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genirq: Allow the irqchip state of an IRQ to be save/restored

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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: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Tested-by: Bjorn 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Marc Zyngier
2015-03-18 11:01:22 +00:00
committed by Thomas Gleixner
parent fe0c52fc00
commit 1b7047edfc
3 changed files with 111 additions and 0 deletions
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6
include/linux/irq.h
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@@ -30,6 +30,7 @@
struct seq_file;
struct module;
struct msi_msg;
enum irqchip_irq_state;
/*
* IRQ line status.
@@ -324,6 +325,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
* irq_request_resources
* @irq_compose_msi_msg: optional to compose 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
*/
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_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;
};