MIPS: ralink: adds irq code

All of the Ralink Wifi SoC currently supported by this series share the same
interrupt controller (INTC).
Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/4890/

arch/mips/ralink/irq.c

+/*
+ * 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.
+ *
+ * Copyright (C) 2009 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/io.h>
+#include <linux/bitops.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/interrupt.h>
+
+#include <asm/irq_cpu.h>
+#include <asm/mipsregs.h>
+
+#include "common.h"
+
+/* INTC register offsets */
+#define INTC_REG_STATUS0	0x00
+#define INTC_REG_STATUS1	0x04
+#define INTC_REG_TYPE		0x20
+#define INTC_REG_RAW_STATUS	0x30
+#define INTC_REG_ENABLE		0x34
+#define INTC_REG_DISABLE	0x38
+
+#define INTC_INT_GLOBAL		BIT(31)
+
+#define RALINK_CPU_IRQ_INTC	(MIPS_CPU_IRQ_BASE + 2)
+#define RALINK_CPU_IRQ_FE	(MIPS_CPU_IRQ_BASE + 5)
+#define RALINK_CPU_IRQ_WIFI	(MIPS_CPU_IRQ_BASE + 6)
+#define RALINK_CPU_IRQ_COUNTER	(MIPS_CPU_IRQ_BASE + 7)
+
+/* we have a cascade of 8 irqs */
+#define RALINK_INTC_IRQ_BASE	8
+
+/* we have 32 SoC irqs */
+#define RALINK_INTC_IRQ_COUNT	32
+
+#define RALINK_INTC_IRQ_PERFC   (RALINK_INTC_IRQ_BASE + 9)
+
+static void __iomem *rt_intc_membase;
+
+static inline void rt_intc_w32(u32 val, unsigned reg)
+{
+	__raw_writel(val, rt_intc_membase + reg);
+}
+
+static inline u32 rt_intc_r32(unsigned reg)
+{
+	return __raw_readl(rt_intc_membase + reg);
+}
+
+static void ralink_intc_irq_unmask(struct irq_data *d)
+{
+	rt_intc_w32(BIT(d->hwirq), INTC_REG_ENABLE);
+}
+
+static void ralink_intc_irq_mask(struct irq_data *d)
+{
+	rt_intc_w32(BIT(d->hwirq), INTC_REG_DISABLE);
+}
+
+static struct irq_chip ralink_intc_irq_chip = {
+	.name		= "INTC",
+	.irq_unmask	= ralink_intc_irq_unmask,
+	.irq_mask	= ralink_intc_irq_mask,
+	.irq_mask_ack	= ralink_intc_irq_mask,
+};
+
+unsigned int __cpuinit get_c0_compare_int(void)
+{
+	return CP0_LEGACY_COMPARE_IRQ;
+}
+
+static void ralink_intc_irq_handler(unsigned int irq, struct irq_desc *desc)
+{
+	u32 pending = rt_intc_r32(INTC_REG_STATUS0);
+
+	if (pending) {
+		struct irq_domain *domain = irq_get_handler_data(irq);
+		generic_handle_irq(irq_find_mapping(domain, __ffs(pending)));
+	} else {
+		spurious_interrupt();
+	}
+}
+
+asmlinkage void plat_irq_dispatch(void)
+{
+	unsigned long pending;
+
+	pending = read_c0_status() & read_c0_cause() & ST0_IM;
+
+	if (pending & STATUSF_IP7)
+		do_IRQ(RALINK_CPU_IRQ_COUNTER);
+
+	else if (pending & STATUSF_IP5)
+		do_IRQ(RALINK_CPU_IRQ_FE);
+
+	else if (pending & STATUSF_IP6)
+		do_IRQ(RALINK_CPU_IRQ_WIFI);
+
+	else if (pending & STATUSF_IP2)
+		do_IRQ(RALINK_CPU_IRQ_INTC);
+
+	else
+		spurious_interrupt();
+}
+
+static int intc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
+{
+	irq_set_chip_and_handler(irq, &ralink_intc_irq_chip, handle_level_irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops irq_domain_ops = {
+	.xlate = irq_domain_xlate_onecell,
+	.map = intc_map,
+};
+
+static int __init intc_of_init(struct device_node *node,
+			       struct device_node *parent)
+{
+	struct resource res;
+	struct irq_domain *domain;
+
+	mips_cpu_irq_init();
+
+	if (of_address_to_resource(node, 0, &res))
+		panic("Failed to get intc memory range");
+
+	if (request_mem_region(res.start, resource_size(&res),
+				res.name) < 0)
+		pr_err("Failed to request intc memory");
+
+	rt_intc_membase = ioremap_nocache(res.start,
+					resource_size(&res));
+	if (!rt_intc_membase)
+		panic("Failed to remap intc memory");
+
+	/* disable all interrupts */
+	rt_intc_w32(~0, INTC_REG_DISABLE);
+
+	/* route all INTC interrupts to MIPS HW0 interrupt */
+	rt_intc_w32(0, INTC_REG_TYPE);
+
+	domain = irq_domain_add_legacy(node, RALINK_INTC_IRQ_COUNT,
+			RALINK_INTC_IRQ_BASE, 0, &irq_domain_ops, NULL);
+	if (!domain)
+		panic("Failed to add irqdomain");
+
+	rt_intc_w32(INTC_INT_GLOBAL, INTC_REG_ENABLE);
+
+	irq_set_chained_handler(RALINK_CPU_IRQ_INTC, ralink_intc_irq_handler);
+	irq_set_handler_data(RALINK_CPU_IRQ_INTC, domain);
+
+	cp0_perfcount_irq = irq_create_mapping(domain, 9);
+
+	return 0;
+}
+
+static struct of_device_id __initdata of_irq_ids[] = {
+	{ .compatible = "ralink,rt2880-intc", .data = intc_of_init },
+	{},
+};
+
+void __init arch_init_irq(void)
+{
+	of_irq_init(of_irq_ids);
+}
+