Merge branch 'for-linus-merged' of master.kernel.org:/home/rmk/linux-2.6-arm
[linux-2.6] / arch / arm / kernel / 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 <mach/ep93xx-regs.h>
19 #include <asm/thread_notify.h>
20 #include <asm/io.h>
21
22 struct crunch_state *crunch_owner;
23
24 void 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
32 static int crunch_enabled(u32 devcfg)
33 {
34         return !!(devcfg & EP93XX_SYSCON_DEVICE_CONFIG_CRUNCH_ENABLE);
35 }
36
37 static 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_RELEASE:
55                 crunch_task_release(thread);
56                 break;
57
58         case THREAD_NOTIFY_SWITCH:
59                 devcfg = __raw_readl(EP93XX_SYSCON_DEVICE_CONFIG);
60                 if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
61                         devcfg ^= EP93XX_SYSCON_DEVICE_CONFIG_CRUNCH_ENABLE;
62                         __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
63                         __raw_writel(devcfg, EP93XX_SYSCON_DEVICE_CONFIG);
64                 }
65                 break;
66         }
67
68         return NOTIFY_DONE;
69 }
70
71 static struct notifier_block crunch_notifier_block = {
72         .notifier_call  = crunch_do,
73 };
74
75 static int __init crunch_init(void)
76 {
77         thread_register_notifier(&crunch_notifier_block);
78         elf_hwcap |= HWCAP_CRUNCH;
79
80         return 0;
81 }
82
83 late_initcall(crunch_init);