[PATCH] irqchip: Add support for Renesas RZ/N1 GPIO interrupt multiplexer

[Phil Edworthy]

On RZ/N1 devices, there are 3 Synopsys DesignWare GPIO blocks each
configured to have 32 interrupt outputs, so we have a total of 96 GPIO
interrupts. All of these are passed to the GPIO IRQ Muxer, which selects
8 of the GPIO interrupts to pass onto the GIC. The interrupt signals
aren't latched, so there is nothing to do in this driver when an interrupt
is received, other than tell the corresponding GPIO block.

Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
---
 .../interrupt-controller/renesas,rzn1-mux.txt      |  85 ++++++++++
 drivers/irqchip/Kconfig                            |  10 ++
 drivers/irqchip/Makefile                           |   1 +
 drivers/irqchip/irq-rzn1-irq-mux.c                 | 178 +++++++++++++++++++++
 4 files changed, 274 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/renesas,rzn1-mux.txt
 create mode 100644 drivers/irqchip/irq-rzn1-irq-mux.c

diff --git a/Documentation/devicetree/bindings/interrupt-controller/renesas,rzn1-mux.txt b/Documentation/devicetree/bindings/interrupt-controller/renesas,rzn1-mux.txt
new file mode 100644
index 0000000..f28a365
--- /dev/null
+++ b/Documentation/devicetree/bindings/interrupt-controller/renesas,rzn1-mux.txt
@@ -0,0 +1,85 @@
+* Renesas RZ/N1 GPIO Interrupt Multiplexer
+
+On Renesas RZ/N1 devices, there are 3 Synopsys DesignWare GPIO blocks each
+configured to have 32 interrupt outputs, so we have a total of 96 GPIO
+interrupts. All of these are passed to the GPIO IRQ Muxer, which selects
+8 of the GPIO interrupts to pass onto the GIC.
+
+A single node in the device tree is used to describe the GPIO IRQ Muxer.
+
+Required properties:
+- compatible: the SoC specific name, i.e. "renesas,r9a06g032-gpioirq"
+   or "renesas,r9a06g033-gpioirq" followed by the SoC family name, i.e.
+   "renesas,rzn1-gpioirq".
+- interrupt-controller: Identifies the node as an interrupt controller.
+- #interrupt-cells: should be <1>. The meaning of the cells is the input
+   interrupt index, 0 to 95.
+- reg: Base address and size of GPIO IRQ Muxer registers.
+- interrupts: The list of interrupts generated by the muxer which are then
+   connected to a parent interrupt controller. The format of the interrupt
+   specifier depends in the interrupt parent controller.
+- gpioirq-#N: One property for each interrupt output from the GPIO IRQ Muxer
+   that specifies the input interrupt to use, #N is from 0 to 7.
+
+Optional properties:
+- interrupt-parent: pHandle of the parent interrupt controller, if not
+   inherited from the parent node.
+
+
+Example:
+
+	The following is an example for the RZ/N1D SoC.
+
+	gpioirq: gpioirq@51000480 {
+		compatible = "renesas,r9a06g032-gpioirq",
+				"renesas,rzn1-gpioirq";
+		reg = <0x51000480 0x20>;
+		interrupts =
+			<GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 104 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 105 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 106 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 107 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 108 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 109 IRQ_TYPE_LEVEL_HIGH>,
+			<GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-controller;
+		#interrupt-cells = <1>;
+		status = "disabled";
+	};
+
+	gpio0: gpio@5000b000 {
+		compatible = "snps,dw-apb-gpio";
+		reg = <0x5000b000 0x80>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clock-names = "bus";
+		clocks = <&hclk_gpio0>;
+		status = "disabled";
+
+		gpio0a: gpio-controller@0 {
+			compatible = "snps,dw-apb-gpio-port";
+			bank-name = "gpio0a";
+			gpio-controller;
+			#gpio-cells = <2>;
+			snps,nr-gpios = <32>;
+			reg = <0>;
+
+			interrupt-controller;
+			interrupt-parent = <&gpioirq>;
+			interrupts =   < 0  1  2  3  4  5  6  7
+					 8  9 10 11 12 13 14 15
+					16 17 18 19 20 21 22 23
+					24 25 26 27 28 29 30 31 >;
+			#interrupt-cells = <2>;
+		};
+	};
+
+
+	The following is an example for a board using this.
+
+	&gpioirq {
+		status = "okay";
+		gpioirq-0 = <24>;	/* gpio0a 24 */
+		gpioirq-4 = <3>;	/* gpio0a 3 */
+	};
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index e9233db..16f2633 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -204,6 +204,16 @@ config RENESAS_IRQC
 	select GENERIC_IRQ_CHIP
 	select IRQ_DOMAIN
 
