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-rw-r--r--arch/arm/kernel/crunch.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/arch/arm/kernel/crunch.c b/arch/arm/kernel/crunch.c
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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/config.h>
14#include <linux/types.h>
15#include <linux/kernel.h>
16#include <linux/signal.h>
17#include <linux/sched.h>
18#include <linux/init.h>
19#include <asm/arch/ep93xx-regs.h>
20#include <asm/thread_notify.h>
21#include <asm/io.h>
22
23struct crunch_state *crunch_owner;
24
25void crunch_task_release(struct thread_info *thread)
26{
27 local_irq_disable();
28 if (crunch_owner == &thread->crunchstate)
29 crunch_owner = NULL;
30 local_irq_enable();
31}
32
33static int crunch_enabled(u32 devcfg)
34{
35 return !!(devcfg & EP93XX_SYSCON_DEVICE_CONFIG_CRUNCH_ENABLE);
36}
37
38static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
39{
40 struct thread_info *thread = (struct thread_info *)t;
41 struct crunch_state *crunch_state;
42 u32 devcfg;
43
44 crunch_state = &thread->crunchstate;
45
46 switch (cmd) {
47 case THREAD_NOTIFY_FLUSH:
48 memset(crunch_state, 0, sizeof(*crunch_state));
49
50 /*
51 * FALLTHROUGH: Ensure we don't try to overwrite our newly
52 * initialised state information on the first fault.
53 */
54
55 case THREAD_NOTIFY_RELEASE:
56 crunch_task_release(thread);
57 break;
58
59 case THREAD_NOTIFY_SWITCH:
60 devcfg = __raw_readl(EP93XX_SYSCON_DEVICE_CONFIG);
61 if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
62 devcfg ^= EP93XX_SYSCON_DEVICE_CONFIG_CRUNCH_ENABLE;
63 __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
64 __raw_writel(devcfg, EP93XX_SYSCON_DEVICE_CONFIG);
65 }
66 break;
67 }
68
69 return NOTIFY_DONE;
70}
71
72static struct notifier_block crunch_notifier_block = {
73 .notifier_call = crunch_do,
74};
75
76static int __init crunch_init(void)
77{
78 thread_register_notifier(&crunch_notifier_block);
79
80 return 0;
81}
82
83late_initcall(crunch_init);