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debug-stub.c

/* debug-stub.c: debug-mode stub
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/serial_reg.h>
#include <linux/start_kernel.h>

#include <asm/system.h>
#include <asm/serial-regs.h>
#include <asm/timer-regs.h>
#include <asm/irc-regs.h>
#include <asm/gdb-stub.h>
#include "gdb-io.h"

/* CPU board CON5 */
#define __UART0(X) (*(volatile uint8_t *)(UART0_BASE + (UART_##X)))

#define LSR_WAIT_FOR0(STATE)              \
do {                                \
} while (!(__UART0(LSR) & UART_LSR_##STATE))

#define FLOWCTL_QUERY0(LINE)  ({ __UART0(MSR) & UART_MSR_##LINE; })
#define FLOWCTL_CLEAR0(LINE)  do { __UART0(MCR) &= ~UART_MCR_##LINE; } while (0)
#define FLOWCTL_SET0(LINE)    do { __UART0(MCR) |= UART_MCR_##LINE; } while (0)

#define FLOWCTL_WAIT_FOR0(LINE)                 \
do {                                \
      gdbstub_do_rx();              \
} while(!FLOWCTL_QUERY(LINE))

struct frv_debug_status __debug_status;

static void __init debug_stub_init(void);

/*****************************************************************************/
/*
 * debug mode handler stub
 * - we come here with the CPU in debug mode and with exceptions disabled
 * - handle debugging services for userspace
 */
asmlinkage void debug_stub(void)
{
      unsigned long hsr0;
      int type = 0;

      static u8 inited = 0;
      if (!inited) {
            debug_stub_init();
            type = -1;
            inited = 1;
      }

      hsr0 = __get_HSR(0);
      if (hsr0 & HSR0_ETMD)
            __set_HSR(0, hsr0 & ~HSR0_ETMD);

      /* disable single stepping */
      __debug_status.dcr &= ~DCR_SE;

      /* kernel mode can propose an exception be handled in debug mode by jumping to a special
       * location */
      if (__debug_frame->pc == (unsigned long) __break_hijack_kernel_event_breaks_here) {
            /* replace the debug frame with the kernel frame and discard
             * the top kernel context */
            *__debug_frame = *__frame;
            __frame = __debug_frame->next_frame;
            __debug_status.brr = (__debug_frame->tbr & TBR_TT) << 12;
            __debug_status.brr |= BRR_EB;
      }

      if (__debug_frame->pc == (unsigned long) __debug_bug_trap + 4) {
            __debug_frame->pc = __debug_frame->lr;
            type = __debug_frame->gr8;
      }

#ifdef CONFIG_GDBSTUB
      gdbstub(type);
#endif

      if (hsr0 & HSR0_ETMD)
            __set_HSR(0, __get_HSR(0) | HSR0_ETMD);

} /* end debug_stub() */

/*****************************************************************************/
/*
 * debug stub initialisation
 */
static void __init debug_stub_init(void)
{
      __set_IRR(6, 0xff000000);     /* map ERRs to NMI */
      __set_IITMR(1, 0x20000000);   /* ERR0/1, UART0/1 IRQ detect levels */

      asm volatile("    movgs gr0,ibar0   \n"
                 "      movgs gr0,ibar1   \n"
                 "      movgs gr0,ibar2   \n"
                 "      movgs gr0,ibar3   \n"
                 "      movgs gr0,dbar0   \n"
                 "      movgs gr0,dbmr00  \n"
                 "      movgs gr0,dbmr01  \n"
                 "      movgs gr0,dbdr00  \n"
                 "      movgs gr0,dbdr01  \n"
                 "      movgs gr0,dbar1   \n"
                 "      movgs gr0,dbmr10  \n"
                 "      movgs gr0,dbmr11  \n"
                 "      movgs gr0,dbdr10  \n"
                 "      movgs gr0,dbdr11  \n"
                 );

      /* deal with debugging stub initialisation and initial pause */
      if (__debug_frame->pc == (unsigned long) __debug_stub_init_break)
            __debug_frame->pc = (unsigned long) start_kernel;

      /* enable the debug events we want to trap */
      __debug_status.dcr = DCR_EBE;

#ifdef CONFIG_GDBSTUB
      gdbstub_init();
#endif

      __clr_MASK_all();
      __clr_MASK(15);
      __clr_RC(15);

} /* end debug_stub_init() */

/*****************************************************************************/
/*
 * kernel "exit" trap for gdb stub
 */
void debug_stub_exit(int status)
{

#ifdef CONFIG_GDBSTUB
      gdbstub_exit(status);
#endif

} /* end debug_stub_exit() */

/*****************************************************************************/
/*
 * send string to serial port
 */
void debug_to_serial(const char *p, int n)
{
      char ch;

      for (; n > 0; n--) {
            ch = *p++;
            FLOWCTL_SET0(DTR);
            LSR_WAIT_FOR0(THRE);
            // FLOWCTL_WAIT_FOR(CTS);

            if (ch == 0x0a) {
                  __UART0(TX) = 0x0d;
                  mb();
                  LSR_WAIT_FOR0(THRE);
                  // FLOWCTL_WAIT_FOR(CTS);
            }
            __UART0(TX) = ch;
            mb();

            FLOWCTL_CLEAR0(DTR);
      }

} /* end debug_to_serial() */

/*****************************************************************************/
/*
 * send string to serial port
 */
void debug_to_serial2(const char *fmt, ...)
{
      va_list va;
      char buf[64];
      int n;

      va_start(va, fmt);
      n = vsprintf(buf, fmt, va);
      va_end(va);

      debug_to_serial(buf, n);

} /* end debug_to_serial2() */

/*****************************************************************************/
/*
 * set up the ttyS0 serial port baud rate timers
 */
void __init console_set_baud(unsigned baud)
{
      unsigned value, high, low;
      u8 lcr;

      /* work out the divisor to give us the nearest higher baud rate */
      value = __serial_clock_speed_HZ / 16 / baud;

      /* determine the baud rate range */
      high = __serial_clock_speed_HZ / 16 / value;
      low = __serial_clock_speed_HZ / 16 / (value + 1);

      /* pick the nearest bound */
      if (low + (high - low) / 2 > baud)
            value++;

      lcr = __UART0(LCR);
      __UART0(LCR) |= UART_LCR_DLAB;
      mb();
      __UART0(DLL) = value & 0xff;
      __UART0(DLM) = (value >> 8) & 0xff;
      mb();
      __UART0(LCR) = lcr;
      mb();

} /* end console_set_baud() */

/*****************************************************************************/
/*
 *
 */
int __init console_get_baud(void)
{
      unsigned value;
      u8 lcr;

      lcr = __UART0(LCR);
      __UART0(LCR) |= UART_LCR_DLAB;
      mb();
      value =  __UART0(DLM) << 8;
      value |= __UART0(DLL);
      __UART0(LCR) = lcr;
      mb();

      return value;
} /* end console_get_baud() */

/*****************************************************************************/
/*
 * display BUG() info
 */
#ifndef CONFIG_NO_KERNEL_MSG
void __debug_bug_printk(const char *file, unsigned line)
{
      printk("kernel BUG at %s:%d!\n", file, line);

} /* end __debug_bug_printk() */
#endif

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