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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
* Copyright (C) 2005-2006, Thomas Gleixner
*
* This file contains the IRQ-resend code
*
* If the interrupt is waiting to be processed, we try to re-run it.
* We can't directly run it from here since the caller might be in an
* interrupt-protected region. Not all irq controller chips can
* retrigger interrupts at the hardware level, so in those cases
* we allow the resending of IRQs via a tasklet.
*/
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include "internals.h"
#ifdef CONFIG_HARDIRQS_SW_RESEND
/* hlist_head to handle software resend of interrupts: */
static HLIST_HEAD(irq_resend_list);
static DEFINE_RAW_SPINLOCK(irq_resend_lock);
/*
* Run software resends of IRQ's
*/
static void resend_irqs(struct tasklet_struct *unused)
{
struct irq_desc *desc;
raw_spin_lock_irq(&irq_resend_lock);
while (!hlist_empty(&irq_resend_list)) {
desc = hlist_entry(irq_resend_list.first, struct irq_desc,
resend_node);
hlist_del_init(&desc->resend_node);
raw_spin_unlock(&irq_resend_lock);
desc->handle_irq(desc);
raw_spin_lock(&irq_resend_lock);
}
raw_spin_unlock_irq(&irq_resend_lock);
}
/* Tasklet to handle resend: */
static DECLARE_TASKLET(resend_tasklet, resend_irqs);
static int irq_sw_resend(struct irq_desc *desc)
{
/*
* Validate whether this interrupt can be safely injected from
* non interrupt context
*/
if (handle_enforce_irqctx(&desc->irq_data))
return -EINVAL;
/*
* If the interrupt is running in the thread context of the parent
* irq we need to be careful, because we cannot trigger it
* directly.
*/
if (irq_settings_is_nested_thread(desc)) {
/*
* If the parent_irq is valid, we retrigger the parent,
* otherwise we do nothing.
*/
if (!desc->parent_irq)
return -EINVAL;
desc = irq_to_desc(desc->parent_irq);
if (!desc)
return -EINVAL;
}
/* Add to resend_list and activate the softirq: */
raw_spin_lock(&irq_resend_lock);
if (hlist_unhashed(&desc->resend_node))
hlist_add_head(&desc->resend_node, &irq_resend_list);
raw_spin_unlock(&irq_resend_lock);
tasklet_schedule(&resend_tasklet);
return 0;
}
void clear_irq_resend(struct irq_desc *desc)
{
raw_spin_lock(&irq_resend_lock);
hlist_del_init(&desc->resend_node);
raw_spin_unlock(&irq_resend_lock);
}
void irq_resend_init(struct irq_desc *desc)
{
INIT_HLIST_NODE(&desc->resend_node);
}
#else
void clear_irq_resend(struct irq_desc *desc) {}
void irq_resend_init(struct irq_desc *desc) {}
static int irq_sw_resend(struct irq_desc *desc)
{
return -EINVAL;
}
#endif
static int try_retrigger(struct irq_desc *desc)
{
if (desc->irq_data.chip->irq_retrigger)
return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
return irq_chip_retrigger_hierarchy(&desc->irq_data);
#else
return 0;
#endif
}
/*
* IRQ resend
*
* Is called with interrupts disabled and desc->lock held.
*/
int check_irq_resend(struct irq_desc *desc, bool inject)
{
int err = 0;
/*
* We do not resend level type interrupts. Level type interrupts
* are resent by hardware when they are still active. Clear the
* pending bit so suspend/resume does not get confused.
*/
if (irq_settings_is_level(desc)) {
desc->istate &= ~IRQS_PENDING;
return -EINVAL;
}
if (desc->istate & IRQS_REPLAY)
return -EBUSY;
if (!(desc->istate & IRQS_PENDING) && !inject)
return 0;
desc->istate &= ~IRQS_PENDING;
if (!try_retrigger(desc))
err = irq_sw_resend(desc);
/* If the retrigger was successful, mark it with the REPLAY bit */
if (!err)
desc->istate |= IRQS_REPLAY;
return err;
}
#ifdef CONFIG_GENERIC_IRQ_INJECTION
/**
* irq_inject_interrupt - Inject an interrupt for testing/error injection
* @irq: The interrupt number
*
* This function must only be used for debug and testing purposes!
*
* Especially on x86 this can cause a premature completion of an interrupt
* affinity change causing the interrupt line to become stale. Very
* unlikely, but possible.
*
* The injection can fail for various reasons:
* - Interrupt is not activated
* - Interrupt is NMI type or currently replaying
* - Interrupt is level type
* - Interrupt does not support hardware retrigger and software resend is
* either not enabled or not possible for the interrupt.
*/
int irq_inject_interrupt(unsigned int irq)
{
struct irq_desc *desc;
unsigned long flags;
int err;
/* Try the state injection hardware interface first */
if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
return 0;
/* That failed, try via the resend mechanism */
desc = irq_get_desc_buslock(irq, &flags, 0);
if (!desc)
return -EINVAL;
/*
* Only try to inject when the interrupt is:
* - not NMI type
* - activated
*/
if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data))
err = -EINVAL;
else
err = check_irq_resend(desc, true);
irq_put_desc_busunlock(desc, flags);
return err;
}
EXPORT_SYMBOL_GPL(irq_inject_interrupt);
#endif
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