linux/arch/mn10300/kernel/gdb-io-serial.c
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   1/* 16550 serial driver for gdbstub I/O
   2 *
   3 * Copyright (C) 2007 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 Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11#include <linux/string.h>
  12#include <linux/kernel.h>
  13#include <linux/signal.h>
  14#include <linux/sched.h>
  15#include <linux/mm.h>
  16#include <linux/console.h>
  17#include <linux/init.h>
  18#include <linux/nmi.h>
  19
  20#include <asm/pgtable.h>
  21#include <asm/system.h>
  22#include <asm/gdb-stub.h>
  23#include <asm/exceptions.h>
  24#include <asm/serial-regs.h>
  25#include <asm/unit/serial.h>
  26
  27/*
  28 * initialise the GDB stub
  29 */
  30void gdbstub_io_init(void)
  31{
  32        u16 tmp;
  33
  34        /* set up the serial port */
  35        GDBPORT_SERIAL_LCR = UART_LCR_WLEN8; /* 1N8 */
  36        GDBPORT_SERIAL_FCR = (UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
  37                              UART_FCR_CLEAR_XMIT);
  38
  39        FLOWCTL_CLEAR(DTR);
  40        FLOWCTL_SET(RTS);
  41
  42        gdbstub_io_set_baud(115200);
  43
  44        /* we want to get serial receive interrupts */
  45        XIRQxICR(GDBPORT_SERIAL_IRQ) = 0;
  46        tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
  47
  48        IVAR0 = EXCEP_IRQ_LEVEL0;
  49        set_intr_stub(EXCEP_IRQ_LEVEL0, gdbstub_io_rx_handler);
  50
  51        XIRQxICR(GDBPORT_SERIAL_IRQ) &= ~GxICR_REQUEST;
  52        XIRQxICR(GDBPORT_SERIAL_IRQ) = GxICR_ENABLE | GxICR_LEVEL_0;
  53        tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
  54
  55        GDBPORT_SERIAL_IER = UART_IER_RDI | UART_IER_RLSI;
  56
  57        /* permit level 0 IRQs to take place */
  58        asm volatile(
  59                "       and %0,epsw     \n"
  60                "       or %1,epsw      \n"
  61                :
  62                : "i"(~EPSW_IM), "i"(EPSW_IE | EPSW_IM_1)
  63                );
  64}
  65
  66/*
  67 * set up the GDB stub serial port baud rate timers
  68 */
  69void gdbstub_io_set_baud(unsigned baud)
  70{
  71        unsigned value;
  72        u8 lcr;
  73
  74        value = 18432000 / 16 / baud;
  75
  76        lcr = GDBPORT_SERIAL_LCR;
  77        GDBPORT_SERIAL_LCR |= UART_LCR_DLAB;
  78        GDBPORT_SERIAL_DLL = value & 0xff;
  79        GDBPORT_SERIAL_DLM = (value >> 8) & 0xff;
  80        GDBPORT_SERIAL_LCR = lcr;
  81}
  82
  83/*
  84 * wait for a character to come from the debugger
  85 */
  86int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
  87{
  88        unsigned ix;
  89        u8 ch, st;
  90
  91        *_ch = 0xff;
  92
  93        if (gdbstub_rx_unget) {
  94                *_ch = gdbstub_rx_unget;
  95                gdbstub_rx_unget = 0;
  96                return 0;
  97        }
  98
  99 try_again:
 100        /* pull chars out of the buffer */
 101        ix = gdbstub_rx_outp;
 102        if (ix == gdbstub_rx_inp) {
 103                if (nonblock)
 104                        return -EAGAIN;
 105#ifdef CONFIG_MN10300_WD_TIMER
 106                watchdog_alert_counter = 0;
 107#endif /* CONFIG_MN10300_WD_TIMER */
 108                goto try_again;
 109        }
 110
 111        ch = gdbstub_rx_buffer[ix++];
 112        st = gdbstub_rx_buffer[ix++];
 113        gdbstub_rx_outp = ix & 0x00000fff;
 114
 115        if (st & UART_LSR_BI) {
 116                gdbstub_proto("### GDB Rx Break Detected ###\n");
 117                return -EINTR;
 118        } else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
 119                gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
 120                return -EIO;
 121        } else {
 122                gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
 123                *_ch = ch & 0x7f;
 124                return 0;
 125        }
 126}
 127
 128/*
 129 * send a character to the debugger
 130 */
 131void gdbstub_io_tx_char(unsigned char ch)
 132{
 133        FLOWCTL_SET(DTR);
 134        LSR_WAIT_FOR(THRE);
 135        /* FLOWCTL_WAIT_FOR(CTS); */
 136
 137        if (ch == 0x0a) {
 138                GDBPORT_SERIAL_TX = 0x0d;
 139                LSR_WAIT_FOR(THRE);
 140                /* FLOWCTL_WAIT_FOR(CTS); */
 141        }
 142        GDBPORT_SERIAL_TX = ch;
 143
 144        FLOWCTL_CLEAR(DTR);
 145}
 146
 147/*
 148 * send a character to the debugger
 149 */
 150void gdbstub_io_tx_flush(void)
 151{
 152        LSR_WAIT_FOR(TEMT);
 153        LSR_WAIT_FOR(THRE);
 154        FLOWCTL_CLEAR(DTR);
 155}
 156