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genirq: Introduce request_any_context_irq()

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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>
This commit is contained in:
Marc Zyngier
2010-03-15 22:56:33 +00:00
committed by Thomas Gleixner
parent 7c7145f6ac
commit ae731f8d07
2 changed files with 60 additions and 0 deletions
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23
include/linux/interrupt.h
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@ -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