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#include <mach/ep93xx-regs.h> 20#include <asm/thread_notify.h> 21 22struct crunch_state *crunch_owner; 23 24void crunch_task_release(struct thread_info *thread) 25{ 26 local_irq_disable(); 27 if (crunch_owner == &thread->crunchstate) 28 crunch_owner = NULL; 29 local_irq_enable(); 30} 31 32static int crunch_enabled(u32 devcfg) 33{ 34 return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA); 35} 36 37static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t) 38{ 39 struct thread_info *thread = (struct thread_info *)t; 40 struct crunch_state *crunch_state; 41 u32 devcfg; 42 43 crunch_state = &thread->crunchstate; 44 45 switch (cmd) { 46 case THREAD_NOTIFY_FLUSH: 47 memset(crunch_state, 0, sizeof(*crunch_state)); 48 49 /* 50 * FALLTHROUGH: Ensure we don't try to overwrite our newly 51 * initialised state information on the first fault. 52 */ 53 54 case THREAD_NOTIFY_EXIT: 55 crunch_task_release(thread); 56 break; 57 58 case THREAD_NOTIFY_SWITCH: 59 devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG); 60 if (crunch_enabled(devcfg) || crunch_owner == crunch_state) { 61 /* 62 * We don't use ep93xx_syscon_swlocked_write() here 63 * because we are on the context switch path and 64 * preemption is already disabled. 65 */ 66 devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA; 67 __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK); 68 __raw_writel(devcfg, EP93XX_SYSCON_DEVCFG); 69 } 70 break; 71 } 72 73 return NOTIFY_DONE; 74} 75 76static struct notifier_block crunch_notifier_block = { 77 .notifier_call = crunch_do, 78}; 79 80static int __init crunch_init(void) 81{ 82 thread_register_notifier(&crunch_notifier_block); 83 elf_hwcap |= HWCAP_CRUNCH; 84 85 return 0; 86} 87 88late_initcall(crunch_init); 89