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
55 static unsigned long no_fiq_insn;
56
57 /* Default reacquire function
58 * - we always relinquish FIQ control
59 * - we always reacquire FIQ control
60 */
fiq_def_op(void * ref,int relinquish)61 static int fiq_def_op(void *ref, int relinquish)
62 {
63 if (!relinquish)
64 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
65
66 return 0;
67 }
68
69 static struct fiq_handler default_owner = {
70 .name = "default",
71 .fiq_op = fiq_def_op,
72 };
73
74 static struct fiq_handler *current_fiq = &default_owner;
75
show_fiq_list(struct seq_file * p,int prec)76 int show_fiq_list(struct seq_file *p, int prec)
77 {
78 if (current_fiq != &default_owner)
79 seq_printf(p, "%*s: %s\n", prec, "FIQ",
80 current_fiq->name);
81
82 return 0;
83 }
84
set_fiq_handler(void * start,unsigned int length)85 void set_fiq_handler(void *start, unsigned int length)
86 {
87 #if defined(CONFIG_CPU_USE_DOMAINS)
88 void *base = (void *)0xffff0000;
89 #else
90 void *base = vectors_page;
91 #endif
92 unsigned offset = FIQ_OFFSET;
93
94 memcpy(base + offset, start, length);
95 flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
96 if (!vectors_high())
97 flush_icache_range(offset, offset + length);
98 }
99
claim_fiq(struct fiq_handler * f)100 int claim_fiq(struct fiq_handler *f)
101 {
102 int ret = 0;
103
104 if (current_fiq) {
105 ret = -EBUSY;
106
107 if (current_fiq->fiq_op != NULL)
108 ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
109 }
110
111 if (!ret) {
112 f->next = current_fiq;
113 current_fiq = f;
114 }
115
116 return ret;
117 }
118
release_fiq(struct fiq_handler * f)119 void release_fiq(struct fiq_handler *f)
120 {
121 if (current_fiq != f) {
122 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
123 f->name, current_fiq->name);
124 dump_stack();
125 return;
126 }
127
128 do
129 current_fiq = current_fiq->next;
130 while (current_fiq->fiq_op(current_fiq->dev_id, 0));
131 }
132
enable_fiq(int fiq)133 void enable_fiq(int fiq)
134 {
135 enable_irq(fiq + FIQ_START);
136 }
137
disable_fiq(int fiq)138 void disable_fiq(int fiq)
139 {
140 disable_irq(fiq + FIQ_START);
141 }
142
143 EXPORT_SYMBOL(set_fiq_handler);
144 EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */
145 EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */
146 EXPORT_SYMBOL(claim_fiq);
147 EXPORT_SYMBOL(release_fiq);
148 EXPORT_SYMBOL(enable_fiq);
149 EXPORT_SYMBOL(disable_fiq);
150
init_FIQ(void)151 void __init init_FIQ(void)
152 {
153 unsigned offset = FIQ_OFFSET;
154 no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
155 }
156