[RFC PATCH v4 07/10] gpio: Initial support for ROHM bd70528 GPIO block

[Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>]

ROHM BD70528 PMIC has 4 GPIO pins. Allow them to be
controlled by GPIO framework.

IRQs are handled by regmap-irq and GPIO driver is not
aware of the irq usage.

Signed-off-by: Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>
---

I dropped the review-by from Linus Walleij because I would like to
get a comment on if locking is required when we check the direction
in order to detect the correct register for getting the pin state.

My initial feeling is that locking makes no sense. If there is a race,
then it is pointless to ask state just when someone is toggling the
direction. State will be depening on the direction toggling anyways.
I would still like to point out this change.

 drivers/gpio/Kconfig        |  11 +++
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-bd70528.c | 228 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 240 insertions(+)
 create mode 100644 drivers/gpio/gpio-bd70528.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b5a2845347ec..c82187648630 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -962,6 +962,17 @@ config GPIO_ARIZONA
 	help
 	  Support for GPIOs on Wolfson Arizona class devices.
 
+config GPIO_BD70528
+	tristate "ROHM BD70528 GPIO support"
+	depends on MFD_ROHM_BD70528
+	help
+	  Support for GPIOs on ROHM BD70528 PMIC. There are four GPIOs
+	  available on the ROHM PMIC in total. The GPIOs can also
+	  generate interrupts.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called gpio-bd70528.
+
 config GPIO_BD9571MWV
 	tristate "ROHM BD9571 GPIO support"
 	depends on MFD_BD9571MWV
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 37628f8dbf70..6f12c83598fc 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_GPIO_ATH79)	+= gpio-ath79.o
 obj-$(CONFIG_GPIO_ASPEED)	+= gpio-aspeed.o
 obj-$(CONFIG_GPIO_RASPBERRYPI_EXP)	+= gpio-raspberrypi-exp.o
 obj-$(CONFIG_GPIO_BCM_KONA)	+= gpio-bcm-kona.o
+obj-$(CONFIG_GPIO_BD70528) 	+= gpio-bd70528.o
 obj-$(CONFIG_GPIO_BD9571MWV)	+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BRCMSTB)	+= gpio-brcmstb.o
 obj-$(CONFIG_GPIO_BT8XX)	+= gpio-bt8xx.o
diff --git a/drivers/gpio/gpio-bd70528.c b/drivers/gpio/gpio-bd70528.c
new file mode 100644
index 000000000000..c88475fcf089
--- /dev/null
+++ b/drivers/gpio/gpio-bd70528.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 ROHM Semiconductors
+// gpio-bd70528.c ROHM BD70528MWV gpio driver
+
+#include <linux/gpio/driver.h>
+#include <linux/gpio.h>
+#include <linux/mfd/rohm-bd70528.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define GPIO_IN_REG(offset) (BD70528_REG_GPIO1_IN + offset*2)
+#define GPIO_OUT_REG(offset) (BD70528_REG_GPIO1_OUT + offset*2)
+
+struct bd70528_gpio {
+	struct rohm_regmap_dev chip;
+	struct gpio_chip gpio;
+};
+
+static int bd70528_set_debounce(struct bd70528_gpio *bdgpio,
+				unsigned int offset, unsigned int debounce)
+{
+	u8 val;
+
+	switch (debounce) {
+	case 0:
+		val = BD70528_DEBOUNCE_DISABLE;
+		break;
+	case 1 ... 15:
+		val = BD70528_DEBOUNCE_15MS;
+		break;
+	case 16 ... 30:
+		val = BD70528_DEBOUNCE_30MS;
+		break;
+	case 31 ... 50:
+		val = BD70528_DEBOUNCE_50MS;
+		break;
+	default:
+		dev_err(bdgpio->chip.dev,
+			"Invalid debouce value %u\n", debounce);
+		return -EINVAL;
+	}
+	return regmap_update_bits(bdgpio->chip.regmap, GPIO_IN_REG(offset),
+				 BD70528_DEBOUNCE_MASK, val);
+}
+
+static int bd70528_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+	int val, ret;
+
+	/* Do we need to do something to IRQs here? */
+	ret = regmap_read(bdgpio->chip.regmap, GPIO_OUT_REG(offset), &val);
+	if (ret) {
+		dev_err(bdgpio->chip.dev, "Could not read gpio direction\n");
+		return ret;
+	}
+
+	return !(val & BD70528_GPIO_OUT_EN_MASK);
+}
+
+static int bd70528_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
+				   unsigned long config)
+{
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+		return regmap_update_bits(bdgpio->chip.regmap,
+					  GPIO_OUT_REG(offset),
+					  BD70528_GPIO_DRIVE_MASK,
+					  BD70528_GPIO_OPEN_DRAIN);
+		break;
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		return regmap_update_bits(bdgpio->chip.regmap,
