From 1a6b69b6548cd0dd82549393f30dd982ceeb79d2 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Thu, 12 Apr 2012 01:40:31 -0400 Subject: [PATCH] ARM: gic: add CPU migration support This is required by the big.LITTLE switcher code. The gic_migrate_target() changes the CPU interface mapping for the current CPU to redirect SGIs to the specified interface, and it also updates the target CPU for each interrupts to that CPU interface if they were targeting the current interface. Finally, pending SGIs for the current CPU are forwarded to the new interface. Because Linux does not use it, the SGI source information for the forwarded SGIs is not preserved. Neither is the source information for the SGIs sent by the current CPU to other CPUs adjusted to match the new CPU interface mapping. The required registers are banked so only the target CPU could do it. Signed-off-by: Nicolas Pitre --- drivers/irqchip/irq-gic.c | 87 +++++++++++++++++++++++++++++++++++++++-- include/linux/irqchip/arm-gic.h | 4 ++ 2 files changed, 88 insertions(+), 3 deletions(-) diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index ee7c503..268874a 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -253,10 +253,9 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val, if (cpu >= NR_GIC_CPU_IF || cpu >= nr_cpu_ids) return -EINVAL; + raw_spin_lock(&irq_controller_lock); mask = 0xff << shift; bit = gic_cpu_map[cpu] << shift; - - raw_spin_lock(&irq_controller_lock); val = readl_relaxed(reg) & ~mask; writel_relaxed(val | bit, reg); raw_spin_unlock(&irq_controller_lock); @@ -646,7 +645,9 @@ static void __init gic_pm_init(struct gic_chip_data *gic) void gic_raise_softirq(const struct cpumask *mask, unsigned int irq) { int cpu; - unsigned long map = 0; + unsigned long flags, map = 0; + + raw_spin_lock_irqsave(&irq_controller_lock, flags); /* Convert our logical CPU mask into a physical one. */ for_each_cpu(cpu, mask) @@ -660,6 +661,86 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq) /* this always happens on GIC0 */ writel_relaxed(map << 16 | irq, gic_data_dist_base(&gic_data[0]) + GIC_DIST_SOFTINT); + + raw_spin_unlock_irqrestore(&irq_controller_lock, flags); +} +#endif + +#ifdef CONFIG_BL_SWITCHER +/* + * gic_migrate_target - migrate IRQs to another CPU interface + * + * @new_cpu_id: the CPU target ID to migrate IRQs to + * + * Migrate all peripheral interrupts with a target matching the current CPU + * to the interface corresponding to @new_cpu_id. The CPU interface mapping + * is also updated. Targets to other CPU interfaces are unchanged. + * This must be called with IRQs locally disabled. + */ +void gic_migrate_target(unsigned int new_cpu_id) +{ + unsigned int cur_cpu_id, gic_irqs, gic_nr = 0; + void __iomem *dist_base; + int i, ror_val, cpu = smp_processor_id(); + u32 val, cur_target_mask, active_mask; + + if (gic_nr >= MAX_GIC_NR) + BUG(); + + dist_base = gic_data_dist_base(&gic_data[gic_nr]); + if (!dist_base) + return; + gic_irqs = gic_data[gic_nr].gic_irqs; + + cur_cpu_id = __ffs(gic_cpu_map[cpu]); + cur_target_mask = 0x01010101 << cur_cpu_id; + ror_val = (cur_cpu_id - new_cpu_id) & 31; + + raw_spin_lock(&irq_controller_lock); + + /* Update the target interface for this logical CPU */ + gic_cpu_map[cpu] = 1 << new_cpu_id; + + /* + * Find all the peripheral interrupts targetting the current + * CPU interface and migrate them to the new CPU interface. + * We skip DIST_TARGET 0 to 7 as they are read-only. + */ + for (i = 8; i < DIV_ROUND_UP(gic_irqs, 4); i++) { + val = readl_relaxed(dist_base + GIC_DIST_TARGET + i * 4); + active_mask = val & cur_target_mask; + if (active_mask) { + val &= ~active_mask; + val |= ror32(active_mask, ror_val); + writel_relaxed(val, dist_base + GIC_DIST_TARGET + i*4); + } + } + + raw_spin_unlock(&irq_controller_lock); + + /* + * Now let's migrate and clear any potential SGIs that might be + * pending for us (cur_cpu_id). Since GIC_DIST_SGI_PENDING_SET + * is a banked register, we can only forward the SGI using + * GIC_DIST_SOFTINT. The original SGI source is lost but Linux + * doesn't use that information anyway. + * + * For the same reason we do not adjust SGI source information + * for previously sent SGIs by us to other CPUs either. + */ + for (i = 0; i < 16; i += 4) { + int j; + val = readl_relaxed(dist_base + GIC_DIST_SGI_PENDING_SET + i); + if (!val) + continue; + writel_relaxed(val, dist_base + GIC_DIST_SGI_PENDING_CLEAR + i); + for (j = i; j < i + 4; j++) { + if (val & 0xff) + writel_relaxed((1 << (new_cpu_id + 16)) | j, + dist_base + GIC_DIST_SOFTINT); + val >>= 8; + } + } } #endif diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h index 3e203eb..40bfcac 100644 --- a/include/linux/irqchip/arm-gic.h +++ b/include/linux/irqchip/arm-gic.h @@ -31,6 +31,8 @@ #define GIC_DIST_TARGET 0x800 #define GIC_DIST_CONFIG 0xc00 #define GIC_DIST_SOFTINT 0xf00 +#define GIC_DIST_SGI_PENDING_CLEAR 0xf10 +#define GIC_DIST_SGI_PENDING_SET 0xf20 #define GICH_HCR 0x0 #define GICH_VTR 0x4 @@ -73,6 +75,8 @@ static inline void gic_init(unsigned int nr, int start, gic_init_bases(nr, start, dist, cpu, 0, NULL); } +void gic_migrate_target(unsigned int new_cpu_id); + #endif /* __ASSEMBLY */ #endif -- 2.7.4