[PATCH] irqchip: add support for Marvell Orion SoCs

[Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>]

This patch adds an irqchip driver for the main interrupt controller found
on Marvell Orion SoCs (Kirkwood, Dove, Orion5x, Discovery Innovation).
Corresponding device tree documentation is also added.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Note: This patch triggers a checkpatch warning for
  WARNING: Avoid CamelCase: <handle_IRQ>

Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Jean-Francois Moine <moinejf@free.fr>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 .../interrupt-controller/marvell,orion-mpic.txt    |   22 ++++
 drivers/irqchip/Kconfig                            |    5 +
 drivers/irqchip/Makefile                           |    1 +
 drivers/irqchip/irq-orion.c                        |  129 ++++++++++++++++++++
 include/linux/irqchip/orion.h                      |   18 +++
 5 files changed, 175 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/marvell,orion-mpic.txt
 create mode 100644 drivers/irqchip/irq-orion.c
 create mode 100644 include/linux/irqchip/orion.h

diff --git a/Documentation/devicetree/bindings/interrupt-controller/marvell,orion-mpic.txt b/Documentation/devicetree/bindings/interrupt-controller/marvell,orion-mpic.txt
new file mode 100644
index 0000000..3b303ec
--- /dev/null
+++ b/Documentation/devicetree/bindings/interrupt-controller/marvell,orion-mpic.txt
@@ -0,0 +1,22 @@
+Marvell Orion SoC main interrupt controller
+
+Required properties:
+- compatible: shall be "marvell,orion-mpic"
+- reg: base address(es) of interrupt registers starting with CAUSE register
+- interrupt-controller: identifies the node as an interrupt controller
+- #interrupt-cells: number of cells to encode an interrupt source, shall be 1.
+
+The interrupt sources map to the corresponding bits in the interrupt
+registers, i.e.
+- 0 maps to bit 0 of first base address,
+- 1 maps to bit 1 of first base address,
+- 32 maps to bit 0 of second base address, and so on.
+
+Example:
+	intc: interrupt-controller {
+		compatible = "marvell,orion-mpic";
+		interrupt-controller;
+		#interrupt-cells = <1>;
+                /* Dove has 64 primary interrupts */
+		reg = <0x20200 0x10>, <0x20210 0x10>;
+	};
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index a350969..8da3559 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -2,6 +2,11 @@ config IRQCHIP
 	def_bool y
 	depends on OF_IRQ
 
+config IRQCHIP_ORION
+	bool
+	select IRQ_DOMAIN
+	select MULTI_IRQ_HANDLER
+
 config ARM_GIC
 	bool
 	select IRQ_DOMAIN
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 98e3b87..8adbd43 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_IRQCHIP)			+= irqchip.o
 
