LXR linux/arch/arm/mach-ep93xx/crunch.c

   1/*
   2 * arch/arm/kernel/crunch.c
   3 * Cirrus MaverickCrunch context switching and handling
   4 *
   5 * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/types.h>
  14#include <linux/kernel.h>
  15#include <linux/signal.h>
  16#include <linux/sched.h>
  17#include <linux/init.h>
  18#include <linux/io.h>
  19
  20#include <asm/thread_notify.h>
  21
  22#include "soc.h"
  23
  24struct crunch_state *crunch_owner;
  25
  26void crunch_task_release(struct thread_info *thread)
  27{
  28        local_irq_disable();
  29        if (crunch_owner == &thread->crunchstate)
  30                crunch_owner = NULL;
  31        local_irq_enable();
  32}
  33
  34static int crunch_enabled(u32 devcfg)
  35{
  36        return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
  37}
  38
  39static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
  40{
  41        struct thread_info *thread = (struct thread_info *)t;
  42        struct crunch_state *crunch_state;
  43        u32 devcfg;
  44
  45        crunch_state = &thread->crunchstate;
  46
  47        switch (cmd) {
  48        case THREAD_NOTIFY_FLUSH:
  49                memset(crunch_state, 0, sizeof(*crunch_state));
  50
  51                /*
  52                 * FALLTHROUGH: Ensure we don't try to overwrite our newly
  53                 * initialised state information on the first fault.
  54                 */
  55
  56        case THREAD_NOTIFY_EXIT:
  57                crunch_task_release(thread);
  58                break;
  59
  60        case THREAD_NOTIFY_SWITCH:
  61                devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
  62                if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
  63                        /*
  64                         * We don't use ep93xx_syscon_swlocked_write() here
  65                         * because we are on the context switch path and
  66                         * preemption is already disabled.
  67                         */
  68                        devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
  69                        __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
  70                        __raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
  71                }
  72                break;
  73        }
  74
  75        return NOTIFY_DONE;
  76}
  77
  78static struct notifier_block crunch_notifier_block = {
  79        .notifier_call  = crunch_do,
  80};
  81
  82int __init crunch_init(void)
  83{
  84        thread_register_notifier(&crunch_notifier_block);
  85        elf_hwcap |= HWCAP_CRUNCH;
  86
  87        return 0;
  88}
  89