genirq: Implement irq_percpu_is_enabled()

Certain interrupt controller drivers have a register set that does not
make it easy to save/restore the mask of enabled/disabled interrupts
at suspend/resume time. At resume time, such drivers rely on the core
kernel irq subsystem to tell whether such or such interrupt is enabled
or not, in order to restore the proper state in the interrupt
controller register.

While the irqd_irq_disabled() provides the relevant information for
global interrupts, there is no similar function to query the
enabled/disabled state of a per-CPU interrupt.

Therefore, this commit complements the percpu_irq API with an
irq_percpu_is_enabled() function.

[ tglx: Simplified the implementation and added kerneldoc ]

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Tawfik Bayouk <tawfik@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Lior Amsalem <alior@marvell.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1445347435-2333-2-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index ad16809c85961e16ebc804280e4a78d66cf77634..cb30edbfe9fcd010b217aa385073d54fa71105c4 100644 (file)
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -195,6 +195,7 @@ extern void disable_irq(unsigned int irq);
 extern void disable_percpu_irq(unsigned int irq);
 extern void enable_irq(unsigned int irq);
 extern void enable_percpu_irq(unsigned int irq, unsigned int type);
+extern bool irq_percpu_is_enabled(unsigned int irq);
 extern void irq_wake_thread(unsigned int irq, void *dev_id);
 
 /* The following three functions are for the core kernel use only. */

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0eebaeef317bc990e3ee1b1bd1719b9e89211685..c84670c373f97bedd73edc5d459c41524a56fe16 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1743,6 +1743,31 @@ out:
 }
 EXPORT_SYMBOL_GPL(enable_percpu_irq);
 
+/**
+ * irq_percpu_is_enabled - Check whether the per cpu irq is enabled
+ * @irq:       Linux irq number to check for
+ *
+ * Must be called from a non migratable context. Returns the enable
+ * state of a per cpu interrupt on the current cpu.
+ */
+bool irq_percpu_is_enabled(unsigned int irq)
+{
+       unsigned int cpu = smp_processor_id();
+       struct irq_desc *desc;
+       unsigned long flags;
+       bool is_enabled;
+
+       desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
+       if (!desc)
+               return false;
+
+       is_enabled = cpumask_test_cpu(cpu, desc->percpu_enabled);
+       irq_put_desc_unlock(desc, flags);
+
+       return is_enabled;
+}
+EXPORT_SYMBOL_GPL(irq_percpu_is_enabled);
+
 void disable_percpu_irq(unsigned int irq)
 {
        unsigned int cpu = smp_processor_id();