summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/fiq.c
blob: 059c3da0fee34fb815ffaeb3f9d4a59f2b79661f (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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/*
 *  linux/arch/arm/kernel/fiq.c
 *
 *  Copyright (C) 1998 Russell King
 *  Copyright (C) 1998, 1999 Phil Blundell
 *
 *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
 *
 *  FIQ support re-written by Russell King to be more generic
 *
 * We now properly support a method by which the FIQ handlers can
 * be stacked onto the vector.  We still do not support sharing
 * the FIQ vector itself.
 *
 * Operation is as follows:
 *  1. Owner A claims FIQ:
 *     - default_fiq relinquishes control.
 *  2. Owner A:
 *     - inserts code.
 *     - sets any registers,
 *     - enables FIQ.
 *  3. Owner B claims FIQ:
 *     - if owner A has a relinquish function.
 *       - disable FIQs.
 *       - saves any registers.
 *       - returns zero.
 *  4. Owner B:
 *     - inserts code.
 *     - sets any registers,
 *     - enables FIQ.
 *  5. Owner B releases FIQ:
 *     - Owner A is asked to reacquire FIQ:
 *	 - inserts code.
 *	 - restores saved registers.
 *	 - enables FIQ.
 *  6. Goto 3
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>

#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/fiq.h>
#include <asm/irq.h>
#include <asm/traps.h>

#define FIQ_OFFSET ({					\
		extern void *vector_fiq_offset;		\
		(unsigned)&vector_fiq_offset;		\
	})

static unsigned long dfl_fiq_insn;
static struct pt_regs dfl_fiq_regs;

/* Default reacquire function
 * - we always relinquish FIQ control
 * - we always reacquire FIQ control
 */
static int fiq_def_op(void *ref, int relinquish)
{
	if (!relinquish) {
		/* Restore default handler and registers */
		local_fiq_disable();
		set_fiq_regs(&dfl_fiq_regs);
		set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
		local_fiq_enable();

		/* FIXME: notify irq controller to standard enable FIQs */
	}

	return 0;
}

static struct fiq_handler default_owner = {
	.name	= "default",
	.fiq_op = fiq_def_op,
};

static struct fiq_handler *current_fiq = &default_owner;

int show_fiq_list(struct seq_file *p, int prec)
{
	if (current_fiq != &default_owner)
		seq_printf(p, "%*s:              %s\n", prec, "FIQ",
			current_fiq->name);

	return 0;
}

void set_fiq_handler(void *start, unsigned int length)
{
	void *base = vectors_page;
	unsigned offset = FIQ_OFFSET;

	memcpy(base + offset, start, length);
	if (!cache_is_vipt_nonaliasing())
		flush_icache_range((unsigned long)base + offset, offset +
				   length);
	flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
}

int claim_fiq(struct fiq_handler *f)
{
	int ret = 0;

	if (current_fiq) {
		ret = -EBUSY;

		if (current_fiq->fiq_op != NULL)
			ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
	}

	if (!ret) {
		f->next = current_fiq;
		current_fiq = f;
	}

	return ret;
}

void release_fiq(struct fiq_handler *f)
{
	if (current_fiq != f) {
		pr_err("%s FIQ trying to release %s FIQ\n",
		       f->name, current_fiq->name);
		dump_stack();
		return;
	}

	do
		current_fiq = current_fiq->next;
	while (current_fiq->fiq_op(current_fiq->dev_id, 0));
}

static int fiq_start;

void enable_fiq(int fiq)
{
	enable_irq(fiq + fiq_start);
}

void disable_fiq(int fiq)
{
	disable_irq(fiq + fiq_start);
}

EXPORT_SYMBOL(set_fiq_handler);
EXPORT_SYMBOL(__set_fiq_regs);	/* defined in fiqasm.S */
EXPORT_SYMBOL(__get_fiq_regs);	/* defined in fiqasm.S */
EXPORT_SYMBOL(claim_fiq);
EXPORT_SYMBOL(release_fiq);
EXPORT_SYMBOL(enable_fiq);
EXPORT_SYMBOL(disable_fiq);

void __init init_FIQ(int start)
{
	unsigned offset = FIQ_OFFSET;
	dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
	get_fiq_regs(&dfl_fiq_regs);
	fiq_start = start;
}