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