Add gpio support for the Congatec Board Controller.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
---
 drivers/gpio/Kconfig     |  10 +++
 drivers/gpio/Makefile    |   1 +
 drivers/gpio/gpio-cgbc.c | 196 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 207 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 58f43bcced7c..ce77bad40087 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -233,6 +233,16 @@ config GPIO_CADENCE
 	help
 	  Say yes here to enable support for Cadence GPIO controller.
 
+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_CLPS711X
 	tristate "CLPS711X GPIO support"
 	depends on ARCH_CLPS711X || COMPILE_TEST
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 64dd6d9d730d..3a96e3c27a2d 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -44,6 +44,7 @@ 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..bdd747cd7250
--- /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 &= ~((u8)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 &= ~((u8)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");

-- 
2.39.5

Hi Thomas,

thanks for your patch!

Some comments:

On Tue, Sep 17, 2024 at 7:00 PM Thomas Richard
<thomas.richard@bootlin.com> wrote:

> Add gpio support for the Congatec Board Controller.
>
> Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>

That's a bit terse commit message. At least mention that it sits under
the MFD.

> @@ -233,6 +233,16 @@ config GPIO_CADENCE
>         help
>           Say yes here to enable support for Cadence GPIO controller.
>
> +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_CLPS711X

This is in the middle of the memory-mapped GPIO drivers.

This is not a memory-mapped driver.

Move it down in the menu to the submenu for MFD GPIO
drivers please.

> +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 &= ~((u8)BIT(offset % 8));

Is that cast really needed? (If you tried without and it
cause compilation problems, I believe you, if someone
smarter than me said it should be there, ignore me.)

> +       if (direction == GPIO_LINE_DIRECTION_IN)
> +               val &= ~((u8)BIT(offset % 8));

Dito.

Apart from this it looks very nice, so with the above
addressed:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij