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linux/arch/mn10300/kernel/gdb-io-ttysm.c
David Howells 5efe92c680 MN10300: Introduce barriers to replace removed volatiles in gdbstub 
Introduce into the MN10300 gdbstub a couple of barrier() calls to replace the
removed volatility of the input/output index variables for the Rx ring buffer.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-19 15:51:36 -08:00

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/* MN10300 On-chip serial driver for gdbstub I/O
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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/system.h>
#include <asm/gdb-stub.h>
#include <asm/exceptions.h>
#include <asm/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, GxICR_LEVEL_0);
set_intr_level(gdbstub_port->tx_irq, GxICR_LEVEL_0);
set_intr_stub(EXCEP_IRQ_LEVEL0, 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 */
asm volatile(
" and %0,epsw \n"
" or %1,epsw \n"
:
: "i"(~EPSW_IM), "i"(EPSW_IE|EPSW_IM_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;
*_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
watchdog_alert_counter = 0;
#endif /* CONFIG_MN10300_WD_TIMER */
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;
}
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