/* 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/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