crunch.c
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/*
* arch/arm/kernel/crunch.c
* Cirrus MaverickCrunch context switching and handling
*
* Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/thread_notify.h>
#include "soc.h"
struct crunch_state *crunch_owner;
void crunch_task_release(struct thread_info *thread)
{
local_irq_disable();
if (crunch_owner == &thread->crunchstate)
crunch_owner = NULL;
local_irq_enable();
}
static int crunch_enabled(u32 devcfg)
{
return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
}
static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
{
struct thread_info *thread = (struct thread_info *)t;
struct crunch_state *crunch_state;
u32 devcfg;
crunch_state = &thread->crunchstate;
switch (cmd) {
case THREAD_NOTIFY_FLUSH:
memset(crunch_state, 0, sizeof(*crunch_state));
/*
* FALLTHROUGH: Ensure we don't try to overwrite our newly
* initialised state information on the first fault.
*/
case THREAD_NOTIFY_EXIT:
crunch_task_release(thread);
break;
case THREAD_NOTIFY_SWITCH:
devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
/*
* We don't use ep93xx_syscon_swlocked_write() here
* because we are on the context switch path and
* preemption is already disabled.
*/
devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
}
break;
}
return NOTIFY_DONE;
}
static struct notifier_block crunch_notifier_block = {
.notifier_call = crunch_do,
};
int __init crunch_init(void)
{
thread_register_notifier(&crunch_notifier_block);
elf_hwcap |= HWCAP_CRUNCH;
return 0;
}