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Diffstat (limited to 'arch/arm/common/gic.c')
| -rw-r--r-- | arch/arm/common/gic.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c new file mode 100644 index 00000000000..d7499071755 --- /dev/null +++ b/arch/arm/common/gic.c @@ -0,0 +1,167 @@ +/* + * linux/arch/arm/common/gic.c + * + * Copyright (C) 2002 ARM Limited, All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Interrupt architecture for the GIC: + * + * o There is one Interrupt Distributor, which receives interrupts + * from system devices and sends them to the Interrupt Controllers. + * + * o There is one CPU Interface per CPU, which sends interrupts sent + * by the Distributor, and interrupts generated locally, to the + * associated CPU. + * + * Note that IRQs 0-31 are special - they are local to each CPU. + * As such, the enable set/clear, pending set/clear and active bit + * registers are banked per-cpu for these sources. + */ +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/smp.h> +#include <linux/cpumask.h> + +#include <asm/irq.h> +#include <asm/io.h> +#include <asm/mach/irq.h> +#include <asm/hardware/gic.h> + +static void __iomem *gic_dist_base; +static void __iomem *gic_cpu_base; + +/* + * Routines to acknowledge, disable and enable interrupts + * + * Linux assumes that when we're done with an interrupt we need to + * unmask it, in the same way we need to unmask an interrupt when + * we first enable it. + * + * The GIC has a seperate notion of "end of interrupt" to re-enable + * an interrupt after handling, in order to support hardware + * prioritisation. + * + * We can make the GIC behave in the way that Linux expects by making + * our "acknowledge" routine disable the interrupt, then mark it as + * complete. + */ +static void gic_ack_irq(unsigned int irq) +{ + u32 mask = 1 << (irq % 32); + writel(mask, gic_dist_base + GIC_DIST_ENABLE_CLEAR + (irq / 32) * 4); + writel(irq, gic_cpu_base + GIC_CPU_EOI); +} + +static void gic_mask_irq(unsigned int irq) +{ + u32 mask = 1 << (irq % 32); + writel(mask, gic_dist_base + GIC_DIST_ENABLE_CLEAR + (irq / 32) * 4); +} + +static void gic_unmask_irq(unsigned int irq) +{ + u32 mask = 1 << (irq % 32); + writel(mask, gic_dist_base + GIC_DIST_ENABLE_SET + (irq / 32) * 4); +} + +static void gic_set_cpu(struct irqdesc *desc, unsigned int irq, unsigned int cpu) +{ + void __iomem *reg = gic_dist_base + GIC_DIST_TARGET + (irq & ~3); + unsigned int shift = (irq % 4) * 8; + u32 val; + + val = readl(reg) & ~(0xff << shift); + val |= 1 << (cpu + shift); + writel(val, reg); +} + +static struct irqchip gic_chip = { + .ack = gic_ack_irq, + .mask = gic_mask_irq, + .unmask = gic_unmask_irq, +#ifdef CONFIG_SMP + .set_cpu = gic_set_cpu, +#endif +}; + +void __init gic_dist_init(void __iomem *base) +{ + unsigned int max_irq, i; + u32 cpumask = 1 << smp_processor_id(); + + cpumask |= cpumask << 8; + cpumask |= cpumask << 16; + + gic_dist_base = base; + + writel(0, base + GIC_DIST_CTRL); + + /* + * Find out how many interrupts are supported. + */ + max_irq = readl(base + GIC_DIST_CTR) & 0x1f; + max_irq = (max_irq + 1) * 32; + + /* + * The GIC only supports up to 1020 interrupt sources. + * Limit this to either the architected maximum, or the + * platform maximum. + */ + if (max_irq > max(1020, NR_IRQS)) + max_irq = max(1020, NR_IRQS); + + /* + * Set all global interrupts to be level triggered, active low. + */ + for (i = 32; i < max_irq; i += 16) + writel(0, base + GIC_DIST_CONFIG + i * 4 / 16); + + /* + * Set all global interrupts to this CPU only. + */ + for (i = 32; i < max_irq; i += 4) + writel(cpumask, base + GIC_DIST_TARGET + i * 4 / 4); + + /* + * Set priority on all interrupts. + */ + for (i = 0; i < max_irq; i += 4) + writel(0xa0a0a0a0, base + GIC_DIST_PRI + i * 4 / 4); + + /* + * Disable all interrupts. + */ + for (i = 0; i < max_irq; i += 32) + writel(0xffffffff, base + GIC_DIST_ENABLE_CLEAR + i * 4 / 32); + + /* + * Setup the Linux IRQ subsystem. + */ + for (i = 29; i < max_irq; i++) { + set_irq_chip(i, &gic_chip); + set_irq_handler(i, do_level_IRQ); + set_irq_flags(i, IRQF_VALID | IRQF_PROBE); + } + + writel(1, base + GIC_DIST_CTRL); +} + +void __cpuinit gic_cpu_init(void __iomem *base) +{ + gic_cpu_base = base; + writel(0xf0, base + GIC_CPU_PRIMASK); + writel(1, base + GIC_CPU_CTRL); +} + +#ifdef CONFIG_SMP +void gic_raise_softirq(cpumask_t cpumask, unsigned int irq) +{ + unsigned long map = *cpus_addr(cpumask); + + writel(map << 16 | irq, gic_dist_base + GIC_DIST_SOFTINT); +} +#endif |