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 parameter set to IRQCHIP_STATE_PENDING, IRQCHIP_STATE_ACTIVE,
IRQCHIP_STATE_MASKED or IRQCHIP_STATE_LINE_LEVEL.
- irq_set_irqchip_state similarly sets the state of the interrupt.
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
include/linux/interrupt.h | 14 ++++++++
include/linux/irq.h | 6 ++++
kernel/irq/manage.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 111 insertions(+)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index d9b05b5..fa7040e 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -356,6 +356,20 @@ static inline int disable_irq_wake(unsigned int irq)
return irq_set_irq_wake(irq, 0);
}
+/*
+ * irq_get_irqchip_state/irq_set_irqchip_state specific flags
+ */
+enum irqchip_irq_state {
+ IRQCHIP_STATE_PENDING, /* Is interrupt pending? */
+ IRQCHIP_STATE_ACTIVE, /* Is interrupt in progress? */
+ IRQCHIP_STATE_MASKED, /* Is interrupt masked? */
+ IRQCHIP_STATE_LINE_LEVEL, /* Is IRQ line high? */
+};
+
+extern int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+ bool *state);
+extern int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+ bool state);
#ifdef CONFIG_IRQ_FORCED_THREADING
extern bool force_irqthreads;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index d09ec7a..77dd2e7 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -30,6 +30,7 @@
struct seq_file;
struct module;
struct msi_msg;
+enum irqchip_irq_state;
/*
* IRQ line status.
@@ -324,6 +325,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
* irq_request_resources
* @irq_compose_msi_msg: optional to compose message content for MSI
* @irq_write_msi_msg: optional to write message content for MSI
+ * @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 {
@@ -363,6 +366,9 @@ struct irq_chip {
void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg);
void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg);
+ int (*irq_get_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool *state);
+ int (*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state);
+
unsigned long flags;
};
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8069237..acb401f5 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1758,3 +1758,94 @@ 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
+ * @which: One of IRQCHIP_STATE_* the caller wants to know about
+ * @state: a pointer to a boolean where the state is to be storeed
+ *
+ * This call snapshots the internal irqchip state of an
+ * interrupt, returning into @state the bit corresponding to
+ * stage @which
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+ bool *state)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+ unsigned long flags;
+ int err = -EINVAL;
+
+ desc = irq_get_desc_buslock(irq, &flags, 0);
+ if (!desc)
+ return err;
+
+ data = irq_desc_get_irq_data(desc);
+
+ do {
+ chip = irq_data_get_irq_chip(data);
+ if (chip->irq_get_irqchip_state)
+ break;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+ data = data->parent_data;
+#else
+ data = NULL;
+#endif
+ } while (data);
+
+ if (data)
+ err = chip->irq_get_irqchip_state(data, which, state);
+
+ irq_put_desc_busunlock(desc, flags);
+ return err;
+}
+
+/**
+ * irq_set_irqchip_state - set the state of a forwarded interrupt.
+ * @irq: Interrupt line that is forwarded to a VM
+ * @which: State to be restored (one of IRQCHIP_STATE_*)
+ * @val: Value corresponding to @which
+ *
+ * This call sets the internal irqchip state of an interrupt,
+ * depending on the value of @which.
+ *
+ * This function should be called with preemption disabled if the
+ * interrupt controller has per-cpu registers.
+ */
+int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+ bool val)
+{
+ struct irq_desc *desc;
+ struct irq_data *data;
+ struct irq_chip *chip;
+ unsigned long flags;
+ int err = -EINVAL;
+
+ desc = irq_get_desc_buslock(irq, &flags, 0);
+ if (!desc)
+ return err;
+
+ data = irq_desc_get_irq_data(desc);
+
+ do {
+ chip = irq_data_get_irq_chip(data);
+ if (chip->irq_set_irqchip_state)
+ break;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+ data = data->parent_data;
+#else
+ data = NULL;
+#endif
+ } while (data);
+
+ if (data)
+ err = chip->irq_set_irqchip_state(data, which, val);
+
+ irq_put_desc_busunlock(desc, flags);
+ return err;
+}
--
2.1.4
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