1 // SPDX-License-Identifier: GPL-2.0
3 * linux/arch/arm/kernel/fiq.c
5 * Copyright (C) 1998 Russell King
6 * Copyright (C) 1998, 1999 Phil Blundell
8 * FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
10 * FIQ support re-written by Russell King to be more generic
12 * We now properly support a method by which the FIQ handlers can
13 * be stacked onto the vector. We still do not support sharing
14 * the FIQ vector itself.
16 * Operation is as follows:
17 * 1. Owner A claims FIQ:
18 * - default_fiq relinquishes control.
21 * - sets any registers,
23 * 3. Owner B claims FIQ:
24 * - if owner A has a relinquish function.
26 * - saves any registers.
30 * - sets any registers,
32 * 5. Owner B releases FIQ:
33 * - Owner A is asked to reacquire FIQ:
35 * - restores saved registers.
39 #include <linux/module.h>
40 #include <linux/kernel.h>
41 #include <linux/init.h>
42 #include <linux/interrupt.h>
43 #include <linux/seq_file.h>
45 #include <asm/cacheflush.h>
49 #include <asm/traps.h>
51 #define FIQ_OFFSET ({ \
52 extern void *vector_fiq_offset; \
53 (unsigned)&vector_fiq_offset; \
56 static unsigned long dfl_fiq_insn;
57 static struct pt_regs dfl_fiq_regs;
59 extern int irq_activate(struct irq_desc *desc);
61 /* Default reacquire function
62 * - we always relinquish FIQ control
63 * - we always reacquire FIQ control
65 static int fiq_def_op(void *ref, int relinquish)
68 /* Restore default handler and registers */
70 set_fiq_regs(&dfl_fiq_regs);
71 set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
74 /* FIXME: notify irq controller to standard enable FIQs */
80 static struct fiq_handler default_owner = {
85 static struct fiq_handler *current_fiq = &default_owner;
87 int show_fiq_list(struct seq_file *p, int prec)
89 if (current_fiq != &default_owner)
90 seq_printf(p, "%*s: %s\n", prec, "FIQ",
96 void set_fiq_handler(void *start, unsigned int length)
98 void *base = vectors_page;
99 unsigned offset = FIQ_OFFSET;
101 memcpy(base + offset, start, length);
102 if (!cache_is_vipt_nonaliasing())
103 flush_icache_range((unsigned long)base + offset,
104 (unsigned long)base + offset + length);
105 flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
108 int claim_fiq(struct fiq_handler *f)
115 if (current_fiq->fiq_op != NULL)
116 ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
120 f->next = current_fiq;
127 void release_fiq(struct fiq_handler *f)
129 if (current_fiq != f) {
130 pr_err("%s FIQ trying to release %s FIQ\n",
131 f->name, current_fiq->name);
137 current_fiq = current_fiq->next;
138 while (current_fiq->fiq_op(current_fiq->dev_id, 0));
141 static int fiq_start;
143 void enable_fiq(int fiq)
145 struct irq_desc *desc = irq_to_desc(fiq + fiq_start);
147 enable_irq(fiq + fiq_start);
150 void disable_fiq(int fiq)
152 disable_irq(fiq + fiq_start);
155 EXPORT_SYMBOL(set_fiq_handler);
156 EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */
157 EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */
158 EXPORT_SYMBOL(claim_fiq);
159 EXPORT_SYMBOL(release_fiq);
160 EXPORT_SYMBOL(enable_fiq);
161 EXPORT_SYMBOL(disable_fiq);
163 void __init init_FIQ(int start)
165 unsigned offset = FIQ_OFFSET;
166 dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
167 get_fiq_regs(&dfl_fiq_regs);