mirror of https://gitee.com/openkylin/linux.git
89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/*
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* arch/arm/kernel/crunch.c
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* Cirrus MaverickCrunch context switching and handling
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*
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* Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <mach/ep93xx-regs.h>
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#include <asm/thread_notify.h>
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struct crunch_state *crunch_owner;
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void crunch_task_release(struct thread_info *thread)
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{
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local_irq_disable();
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if (crunch_owner == &thread->crunchstate)
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crunch_owner = NULL;
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local_irq_enable();
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}
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static int crunch_enabled(u32 devcfg)
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{
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return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
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}
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static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
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{
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struct thread_info *thread = (struct thread_info *)t;
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struct crunch_state *crunch_state;
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u32 devcfg;
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crunch_state = &thread->crunchstate;
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switch (cmd) {
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case THREAD_NOTIFY_FLUSH:
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memset(crunch_state, 0, sizeof(*crunch_state));
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/*
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* FALLTHROUGH: Ensure we don't try to overwrite our newly
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* initialised state information on the first fault.
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*/
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case THREAD_NOTIFY_EXIT:
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crunch_task_release(thread);
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break;
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case THREAD_NOTIFY_SWITCH:
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devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
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if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
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/*
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* We don't use ep93xx_syscon_swlocked_write() here
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* because we are on the context switch path and
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* preemption is already disabled.
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*/
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devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
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__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
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__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
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}
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break;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block crunch_notifier_block = {
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.notifier_call = crunch_do,
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};
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static int __init crunch_init(void)
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{
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thread_register_notifier(&crunch_notifier_block);
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elf_hwcap |= HWCAP_CRUNCH;
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return 0;
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}
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late_initcall(crunch_init);
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