1/*
2 *  linux/arch/arm/kernel/fiq.c
3 *
4 *  Copyright (C) 1998 Russell King
5 *  Copyright (C) 1998, 1999 Phil Blundell
6 *
7 *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
8 *
9 *  FIQ support re-written by Russell King to be more generic
10 *
11 * We now properly support a method by which the FIQ handlers can
12 * be stacked onto the vector.  We still do not support sharing
13 * the FIQ vector itself.
14 *
15 * Operation is as follows:
16 *  1. Owner A claims FIQ:
17 *     - default_fiq relinquishes control.
18 *  2. Owner A:
19 *     - inserts code.
20 *     - sets any registers,
21 *     - enables FIQ.
22 *  3. Owner B claims FIQ:
23 *     - if owner A has a relinquish function.
24 *       - disable FIQs.
25 *       - saves any registers.
26 *       - returns zero.
27 *  4. Owner B:
28 *     - inserts code.
29 *     - sets any registers,
30 *     - enables FIQ.
31 *  5. Owner B releases FIQ:
32 *     - Owner A is asked to reacquire FIQ:
33 *	 - inserts code.
34 *	 - restores saved registers.
35 *	 - enables FIQ.
36 *  6. Goto 3
37 */
38#include <linux/module.h>
39#include <linux/kernel.h>
40#include <linux/init.h>
41#include <linux/interrupt.h>
42#include <linux/seq_file.h>
43
44#include <asm/cacheflush.h>
45#include <asm/cp15.h>
46#include <asm/fiq.h>
47#include <asm/irq.h>
48#include <asm/traps.h>
49
50#define FIQ_OFFSET ({					\
51		extern void *vector_fiq_offset;		\
52		(unsigned)&vector_fiq_offset;		\
53	})
54
55static unsigned long dfl_fiq_insn;
56static struct pt_regs dfl_fiq_regs;
57
58/* Default reacquire function
59 * - we always relinquish FIQ control
60 * - we always reacquire FIQ control
61 */
62static int fiq_def_op(void *ref, int relinquish)
63{
64	if (!relinquish) {
65		/* Restore default handler and registers */
66		local_fiq_disable();
67		set_fiq_regs(&dfl_fiq_regs);
68		set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
69		local_fiq_enable();
70
71		/* FIXME: notify irq controller to standard enable FIQs */
72	}
73
74	return 0;
75}
76
77static struct fiq_handler default_owner = {
78	.name	= "default",
79	.fiq_op = fiq_def_op,
80};
81
82static struct fiq_handler *current_fiq = &default_owner;
83
84int show_fiq_list(struct seq_file *p, int prec)
85{
86	if (current_fiq != &default_owner)
87		seq_printf(p, "%*s:              %s\n", prec, "FIQ",
88			current_fiq->name);
89
90	return 0;
91}
92
93void set_fiq_handler(void *start, unsigned int length)
94{
95	void *base = vectors_page;
96	unsigned offset = FIQ_OFFSET;
97
98	memcpy(base + offset, start, length);
99	if (!cache_is_vipt_nonaliasing())
100		flush_icache_range((unsigned long)base + offset, offset +
101				   length);
102	flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
103}
104
105int claim_fiq(struct fiq_handler *f)
106{
107	int ret = 0;
108
109	if (current_fiq) {
110		ret = -EBUSY;
111
112		if (current_fiq->fiq_op != NULL)
113			ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
114	}
115
116	if (!ret) {
117		f->next = current_fiq;
118		current_fiq = f;
119	}
120
121	return ret;
122}
123
124void release_fiq(struct fiq_handler *f)
125{
126	if (current_fiq != f) {
127		pr_err("%s FIQ trying to release %s FIQ\n",
128		       f->name, current_fiq->name);
129		dump_stack();
130		return;
131	}
132
133	do
134		current_fiq = current_fiq->next;
135	while (current_fiq->fiq_op(current_fiq->dev_id, 0));
136}
137
138static int fiq_start;
139
140void enable_fiq(int fiq)
141{
142	enable_irq(fiq + fiq_start);
143}
144
145void disable_fiq(int fiq)
146{
147	disable_irq(fiq + fiq_start);
148}
149
150EXPORT_SYMBOL(set_fiq_handler);
151EXPORT_SYMBOL(__set_fiq_regs);	/* defined in fiqasm.S */
152EXPORT_SYMBOL(__get_fiq_regs);	/* defined in fiqasm.S */
153EXPORT_SYMBOL(claim_fiq);
154EXPORT_SYMBOL(release_fiq);
155EXPORT_SYMBOL(enable_fiq);
156EXPORT_SYMBOL(disable_fiq);
157
158void __init init_FIQ(int start)
159{
160	unsigned offset = FIQ_OFFSET;
161	dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
162	get_fiq_regs(&dfl_fiq_regs);
163	fiq_start = start;
164}
165