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Commit ae731f8d authored by Marc Zyngier's avatar Marc Zyngier Committed by Thomas Gleixner
Browse files

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: default avatarMarc Zyngier <maz@misterjones.org>
Cc: <joachim.eastwood@jotron.com>
LKML-Reference: <927ea285bd0c68934ddae1a47e44a9ba@localhost>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7c7145f6

include/linux/interrupt.h

+23 −0
Original line number Diff line number Diff line
@@ -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

kernel/irq/manage.c

+37 −0
Original line number Diff line number Diff line
@@ -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);