[ARM] Add support for ARM GIC

Add support for the ARM Generic Interrupt Controller.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 166 insertions, 0 deletions

diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
new file mode 100644
index 0000000..51dbf54
--- /dev/null
+++ b/arch/arm/common/gic.c
@@ -0,0 +1,166 @@
+/*
+ *  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 <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