arch/frv/kernel/debug-stub.c

   1 /* debug-stub.c: debug-mode stub
   2  *
   3  * Copyright (C) 2004 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 License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/string.h>
  13 #include <linux/kernel.h>
  14 #include <linux/signal.h>
  15 #include <linux/sched.h>
  16 #include <linux/init.h>
  17 #include <linux/serial_reg.h>
  18 #include <linux/start_kernel.h>
  19
  20 #include <asm/serial-regs.h>
  21 #include <asm/timer-regs.h>
  22 #include <asm/irc-regs.h>
  23 #include <asm/gdb-stub.h>
  24 #include "gdb-io.h"
  25
  26 /* CPU board CON5 */
  27 #define __UART0(X) (*(volatile uint8_t *)(UART0_BASE + (UART_##X)))
  28
  29 #define LSR_WAIT_FOR0(STATE)                    \
  30 do {                                            \
  31 } while (!(__UART0(LSR) & UART_LSR_##STATE))
  32
  33 #define FLOWCTL_QUERY0(LINE)    ({ __UART0(MSR) & UART_MSR_##LINE; })
  34 #define FLOWCTL_CLEAR0(LINE)    do { __UART0(MCR) &= ~UART_MCR_##LINE; } while (0)
  35 #define FLOWCTL_SET0(LINE)      do { __UART0(MCR) |= UART_MCR_##LINE; } while (0)
  36
  37 #define FLOWCTL_WAIT_FOR0(LINE)                 \
  38 do {                                            \
  39         gdbstub_do_rx();                        \
  40 } while(!FLOWCTL_QUERY(LINE))
  41
  42 struct frv_debug_status __debug_status;
  43
  44 static void __init debug_stub_init(void);
  45
  46 /*****************************************************************************/
  47 /*
  48  * debug mode handler stub
  49  * - we come here with the CPU in debug mode and with exceptions disabled
  50  * - handle debugging services for userspace
  51  */
  52 asmlinkage void debug_stub(void)
  53 {
  54         unsigned long hsr0;
  55         int type = 0;
  56
  57         static u8 inited = 0;
  58         if (!inited) {
  59                 debug_stub_init();
  60                 type = -1;
  61                 inited = 1;
  62         }
  63
  64         hsr0 = __get_HSR(0);
  65         if (hsr0 & HSR0_ETMD)
  66                 __set_HSR(0, hsr0 & ~HSR0_ETMD);
  67
  68         /* disable single stepping */
  69         __debug_status.dcr &= ~DCR_SE;
  70
  71         /* kernel mode can propose an exception be handled in debug mode by jumping to a special
  72          * location */
  73         if (__debug_frame->pc == (unsigned long) __break_hijack_kernel_event_breaks_here) {
  74                 /* replace the debug frame with the kernel frame and discard
  75                  * the top kernel context */
  76                 *__debug_frame = *__frame;
  77                 __frame = __debug_frame->next_frame;
  78                 __debug_status.brr = (__debug_frame->tbr & TBR_TT) << 12;
  79                 __debug_status.brr |= BRR_EB;
  80         }
  81
  82         if (__debug_frame->pc == (unsigned long) __debug_bug_trap + 4) {
  83                 __debug_frame->pc = __debug_frame->lr;
  84                 type = __debug_frame->gr8;
  85         }
  86
  87 #ifdef CONFIG_GDBSTUB
  88         gdbstub(type);
  89 #endif
  90
  91         if (hsr0 & HSR0_ETMD)
  92                 __set_HSR(0, __get_HSR(0) | HSR0_ETMD);
  93
  94 } /* end debug_stub() */
  95
  96 /*****************************************************************************/
  97 /*
  98  * debug stub initialisation
  99  */
 100 static void __init debug_stub_init(void)
 101 {
 102         __set_IRR(6, 0xff000000);       /* map ERRs to NMI */
 103         __set_IITMR(1, 0x20000000);     /* ERR0/1, UART0/1 IRQ detect levels */
 104
 105         asm volatile("  movgs   gr0,ibar0       \n"
 106                      "  movgs   gr0,ibar1       \n"
 107                      "  movgs   gr0,ibar2       \n"
 108                      "  movgs   gr0,ibar3       \n"
 109                      "  movgs   gr0,dbar0       \n"
 110                      "  movgs   gr0,dbmr00      \n"
 111                      "  movgs   gr0,dbmr01      \n"
 112                      "  movgs   gr0,dbdr00      \n"
 113                      "  movgs   gr0,dbdr01      \n"
 114                      "  movgs   gr0,dbar1       \n"
 115                      "  movgs   gr0,dbmr10      \n"
