gdb-io-ttysm.c

Go to the documentation of this file.

/* MN10300 On-chip serial driver for gdbstub I/O
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, 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/mm.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <asm/pgtable.h>
#include <asm/gdb-stub.h>
#include <asm/exceptions.h>
#include <unit/clock.h>
#include "mn10300-serial.h"

#if defined(CONFIG_GDBSTUB_ON_TTYSM0)
struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif0;
#elif defined(CONFIG_GDBSTUB_ON_TTYSM1)
struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif1;
#else
struct mn10300_serial_port *const gdbstub_port = &mn10300_serial_port_sif2;
#endif


/*
 * initialise the GDB stub I/O routines
 */
void __init gdbstub_io_init(void)
{
    uint16_t scxctr;
    int tmp;

    switch (gdbstub_port->clock_src) {
    case MNSCx_CLOCK_SRC_IOCLK:
        gdbstub_port->ioclk = MN10300_IOCLK;
        break;

#ifdef MN10300_IOBCLK
    case MNSCx_CLOCK_SRC_IOBCLK:
        gdbstub_port->ioclk = MN10300_IOBCLK;
        break;
#endif
    default:
        BUG();
    }

    /* set up the serial port */
    gdbstub_io_set_baud(115200);

    /* we want to get serial receive interrupts */
    set_intr_level(gdbstub_port->rx_irq,
        NUM2GxICR_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL));
    set_intr_level(gdbstub_port->tx_irq,
        NUM2GxICR_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL));
    set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_DEBUGGER_IRQ_LEVEL),
        gdbstub_io_rx_handler);

    *gdbstub_port->rx_icr |= GxICR_ENABLE;
    tmp = *gdbstub_port->rx_icr;

    /* enable the device */
    scxctr = SC01CTR_CLN_8BIT;  /* 1N8 */
    switch (gdbstub_port->div_timer) {
    case MNSCx_DIV_TIMER_16BIT:
        scxctr |= SC0CTR_CK_TM8UFLOW_8; /* == SC1CTR_CK_TM9UFLOW_8
                           == SC2CTR_CK_TM10UFLOW_8 */
        break;

    case MNSCx_DIV_TIMER_8BIT:
        scxctr |= SC0CTR_CK_TM2UFLOW_8;
        break;
    }

    scxctr |= SC01CTR_TXE | SC01CTR_RXE;

    *gdbstub_port->_control = scxctr;
    tmp = *gdbstub_port->_control;

    /* permit level 0 IRQs only */
    arch_local_change_intr_mask_level(
        NUM2EPSW_IM(CONFIG_DEBUGGER_IRQ_LEVEL + 1));
}

/*
 * set up the GDB stub serial port baud rate timers
 */
void gdbstub_io_set_baud(unsigned baud)
{
    const unsigned bits = 10; /* 1 [start] + 8 [data] + 0 [parity] +
                   * 1 [stop] */
    unsigned long ioclk = gdbstub_port->ioclk;
    unsigned xdiv, tmp;
    uint16_t tmxbr;
    uint8_t tmxmd;

    if (!baud) {
        baud = 9600;
    } else if (baud == 134) {
        baud = 269; /* 134 is really 134.5 */
        xdiv = 2;
    }

try_alternative:
    xdiv = 1;

    switch (gdbstub_port->div_timer) {
    case MNSCx_DIV_TIMER_16BIT:
        tmxmd = TM8MD_SRC_IOCLK;
        tmxbr = tmp = (ioclk / (baud * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 65535)
            goto timer_okay;

        tmxmd = TM8MD_SRC_IOCLK_8;
        tmxbr = tmp = (ioclk / (baud * 8 * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 65535)
            goto timer_okay;

        tmxmd = TM8MD_SRC_IOCLK_32;
        tmxbr = tmp = (ioclk / (baud * 32 * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 65535)
            goto timer_okay;

        break;

    case MNSCx_DIV_TIMER_8BIT:
        tmxmd = TM2MD_SRC_IOCLK;
        tmxbr = tmp = (ioclk / (baud * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 255)
            goto timer_okay;

        tmxmd = TM2MD_SRC_IOCLK_8;
        tmxbr = tmp = (ioclk / (baud * 8 * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 255)
            goto timer_okay;

        tmxmd = TM2MD_SRC_IOCLK_32;
        tmxbr = tmp = (ioclk / (baud * 32 * xdiv) + 4) / 8 - 1;
        if (tmp > 0 && tmp <= 255)
            goto timer_okay;
        break;
    }

    /* as a last resort, if the quotient is zero, default to 9600 bps */
    baud = 9600;
    goto try_alternative;

timer_okay:
    gdbstub_port->uart.timeout = (2 * bits * HZ) / baud;
    gdbstub_port->uart.timeout += HZ / 50;

