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