/*
* Processor capabilities determination functions.
*
* Copyright (C) xxxx the Anonymous
* Copyright (C) 1994 - 2006 Ralf Baechle
* Copyright (C) 2003, 2004 Maciej W. Rozycki
* Copyright (C) 2001, 2004, 2011, 2012 MIPS Technologies, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/export.h>
#include <asm/bugs.h>
#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/watch.h>
#include <asm/elf.h>
#include <asm/spram.h>
#include <asm/uaccess.h>
/*
* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
* the implementation of the "wait" feature differs between CPU families. This
* points to the function that implements CPU specific wait.
* The wait instruction stops the pipeline and reduces the power consumption of
* the CPU very much.
*/
void (*cpu_wait)(void);
EXPORT_SYMBOL(cpu_wait);
static void r3081_wait(void)
{
unsigned long cfg = read_c0_conf();
write_c0_conf(cfg | R30XX_CONF_HALT);
}
static void r39xx_wait(void)
{
local_irq_disable();
if (!need_resched())
write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
local_irq_enable();
}
extern void r4k_wait(void);
/*
* This variant is preferable as it allows testing need_resched and going to
* sleep depending on the outcome atomically. Unfortunately the "It is
* implementation-dependent whether the pipeline restarts when a non-enabled
* interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
* using this version a gamble.
*/
void r4k_wait_irqoff(void)
{
local_irq_disable();
if (!need_resched())
__asm__(" .set push \n"
" .set mips3 \n"
" wait \n"
" .set pop \n");
local_irq_enable();
__asm__(" .globl __pastwait \n"
"__pastwait: \n");
}
/*
* The RM7000 variant has to handle erratum 38. The workaround is to not
* have any pending stores when the WAIT instruction is executed.
*/
static void rm7k_wait_irqoff(void)
{
local_irq_disable();
if (!need_resched())
__asm__(
" .set push \n"
" .set mips3 \n"
" .set noat \n"
" mfc0 $1, $12 \n"
" sync \n"
" mtc0 $1, $12 # stalls until W stage \n"
" wait \n"
" mtc0 $1, $12 # stalls until W stage \n"
" .set pop \n");
local_irq_enable();
}
/*
* The Au1xxx wait is available only if using 32khz counter or
* external timer source, but specifically not CP0 Counter.
* alchemy/common/time.c may override cpu_wait!
*/
static void au1k_wait(void)
{
__asm__(" .set mips3 \n"
" cache 0x14, 0(%0) \n"
" cache 0x14, 32(%0) \n"
" sync \n"
" nop \n"
" wait \n"
" nop \n"
" nop \n"
" nop \n"
" nop \n"
" .set mips0 \n"
: : "r" (au1k_wait));
}
static int __initdata nowait;
static int __init wait_disable(char *s)
{
nowait = 1;
return 1;
}
__setup("nowait", wait_disable);
static int __cpuinitdata mips_fpu_disabled;
static int __init fpu_disable(char *s)
{
cpu_data