    /* set the timer to produce the required baud rate */
    switch (gdbstub_port->div_timer) {
    case MNSCx_DIV_TIMER_16BIT:
        *gdbstub_port->_tmxmd = 0;
        *gdbstub_port->_tmxbr = tmxbr;
        *gdbstub_port->_tmxmd = TM8MD_INIT_COUNTER;
        *gdbstub_port->_tmxmd = tmxmd | TM8MD_COUNT_ENABLE;
        break;

    case MNSCx_DIV_TIMER_8BIT:
        *gdbstub_port->_tmxmd = 0;
        *(volatile u8 *) gdbstub_port->_tmxbr = (u8)tmxbr;
        *gdbstub_port->_tmxmd = TM2MD_INIT_COUNTER;
        *gdbstub_port->_tmxmd = tmxmd | TM2MD_COUNT_ENABLE;
        break;
    }
}

/*
 * wait for a character to come from the debugger
 */
int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
{
    unsigned ix;
    u8 ch, st;
#if defined(CONFIG_MN10300_WD_TIMER)
    int cpu;
#endif

    *_ch = 0xff;

    if (gdbstub_rx_unget) {
        *_ch = gdbstub_rx_unget;
        gdbstub_rx_unget = 0;
        return 0;
    }

try_again:
    /* pull chars out of the buffer */
    ix = gdbstub_rx_outp;
    barrier();
    if (ix == gdbstub_rx_inp) {
        if (nonblock)
            return -EAGAIN;
#ifdef CONFIG_MN10300_WD_TIMER
    for (cpu = 0; cpu < NR_CPUS; cpu++)
        watchdog_alert_counter[cpu] = 0;
#endif
        goto try_again;
    }

    ch = gdbstub_rx_buffer[ix++];
    st = gdbstub_rx_buffer[ix++];
    barrier();
    gdbstub_rx_outp = ix & (PAGE_SIZE - 1);

    st &= SC01STR_RXF | SC01STR_RBF | SC01STR_FEF | SC01STR_PEF |
        SC01STR_OEF;

    /* deal with what we've got
     * - note that the UART doesn't do BREAK-detection for us
     */
    if (st & SC01STR_FEF && ch == 0) {
        switch (gdbstub_port->rx_brk) {
        case 0: gdbstub_port->rx_brk = 1;   goto try_again;
        case 1: gdbstub_port->rx_brk = 2;   goto try_again;
        case 2:
            gdbstub_port->rx_brk = 3;
            gdbstub_proto("### GDB MNSERIAL Rx Break Detected"
                      " ###\n");
            return -EINTR;
        default:
            goto try_again;
        }
    } else if (st & SC01STR_FEF) {
        if (gdbstub_port->rx_brk)
            goto try_again;

        gdbstub_proto("### GDB MNSERIAL Framing Error ###\n");
        return -EIO;
    } else if (st & SC01STR_OEF) {
        if (gdbstub_port->rx_brk)
            goto try_again;

        gdbstub_proto("### GDB MNSERIAL Overrun Error ###\n");
        return -EIO;
    } else if (st & SC01STR_PEF) {
        if (gdbstub_port->rx_brk)
            goto try_again;

        gdbstub_proto("### GDB MNSERIAL Parity Error ###\n");
        return -EIO;
    } else {
        /* look for the tail-end char on a break run */
        if (gdbstub_port->rx_brk == 3) {
            switch (ch) {
            case 0xFF:
            case 0xFE:
            case 0xFC:
            case 0xF8:
            case 0xF0:
            case 0xE0:
            case 0xC0:
            case 0x80:
            case 0x00:
                gdbstub_port->rx_brk = 0;
                goto try_again;
            default:
                break;
            }
        }

        gdbstub_port->rx_brk = 0;
        gdbstub_io("### GDB Rx %02x (st=%02x) ###\n", ch, st);
        *_ch = ch & 0x7f;
        return 0;
    }
}

/*
 * send a character to the debugger
 */
void gdbstub_io_tx_char(unsigned char ch)
{
    while (*gdbstub_port->_status & SC01STR_TBF)
        continue;

    if (ch == 0x0a) {
        *(u8 *) gdbstub_port->_txb = 0x0d;
        while (*gdbstub_port->_status & SC01STR_TBF)
            continue;
    }

    *(u8 *) gdbstub_port->_txb = ch;
}

/*
 * flush the transmission buffers
 */
void gdbstub_io_tx_flush(void)
{
    while (*gdbstub_port->_status & (SC01STR_TBF | SC01STR_TXF))
        continue;
}