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: */
25 static HLIST_HEAD(irq_resend_list);
26 static DEFINE_RAW_SPINLOCK(irq_resend_lock);
27
28 /*
29 * Run software resends of IRQ's
30 */
31 static 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: */
48 static DECLARE_TASKLET(resend_tasklet, resend_irqs);
49
50 static 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
86 void 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
93 void irq_resend_init(struct irq_desc *desc)
94 {
95 INIT_HLIST_NODE(&desc->resend_node);
96 }
97 #else
98 void clear_irq_resend(struct irq_desc *desc) {}
99 void irq_resend_init(struct irq_desc *desc) {}
100
101 static int irq_sw_resend(struct irq_desc *desc)
102 {
103 return -EINVAL;
104 }
105 #endif
106
107 static 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 */
124 int 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 */
173 int 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 (irq_is_nmi(desc) || !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 }
201 EXPORT_SYMBOL_GPL(irq_inject_interrupt);
202 #endif
203
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