1/*
 2 * linux/arch/arm/kernel/pj4-cp0.c
 3 *
 4 * PJ4 iWMMXt coprocessor context switching and handling
 5 *
 6 * Copyright (c) 2010 Marvell International Inc.
 7 *
 8 * This program is free software; you can redistribute it and/or modify
 9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
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 <asm/thread_notify.h>
20
21static int iwmmxt_do(struct notifier_block *self, unsigned long cmd, void *t)
22{
23	struct thread_info *thread = t;
24
25	switch (cmd) {
26	case THREAD_NOTIFY_FLUSH:
27		/*
28		 * flush_thread() zeroes thread->fpstate, so no need
29		 * to do anything here.
30		 *
31		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
32		 * initialised state information on the first fault.
33		 */
34
35	case THREAD_NOTIFY_EXIT:
36		iwmmxt_task_release(thread);
37		break;
38
39	case THREAD_NOTIFY_SWITCH:
40		iwmmxt_task_switch(thread);
41		break;
42	}
43
44	return NOTIFY_DONE;
45}
46
47static struct notifier_block iwmmxt_notifier_block = {
48	.notifier_call	= iwmmxt_do,
49};
50
51
52static u32 __init pj4_cp_access_read(void)
53{
54	u32 value;
55
56	__asm__ __volatile__ (
57		"mrc	p15, 0, %0, c1, c0, 2\n\t"
58		: "=r" (value));
59	return value;
60}
61
62static void __init pj4_cp_access_write(u32 value)
63{
64	u32 temp;
65
66	__asm__ __volatile__ (
67		"mcr	p15, 0, %1, c1, c0, 2\n\t"
68		"mrc	p15, 0, %0, c1, c0, 2\n\t"
69		"mov	%0, %0\n\t"
70		"sub	pc, pc, #4\n\t"
71		: "=r" (temp) : "r" (value));
72}
73
74
75/*
76 * Disable CP0/CP1 on boot, and let call_fpe() and the iWMMXt lazy
77 * switch code handle iWMMXt context switching.
78 */
79static int __init pj4_cp0_init(void)
80{
81	u32 cp_access;
82
83	cp_access = pj4_cp_access_read() & ~0xf;
84	pj4_cp_access_write(cp_access);
85
86	printk(KERN_INFO "PJ4 iWMMXt coprocessor enabled.\n");
87	elf_hwcap |= HWCAP_IWMMXT;
88	thread_register_notifier(&iwmmxt_notifier_block);
89
90	return 0;
91}
92
93late_initcall(pj4_cp0_init);