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	struct irq_desc *desc;
34
35	raw_spin_lock_irq(&irq_resend_lock);
36	while (!hlist_empty(&irq_resend_list)) {
37		desc = hlist_entry(irq_resend_list.first, struct irq_desc,
38				   resend_node);
39		hlist_del_init(&desc->resend_node);
40		raw_spin_unlock(&irq_resend_lock);
41		desc->handle_irq(desc);
42		raw_spin_lock(&irq_resend_lock);
43	}
44	raw_spin_unlock_irq(&irq_resend_lock);
45}
46
47/* Tasklet to handle resend: */
48static DECLARE_TASKLET(resend_tasklet, resend_irqs);
49
50static int irq_sw_resend(struct irq_desc *desc)
51{
52	/*
53	 * Validate whether this interrupt can be safely injected from
54	 * non interrupt context
55	 */
56	if (handle_enforce_irqctx(&desc->irq_data))
57		return -EINVAL;
58
59	/*
60	 * If the interrupt is running in the thread context of the parent
61	 * irq we need to be careful, because we cannot trigger it
62	 * directly.
63	 */
64	if (irq_settings_is_nested_thread(desc)) {
65		/*
66		 * If the parent_irq is valid, we retrigger the parent,
67		 * otherwise we do nothing.
68		 */
69		if (!desc->parent_irq)
70			return -EINVAL;
71
72		desc = irq_to_desc(desc->parent_irq);
73		if (!desc)
74			return -EINVAL;
75	}
76
77	/* Add to resend_list and activate the softirq: */
78	raw_spin_lock(&irq_resend_lock);
79	if (hlist_unhashed(&desc->resend_node))
80		hlist_add_head(&desc->resend_node, &irq_resend_list);
81	raw_spin_unlock(&irq_resend_lock);
82	tasklet_schedule(&resend_tasklet);
83	return 0;
84}
85
86void clear_irq_resend(struct irq_desc *desc)
87{
88	raw_spin_lock(&irq_resend_lock);
89	hlist_del_init(&desc->resend_node);
90	raw_spin_unlock(&irq_resend_lock);
91}
92
93void irq_resend_init(struct irq_desc *desc)
94{
95	INIT_HLIST_NODE(&desc->resend_node);
96}
97#else
98void clear_irq_resend(struct irq_desc *desc) {}
99void irq_resend_init(struct irq_desc *desc) {}
100
101static int irq_sw_resend(struct irq_desc *desc)
102{
103	return -EINVAL;
104}
105#endif
106
107static int try_retrigger(struct irq_desc *desc)
108{
109	if (desc->irq_data.chip->irq_retrigger)
110		return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
111
112#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
113	return irq_chip_retrigger_hierarchy(&desc->irq_data);
114#else
115	return 0;
116#endif
117}
118
119/*
120 * IRQ resend
121 *
122 * Is called with interrupts disabled and desc->lock held.
123 */
124int check_irq_resend(struct irq_desc *desc, bool inject)
125{
126	int err = 0;
127
128	/*
129	 * We do not resend level type interrupts. Level type interrupts
130	 * are resent by hardware when they are still active. Clear the
131	 * pending bit so suspend/resume does not get confused.
132	 */
133	if (irq_settings_is_level(desc)) {
134		desc->istate &= ~IRQS_PENDING;
135		return -EINVAL;
136	}
137
138	if (desc->istate & IRQS_REPLAY)
139		return -EBUSY;
140
141	if (!(desc->istate & IRQS_PENDING) && !inject)
142		return 0;
143
144	desc->istate &= ~IRQS_PENDING;
145
146	if (!try_retrigger(desc))
147		err = irq_sw_resend(desc);
148
149	/* If the retrigger was successful, mark it with the REPLAY bit */
150	if (!err)
151		desc->istate |= IRQS_REPLAY;
152	return err;
153}
154
155#ifdef CONFIG_GENERIC_IRQ_INJECTION
156/**
157 * irq_inject_interrupt - Inject an interrupt for testing/error injection
158 * @irq:	The interrupt number
159 *
160 * This function must only be used for debug and testing purposes!
161 *
162 * Especially on x86 this can cause a premature completion of an interrupt
163 * affinity change causing the interrupt line to become stale. Very
164 * unlikely, but possible.
165 *
166 * The injection can fail for various reasons:
167 * - Interrupt is not activated
168 * - Interrupt is NMI type or currently replaying
169 * - Interrupt is level type
170 * - Interrupt does not support hardware retrigger and software resend is
171 *   either not enabled or not possible for the interrupt.
172 */
173int irq_inject_interrupt(unsigned int irq)
174{
175	struct irq_desc *desc;
176	unsigned long flags;
177	int err;
178
179	/* Try the state injection hardware interface first */
180	if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
181		return 0;
182
183	/* That failed, try via the resend mechanism */
184	desc = irq_get_desc_buslock(irq, &flags, 0);
185	if (!desc)
186		return -EINVAL;
187
188	/*
189	 * Only try to inject when the interrupt is:
190	 *  - not NMI type
191	 *  - activated
192	 */
193	if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data))
194		err = -EINVAL;
195	else
196		err = check_irq_resend(desc, true);
197
198	irq_put_desc_busunlock(desc, flags);
199	return err;
200}
201EXPORT_SYMBOL_GPL(irq_inject_interrupt);
202#endif
203