gpio: mpfs: add polarfire soc gpio support

Add a driver to support the Polarfire SoC gpio controller. Interrupt
controller support is unavailable for now and will be added at a later
date.

Signed-off-by: Lewis Hanly <lewis.hanly@microchip.com>
Co-developed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241104-tiny-evaluate-9336020b4b6a@spud
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/Kconfig

@@ -544,6 +544,12 @@ config GPIO_PL061
 	help
 	  Say yes here to support the PrimeCell PL061 GPIO device.
 
+config GPIO_POLARFIRE_SOC
+	bool "Microchip FPGA GPIO support"
+	select REGMAP_MMIO
+	help
+	  Say yes here to support the GPIO controllers on Microchip FPGAs.
+
 config GPIO_PXA
 	bool "PXA GPIO support"
 	depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST

drivers/gpio/Makefile

@@ -135,6 +135,7 @@ obj-$(CONFIG_GPIO_PCI_IDIO_16)		+= gpio-pci-idio-16.o
 obj-$(CONFIG_GPIO_PISOSR)		+= gpio-pisosr.o
 obj-$(CONFIG_GPIO_PL061)		+= gpio-pl061.o
 obj-$(CONFIG_GPIO_PMIC_EIC_SPRD)	+= gpio-pmic-eic-sprd.o
+obj-$(CONFIG_GPIO_POLARFIRE_SOC)	+= gpio-mpfs.o
 obj-$(CONFIG_GPIO_PXA)			+= gpio-pxa.o
 obj-$(CONFIG_GPIO_RASPBERRYPI_EXP)	+= gpio-raspberrypi-exp.o
 obj-$(CONFIG_GPIO_RC5T583)		+= gpio-rc5t583.o

