
 246                         goto try_again;
 247
 248                 gdbstub_proto("### GDB MNSERIAL Parity Error ###\n");
 249                 return -EIO;
 250         } else {
 251                 /* look for the tail-end char on a break run */
 252                 if (gdbstub_port->rx_brk == 3) {
 253                         switch (ch) {
 254                         case 0xFF:
 255                         case 0xFE:
 256                         case 0xFC:
 257                         case 0xF8:
 258                         case 0xF0:
 259                         case 0xE0:
 260                         case 0xC0:
 261                         case 0x80:
 262                         case 0x00:
 263                                 gdbstub_port->rx_brk = 0;
 264                                 goto try_again;
 265                         default:
 266                                 break;
 267                         }
 268                 }
 269
 270                 gdbstub_port->rx_brk = 0;
 271                 gdbstub_io("### GDB Rx %02x (st=%02x) ###\n", ch, st);
 272                 *_ch = ch & 0x7f;
 273                 return 0;
 274         }
 275 }
 276
 277 /*
 278  * send a character to the debugger
 279  */
 280 void gdbstub_io_tx_char(unsigned char ch)
 281 {
 282         while (*gdbstub_port->_status & SC01STR_TBF)
 283                 continue;
 284
 285         if (ch == 0x0a) {
 286                 *(u8 *) gdbstub_port->_txb = 0x0d;
 287                 while (*gdbstub_port->_status & SC01STR_TBF)
 288                         continue;
 289         }
 290
 291         *(u8 *) gdbstub_port->_txb = ch;
 292 }
 293
 294 /*
 295  * flush the transmission buffers
 296  */
 297 void gdbstub_io_tx_flush(void)
 298 {
 299         while (*gdbstub_port->_status & (SC01STR_TBF | SC01STR_TXF))
 300                 continue;
 301 }