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
 obj-$(CONFIG_ARCH_EXYNOS)		+= exynos-combiner.o
+obj-$(CONFIG_IRQCHIP_ORION)		+= irq-orion.o
 obj-$(CONFIG_METAG)			+= irq-metag-ext.o
 obj-$(CONFIG_METAG_PERFCOUNTER_IRQS)	+= irq-metag.o
 obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi.o
diff --git a/drivers/irqchip/irq-orion.c b/drivers/irqchip/irq-orion.c
new file mode 100644
index 0000000..ea02e11
--- /dev/null
+++ b/drivers/irqchip/irq-orion.c
@@ -0,0 +1,129 @@
+/*
+ * Marvell Orion SoCs IRQ chip driver.
+ *
+ * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip/orion.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <asm/mach/irq.h>
+
+/* max number of handled irq register blocks */
+#define ORION_MAX_IRQREG		2
+
+#define ORION_IRQ_CAUSE			0x00
+#define ORION_IRQ_MASK			0x04
+#define ORION_IRQ_FIQ_MASK		0x08
+#define ORION_IRQ_ENDP_MASK		0x0c
+
+static void __iomem *orion_irq_base[ORION_MAX_IRQREG];
+static unsigned int orion_irq_regs;
+static struct irq_domain *orion_irq_domain;
+
+asmlinkage void __exception_irq_entry orion_handle_irq(struct pt_regs *regs)
+{
+	int n;
+	for (n = 0; n < orion_irq_regs; n++) {
+		u32 hwirq_base = n * 32;
+		u32 stat = readl_relaxed(orion_irq_base[n] + ORION_IRQ_CAUSE) &
+			   readl_relaxed(orion_irq_base[n] + ORION_IRQ_MASK);
+		while (stat) {
+			u32 hwirq = ffs(stat) - 1;
+			u32 irq = irq_find_mapping(orion_irq_domain,
+						hwirq_base + hwirq);
+			handle_IRQ(irq, regs);
+			stat &= ~(1 << hwirq);
+		}
+	}
+}
+
+static void orion_irq_mask(struct irq_data *irqd)
+{
+	unsigned int irq = irqd_to_hwirq(irqd);
+	unsigned int irq_off = irq % 32;
+	int reg = irq / 32;
+	u32 val;
+
+	val = readl(orion_irq_base[reg] + ORION_IRQ_MASK);
+	writel(val & ~(1 << irq_off), orion_irq_base[reg] + ORION_IRQ_MASK);
+}
+
+static void orion_irq_unmask(struct irq_data *irqd)
+{
+	unsigned int irq = irqd_to_hwirq(irqd);
+	unsigned int irq_off = irq % 32;
+	int reg = irq / 32;
+	u32 val;
+
+	val = readl(orion_irq_base[reg] + ORION_IRQ_MASK);
+	writel(val | (1 << irq_off), orion_irq_base[reg] + ORION_IRQ_MASK);
+}
+
+static struct irq_chip orion_irq_chip = {
+	.name		= "orion_irq",
+	.irq_mask	= orion_irq_mask,
+	.irq_unmask	= orion_irq_unmask,
+};
+
+static int orion_irq_map(struct irq_domain *d, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	irq_set_chip_and_handler(virq, &orion_irq_chip,
+				 handle_level_irq);
+	set_irq_flags(virq, IRQF_VALID | IRQF_PROBE);
+
+	return 0;
+}
+
+static struct irq_domain_ops orion_irq_ops = {
+	.map = orion_irq_map,
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static int __init orion_of_init(struct device_node *np,
+				struct device_node *parent)
+{
+	int n;
+
+	for (n = 0; n < ORION_MAX_IRQREG; n++) {
+		orion_irq_base[n] = of_iomap(np, n);
+
+		if (!orion_irq_base[n])
+			continue;
+
+		/* mask all interrupts */
+		writel(0, orion_irq_base[n] + ORION_IRQ_MASK);
+		orion_irq_regs++;
+	}
+
+	/* at least one irq reg must be set */
+	if (!orion_irq_regs)
+		panic("%s: unable to map IRQC registers\n", np->full_name);
+
+	orion_irq_domain = irq_domain_add_linear(np, orion_irq_regs * 32,
+						 &orion_irq_ops, NULL);
+	if (!orion_irq_domain)
+		panic("%s: unable to create IRQ domain\n", np->full_name);
+
+	set_handle_irq(orion_handle_irq);
+
+	return 0;
+}
+
+static struct of_device_id orion_irq_dt_ids[] __initconst = {
+	{ .compatible = "marvell,orion-mpic", .data = orion_of_init },
+	{ }
+};
+
+void __init orion_init_irq(void)
+{
+	of_irq_init(orion_irq_dt_ids);
+}
diff --git a/include/linux/irqchip/orion.h b/include/linux/irqchip/orion.h
new file mode 100644
index 0000000..04f7bab
--- /dev/null
+++ b/include/linux/irqchip/orion.h
@@ -0,0 +1,18 @@
+/*
+ * Marvell Orion SoCs IRQ chip driver header.
+ *
+ * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __LINUX_IRQCHIP_ORION_H
+#define __LINUX_IRQCHIP_ORION_H
+
+#include <asm/exception.h>
+
+extern void orion_init_irq(void);
+
+#endif
-- 
1.7.2.5