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authorMarc Zyngier <maz@misterjones.org>2010-03-15 22:56:33 +0000
committerThomas Gleixner <tglx@linutronix.de>2010-04-13 16:36:39 +0200
commitae731f8d0785ccd3380f511bae888933b6562e45 (patch)
tree07db03ce79231153a4ae5df75c0ca4dcd96307c2
parent7c7145f6acc68100dbdc5d3c5c64fe3af1c99c89 (diff)
downloadlinux-2.6.34-ux500-ae731f8d0785ccd3380f511bae888933b6562e45.tar.gz
genirq: Introduce request_any_context_irq()
Now that we enjoy threaded interrupts, we're starting to see irq_chip implementations (wm831x, pca953x) that make use of threaded interrupts for the controller, and nested interrupts for the client interrupt. It all works very well, with one drawback: Drivers requesting an IRQ must now know whether the handler will run in a thread context or not, and call request_threaded_irq() or request_irq() accordingly. The problem is that the requesting driver sometimes doesn't know about the nature of the interrupt, specially when the interrupt controller is a discrete chip (typically a GPIO expander connected over I2C) that can be connected to a wide variety of otherwise perfectly supported hardware. This patch introduces the request_any_context_irq() function that mostly mimics the usual request_irq(), except that it checks whether the irq level is configured as nested or not, and calls the right backend. On success, it also returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED. [ tglx: Made return value an enum, simplified code and made the export of request_any_context_irq GPL ] Signed-off-by: Marc Zyngier <maz@misterjones.org> Cc: <joachim.eastwood@jotron.com> LKML-Reference: <927ea285bd0c68934ddae1a47e44a9ba@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--include/linux/interrupt.h23
-rw-r--r--kernel/irq/manage.c37
2 files changed, 60 insertions, 0 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 75f3f00ac1e..d7e7a7660c6 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -77,6 +77,18 @@ enum {
IRQTF_AFFINITY,
};
+/**
+ * These values can be returned by request_any_context_irq() and
+ * describe the context the interrupt will be run in.
+ *
+ * IRQC_IS_HARDIRQ - interrupt runs in hardirq context
+ * IRQC_IS_NESTED - interrupt runs in a nested threaded context
+ */
+enum {
+ IRQC_IS_HARDIRQ = 0,
+ IRQC_IS_NESTED,
+};
+
typedef irqreturn_t (*irq_handler_t)(int, void *);
/**
@@ -120,6 +132,10 @@ request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
+extern int __must_check
+request_any_context_irq(unsigned int irq, irq_handler_t handler,
+ unsigned long flags, const char *name, void *dev_id);
+
extern void exit_irq_thread(void);
#else
@@ -141,6 +157,13 @@ request_threaded_irq(unsigned int irq, irq_handler_t handler,
return request_irq(irq, handler, flags, name, dev);
}
+static inline int __must_check
+request_any_context_irq(unsigned int irq, irq_handler_t handler,
+ unsigned long flags, const char *name, void *dev_id)
+{
+ return request_irq(irq, handler, flags, name, dev_id);
+}
+
static inline void exit_irq_thread(void) { }
#endif
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 704e488730a..84f32278ff1 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1120,3 +1120,40 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
return retval;
}
EXPORT_SYMBOL(request_threaded_irq);
+
+/**
+ * request_any_context_irq - allocate an interrupt line
+ * @irq: Interrupt line to allocate
+ * @handler: Function to be called when the IRQ occurs.
+ * Threaded handler for threaded interrupts.
+ * @flags: Interrupt type flags
+ * @name: An ascii name for the claiming device
+ * @dev_id: A cookie passed back to the handler function
+ *
+ * This call allocates interrupt resources and enables the
+ * interrupt line and IRQ handling. It selects either a
+ * hardirq or threaded handling method depending on the
+ * context.
+ *
+ * On failure, it returns a negative value. On success,
+ * it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
+ */
+int request_any_context_irq(unsigned int irq, irq_handler_t handler,
+ unsigned long flags, const char *name, void *dev_id)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+ int ret;
+
+ if (!desc)
+ return -EINVAL;
+
+ if (desc->status & IRQ_NESTED_THREAD) {
+ ret = request_threaded_irq(irq, NULL, handler,
+ flags, name, dev_id);
+ return !ret ? IRQC_IS_NESTED : ret;
+ }
+
+ ret = request_irq(irq, handler, flags, name, dev_id);
+ return !ret ? IRQC_IS_HARDIRQ : ret;
+}
+EXPORT_SYMBOL_GPL(request_any_context_irq);