ARM: move signal handlers into a vdso-like page
[linux-3.10.git] / arch / arm / kernel / fiq.c
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  */
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
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
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
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
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
133 static int fiq_start;
134
135 void enable_fiq(int fiq)
136 {
137         enable_irq(fiq + fiq_start);
138 }
139
140 void disable_fiq(int fiq)
141 {
142         disable_irq(fiq + fiq_start);
143 }
144
145 EXPORT_SYMBOL(set_fiq_handler);
146 EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
147 EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
148 EXPORT_SYMBOL(claim_fiq);
149 EXPORT_SYMBOL(release_fiq);
150 EXPORT_SYMBOL(enable_fiq);
151 EXPORT_SYMBOL(disable_fiq);
152
153 void __init init_FIQ(int start)
154 {
155         unsigned offset = FIQ_OFFSET;
156         no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
157         fiq_start = start;
158 }