1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/arch/arm/kernel/fiq.c |
4 | * |
5 | * Copyright (C) 1998 Russell King |
6 | * Copyright (C) 1998, 1999 Phil Blundell |
7 | * |
8 | * FIQ support written by Philip Blundell <philb@gnu.org>, 1998. |
9 | * |
10 | * FIQ support re-written by Russell King to be more generic |
11 | * |
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. |
15 | * |
16 | * Operation is as follows: |
17 | * 1. Owner A claims FIQ: |
18 | * - default_fiq relinquishes control. |
19 | * 2. Owner A: |
20 | * - inserts code. |
21 | * - sets any registers, |
22 | * - enables FIQ. |
23 | * 3. Owner B claims FIQ: |
24 | * - if owner A has a relinquish function. |
25 | * - disable FIQs. |
26 | * - saves any registers. |
27 | * - returns zero. |
28 | * 4. Owner B: |
29 | * - inserts code. |
30 | * - sets any registers, |
31 | * - enables FIQ. |
32 | * 5. Owner B releases FIQ: |
33 | * - Owner A is asked to reacquire FIQ: |
34 | * - inserts code. |
35 | * - restores saved registers. |
36 | * - enables FIQ. |
37 | * 6. Goto 3 |
38 | */ |
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> |
44 | |
45 | #include <asm/cacheflush.h> |
46 | #include <asm/cp15.h> |
47 | #include <asm/fiq.h> |
48 | #include <asm/mach/irq.h> |
49 | #include <asm/irq.h> |
50 | #include <asm/traps.h> |
51 | |
52 | #define FIQ_OFFSET ({ \ |
53 | extern void *vector_fiq_offset; \ |
54 | (unsigned)&vector_fiq_offset; \ |
55 | }) |
56 | |
57 | static unsigned long dfl_fiq_insn; |
58 | static struct pt_regs dfl_fiq_regs; |
59 | |
60 | /* Default reacquire function |
61 | * - we always relinquish FIQ control |
62 | * - we always reacquire FIQ control |
63 | */ |
64 | static int fiq_def_op(void *ref, int relinquish) |
65 | { |
66 | if (!relinquish) { |
67 | /* Restore default handler and registers */ |
68 | local_fiq_disable(); |
69 | set_fiq_regs(&dfl_fiq_regs); |
70 | set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn)); |
71 | local_fiq_enable(); |
72 | |
73 | /* FIXME: notify irq controller to standard enable FIQs */ |
74 | } |
75 | |
76 | return 0; |
77 | } |
78 | |
79 | static struct fiq_handler default_owner = { |
80 | .name = "default" , |
81 | .fiq_op = fiq_def_op, |
82 | }; |
83 | |
84 | static struct fiq_handler *current_fiq = &default_owner; |
85 | |
86 | int show_fiq_list(struct seq_file *p, int prec) |
87 | { |
88 | if (current_fiq != &default_owner) |
89 | seq_printf(m: p, fmt: "%*s: %s\n" , prec, "FIQ" , |
90 | current_fiq->name); |
91 | |
92 | return 0; |
93 | } |
94 | |
95 | void set_fiq_handler(void *start, unsigned int length) |
96 | { |
97 | void *base = vectors_page; |
98 | unsigned offset = FIQ_OFFSET; |
99 | |
100 | memcpy(base + offset, start, length); |
101 | if (!cache_is_vipt_nonaliasing()) |
102 | flush_icache_range(start: (unsigned long)base + offset, |
103 | end: (unsigned long)base + offset + length); |
104 | flush_icache_range(start: 0xffff0000 + offset, end: 0xffff0000 + offset + length); |
105 | } |
106 | |
107 | int claim_fiq(struct fiq_handler *f) |
108 | { |
109 | int ret = 0; |
110 | |
111 | if (current_fiq) { |
112 | ret = -EBUSY; |
113 | |
114 | if (current_fiq->fiq_op != NULL) |
115 | ret = current_fiq->fiq_op(current_fiq->dev_id, 1); |
116 | } |
117 | |
118 | if (!ret) { |
119 | f->next = current_fiq; |
120 | current_fiq = f; |
121 | } |
122 | |
123 | return ret; |
124 | } |
125 | |
126 | void release_fiq(struct fiq_handler *f) |
127 | { |
128 | if (current_fiq != f) { |
129 | pr_err("%s FIQ trying to release %s FIQ\n" , |
130 | f->name, current_fiq->name); |
131 | dump_stack(); |
132 | return; |
133 | } |
134 | |
135 | do |
136 | current_fiq = current_fiq->next; |
137 | while (current_fiq->fiq_op(current_fiq->dev_id, 0)); |
138 | } |
139 | |
140 | static int fiq_start; |
141 | |
142 | void enable_fiq(int fiq) |
143 | { |
144 | enable_irq(irq: fiq + fiq_start); |
145 | } |
146 | |
147 | void disable_fiq(int fiq) |
148 | { |
149 | disable_irq(irq: fiq + fiq_start); |
150 | } |
151 | |
152 | EXPORT_SYMBOL(set_fiq_handler); |
153 | EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ |
154 | EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ |
155 | EXPORT_SYMBOL(claim_fiq); |
156 | EXPORT_SYMBOL(release_fiq); |
157 | EXPORT_SYMBOL(enable_fiq); |
158 | EXPORT_SYMBOL(disable_fiq); |
159 | |
160 | void __init init_FIQ(int start) |
161 | { |
162 | unsigned offset = FIQ_OFFSET; |
163 | dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset); |
164 | get_fiq_regs(&dfl_fiq_regs); |
165 | fiq_start = start; |
166 | } |
167 | |