Merge branch 'for-linus-3.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...
[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 static unsigned long no_fiq_insn;
51
52 /* Default reacquire function
53  * - we always relinquish FIQ control
54  * - we always reacquire FIQ control
55  */
56 static int fiq_def_op(void *ref, int relinquish)
57 {
58         if (!relinquish)
59                 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
60
61         return 0;
62 }
63
64 static struct fiq_handler default_owner = {
65         .name   = "default",
66         .fiq_op = fiq_def_op,
67 };
68
69 static struct fiq_handler *current_fiq = &default_owner;
70
71 int show_fiq_list(struct seq_file *p, int prec)
72 {
73         if (current_fiq != &default_owner)
74                 seq_printf(p, "%*s:              %s\n", prec, "FIQ",
75                         current_fiq->name);
76
77         return 0;
78 }
79
80 void set_fiq_handler(void *start, unsigned int length)
81 {
82 #if defined(CONFIG_CPU_USE_DOMAINS)
83         memcpy((void *)0xffff001c, start, length);
84 #else
85         memcpy(vectors_page + 0x1c, start, length);
86 #endif
87         flush_icache_range(0xffff001c, 0xffff001c + length);
88         if (!vectors_high())
89                 flush_icache_range(0x1c, 0x1c + length);
90 }
91
92 int claim_fiq(struct fiq_handler *f)
93 {
94         int ret = 0;
95
96         if (current_fiq) {
97                 ret = -EBUSY;
98
99                 if (current_fiq->fiq_op != NULL)
100                         ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
101         }
102
103         if (!ret) {
104                 f->next = current_fiq;
105                 current_fiq = f;
106         }
107
108         return ret;
109 }
110
111 void release_fiq(struct fiq_handler *f)
112 {
113         if (current_fiq != f) {
114                 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
115                        f->name, current_fiq->name);
116                 dump_stack();
117                 return;
118         }
119
120         do
121                 current_fiq = current_fiq->next;
122         while (current_fiq->fiq_op(current_fiq->dev_id, 0));
123 }
124
125 static int fiq_start;
126
127 void enable_fiq(int fiq)
128 {
129         enable_irq(fiq + fiq_start);
130 }
131
132 void disable_fiq(int fiq)
133 {
134         disable_irq(fiq + fiq_start);
135 }
136
137 EXPORT_SYMBOL(set_fiq_handler);
138 EXPORT_SYMBOL(__set_fiq_regs);  /* defined in fiqasm.S */
139 EXPORT_SYMBOL(__get_fiq_regs);  /* defined in fiqasm.S */
140 EXPORT_SYMBOL(claim_fiq);
141 EXPORT_SYMBOL(release_fiq);
142 EXPORT_SYMBOL(enable_fiq);
143 EXPORT_SYMBOL(disable_fiq);
144
145 void __init init_FIQ(int start)
146 {
147         no_fiq_insn = *(unsigned long *)0xffff001c;
148         fiq_start = start;
149 }