irqchip: Add sl28cpld interrupt controller support

Add support for the interrupt controller inside the sl28 CPLD management
controller.

The interrupt controller can handle at most 8 interrupts and is really
simplistic and consists only of an interrupt mask and an interrupt
pending register.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/irqchip/Kconfig

@@ -246,6 +246,14 @@ config RENESAS_RZA1_IRQC
 	  Enable support for the Renesas RZ/A1 Interrupt Controller, to use up
 	  to 8 external interrupts with configurable sense select.
 
+config SL28CPLD_INTC
+	bool "Kontron sl28cpld IRQ controller"
+	depends on MFD_SL28CPLD=y || COMPILE_TEST
+	select REGMAP_IRQ
+	help
+	  Interrupt controller driver for the board management controller
+	  found on the Kontron sl28 CPLD.
+
 config ST_IRQCHIP
 	bool
 	select REGMAP

drivers/irqchip/Makefile

@@ -111,3 +111,4 @@ obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
 obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
 obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o
 obj-$(CONFIG_LOONGSON_PCH_MSI)		+= irq-loongson-pch-msi.o
+obj-$(CONFIG_SL28CPLD_INTC)		+= irq-sl28cpld.o

drivers/irqchip/irq-sl28cpld.c

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sl28cpld interrupt controller driver
+ *
+ * Copyright 2020 Kontron Europe GmbH
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define INTC_IE 0x00
+#define INTC_IP 0x01
+
+static const struct regmap_irq sl28cpld_irqs[] = {
+	REGMAP_IRQ_REG_LINE(0, 8),
+	REGMAP_IRQ_REG_LINE(1, 8),
+	REGMAP_IRQ_REG_LINE(2, 8),
+	REGMAP_IRQ_REG_LINE(3, 8),
+	REGMAP_IRQ_REG_LINE(4, 8),
+	REGMAP_IRQ_REG_LINE(5, 8),
+	REGMAP_IRQ_REG_LINE(6, 8),
+	REGMAP_IRQ_REG_LINE(7, 8),
+};
+
+struct sl28cpld_intc {
+	struct regmap *regmap;
+	struct regmap_irq_chip chip;
+	struct regmap_irq_chip_data *irq_data;
+};
+
+static int sl28cpld_intc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sl28cpld_intc *irqchip;
+	int irq;
+	u32 base;
+	int ret;
+
+	if (!dev->parent)
+		return -ENODEV;
+
+	irqchip = devm_kzalloc(dev, sizeof(*irqchip), GFP_KERNEL);
+	if (!irqchip)
+		return -ENOMEM;
+
+	irqchip->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!irqchip->regmap)
+		return -ENODEV;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = device_property_read_u32(&pdev->dev, "reg", &base);
+	if (ret)
+		return -EINVAL;
+
+	irqchip->chip.name = "sl28cpld-intc";
+	irqchip->chip.irqs = sl28cpld_irqs;
+	irqchip->chip.num_irqs = ARRAY_SIZE(sl28cpld_irqs);
+	irqchip->chip.num_regs = 1;
+	irqchip->chip.status_base = base + INTC_IP;
+	irqchip->chip.mask_base = base + INTC_IE;
+	irqchip->chip.mask_invert = true,
+	irqchip->chip.ack_base = base + INTC_IP;
+
+	return devm_regmap_add_irq_chip_fwnode(dev, dev_fwnode(dev),
+					       irqchip->regmap, irq,
+					       IRQF_SHARED | IRQF_ONESHOT, 0,
+					       &irqchip->chip,
+					       &irqchip->irq_data);
+}
+
+static const struct of_device_id sl28cpld_intc_of_match[] = {
+	{ .compatible = "kontron,sl28cpld-intc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sl28cpld_intc_of_match);
+
+static struct platform_driver sl28cpld_intc_driver = {
+	.probe = sl28cpld_intc_probe,
+	.driver = {
+		.name = "sl28cpld-intc",
+		.of_match_table = sl28cpld_intc_of_match,
+	}
+};
+module_platform_driver(sl28cpld_intc_driver);
+
+MODULE_DESCRIPTION("sl28cpld Interrupt Controller Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");