gpio: Congatec Board Controller gpio driver

Add gpio support for the Congatec Board Controller.
This Board Controller has 14 GPIO pins.

The driver is probed by the Congatec Board Controller MFD driver.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20241001-congatec-board-controller-v3-2-39ceceed5c47@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>

3 files changed, 207 insertions, 0 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index d93cd4f722b4..29d037c6083b 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1287,6 +1287,16 @@ config GPIO_BD9571MWV
 	  This driver can also be built as a module. If so, the module
 	  will be called gpio-bd9571mwv.
 
+config GPIO_CGBC
+	tristate "Congatec Board Controller GPIO support"
+	depends on MFD_CGBC
+	help
+	  Select this option to enable GPIO support for the Congatec Board
+	  Controller.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called gpio-cgbc.
+
 config GPIO_CROS_EC
 	tristate "ChromeOS EC GPIO support"
 	depends on CROS_EC
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 1429e8c0229b..3cdfa927ed98 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_GPIO_BD9571MWV)		+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BRCMSTB)		+= gpio-brcmstb.o
 obj-$(CONFIG_GPIO_BT8XX)		+= gpio-bt8xx.o
 obj-$(CONFIG_GPIO_CADENCE)		+= gpio-cadence.o
+obj-$(CONFIG_GPIO_CGBC)			+= gpio-cgbc.o
 obj-$(CONFIG_GPIO_CLPS711X)		+= gpio-clps711x.o
 obj-$(CONFIG_GPIO_SNPS_CREG)		+= gpio-creg-snps.o
 obj-$(CONFIG_GPIO_CROS_EC)		+= gpio-cros-ec.o
diff --git a/drivers/gpio/gpio-cgbc.c b/drivers/gpio/gpio-cgbc.c
new file mode 100644
index 000000000000..9213faa11522
--- /dev/null
+++ b/drivers/gpio/gpio-cgbc.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Congatec Board Controller GPIO driver
+ *
+ * Copyright (C) 2024 Bootlin
+ * Author: Thomas Richard <thomas.richard@bootlin.com>
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/mfd/cgbc.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+
+#define CGBC_GPIO_NGPIO	14
+
+#define CGBC_GPIO_CMD_GET	0x64
+#define CGBC_GPIO_CMD_SET	0x65
+#define CGBC_GPIO_CMD_DIR_GET	0x66
+#define CGBC_GPIO_CMD_DIR_SET	0x67
+
+struct cgbc_gpio_data {
+	struct gpio_chip	chip;
+	struct cgbc_device_data	*cgbc;
+	struct mutex lock;
+};
+
+static int cgbc_gpio_cmd(struct cgbc_device_data *cgbc,
+			 u8 cmd0, u8 cmd1, u8 cmd2, u8 *value)
+{
+	u8 cmd[3] = {cmd0, cmd1, cmd2};
+
+	return cgbc_command(cgbc, cmd, sizeof(cmd), value, 1, NULL);
+}
+
+static int cgbc_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+	struct cgbc_device_data *cgbc = gpio->cgbc;
+	int ret;
+	u8 val;
+
+	scoped_guard(mutex, &gpio->lock)
+		ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);
+
+	offset %= 8;
+
+	if (ret)
+		return ret;
+	else
+		return (int)(val & (u8)BIT(offset));
+}
+
+static void __cgbc_gpio_set(struct gpio_chip *chip,
+			    unsigned int offset, int value)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+	struct cgbc_device_data *cgbc = gpio->cgbc;
+	u8 val;
+	int ret;
+
+	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);
+	if (ret)
+		return;
+
+	if (value)
+		val |= BIT(offset % 8);
+	else
+		val &= ~(BIT(offset % 8));
+
+	cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_SET, (offset > 7) ? 1 : 0, val, &val);
+}
+
+static void cgbc_gpio_set(struct gpio_chip *chip,
+			  unsigned int offset, int value)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+
+	scoped_guard(mutex, &gpio->lock)
+		__cgbc_gpio_set(chip, offset, value);
+}
+
+static int cgbc_gpio_direction_set(struct gpio_chip *chip,
+				   unsigned int offset, int direction)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+	struct cgbc_device_data *cgbc = gpio->cgbc;
+	int ret;
+	u8 val;
+
+	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
+	if (ret)
+		goto end;
+
+	if (direction == GPIO_LINE_DIRECTION_IN)
+		val &= ~(BIT(offset % 8));
+	else
+		val |= BIT(offset % 8);
+
+	ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_SET, (offset > 7) ? 1 : 0, val, &val);
+
+end:
+	return ret;
+}
+
+static int cgbc_gpio_direction_input(struct gpio_chip *chip,
+				     unsigned int offset)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+
+	guard(mutex)(&gpio->lock);
+	return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_IN);
+}
+
+static int cgbc_gpio_direction_output(struct gpio_chip *chip,
+				      unsigned int offset, int value)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+
+	guard(mutex)(&gpio->lock);
+
+	__cgbc_gpio_set(chip, offset, value);
+	return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_OUT);
+}
+
+static int cgbc_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
+	struct cgbc_device_data *cgbc = gpio->cgbc;
+	int ret;
+	u8 val;
+
+	scoped_guard(mutex, &gpio->lock)
+		ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
+
+	if (ret)
+		return ret;
+
+	if (val & BIT(offset % 8))
+		return GPIO_LINE_DIRECTION_OUT;
+	else
+		return GPIO_LINE_DIRECTION_IN;
+}
+
+static int cgbc_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cgbc_device_data *cgbc = dev_get_drvdata(dev->parent);
+	struct cgbc_gpio_data *gpio;
+	struct gpio_chip *chip;
+	int ret;
+
+	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->cgbc = cgbc;
+
+	platform_set_drvdata(pdev, gpio);
+
+	chip = &gpio->chip;
+	chip->label = dev_name(&pdev->dev);
+	chip->owner = THIS_MODULE;
+	chip->parent = dev;
+	chip->base = -1;
+	chip->direction_input = cgbc_gpio_direction_input;
+	chip->direction_output = cgbc_gpio_direction_output;
+	chip->get_direction = cgbc_gpio_get_direction;
+	chip->get = cgbc_gpio_get;
+	chip->set = cgbc_gpio_set;
+	chip->ngpio = CGBC_GPIO_NGPIO;
+
+	ret = devm_mutex_init(dev, &gpio->lock);
+	if (ret)
+		return ret;
+
+	ret = devm_gpiochip_add_data(dev, chip, gpio);
+	if (ret)
+		return dev_err_probe(dev, ret, "Could not register GPIO chip\n");
+
+	return 0;
+}
+
+static struct platform_driver cgbc_gpio_driver = {
+	.driver = {
+		.name = "cgbc-gpio",
+	},
+	.probe	= cgbc_gpio_probe,
+};
+
+module_platform_driver(cgbc_gpio_driver);
+
+MODULE_DESCRIPTION("Congatec Board Controller GPIO Driver");
+MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:cgbc-gpio");