Despite Linux offering a rather fine grained control over the life cycle of an interrupt, there is a few cases where it would be very useful to snapshot (or even set) the internal state of the interrupt controller for a given interrupt line: - With KVM, a device shared between VMs must have its whole context switched, and that includes the interrupt line state. KVM/arm is moving to using this. - Some GPIO controllers seem to require peeking into the interrupt controller they are connected to to report their internal state. Instead of letting people facing this situation doing horrible (controller specific) hacks in their code, let's offer a couple of new entry points that allow a few attributes to be read and set. Of course, this is a very dangerous thing to do if you don't know what you doing, and I wouldn't expect most drivers to use this. But this can also be a life saver at times. This patch series implement said API, and adds support for this to the two main ARM interrupt controllers (GIC and GICv3). Available at: git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/irqchip_state This has been fairly heavily tested with KVM on ARM, which makes use of this feature to context switch the timer interrupt (see the last three patch in the above branch). Thanks, M. * From v3 [3] - Rebased on top of 4.0-rc4 * From v2 [2]: - Rebased on top of 3.19-rc3 - Fixed irq_set_irqchip_state return value * From v1 [1]: - Rebased on top of 3.18-rc7 + tip/irq/irqdomain-arm - Now deals with stacked domains - Changed the API to be less ambiguous (after review by tglx) - Added IRQCHIP_STATE_LINE_LEVEL (as requested by Bjorn Anderson) [1] https://lkml.org/lkml/2014/10/25/134 [2] https://lkml.org/lkml/2014/12/3/612 [3] http://lkml.iu.edu/hypermail/linux/kernel/1501.0/03473.html Marc Zyngier (3): genirq: Allow the irqchip state of an IRQ to be save/restored irqchip: GIC: Add support for irq_{get,set}_irqchip_state irqchip: GICv3: Add support for irq_{get,set}_irqchip_state drivers/irqchip/irq-gic-v3.c | 83 +++++++++++++++++++++++++++++++++------- drivers/irqchip/irq-gic.c | 69 +++++++++++++++++++++++++++++++-- include/linux/interrupt.h | 14 +++++++ include/linux/irq.h | 6 +++ kernel/irq/manage.c | 91 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 246 insertions(+), 17 deletions(-) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