+					  GPIO_OUT_REG(offset),
+					  BD70528_GPIO_DRIVE_MASK,
+					  BD70528_GPIO_PUSH_PULL);
+		break;
+	case PIN_CONFIG_INPUT_DEBOUNCE:
+		return bd70528_set_debounce(bdgpio, offset,
+					    pinconf_to_config_argument(config));
+		break;
+	default:
+		break;
+	}
+	return -ENOTSUPP;
+}
+
+static int bd70528_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+
+	/* Do we need to do something to IRQs here? */
+	return regmap_update_bits(bdgpio->chip.regmap, GPIO_OUT_REG(offset),
+				 BD70528_GPIO_OUT_EN_MASK,
+				 BD70528_GPIO_OUT_DISABLE);
+}
+static void bd70528_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			     int value)
+{
+	int ret;
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+	u8 val = (value) ? BD70528_GPIO_OUT_HI : BD70528_GPIO_OUT_LO;
+
+	ret = regmap_update_bits(bdgpio->chip.regmap, GPIO_OUT_REG(offset),
+				  BD70528_GPIO_OUT_MASK, val);
+	if (ret)
+		dev_err(bdgpio->chip.dev, "Could not set gpio to %d\n", value);
+}
+
+static int bd70528_direction_output(struct gpio_chip *chip, unsigned int offset,
+				    int value)
+{
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+
+	bd70528_gpio_set(chip, offset, value);
+	return regmap_update_bits(bdgpio->chip.regmap, GPIO_OUT_REG(offset),
+				 BD70528_GPIO_OUT_EN_MASK,
+				 BD70528_GPIO_OUT_ENABLE);
+}
+
+#define GPIO_IN_STATE_MASK(offset) (BD70528_GPIO_IN_STATE_BASE << offset)
+
+static int bd70528_gpio_get_o(struct bd70528_gpio *bdgpio, unsigned int offset)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(bdgpio->chip.regmap, GPIO_OUT_REG(offset), &val);
+	if (!ret)
+		ret = !!(val & BD70528_GPIO_OUT_MASK);
+	else
+		dev_err(bdgpio->chip.dev, "GPIO (out) state read failed\n");
+
+	return ret;
+}
+
+static int bd70528_gpio_get_i(struct bd70528_gpio *bdgpio, unsigned int offset)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(bdgpio->chip.regmap, BD70528_REG_GPIO_STATE, &val);
+
+	if (!ret)
+		ret = !(val & GPIO_IN_STATE_MASK(offset));
+	else
+		dev_err(bdgpio->chip.dev, "GPIO (in) state read failed\n");
+
+	return ret;
+}
+
+static int bd70528_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	int ret = -EINVAL;
+	struct bd70528_gpio *bdgpio = gpiochip_get_data(chip);
+
+	/*
+	 * Do we need a lock here or does the GPIO framework
+	 * already guarantee that no one is changing the direction while
+	 * value is being read?
+	 */
+	ret = bd70528_get_direction(chip, offset);
+	if (ret == GPIOF_DIR_OUT)
+		ret = bd70528_gpio_get_o(bdgpio, offset);
+	else if (ret == GPIOF_DIR_IN)
+		ret = bd70528_gpio_get_i(bdgpio, offset);
+	else
+		dev_err(bdgpio->chip.dev, "failed to read GPIO direction\n");
+
+	return ret;
+}
+
+static int bd70528_probe(struct platform_device *pdev)
+{
+	struct bd70528_gpio *bdgpio;
+	struct bd70528 *bd70528;
+	int ret;
+
+	bd70528 = dev_get_drvdata(pdev->dev.parent);
+	if (!bd70528) {
+		dev_err(&pdev->dev, "No MFD driver data\n");
+		return -EINVAL;
+	}
+
+	bdgpio = devm_kzalloc(&pdev->dev, sizeof(*bdgpio),
+				    GFP_KERNEL);
+	if (!bdgpio)
+		return -ENOMEM;
+	bdgpio->chip.dev = &pdev->dev;
+	bdgpio->gpio.parent = pdev->dev.parent;
+	bdgpio->gpio.label = "bd70528-gpio";
+	bdgpio->gpio.owner = THIS_MODULE;
+	bdgpio->gpio.get_direction = &bd70528_get_direction;
+	bdgpio->gpio.direction_input = &bd70528_direction_input;
+	bdgpio->gpio.direction_output = &bd70528_direction_output;
+	bdgpio->gpio.set_config = &bd70528_gpio_set_config;
+	bdgpio->gpio.can_sleep = true;
+	bdgpio->gpio.get = &bd70528_gpio_get;
+	bdgpio->gpio.set = &bd70528_gpio_set;
+	bdgpio->gpio.ngpio = 4;
+	bdgpio->gpio.base = -1;
+#ifdef CONFIG_OF_GPIO
+	bdgpio->gpio.of_node = pdev->dev.parent->of_node;
+#endif
+	bdgpio->chip.regmap = bd70528->chip.regmap;
+
+	ret = devm_gpiochip_add_data(&pdev->dev, &bdgpio->gpio,
+				     bdgpio);
+	if (ret)
+		dev_err(&pdev->dev, "gpio_init: Failed to add bd70528-gpio\n");
+
+	return ret;
+}
+
+static struct platform_driver bd70528_gpio = {
+	.driver = {
+		.name = "bd70528-gpio"
+	},
+	.probe = bd70528_probe,
+};
+
+module_platform_driver(bd70528_gpio);
+
+MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("BD70528 voltage regulator driver");
+MODULE_LICENSE("GPL");
-- 
2.14.3


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~