To support IPI FIQ we alter gic_cpu_init() to honour SMP_IPI_FIQ_MASK and register a fairly high priority notifier to acknowledge and clear the IPI when it is triggered.
For the IPI FIQ to be useful we must also make it safe to call gic_raise_softirq() from the FIQ handler by altering the locking strategy slightly.
Signed-off-by: Daniel Thompson daniel.thompson@linaro.org --- arch/arm/kernel/fiq.c | 3 ++ drivers/irqchip/irq-gic.c | 125 ++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 107 insertions(+), 21 deletions(-)
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c index c6b3bed..115d319 100644 --- a/arch/arm/kernel/fiq.c +++ b/arch/arm/kernel/fiq.c @@ -232,6 +232,9 @@ asmlinkage void __exception_irq_entry fiq_nmi_handler(struct pt_regs *regs) #ifdef CONFIG_KGDB_FIQ kgdb_handle_fiq(regs); #endif +#ifdef CONFIG_ARM_GIC + gic_handle_fiq_ipi(); +#endif
nmi_exit(); set_irq_regs(old_regs); diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index d928912..8834749 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -39,6 +39,7 @@ #include <linux/slab.h> #include <linux/irqchip/chained_irq.h> #include <linux/irqchip/arm-gic.h> +#include <linux/ratelimit.h>
#include <asm/cputype.h> #ifdef CONFIG_FIQ @@ -51,6 +52,10 @@ #include "irq-gic-common.h" #include "irqchip.h"
+#ifndef SMP_IPI_FIQ_MASK +#define SMP_IPI_FIQ_MASK 0 +#endif + union gic_base { void __iomem *common_base; void __percpu * __iomem *percpu_base; @@ -77,6 +82,8 @@ struct gic_chip_data { };
static DEFINE_RAW_SPINLOCK(irq_controller_lock); +/* A fiq-safe spinlock must only be locked when the FIQ is masked */ +static DEFINE_RAW_SPINLOCK(fiq_safe_migration_lock);
/* * The GIC mapping of CPU interfaces does not necessarily match @@ -346,20 +353,21 @@ static struct irq_chip gic_chip = { * match what "ARM strongly recommends" for a system where no Group 1 * interrupt must ever preempt a Group 0 interrupt. */ -static void gic_set_group_irq(struct irq_data *d, int group) +static void gic_set_group_irq(void __iomem *base, unsigned int hwirq, + int group) { - unsigned int grp_reg = gic_irq(d) / 32 * 4; - u32 grp_mask = 1 << (gic_irq(d) % 32); + unsigned int grp_reg = hwirq / 32 * 4; + u32 grp_mask = 1 << (hwirq % 32); u32 grp_val;
- unsigned int pri_reg = (gic_irq(d) / 4) * 4; - u32 pri_mask = 1 << (7 + ((gic_irq(d) % 4) * 8)); + unsigned int pri_reg = (hwirq / 4) * 4; + u32 pri_mask = 1 << (7 + ((hwirq % 4) * 8)); u32 pri_val;
raw_spin_lock(&irq_controller_lock);
- grp_val = readl_relaxed(gic_dist_base(d) + GIC_DIST_IGROUP + grp_reg); - pri_val = readl_relaxed(gic_dist_base(d) + GIC_DIST_PRI + pri_reg); + grp_val = readl_relaxed(base + GIC_DIST_IGROUP + grp_reg); + pri_val = readl_relaxed(base + GIC_DIST_PRI + pri_reg);
if (group) { grp_val |= grp_mask; @@ -369,20 +377,20 @@ static void gic_set_group_irq(struct irq_data *d, int group) pri_val &= ~pri_mask; }
- writel_relaxed(grp_val, gic_dist_base(d) + GIC_DIST_IGROUP + grp_reg); - writel_relaxed(pri_val, gic_dist_base(d) + GIC_DIST_PRI + pri_reg); + writel_relaxed(grp_val, base + GIC_DIST_IGROUP + grp_reg); + writel_relaxed(pri_val, base + GIC_DIST_PRI + pri_reg);
raw_spin_unlock(&irq_controller_lock); }
static void gic_enable_fiq(struct irq_data *d) { - gic_set_group_irq(d, 0); + gic_set_group_irq(gic_dist_base(d), gic_irq(d), 0); }
static void gic_disable_fiq(struct irq_data *d) { - gic_set_group_irq(d, 1); + gic_set_group_irq(gic_dist_base(d), gic_irq(d), 1); }
static int gic_ack_fiq(struct irq_data *d) @@ -390,8 +398,22 @@ static int gic_ack_fiq(struct irq_data *d) struct gic_chip_data *gic = irq_data_get_irq_chip_data(d); u32 irqstat, irqnr;
- irqstat = readl_relaxed(gic_data_cpu_base(gic) + GIC_CPU_INTACK); - irqnr = irqstat & GICC_IAR_INT_ID_MASK; + while (1) { + writel_relaxed(0x70, gic_data_cpu_base(gic) + GIC_CPU_PRIMASK); + irqstat = + readl_relaxed(gic_data_cpu_base(gic) + GIC_CPU_INTACK); + writel_relaxed(0xf0, gic_data_cpu_base(gic) + GIC_CPU_PRIMASK); + + irqnr = irqstat & GICC_IAR_INT_ID_MASK; + if (irqnr > 15) + break; + + /* we've got an IPI which we can simply acknowledge + * and move on + */ + gic_eoi_irq(d); + } + return irq_find_mapping(gic->domain, irqnr); }
