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         local_change_intr_mask_level(NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
  77 }
  78
  79 /*
  80  * set up the GDB stub serial port baud rate timers
  81  */
  82 void gdbstub_io_set_baud(unsigned baud)
  83 {
  84         unsigned value;
  85         u8 lcr;
  86
  87         value = 18432000 / 16 / baud;
  88
  89         lcr = GDBPORT_SERIAL_LCR;
  90         GDBPORT_SERIAL_LCR |= UART_LCR_DLAB;
  91         GDBPORT_SERIAL_DLL = value & 0xff;
  92         GDBPORT_SERIAL_DLM = (value >> 8) & 0xff;
  93         GDBPORT_SERIAL_LCR = lcr;
  94 }
  95
  96 /*
  97  * wait for a character to come from the debugger
  98  */
  99 int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
 100 {
 101         unsigned ix;
 102         u8 ch, st;
 103 #if defined(CONFIG_MN10300_WD_TIMER)
 104         int cpu;
 105 #endif
 106
 107         *_ch = 0xff;
 108
 109         if (gdbstub_rx_unget) {
 110                 *_ch = gdbstub_rx_unget;
 111                 gdbstub_rx_unget = 0;
 112                 return 0;
 113         }
 114
 115  try_again:
 116         /* pull chars out of the buffer */
 117         ix = gdbstub_rx_outp;
 118         barrier();
 119         if (ix == gdbstub_rx_inp) {
 120                 if (nonblock)
 121                         return -EAGAIN;
 122 #ifdef CONFIG_MN10300_WD_TIMER
 123         for (cpu = 0; cpu < NR_CPUS; cpu++)
 124                 watchdog_alert_counter[cpu] = 0;
 125 #endif
 126                 goto try_again;
 127         }
 128
 129         ch = gdbstub_rx_buffer[ix++];
 130         st = gdbstub_rx_buffer[ix++];
 131         barrier();
 132         gdbstub_rx_outp = ix & 0x00000fff;
 133
 134         if (st & UART_LSR_BI) {
 135                 gdbstub_proto("### GDB Rx Break Detected ###\n");
 136                 return -EINTR;
 137         } else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
 138                 gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
 139                 return -EIO;
 140         } else {
 141                 gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
 142                 *_ch = ch & 0x7f;
 143                 return 0;
 144         }
 145 }
 146
 147 /*
 148  * send a character to the debugger
 149  */
 150 void gdbstub_io_tx_char(unsigned char ch)
 151 {
 152         FLOWCTL_SET(DTR);
 153         LSR_WAIT_FOR(THRE);
 154         /* FLOWCTL_WAIT_FOR(CTS); */
 155
 156         if (ch == 0x0a) {
 157                 GDBPORT_SERIAL_TX = 0x0d;
 158                 LSR_WAIT_FOR(THRE);
 159                 /* FLOWCTL_WAIT_FOR(CTS); */
 160         }
 161         GDBPORT_SERIAL_TX = ch;
 162
 163         FLOWCTL_CLEAR(DTR);
 164 }
 165
 166 /*
 167  * send a character to the debugger
 168  */
 169 void gdbstub_io_tx_flush(void)
 170 {
 171         LSR_WAIT_FOR(TEMT);
 172         LSR_WAIT_FOR(THRE);
 173         FLOWCTL_CLEAR(DTR);
 174 }