1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
4 * Copyright (C) 2005-2006, Thomas Gleixner
6 * This file contains the IRQ-resend code
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.
15 #include <linux/irq.h>
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/interrupt.h>
20 #include "internals.h"
22 #ifdef CONFIG_HARDIRQS_SW_RESEND
24 /* hlist_head to handle software resend of interrupts: */
25 static HLIST_HEAD(irq_resend_list);
26 static DEFINE_RAW_SPINLOCK(irq_resend_lock);
29 * Run software resends of IRQ's
31 static void resend_irqs(struct tasklet_struct *unused)
33 struct irq_desc *desc;
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,
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);
44 raw_spin_unlock_irq(&irq_resend_lock);
47 /* Tasklet to handle resend: */
48 static DECLARE_TASKLET(resend_tasklet, resend_irqs);
50 static int irq_sw_resend(struct irq_desc *desc)
53 * Validate whether this interrupt can be safely injected from
54 * non interrupt context
56 if (handle_enforce_irqctx(&desc->irq_data))
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
64 if (irq_settings_is_nested_thread(desc)) {
66 * If the parent_irq is valid, we retrigger the parent,
67 * otherwise we do nothing.
69 if (!desc->parent_irq)
73 /* Add to resend_list and activate the softirq: */
74 raw_spin_lock(&irq_resend_lock);
75 hlist_add_head(&desc->resend_node, &irq_resend_list);
76 raw_spin_unlock(&irq_resend_lock);
77 tasklet_schedule(&resend_tasklet);
81 void clear_irq_resend(struct irq_desc *desc)
83 raw_spin_lock(&irq_resend_lock);
84 hlist_del_init(&desc->resend_node);
85 raw_spin_unlock(&irq_resend_lock);
88 void irq_resend_init(struct irq_desc *desc)
90 INIT_HLIST_NODE(&desc->resend_node);
93 void clear_irq_resend(struct irq_desc *desc) {}
94 void irq_resend_init(struct irq_desc *desc) {}
96 static int irq_sw_resend(struct irq_desc *desc)
102 static int try_retrigger(struct irq_desc *desc)
104 if (desc->irq_data.chip->irq_retrigger)
105 return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
107 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
108 return irq_chip_retrigger_hierarchy(&desc->irq_data);
117 * Is called with interrupts disabled and desc->lock held.
119 int check_irq_resend(struct irq_desc *desc, bool inject)
124 * We do not resend level type interrupts. Level type interrupts
125 * are resent by hardware when they are still active. Clear the
126 * pending bit so suspend/resume does not get confused.
128 if (irq_settings_is_level(desc)) {
129 desc->istate &= ~IRQS_PENDING;
133 if (desc->istate & IRQS_REPLAY)
136 if (!(desc->istate & IRQS_PENDING) && !inject)
139 desc->istate &= ~IRQS_PENDING;
141 if (!try_retrigger(desc))
142 err = irq_sw_resend(desc);
144 /* If the retrigger was successful, mark it with the REPLAY bit */
146 desc->istate |= IRQS_REPLAY;
150 #ifdef CONFIG_GENERIC_IRQ_INJECTION
152 * irq_inject_interrupt - Inject an interrupt for testing/error injection
153 * @irq: The interrupt number
155 * This function must only be used for debug and testing purposes!
157 * Especially on x86 this can cause a premature completion of an interrupt
158 * affinity change causing the interrupt line to become stale. Very
159 * unlikely, but possible.
161 * The injection can fail for various reasons:
162 * - Interrupt is not activated
163 * - Interrupt is NMI type or currently replaying
164 * - Interrupt is level type
165 * - Interrupt does not support hardware retrigger and software resend is
166 * either not enabled or not possible for the interrupt.
168 int irq_inject_interrupt(unsigned int irq)
170 struct irq_desc *desc;
174 /* Try the state injection hardware interface first */
175 if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
178 /* That failed, try via the resend mechanism */
179 desc = irq_get_desc_buslock(irq, &flags, 0);
184 * Only try to inject when the interrupt is:
188 if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data))
191 err = check_irq_resend(desc, true);
193 irq_put_desc_busunlock(desc, flags);
196 EXPORT_SYMBOL_GPL(irq_inject_interrupt);