1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
4 * Copyright (C) 2005-2006, Thomas Gleixner
5 *
6 * This file contains the IRQ-resend code
7 *
8 * If the interrupt is waiting to be processed, we try to re-run it.
9 * We can't directly run it from here since the caller might be in an
10 * interrupt-protected region. Not all irq controller chips can
11 * retrigger interrupts at the hardware level, so in those cases
12 * we allow the resending of IRQs via a tasklet.
13 */
14
15#include <linux/irq.h>
16#include <linux/module.h>
17#include <linux/random.h>
18#include <linux/interrupt.h>
19
20#include "internals.h"
21
22#ifdef CONFIG_HARDIRQS_SW_RESEND
23
24/* hlist_head to handle software resend of interrupts: */
25static HLIST_HEAD(irq_resend_list);
26static DEFINE_RAW_SPINLOCK(irq_resend_lock);
27
28/*
29 * Run software resends of IRQ's
30 */
31static void resend_irqs(struct tasklet_struct *unused)
32{
33 guard(raw_spinlock_irq)(l: &irq_resend_lock);
34 while (!hlist_empty(h: &irq_resend_list)) {
35 struct irq_desc *desc;
36
37 desc = hlist_entry(irq_resend_list.first, struct irq_desc, resend_node);
38 hlist_del_init(n: &desc->resend_node);
39
40 raw_spin_unlock(&irq_resend_lock);
41 desc->handle_irq(desc);
42 raw_spin_lock(&irq_resend_lock);
43 }
44}
45
46/* Tasklet to handle resend: */
47static DECLARE_TASKLET(resend_tasklet, resend_irqs);
48
49static int irq_sw_resend(struct irq_desc *desc)
50{
51 /*
52 * Validate whether this interrupt can be safely injected from
53 * non interrupt context
54 */
55 if (irqd_is_handle_enforce_irqctx(d: &desc->irq_data))
56 return -EINVAL;
57
58 /*
59 * If the interrupt is running in the thread context of the parent
60 * irq we need to be careful, because we cannot trigger it
61 * directly.
62 */
63 if (irq_settings_is_nested_thread(desc)) {
64 /*
65 * If the parent_irq is valid, we retrigger the parent,
66 * otherwise we do nothing.
67 */
68 if (!desc->parent_irq)
69 return -EINVAL;
70
71 desc = irq_to_desc(irq: desc->parent_irq);
72 if (!desc)
73 return -EINVAL;
74 }
75
76 /* Add to resend_list and activate the softirq: */
77 scoped_guard(raw_spinlock, &irq_resend_lock) {
78 if (hlist_unhashed(h: &desc->resend_node))
79 hlist_add_head(n: &desc->resend_node, h: &irq_resend_list);
80 }
81 tasklet_schedule(t: &resend_tasklet);
82 return 0;
83}
84
85void clear_irq_resend(struct irq_desc *desc)
86{
87 guard(raw_spinlock)(l: &irq_resend_lock);
88 hlist_del_init(n: &desc->resend_node);
89}
90
91void irq_resend_init(struct irq_desc *desc)
92{
93 INIT_HLIST_NODE(h: &desc->resend_node);
94}
95#else
96void clear_irq_resend(struct irq_desc *desc) {}
97void irq_resend_init(struct irq_desc *desc) {}
98
99static int irq_sw_resend(struct irq_desc *desc)
100{
101 return -EINVAL;
102}
103#endif
104
105static int try_retrigger(struct irq_desc *desc)
106{
107 if (desc->irq_data.chip->irq_retrigger)
108 return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
109
110#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
111 return irq_chip_retrigger_hierarchy(data: &desc->irq_data);
112#else
113 return 0;
114#endif
115}
116
117/*
118 * IRQ resend
119 *
120 * Is called with interrupts disabled and desc->lock held.
121 */
122int check_irq_resend(struct irq_desc *desc, bool inject)
123{
124 int err = 0;
125
126 /*
127 * We do not resend level type interrupts. Level type interrupts
128 * are resent by hardware when they are still active. Clear the
129 * pending bit so suspend/resume does not get confused.
130 */
131 if (irq_settings_is_level(desc)) {
132 desc->istate &= ~IRQS_PENDING;
133 return -EINVAL;
134 }
135
136 if (desc->istate & IRQS_REPLAY)
137 return -EBUSY;
138
139 if (!(desc->istate & IRQS_PENDING) && !inject)
140 return 0;
141
142 desc->istate &= ~IRQS_PENDING;
143
144 if (!try_retrigger(desc))
145 err = irq_sw_resend(desc);
146
147 /* If the retrigger was successful, mark it with the REPLAY bit */
148 if (!err)
149 desc->istate |= IRQS_REPLAY;
150 return err;
151}
152
153#ifdef CONFIG_GENERIC_IRQ_INJECTION
154/**
155 * irq_inject_interrupt - Inject an interrupt for testing/error injection
156 * @irq: The interrupt number
157 *
158 * This function must only be used for debug and testing purposes!
159 *
160 * Especially on x86 this can cause a premature completion of an interrupt
161 * affinity change causing the interrupt line to become stale. Very
162 * unlikely, but possible.
163 *
164 * The injection can fail for various reasons:
165 * - Interrupt is not activated
166 * - Interrupt is NMI type or currently replaying
167 * - Interrupt is level type
168 * - Interrupt does not support hardware retrigger and software resend is
169 * either not enabled or not possible for the interrupt.
170 */
171int irq_inject_interrupt(unsigned int irq)
172{
173 int err = -EINVAL;
174
175 /* Try the state injection hardware interface first */
176 if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
177 return 0;
178
179 /* That failed, try via the resend mechanism */
180 scoped_irqdesc_get_and_buslock(irq, 0) {
181 struct irq_desc *desc = scoped_irqdesc;
182
183 /*
184 * Only try to inject when the interrupt is:
185 * - not NMI type
186 * - activated
187 */
188 if (!irq_is_nmi(desc) && irqd_is_activated(&desc->irq_data))
189 err = check_irq_resend(desc, true);
190 }
191 return err;
192}
193EXPORT_SYMBOL_GPL(irq_inject_interrupt);
194#endif
195