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 static unsigned long no_fiq_insn;
51 /* Default reacquire function
52 * - we always relinquish FIQ control
53 * - we always reacquire FIQ control
55 static int fiq_def_op(void *ref, int relinquish)
58 set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
63 static struct fiq_handler default_owner = {
68 static struct fiq_handler *current_fiq = &default_owner;
70 int show_fiq_list(struct seq_file *p, void *v)
72 if (current_fiq != &default_owner)
73 seq_printf(p, "FIQ: %s\n", current_fiq->name);
78 void set_fiq_handler(void *start, unsigned int length)
80 memcpy((void *)0xffff001c, start, length);
81 flush_icache_range(0xffff001c, 0xffff001c + length);
83 flush_icache_range(0x1c, 0x1c + length);
87 * Taking an interrupt in FIQ mode is death, so both these functions
88 * disable irqs for the duration.
90 void set_fiq_regs(struct pt_regs *regs)
92 register unsigned long tmp, tmp2;
96 msr cpsr_c, %1 @ select FIQ mode\n\
98 ldmia %2, {r8 - r14}\n\
99 msr cpsr_c, %0 @ return to SVC mode\n\
101 : "=&r" (tmp), "=&r" (tmp2)
102 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)
103 /* These registers aren't modified by the above code in a way
104 visible to the compiler, but we mark them as clobbers anyway
105 so that GCC won't put any of the input or output operands in
107 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
110 void get_fiq_regs(struct pt_regs *regs)
112 register unsigned long tmp, tmp2;
116 msr cpsr_c, %1 @ select FIQ mode\n\
118 stmia %2, {r8 - r14}\n\
119 msr cpsr_c, %0 @ return to SVC mode\n\
121 : "=&r" (tmp), "=&r" (tmp2)
122 : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)
123 /* These registers aren't modified by the above code in a way
124 visible to the compiler, but we mark them as clobbers anyway
125 so that GCC won't put any of the input or output operands in
127 : "r8", "r9", "r10", "r11", "r12", "r13", "r14");
130 int claim_fiq(struct fiq_handler *f)
137 if (current_fiq->fiq_op != NULL)
138 ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
142 f->next = current_fiq;
149 void release_fiq(struct fiq_handler *f)
151 if (current_fiq != f) {
152 printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
153 f->name, current_fiq->name);
159 current_fiq = current_fiq->next;
160 while (current_fiq->fiq_op(current_fiq->dev_id, 0));
163 void enable_fiq(int fiq)
165 enable_irq(fiq + FIQ_START);
168 void disable_fiq(int fiq)
170 disable_irq(fiq + FIQ_START);
173 EXPORT_SYMBOL(set_fiq_handler);
174 EXPORT_SYMBOL(set_fiq_regs);
175 EXPORT_SYMBOL(get_fiq_regs);
176 EXPORT_SYMBOL(claim_fiq);
177 EXPORT_SYMBOL(release_fiq);
178 EXPORT_SYMBOL(enable_fiq);
179 EXPORT_SYMBOL(disable_fiq);
181 void __init init_FIQ(void)
183 no_fiq_insn = *(unsigned long *)0xffff001c;