summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/pj4-cp0.c
blob: 8153e36b24917e96c8fa69d18bd78e8b0c130c1a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/*
 * linux/arch/arm/kernel/pj4-cp0.c
 *
 * PJ4 iWMMXt coprocessor context switching and handling
 *
 * Copyright (c) 2010 Marvell International Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/thread_notify.h>
#include <asm/cputype.h>

static int iwmmxt_do(struct notifier_block *self, unsigned long cmd, void *t)
{
	struct thread_info *thread = t;

	switch (cmd) {
	case THREAD_NOTIFY_FLUSH:
		/*
		 * flush_thread() zeroes thread->fpstate, so no need
		 * to do anything here.
		 *
		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
		 * initialised state information on the first fault.
		 */

	case THREAD_NOTIFY_EXIT:
		iwmmxt_task_release(thread);
		break;

	case THREAD_NOTIFY_SWITCH:
		iwmmxt_task_switch(thread);
		break;
	}

	return NOTIFY_DONE;
}

static struct notifier_block __maybe_unused iwmmxt_notifier_block = {
	.notifier_call	= iwmmxt_do,
};


static u32 __init pj4_cp_access_read(void)
{
	u32 value;

	__asm__ __volatile__ (
		"mrc	p15, 0, %0, c1, c0, 2\n\t"
		: "=r" (value));
	return value;
}

static void __init pj4_cp_access_write(u32 value)
{
	u32 temp;

	__asm__ __volatile__ (
		"mcr	p15, 0, %1, c1, c0, 2\n\t"
		"mrc	p15, 0, %0, c1, c0, 2\n\t"
		"mov	%0, %0\n\t"
		"sub	pc, pc, #4\n\t"
		: "=r" (temp) : "r" (value));
}

static int __init pj4_get_iwmmxt_version(void)
{
	u32 cp_access, wcid;

	cp_access = pj4_cp_access_read();
	pj4_cp_access_write(cp_access | 0xf);

	/* check if coprocessor 0 and 1 are available */
	if ((pj4_cp_access_read() & 0xf) != 0xf) {
		pj4_cp_access_write(cp_access);
		return -ENODEV;
	}

	/* read iWMMXt coprocessor id register p1, c0 */
	__asm__ __volatile__ ("mrc    p1, 0, %0, c0, c0, 0\n" : "=r" (wcid));

	pj4_cp_access_write(cp_access);

	/* iWMMXt v1 */
	if ((wcid & 0xffffff00) == 0x56051000)
		return 1;
	/* iWMMXt v2 */
	if ((wcid & 0xffffff00) == 0x56052000)
		return 2;

	return -EINVAL;
}

/*
 * Disable CP0/CP1 on boot, and let call_fpe() and the iWMMXt lazy
 * switch code handle iWMMXt context switching.
 */
static int __init pj4_cp0_init(void)
{
	u32 __maybe_unused cp_access;
	int vers;

	if (!cpu_is_pj4())
		return 0;

	vers = pj4_get_iwmmxt_version();
	if (vers < 0)
		return 0;

#ifndef CONFIG_IWMMXT
	pr_info("PJ4 iWMMXt coprocessor detected, but kernel support is missing.\n");
#else
	cp_access = pj4_cp_access_read() & ~0xf;
	pj4_cp_access_write(cp_access);

	pr_info("PJ4 iWMMXt v%d coprocessor enabled.\n", vers);
	elf_hwcap |= HWCAP_IWMMXT;
	thread_register_notifier(&iwmmxt_notifier_block);
#endif

	return 0;
}

late_initcall(pj4_cp0_init);
OpenPOWER on IntegriCloud