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 #include <asm/smp.h>
  27
  28 /*
  29  * initialise the GDB stub
  30  */
  31 void gdbstub_io_init(void)
  32 {
  33         u16 tmp;
  34
  35         /* set up the serial port */
  36         GDBPORT_SERIAL_LCR = UART_LCR_WLEN8; /* 1N8 */
  37         GDBPORT_SERIAL_FCR = (UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
  38                               UART_FCR_CLEAR_XMIT);
  39
  40         FLOWCTL_CLEAR(DTR);
  41         FLOWCTL_SET(RTS);
  42
  43         gdbstub_io_set_baud(115200);
  44
  45         /* we want to get serial receive interrupts */
  46         XIRQxICR(GDBPORT_SERIAL_IRQ) = 0;
  47         tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
  48
  49 #if   CONFIG_GDBSTUB_IRQ_LEVEL == 0
  50         IVAR0 = EXCEP_IRQ_LEVEL0;
  51 #elif CONFIG_GDBSTUB_IRQ_LEVEL == 1
  52         IVAR1 = EXCEP_IRQ_LEVEL1;
  53 #elif CONFIG_GDBSTUB_IRQ_LEVEL == 2
  54         IVAR2 = EXCEP_IRQ_LEVEL2;
  55 #elif CONFIG_GDBSTUB_IRQ_LEVEL == 3
  56         IVAR3 = EXCEP_IRQ_LEVEL3;
  57 #elif CONFIG_GDBSTUB_IRQ_LEVEL == 4
  58         IVAR4 = EXCEP_IRQ_LEVEL4;
  59 #elif CONFIG_GDBSTUB_IRQ_LEVEL == 5
  60         IVAR5 = EXCEP_IRQ_LEVEL5;
  61 #else
  62 #error "Unknown irq level for gdbstub."
  63 #endif
  64
  65         set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL),
  66                 gdbstub_io_rx_handler);
  67
  68         XIRQxICR(GDBPORT_SERIAL_IRQ) &= ~GxICR_REQUEST;
  69         XIRQxICR(GDBPORT_SERIAL_IRQ) =
  70                 GxICR_ENABLE | NUM2GxICR_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL);
  71         tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
  72
  73         GDBPORT_SERIAL_IER = UART_IER_RDI | UART_IER_RLSI;
  74
  75         /* permit level 0 IRQs to take place */
  76         arch_local_change_intr_mask_level(
  77                 NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
  78 }
  79
  80 /*
  81  * set up the GDB stub serial port baud rate timers
  82  */
  83 void gdbstub_io_set_baud(unsigned baud)
  84 {
  85         unsigned value;
  86         u8 lcr;
  87
  88         value = 18432000 / 16 / baud;
  89
  90         lcr = GDBPORT_SERIAL_LCR;
  91         GDBPORT_SERIAL_LCR |= UART_LCR_DLAB;
  92         GDBPORT_SERIAL_DLL = value & 0xff;
  93         GDBPORT_SERIAL_DLM = (value >> 8) & 0xff;
  94         GDBPORT_SERIAL_LCR = lcr;
  95 }
  96
  97 /*
  98  * wait for a character to come from the debugger
  99  */
 100 int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
 101 {
 102         unsigned ix;
 103         u8 ch, st;
 104 #if defined(CONFIG_MN10300_WD_TIMER)
 105         int cpu;
 106 #endif
 107
 108         *_ch = 0xff;
 109
 110         if (gdbstub_rx_unget) {
 111                 *_ch = gdbstub_rx_unget;
 112                 gdbstub_rx_unget = 0;
 113                 return 0;
 114         }
 115
 116  try_again:
 117         /* pull chars out of the buffer */
 118         ix = gdbstub_rx_outp;
 119         barrier();
 120         if (ix == gdbstub_rx_inp) {
 121                 if (nonblock)
 122                         return -EAGAIN;
 123 #ifdef CONFIG_MN10300_WD_TIMER
 124         for (cpu = 0; cpu < NR_CPUS; cpu++)
 125                 watchdog_alert_counter[cpu] = 0;
 126 #endif
 127                 goto try_again;
 128         }
 129
 130         ch = gdbstub_rx_buffer[ix++];
 131         st = gdbstub_rx_buffer[ix++];
 132         barrier();
 133         gdbstub_rx_outp = ix & 0x00000fff;
 134
 135         if (st & UART_LSR_BI) {
 136                 gdbstub_proto("### GDB Rx Break Detected ###\n");
 137                 return -EINTR;
 138         } else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
 139                 gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
 140                 return -EIO;
 141         } else {
 142                 gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
 143                 *_ch = ch & 0x7f;
 144                 return 0;
 145         }
 146 }
 147
 148 /*
 149  * send a character to the debugger
 150  */
 151 void gdbstub_io_tx_char(unsigned char ch)
 152 {
 153         FLOWCTL_SET(DTR);
 154         LSR_WAIT_FOR(THRE);
 155         /* FLOWCTL_WAIT_FOR(CTS); */
 156
 157         if (ch == 0x0a) {
 158                 GDBPORT_SERIAL_TX = 0x0d;
 159                 LSR_WAIT_FOR(THRE);
 160                 /* FLOWCTL_WAIT_FOR(CTS); */
 161         }
 162         GDBPORT_SERIAL_TX = ch;
 163
 164         FLOWCTL_CLEAR(DTR);
 165 }
 166
 167 /*
 168  * send a character to the debugger
 169  */
 170 void gdbstub_io_tx_flush(void)
 171 {
 172         LSR_WAIT_FOR(TEMT);
 173         LSR_WAIT_FOR(THRE);
 174         FLOWCTL_CLEAR(DTR);
 175 }