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Commit 1b7047ed authored by Marc Zyngier's avatar Marc Zyngier Committed by Thomas Gleixner
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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: default avatarMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: default avatarBjorn Andersson <bjorn.andersson@sonymobile.com>
Tested-by: default avatarBjorn 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent fe0c52fc

include/linux/interrupt.h

+14 −0
Original line number Original line Diff line number Diff line
@@ -361,6 +361,20 @@ static inline int disable_irq_wake(unsigned int irq) 
	return irq_set_irq_wake(irq, 0);

	return irq_set_irq_wake(irq, 0);

}

}





/*

 * irq_get_irqchip_state/irq_set_irqchip_state specific flags

 */

enum irqchip_irq_state {

	IRQCHIP_STATE_PENDING,		/* Is interrupt pending? */

	IRQCHIP_STATE_ACTIVE,		/* Is interrupt in progress? */

	IRQCHIP_STATE_MASKED,		/* Is interrupt masked? */

	IRQCHIP_STATE_LINE_LEVEL,	/* Is IRQ line high? */

};



extern int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,

				 bool *state);

extern int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,

				 bool state);





#ifdef CONFIG_IRQ_FORCED_THREADING

#ifdef CONFIG_IRQ_FORCED_THREADING

extern bool force_irqthreads;

extern bool force_irqthreads;

include/linux/irq.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -30,6 +30,7 @@ 
struct seq_file;

struct seq_file;

struct module;

struct module;

struct msi_msg;

struct msi_msg;

enum irqchip_irq_state;





/*

/*

 * IRQ line status.

 * IRQ line status.
@@ -324,6 +325,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) 
 *				irq_request_resources

 *				irq_request_resources

 * @irq_compose_msi_msg:	optional to compose message content for MSI

 * @irq_compose_msi_msg:	optional to compose message content for MSI

 * @irq_write_msi_msg:	optional to write message content for MSI

 * @irq_write_msi_msg:	optional to write message content for MSI

 * @irq_get_irqchip_state:	return the internal state of an interrupt

 * @irq_set_irqchip_state:	set the internal state of a interrupt

 * @flags:		chip specific flags

 * @flags:		chip specific flags

 */

 */

struct irq_chip {

struct irq_chip {
@@ -363,6 +366,9 @@ struct irq_chip { 
	void		(*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg);

	void		(*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg);

	void		(*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg);

	void		(*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg);





	int		(*irq_get_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool *state);

	int		(*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state);



	unsigned long	flags;

	unsigned long	flags;

};

};

kernel/irq/manage.c

+91 −0
Original line number Original line Diff line number Diff line
@@ -1798,3 +1798,94 @@ int request_percpu_irq(unsigned int irq, irq_handler_t handler, 




	return retval;

	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;

}