 116                      "  movgs   gr0,dbmr11      \n"
 117                      "  movgs   gr0,dbdr10      \n"
 118                      "  movgs   gr0,dbdr11      \n"
 119                      );
 120
 121         /* deal with debugging stub initialisation and initial pause */
 122         if (__debug_frame->pc == (unsigned long) __debug_stub_init_break)
 123                 __debug_frame->pc = (unsigned long) start_kernel;
 124
 125         /* enable the debug events we want to trap */
 126         __debug_status.dcr = DCR_EBE;
 127
 128 #ifdef CONFIG_GDBSTUB
 129         gdbstub_init();
 130 #endif
 131
 132         __clr_MASK_all();
 133         __clr_MASK(15);
 134         __clr_RC(15);
 135
 136 } /* end debug_stub_init() */
 137
 138 /*****************************************************************************/
 139 /*
 140  * kernel "exit" trap for gdb stub
 141  */
 142 void debug_stub_exit(int status)
 143 {
 144
 145 #ifdef CONFIG_GDBSTUB
 146         gdbstub_exit(status);
 147 #endif
 148
 149 } /* end debug_stub_exit() */
 150
 151 /*****************************************************************************/
 152 /*
 153  * send string to serial port
 154  */
 155 void debug_to_serial(const char *p, int n)
 156 {
 157         char ch;
 158
 159         for (; n > 0; n--) {
 160                 ch = *p++;
 161                 FLOWCTL_SET0(DTR);
 162                 LSR_WAIT_FOR0(THRE);
 163                 // FLOWCTL_WAIT_FOR(CTS);
 164
 165                 if (ch == 0x0a) {
 166                         __UART0(TX) = 0x0d;
 167                         mb();
 168                         LSR_WAIT_FOR0(THRE);
 169                         // FLOWCTL_WAIT_FOR(CTS);
 170                 }
 171                 __UART0(TX) = ch;
 172                 mb();
 173
 174                 FLOWCTL_CLEAR0(DTR);
 175         }
 176
 177 } /* end debug_to_serial() */
 178
 179 /*****************************************************************************/
 180 /*
 181  * send string to serial port
 182  */
 183 void debug_to_serial2(const char *fmt, ...)
 184 {
 185         va_list va;
 186         char buf[64];
 187         int n;
 188
 189         va_start(va, fmt);
 190         n = vsprintf(buf, fmt, va);
 191         va_end(va);
 192
 193         debug_to_serial(buf, n);
 194
 195 } /* end debug_to_serial2() */
 196
 197 /*****************************************************************************/
 198 /*
 199  * set up the ttyS0 serial port baud rate timers
 200  */
 201 void __init console_set_baud(unsigned baud)
 202 {
 203         unsigned value, high, low;
 204         u8 lcr;
 205
 206         /* work out the divisor to give us the nearest higher baud rate */
 207         value = __serial_clock_speed_HZ / 16 / baud;
 208
 209         /* determine the baud rate range */
 210         high = __serial_clock_speed_HZ / 16 / value;
 211         low = __serial_clock_speed_HZ / 16 / (value + 1);
 212
 213         /* pick the nearest bound */
 214         if (low + (high - low) / 2 > baud)
 215                 value++;
 216
 217         lcr = __UART0(LCR);
 218         __UART0(LCR) |= UART_LCR_DLAB;
 219         mb();
 220         __UART0(DLL) = value & 0xff;
 221         __UART0(DLM) = (value >> 8) & 0xff;
 222         mb();
 223         __UART0(LCR) = lcr;
 224         mb();
 225
 226 } /* end console_set_baud() */
 227
 228 /*****************************************************************************/
 229 /*
 230  *
 231  */
 232 int __init console_get_baud(void)
 233 {
 234         unsigned value;
 235         u8 lcr;
 236
 237         lcr = __UART0(LCR);
 238         __UART0(LCR) |= UART_LCR_DLAB;
 239         mb();
 240         value =  __UART0(DLM) << 8;
 241         value |= __UART0(DLL);
 242         __UART0(LCR) = lcr;
 243         mb();
 244
 245         return value;
 246 } /* end console_get_baud() */
 247
 248 /*****************************************************************************/
 249 /*
 250  * display BUG() info
 251  */
 252 #ifndef CONFIG_NO_KERNEL_MSG
 253 void __debug_bug_printk(const char *file, unsigned line)
 254 {
 255         printk("kernel BUG at %s:%d!\n", file, line);
 256
 257 } /* end __debug_bug_printk() */
 258 #endif