There is a number of cases where a kernel subsystem may want to
introspect the state of an interrupt at the irqchip level:
- When a peripheral is shared between virtual machines, its interrupt
state becomes part of the guest's state, and must be switched accordingly.
KVM on arm/arm64 requires this for its guest-visible timer
- Some GPIO controllers seem to require peeking into the interrupt controller
they are connected to to report their internal state
This seem to be a pattern that is common enough for the core code to try and
support this without too many horrible hacks. Introduce a pair of accessors
(irq_get_irqchip_state/irq_set_irqchip_state) to retrieve the bits that can
be of interest to another subsystem: pending, active, and masked.
- irq_get_irqchip_state returns the state of the interrupt according to a
state parameter set to IRQCHIP_STATE_PENDING, IRQCHIP_STATE_ACTIVE
or IRQCHIP_STATE_MASKED.
- irq_set_irqchip_state sets the state of the interrupt according to
a similar state.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
include/linux/interrupt.h | 2 ++
include/linux/irq.h | 18 ++++++++++++
kernel/irq/manage.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 91 insertions(+)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 69517a2..80818b4 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -356,6 +356,8 @@ static inline int disable_irq_wake(unsigned int irq)
return irq_set_irq_wake(irq, 0);
}
+extern int irq_get_irqchip_state(unsigned int irq, int state);
+extern int irq_set_irqchip_state(unsigned int irq, int state, int val);
#ifdef CONFIG_IRQ_FORCED_THREADING
extern bool force_irqthreads;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 03f48d9..257d59a 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -315,6 +315,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
* any other callback related to this irq
* @irq_release_resources: optional to release resources acquired with
* irq_request_resources
+ * @irq_get_irqchip_state: return the internal state of an interrupt
+ * @irq_set_irqchip_state: set the internal state of a interrupt
* @flags: chip specific flags
*/
struct irq_chip {
@@ -351,6 +353,9 @@ struct irq_chip {
int (*irq_request_resources)(struct irq_data *data);
void (*irq_release_resources)(struct irq_data *data);
+ int (*irq_get_irqchip_state)(struct irq_data *data, int state);
+ void (*irq_set_irqchip_state)(struct irq_data *data, int state, int val);
+
unsigned long flags;
};
@@ -376,6 +381,19 @@ enum {
IRQCHIP_EOI_THREADED = (1 << 6),
};
+/*
+ * irq_get_irqchip_state/irq_set_irqchip_state specific flags:
+ *
+ * IRQCHIP_STATE_PENDING: Interrupt asserted at the pin level
+ * IRQCHIP_STATE_ACTIVE: Interrupt in progress (ACKed, but not EOIed)
+ * IRQCHIP_STATE_MASKED: Interrupt is masked
+ */
+enum {
+ IRQCHIP_STATE_PENDING,
+ IRQCHIP_STATE_ACTIVE,
+ IRQCHIP_STATE_MASKED,
+};
+
/* This include will go away once we isolated irq_desc usage to core code */
#include <linux/irqdesc.h>
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0a9104b..6a4c03f 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1756,3 +1756,74 @@ int request_percpu_irq(unsigned int irq, irq_handler_t handler,
return retval;
}
+
+/**
+ * irq_get_irqchip_state - returns the irqchip state of a interrupt.
+ * @irq: Interrupt line that is forwarded to a VM
+ * @state: One of IRQCHIP_STATE_* the caller wants to know about
+ *
+ * This call snapshots the internal irqchip state of an
+ * interrupt, returning the bit corresponding to the requested
+ * @state.
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_get_irqchip_state(unsigned int irq, int state)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+ int val;
+
+ desc = irq_to_desc(irq);
+ if (!desc)
+ return -EINVAL;
+
+ data = irq_desc_get_irq_data(desc);
+
+ chip = irq_desc_get_chip(desc);
+ if (!chip->irq_get_irqchip_state)
+ return -EINVAL;
+
+ chip_bus_lock(desc);
+ val = chip->irq_get_irqchip_state(data, state);
+ chip_bus_sync_unlock(desc);
+
+ return val;
+}
+
+/**
+ * irq_set_irqchip_state - set the state of a forwarded interrupt.
+ * @irq: Interrupt line that is forwarded to a VM
+ * @state: State to be restored (one of IRQCHIP_STATE_*)
+ * @val: value corresponding to @state
+ *
+ * This call sets the internal irqchip state of an interrupt,
+ * depending on the value of @state.
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_set_irqchip_state(unsigned int irq, int state, int val)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+
+ desc = irq_to_desc(irq);
+ if (!desc)
+ return -EINVAL;
+
+ data = irq_desc_get_irq_data(desc);
+
+ chip = irq_desc_get_chip(desc);
+ if (!chip->irq_set_irqchip_state)
+ return -EINVAL;
+
+ chip_bus_lock(desc);
+ chip->irq_set_irqchip_state(data, state, val);
+ chip_bus_sync_unlock(desc);
+
+ return 0;
+}
--
2.1.0
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