xref: /openbmc/linux/kernel/irq/resend.c (revision 9f5deb55)
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  */
resend_irqs(struct tasklet_struct * unused)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 
irq_sw_resend(struct irq_desc * desc)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 
clear_irq_resend(struct irq_desc * desc)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 
irq_resend_init(struct irq_desc * desc)93 void irq_resend_init(struct irq_desc *desc)
94 {
95 	INIT_HLIST_NODE(&desc->resend_node);
96 }
97 #else
clear_irq_resend(struct irq_desc * desc)98 void clear_irq_resend(struct irq_desc *desc) {}
irq_resend_init(struct irq_desc * desc)99 void irq_resend_init(struct irq_desc *desc) {}
100 
irq_sw_resend(struct irq_desc * desc)101 static int irq_sw_resend(struct irq_desc *desc)
102 {
103 	return -EINVAL;
104 }
105 #endif
106 
try_retrigger(struct irq_desc * desc)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  */
check_irq_resend(struct irq_desc * desc,bool inject)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  */
irq_inject_interrupt(unsigned int irq)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 ((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 }
201 EXPORT_SYMBOL_GPL(irq_inject_interrupt);
202 #endif
203