@@ -430,7 +452,43 @@ static void __init gic_init_fiq(struct gic_chip_data *gic, for (i = 0; i < num_irqs; i++) fiq_register_mapping(first_irq + i, &gic_fiq); } + +/* + * Fully acknowledge (both ack and eoi) a FIQ-based IPI + */ +static int gic_handle_fiq_ipi(struct notifier_block *nb, unsigned long regs, + void *data) +{ + struct gic_chip_data *gic = &gic_data[0]; + void __iomem *cpu_base = gic_data_cpu_base(gic); + unsigned long irqstat, irqnr; + + if (WARN_ON(!in_nmi())) + return NOTIFY_BAD; + + while ((1u << readl_relaxed(cpu_base + GIC_CPU_HIGHPRI)) & + SMP_IPI_FIQ_MASK) { + irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK); + writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI); + + irqnr = irqstat & GICC_IAR_INT_ID_MASK; + WARN_RATELIMIT(irqnr > 16, + "Unexpected irqnr %lu (bad prioritization?)\n", + irqnr); + } + + return NOTIFY_OK; +} + +/* + * Notifier to ensure IPI FIQ is acknowledged correctly. + */ +static struct notifier_block gic_fiq_ipi_notifier = { + .notifier_call = gic_handle_fiq_ipi, +}; #else /* CONFIG_FIQ */ +static inline void gic_set_group_irq(void __iomem *base, unsigned int hwirq, + int group) {} static inline void gic_init_fiq(struct gic_chip_data *gic, irq_hw_number_t first_irq, unsigned int num_irqs) {} @@ -527,14 +585,19 @@ static void gic_cpu_init(struct gic_chip_data *gic) gic_cpu_config(dist_base, NULL);
/* - * Set all PPI and SGI interrupts to be group 1. - * - * If grouping is not available (not implemented or prohibited by - * security mode) these registers are read-as-zero/write-ignored. + * Optionally set all PPI and SGI interrupts to be group 1. */ if (gic_data_fiq_enable(gic)) writel_relaxed(0xffffffff, dist_base + GIC_DIST_IGROUP + 0);
+ /* + * Optionally shift the FIQ based IPIs to group 0. + */ + if (gic_data_fiq_enable(gic)) + for (i = 0; i < 16; i++) + if (SMP_IPI_FIQ_MASK & (1 << i)) + gic_set_group_irq(dist_base, i, 0); + writel_relaxed(0xf0, base + GIC_CPU_PRIMASK); if (gic_data_fiq_enable(gic)) writel_relaxed(0x1f, base + GIC_CPU_CTRL); @@ -747,7 +810,17 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq) unsigned long flags, map = 0; unsigned long softint;
- raw_spin_lock_irqsave(&irq_controller_lock, flags); + /* + * The locking in this function ensures we don't use stale cpu mappings + * and thus we never route an IPI to the wrong physical core during a + * big.LITTLE switch. The switch code takes both of these locks meaning + * we can choose whichever lock is safe to use from our current calling + * context. + */ + if (in_nmi()) + raw_spin_lock(&fiq_safe_migration_lock); + else + raw_spin_lock_irqsave(&irq_controller_lock, flags);
/* Convert our logical CPU mask into a physical one. */ for_each_cpu(cpu, mask) @@ -761,12 +834,16 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
/* this always happens on GIC0 */ softint = map << 16 | irq; - if (gic_data_fiq_enable(&gic_data[0])) + if (gic_data_fiq_enable(&gic_data[0]) && + !(SMP_IPI_FIQ_MASK & (1 << irq))) softint |= 0x8000; writel_relaxed(softint, gic_data_dist_base(&gic_data[0]) + GIC_DIST_SOFTINT);
- raw_spin_unlock_irqrestore(&irq_controller_lock, flags); + if (in_nmi()) + raw_spin_unlock(&fiq_safe_migration_lock); + else + raw_spin_unlock_irqrestore(&irq_controller_lock, flags); } #endif
@@ -814,7 +891,7 @@ int gic_get_cpu_id(unsigned int cpu) * 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. + * This must be called with IRQ and FIQ locally disabled. */ void gic_migrate_target(unsigned int new_cpu_id) { @@ -836,6 +913,7 @@ void gic_migrate_target(unsigned int new_cpu_id) ror_val = (cur_cpu_id - new_cpu_id) & 31;
raw_spin_lock(&irq_controller_lock); + raw_spin_lock(&fiq_safe_migration_lock);
/* Update the target interface for this logical CPU */ gic_cpu_map[cpu] = 1 << new_cpu_id; @@ -855,6 +933,7 @@ void gic_migrate_target(unsigned int new_cpu_id) } }
+ raw_spin_unlock(&fiq_safe_migration_lock); raw_spin_unlock(&irq_controller_lock);
/* @@ -1125,6 +1204,10 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start, #ifdef CONFIG_SMP set_smp_cross_call(gic_raise_softirq); register_cpu_notifier(&gic_cpu_notifier); +#ifdef CONFIG_FIQ + if (gic_data_fiq_enable(gic)) + register_fiq_nmi_notifier(&gic_fiq_ipi_notifier); +#endif #endif set_handle_irq(gic_handle_irq); }