drivers/gpio/gpio-mpfs.c

@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Microchip PolarFire SoC (MPFS) GPIO controller driver
+ *
+ * Copyright (c) 2018-2024 Microchip Technology Inc. and its subsidiaries
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.h>
+#include <linux/init.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/spinlock.h>
+
+#define MPFS_GPIO_CTRL(i)		(0x4 * (i))
+#define MPFS_MAX_NUM_GPIO		32
+#define MPFS_GPIO_EN_INT		3
+#define MPFS_GPIO_EN_OUT_BUF		BIT(2)
+#define MPFS_GPIO_EN_IN			BIT(1)
+#define MPFS_GPIO_EN_OUT		BIT(0)
+#define MPFS_GPIO_DIR_MASK		GENMASK(2, 0)
+
+#define MPFS_GPIO_TYPE_INT_EDGE_BOTH	0x80
+#define MPFS_GPIO_TYPE_INT_EDGE_NEG	0x60
+#define MPFS_GPIO_TYPE_INT_EDGE_POS	0x40
+#define MPFS_GPIO_TYPE_INT_LEVEL_LOW	0x20
+#define MPFS_GPIO_TYPE_INT_LEVEL_HIGH	0x00
+#define MPFS_GPIO_TYPE_INT_MASK		GENMASK(7, 5)
+#define MPFS_IRQ_REG			0x80
+#define MPFS_INP_REG			0x84
+#define MPFS_OUTP_REG			0x88
+
+struct mpfs_gpio_chip {
+	struct regmap *regs;
+	struct gpio_chip gc;
+};
+
+static const struct regmap_config mpfs_gpio_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+};
+
+static int mpfs_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio_index)
+{
+	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
+
+	regmap_update_bits(mpfs_gpio->regs, MPFS_GPIO_CTRL(gpio_index),
+			   MPFS_GPIO_DIR_MASK, MPFS_GPIO_EN_IN);
+
+	return 0;
+}
+
+static int mpfs_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio_index, int value)
+{
+	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
+
+	regmap_update_bits(mpfs_gpio->regs, MPFS_GPIO_CTRL(gpio_index),
+			   MPFS_GPIO_DIR_MASK, MPFS_GPIO_EN_IN);
+	regmap_update_bits(mpfs_gpio->regs, MPFS_OUTP_REG, BIT(gpio_index),
+			   value << gpio_index);
+
+	return 0;
+}
+
+static int mpfs_gpio_get_direction(struct gpio_chip *gc,
+				   unsigned int gpio_index)
+{
+	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
+	unsigned int gpio_cfg;
+
+	regmap_read(mpfs_gpio->regs, MPFS_GPIO_CTRL(gpio_index), &gpio_cfg);
+	if (gpio_cfg & MPFS_GPIO_EN_IN)
+		return GPIO_LINE_DIRECTION_IN;
+
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static int mpfs_gpio_get(struct gpio_chip *gc, unsigned int gpio_index)
+{
+	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
+
+	if (mpfs_gpio_get_direction(gc, gpio_index) == GPIO_LINE_DIRECTION_OUT)
+		return regmap_test_bits(mpfs_gpio->regs, MPFS_OUTP_REG, BIT(gpio_index));
+	else
+		return regmap_test_bits(mpfs_gpio->regs, MPFS_INP_REG, BIT(gpio_index));
+}
+
+static void mpfs_gpio_set(struct gpio_chip *gc, unsigned int gpio_index, int value)
+{
+	struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
+
+	mpfs_gpio_get(gc, gpio_index);
+
+	regmap_update_bits(mpfs_gpio->regs, MPFS_OUTP_REG, BIT(gpio_index),
+			   value << gpio_index);
+
+	mpfs_gpio_get(gc, gpio_index);
+}
+
+static int mpfs_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mpfs_gpio_chip *mpfs_gpio;
+	struct clk *clk;
+	void __iomem *base;
+	int ngpios;
+
+	mpfs_gpio = devm_kzalloc(dev, sizeof(*mpfs_gpio), GFP_KERNEL);
+	if (!mpfs_gpio)
+		return -ENOMEM;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return dev_err_probe(dev, PTR_ERR(base), "failed to ioremap memory resource\n");
+
+	mpfs_gpio->regs = devm_regmap_init_mmio(dev, base, &mpfs_gpio_regmap_config);
+	if (IS_ERR(mpfs_gpio->regs))
+		return dev_err_probe(dev, PTR_ERR(mpfs_gpio->regs),
+				     "failed to initialise regmap\n");
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "failed to get and enable clock\n");
+
+	ngpios = MPFS_MAX_NUM_GPIO;
+	device_property_read_u32(dev, "ngpios", &ngpios);
+	if (ngpios > MPFS_MAX_NUM_GPIO)
+		ngpios = MPFS_MAX_NUM_GPIO;
+
+	mpfs_gpio->gc.direction_input = mpfs_gpio_direction_input;
+	mpfs_gpio->gc.direction_output = mpfs_gpio_direction_output;
+	mpfs_gpio->gc.get_direction = mpfs_gpio_get_direction;
+	mpfs_gpio->gc.get = mpfs_gpio_get;
+	mpfs_gpio->gc.set = mpfs_gpio_set;
+	mpfs_gpio->gc.base = -1;
+	mpfs_gpio->gc.ngpio = ngpios;
+	mpfs_gpio->gc.label = dev_name(dev);
+	mpfs_gpio->gc.parent = dev;
+	mpfs_gpio->gc.owner = THIS_MODULE;
+
+	return devm_gpiochip_add_data(dev, &mpfs_gpio->gc, mpfs_gpio);
+}
+
+static const struct of_device_id mpfs_gpio_of_ids[] = {
+	{ .compatible = "microchip,mpfs-gpio", },
+	{ /* end of list */ }
+};
+
+static struct platform_driver mpfs_gpio_driver = {
+	.probe = mpfs_gpio_probe,
+	.driver = {
+		.name = "microchip,mpfs-gpio",
+		.of_match_table = mpfs_gpio_of_ids,
+	},
+};
+builtin_platform_driver(mpfs_gpio_driver);