[PATCH v1 2/2] gpio: ds4520: Add ADI DS4520 Regulator Support

[Okan Sahin <okan.sahin@analog.com>]

Gpio I/O expander.

Signed-off-by: Okan Sahin <okan.sahin@analog.com>
---
 drivers/gpio/Kconfig       |  10 ++
 drivers/gpio/Makefile      |   1 +
 drivers/gpio/gpio-ds4520.c | 198 +++++++++++++++++++++++++++++++++++++
 3 files changed, 209 insertions(+)
 create mode 100644 drivers/gpio/gpio-ds4520.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 13be729710f2..20aa28e208d5 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1000,6 +1000,16 @@ config GPIO_ADNP
 	  enough to represent all pins, but the driver will assume a
 	  register layout for 64 pins (8 registers).
 
+config GPIO_DS4520
+	tristate "DS4520 I2C GPIO expander"
+	select REGMAP_I2C
+	help
+	  GPIO driver for Maxim MAX7300 I2C-based GPIO expander.
+	  Say yes here to enable the GPIO driver for the ADI DS4520 chip.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gpio-ds4520.
+
 config GPIO_GW_PLD
 	tristate "Gateworks PLD GPIO Expander"
 	depends on OF_GPIO
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index c048ba003367..6f8656d5d617 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_GPIO_DA9052)		+= gpio-da9052.o
 obj-$(CONFIG_GPIO_DA9055)		+= gpio-da9055.o
 obj-$(CONFIG_GPIO_DAVINCI)		+= gpio-davinci.o
 obj-$(CONFIG_GPIO_DLN2)			+= gpio-dln2.o
+obj-$(CONFIG_GPIO_DS4520)		+= gpio-ds4520.o
 obj-$(CONFIG_GPIO_DWAPB)		+= gpio-dwapb.o
 obj-$(CONFIG_GPIO_EIC_SPRD)		+= gpio-eic-sprd.o
 obj-$(CONFIG_GPIO_EM)			+= gpio-em.o
diff --git a/drivers/gpio/gpio-ds4520.c b/drivers/gpio/gpio-ds4520.c
new file mode 100644
index 000000000000..8f878e7824b8
--- /dev/null
+++ b/drivers/gpio/gpio-ds4520.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023 Analog Devices, Inc.
+ * Driver for the DS4520 I/O Expander
+ */
+
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+
+#define NUMBER_OF_GPIO	9
+
+#define PULLUP0		0xF0
+#define IO_CONTROL0	0xF2
+#define IO_STATUS0	0xF8
+
+#define REG_SIZE	8
+
+struct ds4520_gpio_priv {
+	struct regmap *regmap;
+	struct gpio_chip gpio_chip;
+};
+
+static int ds4520_gpio_get_direction(struct gpio_chip *chip,
+				     unsigned int offset)
+{
+	struct ds4520_gpio_priv *priv = gpiochip_get_data(chip);
+	u32 val_io_control = 0, val_pullup = 0;
+	u8 reg_offset = (offset / REG_SIZE);
+	int ret;
+
+	ret = regmap_set_bits(priv->regmap, 0xF4, 0x01);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(priv->regmap, IO_CONTROL0 + reg_offset,
+			  &val_io_control);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(priv->regmap, PULLUP0 + reg_offset, &val_pullup);
+	if (ret)
+		return ret;
+
+	if ((val_io_control & (1 << (offset % 8)))
+	    == (val_pullup & (1 << (offset % 8))))
+		return GPIO_LINE_DIRECTION_OUT;
+	else
+		return GPIO_LINE_DIRECTION_IN;
+}
+
+static int ds4520_gpio_direction_input(struct gpio_chip *chip,
+				       unsigned int offset)
+{
+	struct ds4520_gpio_priv *priv = gpiochip_get_data(chip);
+	u8 reg_offset = (offset / REG_SIZE);
+	u8 mask = BIT(offset % 8);
+	int ret;
+
