genirq: Allow the irqchip state of an IRQ to be save/restored
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.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Tested-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Phong Vo <pvo@apm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Tin Huynh <tnhuynh@apm.com>
Cc: Y Vo <yvo@apm.com>
Cc: Toan Le <toanle@apm.com>
Cc: Bjorn Andersson <bjorn@kryo.se>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1426676484-21812-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 150dde0..950ae45 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -361,6 +361,20 @@
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 @@
* 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 @@
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 c0a1100..e68932b 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1798,3 +1798,94 @@
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;
+}