The GIC register accesses today make use of readl()/writel() which prove to be very expensive when used along with mandatory barriers. This mandatory barriers also introduces an un-necessary and expensive l2x0_sync() operation. On Cortex-A9 MP cores, GIC IO accesses from CPU are direct and doesn't go through L2X0 write buffer.
Also since a DSB does not guarantee that the device state has been changed, a read back from the device is introduced wherever necessary. Signed-off-by: Santosh Shilimkar <santosh.shilim...@ti.com> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <will.dea...@arm.com> --- V2: Incorporated comments from Catalin Marinas. Boot tested with OMAP4430 SDP. arch/arm/common/gic.c | 49 +++++++++++++++++++++++++------------------------ 1 files changed, 25 insertions(+), 24 deletions(-) diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c index f70ec7d..98f9137 100644 --- a/arch/arm/common/gic.c +++ b/arch/arm/common/gic.c @@ -89,7 +89,7 @@ static void gic_ack_irq(struct irq_data *d) spin_lock(&irq_controller_lock); if (gic_arch_extn.irq_ack) gic_arch_extn.irq_ack(d); - writel(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI); + writel_relaxed(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI); spin_unlock(&irq_controller_lock); } @@ -98,7 +98,8 @@ static void gic_mask_irq(struct irq_data *d) u32 mask = 1 << (d->irq % 32); spin_lock(&irq_controller_lock); - writel(mask, gic_dist_base(d) + GIC_DIST_ENABLE_CLEAR + (gic_irq(d) / 32) * 4); + writel_relaxed(mask, gic_dist_base(d) + GIC_DIST_ENABLE_CLEAR + (gic_irq(d) / 32) * 4); + readl_relaxed(gic_dist_base(d) + GIC_DIST_ENABLE_CLEAR + (gic_irq(d) / 32) * 4); if (gic_arch_extn.irq_mask) gic_arch_extn.irq_mask(d); spin_unlock(&irq_controller_lock); @@ -111,7 +112,7 @@ static void gic_unmask_irq(struct irq_data *d) spin_lock(&irq_controller_lock); if (gic_arch_extn.irq_unmask) gic_arch_extn.irq_unmask(d); - writel(mask, gic_dist_base(d) + GIC_DIST_ENABLE_SET + (gic_irq(d) / 32) * 4); + writel_relaxed(mask, gic_dist_base(d) + GIC_DIST_ENABLE_SET + (gic_irq(d) / 32) * 4); spin_unlock(&irq_controller_lock); } @@ -138,7 +139,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type) if (gic_arch_extn.irq_set_type) gic_arch_extn.irq_set_type(d, type); - val = readl(base + GIC_DIST_CONFIG + confoff); + val = readl_relaxed(base + GIC_DIST_CONFIG + confoff); if (type == IRQ_TYPE_LEVEL_HIGH) val &= ~confmask; else if (type == IRQ_TYPE_EDGE_RISING) @@ -148,15 +149,15 @@ static int gic_set_type(struct irq_data *d, unsigned int type) * As recommended by the spec, disable the interrupt before changing * the configuration */ - if (readl(base + GIC_DIST_ENABLE_SET + enableoff) & enablemask) { - writel(enablemask, base + GIC_DIST_ENABLE_CLEAR + enableoff); + if (readl_relaxed(base + GIC_DIST_ENABLE_SET + enableoff) & enablemask) { + writel_relaxed(enablemask, base + GIC_DIST_ENABLE_CLEAR + enableoff); enabled = true; } - writel(val, base + GIC_DIST_CONFIG + confoff); + writel_relaxed(val, base + GIC_DIST_CONFIG + confoff); if (enabled) - writel(enablemask, base + GIC_DIST_ENABLE_SET + enableoff); + writel_relaxed(enablemask, base + GIC_DIST_ENABLE_SET + enableoff); spin_unlock(&irq_controller_lock); @@ -188,8 +189,8 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val, spin_lock(&irq_controller_lock); d->node = cpu; - val = readl(reg) & ~mask; - writel(val | bit, reg); + val = readl_relaxed(reg) & ~mask; + writel_relaxed(val | bit, reg); spin_unlock(&irq_controller_lock); return 0; @@ -222,7 +223,7 @@ static void gic_handle_cascade_irq(unsigned int irq, struct irq_desc *desc) chip->irq_ack(&desc->irq_data); spin_lock(&irq_controller_lock); - status = readl(chip_data->cpu_base + GIC_CPU_INTACK); + status = readl_relaxed(chip_data->cpu_base + GIC_CPU_INTACK); spin_unlock(&irq_controller_lock); gic_irq = (status & 0x3ff); @@ -272,13 +273,13 @@ static void __init gic_dist_init(struct gic_chip_data *gic, cpumask |= cpumask << 8; cpumask |= cpumask << 16; - writel(0, base + GIC_DIST_CTRL); + writel_relaxed(0, base + GIC_DIST_CTRL); /* * Find out how many interrupts are supported. * The GIC only supports up to 1020 interrupt sources. */ - gic_irqs = readl(base + GIC_DIST_CTR) & 0x1f; + gic_irqs = readl_relaxed(base + GIC_DIST_CTR) & 0x1f; gic_irqs = (gic_irqs + 1) * 32; if (gic_irqs > 1020) gic_irqs = 1020; @@ -287,26 +288,26 @@ static void __init gic_dist_init(struct gic_chip_data *gic, * Set all global interrupts to be level triggered, active low. */ for (i = 32; i < gic_irqs; i += 16) - writel(0, base + GIC_DIST_CONFIG + i * 4 / 16); + writel_relaxed(0, base + GIC_DIST_CONFIG + i * 4 / 16); /* * Set all global interrupts to this CPU only. */ for (i = 32; i < gic_irqs; i += 4) - writel(cpumask, base + GIC_DIST_TARGET + i * 4 / 4); + writel_relaxed(cpumask, base + GIC_DIST_TARGET + i * 4 / 4); /* * Set priority on all global interrupts. */ for (i = 32; i < gic_irqs; i += 4) - writel(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4); + writel_relaxed(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4); /* * Disable all interrupts. Leave the PPI and SGIs alone * as these enables are banked registers. */ for (i = 32; i < gic_irqs; i += 32) - writel(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32); + writel_relaxed(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32); /* * Limit number of interrupts registered to the platform maximum @@ -324,7 +325,7 @@ static void __init gic_dist_init(struct gic_chip_data *gic, set_irq_flags(i, IRQF_VALID | IRQF_PROBE); } - writel(1, base + GIC_DIST_CTRL); + writel_relaxed(1, base + GIC_DIST_CTRL); } static void __cpuinit gic_cpu_init(struct gic_chip_data *gic) @@ -337,17 +338,17 @@ static void __cpuinit gic_cpu_init(struct gic_chip_data *gic) * Deal with the banked PPI and SGI interrupts - disable all * PPI interrupts, ensure all SGI interrupts are enabled. */ - writel(0xffff0000, dist_base + GIC_DIST_ENABLE_CLEAR); - writel(0x0000ffff, dist_base + GIC_DIST_ENABLE_SET); + writel_relaxed(0xffff0000, dist_base + GIC_DIST_ENABLE_CLEAR); + writel_relaxed(0x0000ffff, dist_base + GIC_DIST_ENABLE_SET); /* * Set priority on PPI and SGI interrupts */ for (i = 0; i < 32; i += 4) - writel(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4); + writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4); - writel(0xf0, base + GIC_CPU_PRIMASK); - writel(1, base + GIC_CPU_CTRL); + writel_relaxed(0xf0, base + GIC_CPU_PRIMASK); + writel_relaxed(1, base + GIC_CPU_CTRL); } void __init gic_init(unsigned int gic_nr, unsigned int irq_start, @@ -392,6 +393,6 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq) unsigned long map = *cpus_addr(*mask); /* this always happens on GIC0 */ - writel(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT); + writel_relaxed(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT); } #endif -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html