arch/mn10300/kernel/gdb-io-serial.c

   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 <unit/serial.h>
  26
  27 /*
  28  * initialise the GDB stub
  29  */
  30 void 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  */
  69 void 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  */
  86 int 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         barrier();
 103         if (ix == gdbstub_rx_inp) {
 104                 if (nonblock)
 105                         return -EAGAIN;
 106 #ifdef CONFIG_MN10300_WD_TIMER
 107                 watchdog_alert_counter = 0;
 108 #endif /* CONFIG_MN10300_WD_TIMER */
 109                 goto try_again;
 110         }
 111
 112         ch = gdbstub_rx_buffer[ix++];
 113         st = gdbstub_rx_buffer[ix++];
 114         barrier();
 115         gdbstub_rx_outp = ix & 0x00000fff;
 116
 117         if (st & UART_LSR_BI) {
 118                 gdbstub_proto("### GDB Rx Break Detected ###\n");
 119                 return -EINTR;
 120         } else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
 121                 gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
 122                 return -EIO;
 123         } else {
 124                 gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
 125                 *_ch = ch & 0x7f;
 126                 return 0;
 127         }
 128 }
 129
 130 /*
 131  * send a character to the debugger
 132  */
 133 void gdbstub_io_tx_char(unsigned char ch)
 134 {
 135         FLOWCTL_SET(DTR);
 136         LSR_WAIT_FOR(THRE);
 137         /* FLOWCTL_WAIT_FOR(CTS); */
 138
 139         if (ch == 0x0a) {
 140                 GDBPORT_SERIAL_TX = 0x0d;
 141                 LSR_WAIT_FOR(THRE);
 142                 /* FLOWCTL_WAIT_FOR(CTS); */
 143         }
 144         GDBPORT_SERIAL_TX = ch;
 145
 146         FLOWCTL_CLEAR(DTR);
 147 }
 148
 149 /*
 150  * send a character to the debugger
 151  */
 152 void gdbstub_io_tx_flush(void)
 153 {
 154         LSR_WAIT_FOR(TEMT);
 155         LSR_WAIT_FOR(THRE);
 156         FLOWCTL_CLEAR(DTR);
 157 }