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authorMarc Zyngier <marc.zyngier@arm.com>2015-03-18 11:01:22 +0000
committerThomas Gleixner <tglx@linutronix.de>2015-04-08 23:28:28 +0200
commit1b7047edfcfb257f69e306c9afbab150cb987717 (patch)
tree68b2383acee6ce6a58900507e797e9c6178e4a5b /kernel
parentfe0c52fc003bc046380e52fe6799c96d770770cc (diff)
downloadlinux-1b7047edfcfb257f69e306c9afbab150cb987717.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/irq/manage.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c0a1100d911f..e68932bb308e 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1798,3 +1798,94 @@ 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;
+}