This patchset modifies the GIC driver to allow it, on supported platforms, to route IPI interrupts to FIQ. It then uses this feature to allow the NMI backtrace code on arm to be implemented using FIQ.
The patches have been runtime tested on the following systems, covering both arm and arm64 systems and those with and without FIQ support:
* Freescale i.MX6 (arm, gicv1, supports FIQ) * Qualcomm Snapdragon 600 (arm, gicv2, does not support FIQ) * Hisilicon 6220 (arm64, gicv2, does not support FIQ)
v22:
* Rebase on v4.4-rc5 to adopt the new NMI backtrace code from Russell King.
* Polished a few comments and reorganised the patches very slightly (shifted a couple of arm changes to patch 4).
* Fixed bug in the way gic_handle_fiq() checks whether it is safe for it to read IAR.
v21:
* Change the way SGIs are raised to try to increase robustness starting secondary cores. This is a theoretic fix for a regression reported by Mark Rutland on vexpress-tc2 but it also allows us to remove igroup0_shadow entirely since it is no longer needed.
* Fix a couple of variable names and add comments to describe the hardware behavior better (Mark Rutland).
* Improved MULTI_IRQ_HANDLER support by clearing FIQs using handle_arch_irq (Marc Zygnier).
* Fix gic_cpu_if_down() to ensure group 1 interrupts are disabled when the interface is brought down.
For changes in v20 and earlier see: http://thread.gmane.org/gmane.linux.kernel/1928465
Daniel Thompson (4): irqchip: gic: Optimize locking in gic_raise_softirq irqchip: gic: Make gic_raise_softirq FIQ-safe irqchip: gic: Introduce plumbing for IPI FIQ ARM: Allow IPI_CPU_BACKTRACE to exploit FIQ
arch/arm/include/asm/smp.h | 9 ++ arch/arm/kernel/smp.c | 6 + arch/arm/kernel/traps.c | 9 +- drivers/irqchip/irq-gic.c | 235 ++++++++++++++++++++++++++++++++++++---- include/linux/irqchip/arm-gic.h | 6 + 5 files changed, 245 insertions(+), 20 deletions(-)
-- 2.5.0