/* * 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 <mach/ep93xx-regs.h> #include <asm/thread_notify.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, }; static int __init crunch_init(void) { thread_register_notifier(&crunch_notifier_block); elf_hwcap |= HWCAP_CRUNCH; return 0; } late_initcall(crunch_init);