2 * linux/arch/arm/kernel/fiq.c
4 * Copyright (C) 1998 Russell King
5 * Copyright (C) 1998, 1999 Phil Blundell
7 * FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
9 * FIQ support re-written by Russell King to be more generic
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.
15 * Operation is as follows:
16 * 1. Owner A claims FIQ:
17 * - default_fiq relinquishes control.
20 * - sets any registers,
22 * 3. Owner B claims FIQ:
23 * - if owner A has a relinquish function.
25 * - saves any registers.
29 * - sets any registers,
31 * 5. Owner B releases FIQ:
32 * - Owner A is asked to reacquire FIQ:
34 * - restores saved registers.
38 #include <linux/module.h>
39 #include <linux/kernel.h>
40 #include <linux/init.h>
41 #include <linux/seq_file.h>
43 #include <asm/cacheflush.h>
46 #include <asm/system.h>
47 #include <asm/uaccess.h>
49 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
50 #warning This file requires GCC 3.3.x or older to build. Alternatively,
51 #warning please talk to GCC people to resolve the issues with the
52 #warning assembly clobber list.
55 static unsigned long no_fiq_insn;
57 /* Default reacquire function
58 * - we always relinquish FIQ control
59 * - we always reacquire FIQ control
61 static int fiq_def_op(void *ref, int relinquish)
64 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
69 static struct fiq_handler default_owner = {
74 static struct fiq_handler *current_fiq = &default_owner;
76 int show_fiq_list(struct seq_file *p, void *v)
78 if (current_fiq != &default_owner)
79 seq_printf(p, "FIQ: %s\n", current_fiq->name);
84 void set_fiq_handler(void *start, unsigned int length)
86 memcpy((void *)0xffff001c, start, length);
87 flush_icache_range(0xffff001c, 0xffff001c + length);
89 flush_icache_range(0x1c, 0x1c + length);
93 * Taking an interrupt in FIQ mode is death, so both these functions
94 * disable irqs for the duration.
96 void set_fiq_regs(struct pt_regs *regs)
98 register unsigned long tmp;
101 msr cpsr_c, %2 @ select FIQ mode\n\
103 ldmia %1, {r8 - r14}\n\
104 msr cpsr_c, %0 @ return to SVC mode\n\
107 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)
108 /* These registers aren't modified by the above code in a way
109 visible to the compiler, but we mark them as clobbers anyway
110 so that GCC won't put any of the input or output operands in
112 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
115 void get_fiq_regs(struct pt_regs *regs)
117 register unsigned long tmp;
120 msr cpsr_c, %2 @ select FIQ mode\n\
122 stmia %1, {r8 - r14}\n\
123 msr cpsr_c, %0 @ return to SVC mode\n\
126 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)
127 /* These registers aren't modified by the above code in a way
128 visible to the compiler, but we mark them as clobbers anyway
129 so that GCC won't put any of the input or output operands in
131 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
134 int claim_fiq(struct fiq_handler *f)
141 if (current_fiq->fiq_op != NULL)
142 ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
146 f->next = current_fiq;
153 void release_fiq(struct fiq_handler *f)
155 if (current_fiq != f) {
156 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
157 f->name, current_fiq->name);
163 current_fiq = current_fiq->next;
164 while (current_fiq->fiq_op(current_fiq->dev_id, 0));
167 void enable_fiq(int fiq)
169 enable_irq(fiq + FIQ_START);
172 void disable_fiq(int fiq)
174 disable_irq(fiq + FIQ_START);
177 EXPORT_SYMBOL(set_fiq_handler);
178 EXPORT_SYMBOL(set_fiq_regs);
179 EXPORT_SYMBOL(get_fiq_regs);
180 EXPORT_SYMBOL(claim_fiq);
181 EXPORT_SYMBOL(release_fiq);
182 EXPORT_SYMBOL(enable_fiq);
183 EXPORT_SYMBOL(disable_fiq);
185 void __init init_FIQ(void)
187 no_fiq_insn = *(unsigned long *)0xffff001c;