gpio: Add support for the sl28cpld GPIO controller

Add support for the GPIO controller of the sl28 board management
controller. This driver is part of a multi-function device.

A controller has 8 lines. There are three different flavors:
full-featured GPIO with interrupt support, input-only and output-only.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/gpio/Kconfig

@@ -1223,6 +1223,18 @@ config GPIO_RC5T583
 	  This driver provides the support for driving/reading the gpio pins
 	  of RC5T583 device through standard gpio library.
 
+config GPIO_SL28CPLD
+	tristate "Kontron sl28cpld GPIO support"
+	depends on MFD_SL28CPLD || COMPILE_TEST
+	select GPIO_REGMAP
+	select GPIOLIB_IRQCHIP
+	select REGMAP_IRQ
+	help
+	  This enables support for the GPIOs found on the Kontron sl28 CPLD.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called gpio-sl28cpld.
+
 config GPIO_STMPE
 	bool "STMPE GPIOs"
 	depends on MFD_STMPE

drivers/gpio/Makefile

@@ -132,6 +132,7 @@ obj-$(CONFIG_GPIO_SCH311X)		+= gpio-sch311x.o
 obj-$(CONFIG_GPIO_SCH)			+= gpio-sch.o
 obj-$(CONFIG_GPIO_SIFIVE)		+= gpio-sifive.o
 obj-$(CONFIG_GPIO_SIOX)			+= gpio-siox.o
+obj-$(CONFIG_GPIO_SL28CPLD)		+= gpio-sl28cpld.o
 obj-$(CONFIG_GPIO_SODAVILLE)		+= gpio-sodaville.o
 obj-$(CONFIG_GPIO_SPEAR_SPICS)		+= gpio-spear-spics.o
 obj-$(CONFIG_GPIO_SPRD)			+= gpio-sprd.o

drivers/gpio/gpio-sl28cpld.c

@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sl28cpld GPIO driver
+ *
+ * Copyright 2020 Michael Walle <michael@walle.cc>
+ */
+
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/regmap.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/* GPIO flavor */
+#define GPIO_REG_DIR	0x00
+#define GPIO_REG_OUT	0x01
+#define GPIO_REG_IN	0x02
+#define GPIO_REG_IE	0x03
+#define GPIO_REG_IP	0x04
+
+/* input-only flavor */
+#define GPI_REG_IN	0x00
+
+/* output-only flavor */
+#define GPO_REG_OUT	0x00
+
+enum sl28cpld_gpio_type {
+	SL28CPLD_GPIO = 1,
+	SL28CPLD_GPI,
+	SL28CPLD_GPO,
+};
+
+static const struct regmap_irq sl28cpld_gpio_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),
+};
+
+static int sl28cpld_gpio_irq_init(struct platform_device *pdev,
+				  unsigned int base,
+				  struct gpio_regmap_config *config)
+{
+	struct regmap_irq_chip_data *irq_data;
+	struct regmap_irq_chip *irq_chip;
+	struct device *dev = &pdev->dev;
+	int irq, ret;
+
+	if (!device_property_read_bool(dev, "interrupt-controller"))
+		return 0;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	irq_chip = devm_kzalloc(dev, sizeof(*irq_chip), GFP_KERNEL);
+	if (!irq_chip)
+		return -ENOMEM;
+
+	irq_chip->name = "sl28cpld-gpio-irq",
+	irq_chip->irqs = sl28cpld_gpio_irqs;
+	irq_chip->num_irqs = ARRAY_SIZE(sl28cpld_gpio_irqs);
+	irq_chip->num_regs = 1;
+	irq_chip->status_base = base + GPIO_REG_IP;
+	irq_chip->mask_base = base + GPIO_REG_IE;
+	irq_chip->mask_invert = true,
+	irq_chip->ack_base = base + GPIO_REG_IP;
+
+	ret = devm_regmap_add_irq_chip_fwnode(dev, dev_fwnode(dev),
+					      config->regmap, irq,
+					      IRQF_SHARED | IRQF_ONESHOT,
+					      0, irq_chip, &irq_data);
+	if (ret)
+		return ret;
+
+	config->irq_domain = regmap_irq_get_domain(irq_data);
+
+	return 0;
+}
+
+static int sl28cpld_gpio_probe(struct platform_device *pdev)
+{
+	struct gpio_regmap_config config = {0};
+	enum sl28cpld_gpio_type type;
+	struct regmap *regmap;
+	u32 base;
+	int ret;
+
+	if (!pdev->dev.parent)
+		return -ENODEV;
+
+	type = (uintptr_t)device_get_match_data(&pdev->dev);
+	if (!type)
+		return -ENODEV;
+
+	ret = device_property_read_u32(&pdev->dev, "reg", &base);
+	if (ret)
+		return -EINVAL;
+
+	regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!regmap)
+		return -ENODEV;
+
+	config.regmap = regmap;
+	config.parent = &pdev->dev;
+	config.ngpio = 8;
+
+	switch (type) {
+	case SL28CPLD_GPIO:
+		config.reg_dat_base = base + GPIO_REG_IN;
+		config.reg_set_base = base + GPIO_REG_OUT;
+		/* reg_dir_out_base might be zero */
+		config.reg_dir_out_base = GPIO_REGMAP_ADDR(base + GPIO_REG_DIR);
+
+		/* This type supports interrupts */
+		ret = sl28cpld_gpio_irq_init(pdev, base, &config);
+		if (ret)
+			return ret;
+		break;
+	case SL28CPLD_GPO:
+		config.reg_set_base = base + GPO_REG_OUT;
+		break;
+	case SL28CPLD_GPI:
+		config.reg_dat_base = base + GPI_REG_IN;
+		break;
+	default:
+		dev_err(&pdev->dev, "unknown type %d\n", type);
+		return -ENODEV;
+	}
+
+	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(&pdev->dev, &config));
+}
+
+static const struct of_device_id sl28cpld_gpio_of_match[] = {
+	{ .compatible = "kontron,sl28cpld-gpio", .data = (void *)SL28CPLD_GPIO },
+	{ .compatible = "kontron,sl28cpld-gpi", .data = (void *)SL28CPLD_GPI },
+	{ .compatible = "kontron,sl28cpld-gpo", .data = (void *)SL28CPLD_GPO },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sl28cpld_gpio_of_match);
+
+static struct platform_driver sl28cpld_gpio_driver = {
+	.probe = sl28cpld_gpio_probe,
+	.driver = {
+		.name = "sl28cpld-gpio",
+		.of_match_table = sl28cpld_gpio_of_match,
+	},
+};
+module_platform_driver(sl28cpld_gpio_driver);
+
+MODULE_DESCRIPTION("sl28cpld GPIO Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");