[v3,08/15] gpio: support ROHM BD71815 GPOs

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index e3607ec4c2e8..d3b3de514f6e 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1105,6 +1105,16 @@  config GPIO_BD70528
 	  This driver can also be built as a module. If so, the module
 	  will be called gpio-bd70528.
 
+config GPIO_BD71815
+	tristate "ROHM BD71815 PMIC GPIO support"
+	depends on MFD_ROHM_BD71828
+	help
+	  Support for GPO(s) on ROHM BD71815 PMIC. There are two GPOs
+	  available on the ROHM PMIC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called gpio-bd71815.
+
 config GPIO_BD71828
 	tristate "ROHM BD71828 GPIO support"
 	depends on MFD_ROHM_BD71828
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index c58a90a3c3b1..4c12f31db31f 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -39,6 +39,7 @@  obj-$(CONFIG_GPIO_ATH79)		+= gpio-ath79.o
 obj-$(CONFIG_GPIO_BCM_KONA)		+= gpio-bcm-kona.o
 obj-$(CONFIG_GPIO_BCM_XGS_IPROC)	+= gpio-xgs-iproc.o
 obj-$(CONFIG_GPIO_BD70528)		+= gpio-bd70528.o
+obj-$(CONFIG_GPIO_BD71815)		+= gpio-bd71815.o
 obj-$(CONFIG_GPIO_BD71828)		+= gpio-bd71828.o
 obj-$(CONFIG_GPIO_BD9571MWV)		+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BRCMSTB)		+= gpio-brcmstb.o
diff --git a/drivers/gpio/gpio-bd71815.c b/drivers/gpio/gpio-bd71815.c
new file mode 100644
index 000000000000..5552a23c8e53
--- /dev/null
+++ b/drivers/gpio/gpio-bd71815.c
@@ -0,0 +1,176 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support to GPOs on ROHM BD71815
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+/* For the BD71815 register definitions */
+#include <linux/mfd/rohm-bd71815.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct bd71815_gpio {
+	struct gpio_chip chip;
+	struct device *dev;
+	struct regmap *regmap;
+	/*
+	 * Sigh. The BD71815 and BD71817 were originally designed to support two
+	 * GPO pins. At some point it was noticed the second GPO pin which is
+	 * the E5 pin located at the center of IC is hard to use on PCB (due to
+	 * the location). It was decided to not promote this second GPO and pin
+	 * is marked as GND on the data-sheet. The functionality is still there
+	 * though! I guess driving GPO connected to ground is a bad idea. Thus
+	 * we do not support it by default. OTOH - the original driver written
+	 * by colleagues at Embest did support controlling this second GPO. It
+	 * is thus possible this is used in some of the products.
+	 *
+	 * This driver does not by default support configuring this second GPO
+	 * but allows using it by providing the DT property
+	 * "rohm,enable-hidden-gpo".
+	 */
+	bool e5_pin_is_gpo;
+};
+
+static int bd71815gpo_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
+	int ret = 0;
+	int val;
+
+	ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
+	if (ret)
+		return ret;
+
+	return (val >> offset) & 1;
+}
+
+static void bd71815gpo_set(struct gpio_chip *chip, unsigned int offset,
+			   int value)
+{
+	struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
+	int ret, bit;
+
+	if (!bd71815->e5_pin_is_gpo && offset)
+		return;
+
+	bit = BIT(offset);
+
+	if (value)
+		ret = regmap_set_bits(bd71815->regmap, BD71815_REG_GPO, bit);
+	else
+		ret = regmap_clear_bits(bd71815->regmap, BD71815_REG_GPO, bit);
+
+	if (ret)
+		dev_warn(bd71815->dev, "failed to toggle GPO\n");
+}
+
+static int bd71815_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
+				   unsigned long config)
+{
+	struct bd71815_gpio *bdgpio = gpiochip_get_data(chip);
+
+	if (!bdgpio->e5_pin_is_gpo && offset)
+		return -EOPNOTSUPP;
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+		return regmap_update_bits(bdgpio->regmap,
+					  BD71815_REG_GPO,
+					  BD71815_GPIO_DRIVE_MASK << offset,
+					  BD71815_GPIO_OPEN_DRAIN << offset);
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		return regmap_update_bits(bdgpio->regmap,
+					  BD71815_REG_GPO,
+					  BD71815_GPIO_DRIVE_MASK << offset,
+					  BD71815_GPIO_CMOS << offset);
+	default:
+		break;
+	}
+	return -EOPNOTSUPP;
+}
+
+/* BD71815 GPIO is actually GPO */
+static int bd71815gpo_direction_get(struct gpio_chip *gc, unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+/* Template for GPIO chip */
+static const struct gpio_chip bd71815gpo_chip = {
+	.label			= "bd71815",
+	.owner			= THIS_MODULE,
+	.get			= bd71815gpo_get,
+	.get_direction		= bd71815gpo_direction_get,
+	.set			= bd71815gpo_set,
+	.set_config		= bd71815_gpio_set_config,
+	.can_sleep		= 1,
+};
+
+static int gpo_bd71815_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct bd71815_gpio *g;
+	struct device *dev;
+	struct device *parent;
+
+	/*
+	 * Bind devm lifetime to this platform device => use dev for devm.
+	 * also the prints should originate from this device.
+	 */
+	dev = &pdev->dev;
+	/* The device-tree and regmap come from MFD => use parent for that */
+	parent = dev->parent;
+
+	g = devm_kzalloc(dev, sizeof(*g), GFP_KERNEL);
+	if (!g)
+		return -ENOMEM;
+
+	g->e5_pin_is_gpo = of_property_read_bool(parent->of_node,
+						 "rohm,enable-hidden-gpo");
+	g->chip = bd71815gpo_chip;
+	g->chip.base = -1;
+
+	if (g->e5_pin_is_gpo)
+		g->chip.ngpio = 2;
+	else
+		g->chip.ngpio = 1;
+
+	g->chip.parent = parent;
+	g->chip.of_node = parent->of_node;
+	g->regmap = dev_get_regmap(parent, NULL);
+	g->dev = dev;
+
+	ret = devm_gpiochip_add_data(dev, &g->chip, g);
+	if (ret < 0) {
+		dev_err(dev, "could not register gpiochip, %d\n", ret);
+		return ret;
+	}
+
+	return ret;
+}
+static const struct platform_device_id bd7181x_gpo_id[] = {
+	{ "bd71815-gpo" },
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, bd7181x_gpo_id);
+
+static struct platform_driver gpo_bd71815_driver = {
+	.driver = {
+		.name	= "bd71815-gpo",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= gpo_bd71815_probe,
+	.id_table	= bd7181x_gpo_id,
+};
+
+module_platform_driver(gpo_bd71815_driver);
+
+/* Note:  this hardware lives inside an I2C-based multi-function device. */
+MODULE_ALIAS("platform:bd71815-gpo");
+
+MODULE_AUTHOR("Peter Yang <yanglsh@embest-tech.com>");
+MODULE_DESCRIPTION("GPO interface for BD71815");
+MODULE_LICENSE("GPL");