+	ret = regmap_clear_bits(priv->regmap, IO_CONTROL0 + reg_offset, mask);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(priv->regmap, PULLUP0 + reg_offset, mask);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ds4520_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ds4520_gpio_priv *priv = gpiochip_get_data(chip);
+	u8 reg_offset = (offset / REG_SIZE);
+	u8 mask = BIT(offset % 8);
+	u32 val = 0;
+	int ret;
+
+	ret = regmap_read(priv->regmap, IO_STATUS0 + reg_offset, &val);
+	if (ret)
+		return ret;
+
+	return !!(val & mask);
+}
+
+static void ds4520_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			    int value)
+{
+	struct ds4520_gpio_priv *priv = gpiochip_get_data(chip);
+	u8 reg_offset = (offset / REG_SIZE);
+	u8 mask = BIT(offset % 8);
+
+	regmap_update_bits(priv->regmap, PULLUP0 + reg_offset, mask,
+			   value ? mask : 0);
+	regmap_update_bits(priv->regmap, IO_CONTROL0 + reg_offset, mask,
+			   value ? mask : 0);
+}
+
+static int ds4520_gpio_direction_output(struct gpio_chip *chip,
+					unsigned int offset, int value)
+{
+	struct ds4520_gpio_priv *priv = gpiochip_get_data(chip);
+	u8 reg_offset = (offset / REG_SIZE);
+	u8 mask = BIT(offset % 8);
+	int ret;
+
+	ret = regmap_clear_bits(priv->regmap, IO_CONTROL0 + reg_offset, mask);
+	if (ret)
+		return ret;
+
+	ds4520_gpio_set(chip, offset, value);
+
+	return 0;
+}
+
+static const struct regmap_config ds4520_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct gpio_chip ds4520_chip = {
+	.label			= "ds4520-gpio",
+	.owner			= THIS_MODULE,
+	.get_direction		= ds4520_gpio_get_direction,
+	.direction_input	= ds4520_gpio_direction_input,
+	.direction_output	= ds4520_gpio_direction_output,
+	.get			= ds4520_gpio_get,
+	.set			= ds4520_gpio_set,
+	.base			= -1,
+	.can_sleep		= true,
+};
+
+static int ds4520_gpio_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct ds4520_gpio_priv *priv;
+	u32 ngpio;
+	int ret;
+
+	ngpio = NUMBER_OF_GPIO;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->gpio_chip = ds4520_chip;
+	priv->gpio_chip.label = "ds4520-gpio";
+	priv->gpio_chip.ngpio = ngpio;
+	priv->gpio_chip.parent = dev;
+
+	priv->regmap = devm_regmap_init_i2c(client, &ds4520_regmap_config);
+	if (IS_ERR(priv->regmap)) {
+		ret = PTR_ERR(priv->regmap);
+		dev_err_probe(dev, ret,
+			      "Failed to allocate register map\n");
+		return ret;
+	}
+
+	ret = devm_gpiochip_add_data(dev, &priv->gpio_chip, priv);
+	if (ret) {
+		dev_err_probe(dev, ret, "Unable to register gpiochip\n");
+		return ret;
+	}
+
+	i2c_set_clientdata(client, priv);
+
+	return 0;
+}
+
+static const struct of_device_id ds4520_gpio_of_match_table[] = {
+	{
+		.compatible = "adi,ds4520-gpio"
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ds4520_gpio_of_match_table);
+
+static const struct i2c_device_id ds4520_gpio_id_table[] = {
+	{ "ds4520-gpio" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, ds4520_gpio_id_table);
+
+static struct i2c_driver ds4520_gpio_driver = {
+	.driver = {
+		.name = "ds4520-gpio",
+		.of_match_table = ds4520_gpio_of_match_table,
+	},
+	.probe_new = ds4520_gpio_probe,
+	.id_table = ds4520_gpio_id_table,
+};
+module_i2c_driver(ds4520_gpio_driver);
+
+MODULE_DESCRIPTION("DS4520 I/O Expander");
+MODULE_AUTHOR("Okan Sahin <okan.sahin@analog.com>");
+MODULE_LICENSE("GPL");
-- 
2.30.2