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-rw-r--r--arch/arm26/kernel/fiq.c201
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diff --git a/arch/arm26/kernel/fiq.c b/arch/arm26/kernel/fiq.c
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1/*
2 * linux/arch/arm26/kernel/fiq.c
3 *
4 * Copyright (C) 1998 Russell King
5 * Copyright (C) 1998, 1999 Phil Blundell
6 * Copyright (C) 2003 Ian Molton
7 *
8 * FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
9 *
10 * FIQ support re-written by Russell King to be more generic
11 *
12 * We now properly support a method by which the FIQ handlers can
13 * be stacked onto the vector. We still do not support sharing
14 * the FIQ vector itself.
15 *
16 * Operation is as follows:
17 * 1. Owner A claims FIQ:
18 * - default_fiq relinquishes control.
19 * 2. Owner A:
20 * - inserts code.
21 * - sets any registers,
22 * - enables FIQ.
23 * 3. Owner B claims FIQ:
24 * - if owner A has a relinquish function.
25 * - disable FIQs.
26 * - saves any registers.
27 * - returns zero.
28 * 4. Owner B:
29 * - inserts code.
30 * - sets any registers,
31 * - enables FIQ.
32 * 5. Owner B releases FIQ:
33 * - Owner A is asked to reacquire FIQ:
34 * - inserts code.
35 * - restores saved registers.
36 * - enables FIQ.
37 * 6. Goto 3
38 */
39#include <linux/module.h>
40#include <linux/mm.h>
41#include <linux/mman.h>
42#include <linux/init.h>
43#include <linux/seq_file.h>
44
45#include <asm/fiq.h>
46#include <asm/io.h>
47#include <asm/irq.h>
48#include <asm/pgalloc.h>
49#include <asm/system.h>
50#include <asm/uaccess.h>
51
52#define FIQ_VECTOR (vectors_base() + 0x1c)
53
54static unsigned long no_fiq_insn;
55
56#define unprotect_page_0()
57#define protect_page_0()
58
59/* Default reacquire function
60 * - we always relinquish FIQ control
61 * - we always reacquire FIQ control
62 */
63static int fiq_def_op(void *ref, int relinquish)
64{
65 if (!relinquish) {
66 unprotect_page_0();
67 *(unsigned long *)FIQ_VECTOR = no_fiq_insn;
68 protect_page_0();
69 }
70
71 return 0;
72}
73
74static struct fiq_handler default_owner = {
75 .name = "default",
76 .fiq_op = fiq_def_op,
77};
78
79static struct fiq_handler *current_fiq = &default_owner;
80
81int show_fiq_list(struct seq_file *p, void *v)
82{
83 if (current_fiq != &default_owner)
84 seq_printf(p, "FIQ: %s\n", current_fiq->name);
85
86 return 0;
87}
88
89void set_fiq_handler(void *start, unsigned int length)
90{
91 unprotect_page_0();
92
93 memcpy((void *)FIQ_VECTOR, start, length);
94
95 protect_page_0();
96}
97
98/*
99 * Taking an interrupt in FIQ mode is death, so both these functions
100 * disable irqs for the duration.
101 */
102void set_fiq_regs(struct pt_regs *regs)
103{
104 register unsigned long tmp, tmp2;
105 __asm__ volatile (
106 "mov %0, pc \n"
107 "bic %1, %0, #0x3 \n"
108 "orr %1, %1, %3 \n"
109 "teqp %1, #0 @ select FIQ mode \n"
110 "mov r0, r0 \n"
111 "ldmia %2, {r8 - r14} \n"
112 "teqp %0, #0 @ return to SVC mode \n"
113 "mov r0, r0 "
114 : "=&r" (tmp), "=&r" (tmp2)
115 : "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | MODE_FIQ26)
116 /* These registers aren't modified by the above code in a way
117 visible to the compiler, but we mark them as clobbers anyway
118 so that GCC won't put any of the input or output operands in
119 them. */
120 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
121}
122
123void get_fiq_regs(struct pt_regs *regs)
124{
125 register unsigned long tmp, tmp2;
126 __asm__ volatile (
127 "mov %0, pc \n"
128 "bic %1, %0, #0x3 \n"
129 "orr %1, %1, %3 \n"
130 "teqp %1, #0 @ select FIQ mode \n"
131 "mov r0, r0 \n"
132 "stmia %2, {r8 - r14} \n"
133 "teqp %0, #0 @ return to SVC mode \n"
134 "mov r0, r0 "
135 : "=&r" (tmp), "=&r" (tmp2)
136 : "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | MODE_FIQ26)
137 /* These registers aren't modified by the above code in a way
138 visible to the compiler, but we mark them as clobbers anyway
139 so that GCC won't put any of the input or output operands in
140 them. */
141 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
142}
143
144int claim_fiq(struct fiq_handler *f)
145{
146 int ret = 0;
147
148 if (current_fiq) {
149 ret = -EBUSY;
150
151 if (current_fiq->fiq_op != NULL)
152 ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
153 }
154
155 if (!ret) {
156 f->next = current_fiq;
157 current_fiq = f;
158 }
159
160 return ret;
161}
162
163void release_fiq(struct fiq_handler *f)
164{
165 if (current_fiq != f) {
166 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
167 f->name, current_fiq->name);
168#ifdef CONFIG_DEBUG_ERRORS
169 __backtrace();
170#endif
171 return;
172 }
173
174 do
175 current_fiq = current_fiq->next;
176 while (current_fiq->fiq_op(current_fiq->dev_id, 0));
177}
178
179void enable_fiq(int fiq)
180{
181 enable_irq(fiq + FIQ_START);
182}
183
184void disable_fiq(int fiq)
185{
186 disable_irq(fiq + FIQ_START);
187}
188
189EXPORT_SYMBOL(set_fiq_handler);
190EXPORT_SYMBOL(set_fiq_regs);
191EXPORT_SYMBOL(get_fiq_regs);
192EXPORT_SYMBOL(claim_fiq);
193EXPORT_SYMBOL(release_fiq);
194EXPORT_SYMBOL(enable_fiq);
195EXPORT_SYMBOL(disable_fiq);
196
197void __init init_FIQ(void)
198{
199 no_fiq_insn = *(unsigned long *)FIQ_VECTOR;
200 set_fs(get_fs());
201}
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