linux/arch/mips/mti-sead3/sead3-init.c
Steven J. Hill 2a0b24f56c MIPS: microMIPS: Add support for exception handling.
All exceptions must be taken in microMIPS mode, never in classic
MIPS mode or the kernel falls apart. A few NOP instructions are
used to maintain the correct alignment of microMIPS versions of
the exception vectors.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
2013-05-09 17:55:18 +02:00

153 lines
3.9 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/init.h>
#include <linux/io.h>
#include <asm/bootinfo.h>
#include <asm/cacheflush.h>
#include <asm/traps.h>
#include <asm/mips-boards/generic.h>
#include <asm/fw/fw.h>
extern char except_vec_nmi;
extern char except_vec_ejtag_debug;
#ifdef CONFIG_SERIAL_8250_CONSOLE
static void __init console_config(void)
{
char console_string[40];
int baud = 0;
char parity = '\0', bits = '\0', flow = '\0';
char *s;
if ((strstr(fw_getcmdline(), "console=")) == NULL) {
s = fw_getenv("modetty0");
if (s) {
while (*s >= '0' && *s <= '9')
baud = baud*10 + *s++ - '0';
if (*s == ',')
s++;
if (*s)
parity = *s++;
if (*s == ',')
s++;
if (*s)
bits = *s++;
if (*s == ',')
s++;
if (*s == 'h')
flow = 'r';
}
if (baud == 0)
baud = 38400;
if (parity != 'n' && parity != 'o' && parity != 'e')
parity = 'n';
if (bits != '7' && bits != '8')
bits = '8';
if (flow == '\0')
flow = 'r';
sprintf(console_string, " console=ttyS0,%d%c%c%c", baud,
parity, bits, flow);
strcat(fw_getcmdline(), console_string);
}
}
#endif
static void __init mips_nmi_setup(void)
{
void *base;
base = cpu_has_veic ?
(void *)(CAC_BASE + 0xa80) :
(void *)(CAC_BASE + 0x380);
#ifdef CONFIG_CPU_MICROMIPS
/*
* Decrement the exception vector address by one for microMIPS.
*/
memcpy(base, (&except_vec_nmi - 1), 0x80);
/*
* This is a hack. We do not know if the boot loader was built with
* microMIPS instructions or not. If it was not, the NMI exception
* code at 0x80000a80 will be taken in MIPS32 mode. The hand coded
* assembly below forces us into microMIPS mode if we are a pure
* microMIPS kernel. The assembly instructions are:
*
* 3C1A8000 lui k0,0x8000
* 375A0381 ori k0,k0,0x381
* 03400008 jr k0
* 00000000 nop
*
* The mode switch occurs by jumping to the unaligned exception
* vector address at 0x80000381 which would have been 0x80000380
* in MIPS32 mode. The jump to the unaligned address transitions
* us into microMIPS mode.
*/
if (!cpu_has_veic) {
void *base2 = (void *)(CAC_BASE + 0xa80);
*((unsigned int *)base2) = 0x3c1a8000;
*((unsigned int *)base2 + 1) = 0x375a0381;
*((unsigned int *)base2 + 2) = 0x03400008;
*((unsigned int *)base2 + 3) = 0x00000000;
flush_icache_range((unsigned long)base2,
(unsigned long)base2 + 0x10);
}
#else
memcpy(base, &except_vec_nmi, 0x80);
#endif
flush_icache_range((unsigned long)base, (unsigned long)base + 0x80);
}
static void __init mips_ejtag_setup(void)
{
void *base;
base = cpu_has_veic ?
(void *)(CAC_BASE + 0xa00) :
(void *)(CAC_BASE + 0x300);
#ifdef CONFIG_CPU_MICROMIPS
/* Deja vu... */
memcpy(base, (&except_vec_ejtag_debug - 1), 0x80);
if (!cpu_has_veic) {
void *base2 = (void *)(CAC_BASE + 0xa00);
*((unsigned int *)base2) = 0x3c1a8000;
*((unsigned int *)base2 + 1) = 0x375a0301;
*((unsigned int *)base2 + 2) = 0x03400008;
*((unsigned int *)base2 + 3) = 0x00000000;
flush_icache_range((unsigned long)base2,
(unsigned long)base2 + 0x10);
}
#else
memcpy(base, &except_vec_ejtag_debug, 0x80);
#endif
flush_icache_range((unsigned long)base, (unsigned long)base + 0x80);
}
void __init prom_init(void)
{
board_nmi_handler_setup = mips_nmi_setup;
board_ejtag_handler_setup = mips_ejtag_setup;
fw_init_cmdline();
#ifdef CONFIG_EARLY_PRINTK
if ((strstr(fw_getcmdline(), "console=ttyS0")) != NULL)
fw_init_early_console(0);
else if ((strstr(fw_getcmdline(), "console=ttyS1")) != NULL)
fw_init_early_console(1);
#endif
#ifdef CONFIG_SERIAL_8250_CONSOLE
if ((strstr(fw_getcmdline(), "console=")) == NULL)
strcat(fw_getcmdline(), " console=ttyS0,38400n8r");
console_config();
#endif
}
void prom_free_prom_memory(void)
{
}