From 10d9eb8a17cfb697967928bde06f3e7e530b03ac Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Tue, 19 Mar 2013 23:59:04 -0400 Subject: [PATCH] drivers: irq-chip: irq-gic: introduce gic_cpu_if_down() When processors are about to hit low power states, the assertion of standbywfi signal, triggered by the wfi instruction, is essential to entering low power modes. If an IRQ is pending on the processor at the time wfi is issued, the wfi instruction completes and the processor restarts execution without asserting the standbywfi signal. Depending on the platform power controller HW this behaviour can be acceptable or not; if this behaviour must be prevented software should be provided with a way to disable the routing of interrupts to the core IRQ pins. On systems where raw GIC distributor interrupts are connected to the power controller as wake-up events (hence the power controller still senses IRQs and can wake up cores upon IRQ pending), the GIC CPU interface can be disabled on power down, so that the GIC CPU IF output is gated and wfi cannot complete, thereby preventing the standbywfi issue. This patch adds a simple function to the GIC driver that allows to disable the GIC CPU IF from power down procedures. Signed-off-by: Nicolas Pitre Signed-off-by: Lorenzo Pieralisi [rewrote commit log] Signed-off-by: Olof Johansson --- drivers/irqchip/irq-gic.c | 6 ++++++ include/linux/irqchip/arm-gic.h | 1 + 2 files changed, 7 insertions(+) diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index ee7c50312066..d0e948084eaf 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -453,6 +453,12 @@ static void gic_cpu_init(struct gic_chip_data *gic) writel_relaxed(1, base + GIC_CPU_CTRL); } +void gic_cpu_if_down(void) +{ + void __iomem *cpu_base = gic_data_cpu_base(&gic_data[0]); + writel_relaxed(0, cpu_base + GIC_CPU_CTRL); +} + #ifdef CONFIG_CPU_PM /* * Saves the GIC distributor registers during suspend or idle. Must be called diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h index 3e203eb23cc7..0e5d9ecdb2b6 100644 --- a/include/linux/irqchip/arm-gic.h +++ b/include/linux/irqchip/arm-gic.h @@ -66,6 +66,7 @@ extern struct irq_chip gic_arch_extn; void gic_init_bases(unsigned int, int, void __iomem *, void __iomem *, u32 offset, struct device_node *); void gic_cascade_irq(unsigned int gic_nr, unsigned int irq); +void gic_cpu_if_down(void); static inline void gic_init(unsigned int nr, int start, void __iomem *dist , void __iomem *cpu)