+config RENESAS_RZN1_IRQ_MUX
+	bool "Renesas RZ/N1 GPIO IRQ multiplexer support"
+	depends on ARCH_RZN1
+	select IRQ_DOMAIN
+	select IRQ_DOMAIN_HIERARCHY
+	help
+	  Say yes here to add support for the GPIO IRQ multiplexer embedded
+	  in Renesas RZ/N1 SoC devices. The GPIO IRQ Muxer selects which of
+	  the interrupts coming from the GPIO controllers are used.
+
 config ST_IRQCHIP
 	bool
 	select REGMAP
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 5ed465a..8197936 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_SIRF_IRQ)			+= irq-sirfsoc.o
 obj-$(CONFIG_JCORE_AIC)			+= irq-jcore-aic.o
 obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
 obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o
+obj-$(CONFIG_RENESAS_RZN1_IRQ_MUX)	+= irq-rzn1-irq-mux.o
 obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
 obj-$(CONFIG_ARCH_NSPIRE)		+= irq-zevio.o
 obj-$(CONFIG_ARCH_VT8500)		+= irq-vt8500.o
diff --git a/drivers/irqchip/irq-rzn1-irq-mux.c b/drivers/irqchip/irq-rzn1-irq-mux.c
new file mode 100644
index 0000000..50ba85f
--- /dev/null
+++ b/drivers/irqchip/irq-rzn1-irq-mux.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RZ/N1 GPIO IRQ Muxer
+ *
+ * Copyright (C) 2018 Renesas Electronics Europe Limited
+ *
+ * On RZ/N1 devices, there are 3 Synopsys DesignWare GPIO blocks each configured
+ * to have 32 interrupt outputs, so we have a total of 96 GPIO interrupts.
+ * All of these are passed to the GPIO IRQ Muxer, which selects 8 of the GPIO
+ * interrupts to pass onto the GIC.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+
+#define NR_GPIO_IRQS		96
+
+struct girq_irq {
+	int out;
+	int in;
+};
+
+struct girq_priv {
+	struct device *dev;
+	u32 __iomem *regs;
+	struct irq_chip irq_chip;
+	struct irq_domain *irq_domain;
+	int nr_irqs;
+	struct girq_irq *irq;
+};
+
+static void girq_enable(struct irq_data *d)
+{
+	/*
+	 * Either irq_chip->irq_enable must call something or you have to
+	 * implement irq_chip->irq_setup.
+	 */
+}
+
+static void girq_handler(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct girq_priv *p = irq_desc_get_handler_data(desc);
+	int irq = irq_desc_get_irq(desc);
+	int i;
+
+	chained_irq_enter(chip, desc);
+
+	for (i = 0; i < p->nr_irqs; i++) {
+		if (irq == p->irq[i].out) {
+			generic_handle_irq(irq_find_mapping(p->irq_domain,
+					   p->irq[i].in));
+			break;
+		}
+	}
+
+	if (i == p->nr_irqs)
+		handle_bad_irq(desc);
+
+	chained_irq_exit(chip, desc);
+}
+
+static int girq_domain_map(struct irq_domain *h, unsigned int irq,
+				irq_hw_number_t hwirq)
+{
+	struct girq_priv *p = h->host_data;
+
+	irq_set_chip_data(irq, h->host_data);
+	irq_set_chip_and_handler(irq, &p->irq_chip, handle_simple_irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops girq_domain_ops = {
+	.map	= girq_domain_map,
+};
+
+static int girq_probe(struct platform_device *pdev)
+{
+	struct girq_priv *p;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+	const char *name = dev_name(&pdev->dev);
+	int i;
+
+	p = devm_kzalloc(dev, sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+	p->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	p->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(p->regs))
+		return PTR_ERR(p->regs);
+
+	p->nr_irqs = of_irq_count(np);
+	p->irq = devm_kzalloc(dev, p->nr_irqs * sizeof(*p->irq), GFP_KERNEL);
+	if (!p->irq)
+		return -ENOMEM;
+
+	/* Get the fixed output interrupts */
+	for (i = 0; i < p->nr_irqs; i++) {
+		int irq = irq_of_parse_and_map(dev->of_node, i);
+
+		if (!irq) {
+			dev_err(dev, "cannot get interrupt\n");
+			return -ENOENT;
+		}
+
+		irq_set_chained_handler_and_data(irq, girq_handler, p);
+		p->irq[i].out = irq;
+	}
+
+	/* Create IRQ domain for the interrupts coming from the GPIO blocks */
+	p->irq_chip.name = name;
+	p->irq_chip.irq_enable = girq_enable;
+
+	p->irq_domain = irq_domain_add_linear(np, NR_GPIO_IRQS,
+					      &girq_domain_ops, p);
+	if (!p->irq_domain) {
+		dev_err(dev, "cannot initialize irq domain\n");
+		return -ENXIO;
+	}
+
+	/* Set the hardware to select the GPIO irq */
+	for (i = 0; i < p->nr_irqs; i++) {
+		char prop[16];
+
+		sprintf(prop, "gpioirq-%d", i);
+		if (!of_property_read_s32(np, prop, &p->irq[i].in))
+			writel(p->irq[i].in, &p->regs[i]);
+	}
+
+	platform_set_drvdata(pdev, p);
+
+	dev_info(dev, "probed\n");
+
+	return 0;
+}
+
+static int girq_remove(struct platform_device *pdev)
+{
+	struct girq_priv *p = platform_get_drvdata(pdev);
+
+	irq_domain_remove(p->irq_domain);
+
+	return 0;
+}
+
+static const struct of_device_id girq_match[] = {
+	{ .compatible = "renesas,rzn1-gpioirq", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, girq_match);
+
+static struct platform_driver girq_driver = {
+	.driver = {
+		.name = "gpio_irq_mux",
+		.owner = THIS_MODULE,
+		.of_match_table = girq_match,
+	},
+	.probe = girq_probe,
+	.remove = girq_remove,
+};
+
+module_platform_driver(girq_driver);
+
+MODULE_DESCRIPTION("Renesas RZ/N1 GPIO IRQ Multiplexer Driver");
+MODULE_AUTHOR("Phil Edworthy <phil.edworthy@xxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4