gpio: tps65219: add GPIO support for TPS65219 PMIC

Add support for TPS65219 PMICs GPIO interface.

3 GPIO pins:
- GPIO0 only is IO but input mode reserved for MULTI_DEVICE_ENABLE usage.
- GPIO1 and GPIO2 are Output only and referred as GPO1 and GPO2 in spec.

GPIO0 is statically configured as input or output prior to Linux boot.
it is used for MULTI_DEVICE_ENABLE function.
This setting is statically configured by NVM.
GPIO0 can't be used as a generic GPIO (specification Table 8-34).
It's either a GPO when MULTI_DEVICE_EN=0 or a GPI when MULTI_DEVICE_EN=1.

Datasheet describes specific usage for non standard GPIO.

Datasheet: https://www.ti.com/lit/ds/symlink/tps65219.pdf
Co-developed-by: Jonathan Cormier <jcormier@criticallink.com>
Signed-off-by: Jonathan Cormier <jcormier@criticallink.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jerome Neanne <jneanne@baylibre.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: jneanne

MAINTAINERS

@@ -15392,6 +15392,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap.git
 F:	arch/arm/configs/omap2plus_defconfig
 F:	arch/arm/mach-omap2/
 F:	drivers/bus/ti-sysc.c
+F:	drivers/gpio/gpio-tps65219.c
 F:	drivers/i2c/busses/i2c-omap.c
 F:	drivers/irqchip/irq-omap-intc.c
 F:	drivers/mfd/*omap*.c

drivers/gpio/Kconfig

@@ -1440,6 +1440,22 @@ config GPIO_TPS65218
 	  Select this option to enable GPIO driver for the TPS65218
 	  chip family.
 
+config GPIO_TPS65219
+	tristate "TPS65219 GPIO"
+	depends on MFD_TPS65219
+	default MFD_TPS65219
+	help
+	  Select this option to enable GPIO driver for the TPS65219 chip
+	  family.
+	  GPIO0 is statically configured as either input or output prior to
+	  Linux boot. It is used for MULTI_DEVICE_ENABLE function. This setting
+	  is statically configured by NVM. GPIO0 can't be used as a generic
+	  GPIO. It's either a GPO when MULTI_DEVICE_EN=0 or a GPI when
+	  MULTI_DEVICE_EN=1.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called gpio_tps65219.
+
 config GPIO_TPS6586X
 	bool "TPS6586X GPIO"
 	depends on MFD_TPS6586X

drivers/gpio/Makefile

@@ -161,6 +161,7 @@ obj-$(CONFIG_GPIO_TN48M_CPLD)		+= gpio-tn48m.o
 obj-$(CONFIG_GPIO_TPIC2810)		+= gpio-tpic2810.o
 obj-$(CONFIG_GPIO_TPS65086)		+= gpio-tps65086.o
 obj-$(CONFIG_GPIO_TPS65218)		+= gpio-tps65218.o
+obj-$(CONFIG_GPIO_TPS65219)		+= gpio-tps65219.o
 obj-$(CONFIG_GPIO_TPS6586X)		+= gpio-tps6586x.o
 obj-$(CONFIG_GPIO_TPS65910)		+= gpio-tps65910.o
 obj-$(CONFIG_GPIO_TPS65912)		+= gpio-tps65912.o

drivers/gpio/gpio-tps65219.c

@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO driver for TI TPS65219 PMICs
+ *
+ * Copyright (C) 2022 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#include <linux/bits.h>
+#include <linux/gpio/driver.h>
+#include <linux/mfd/tps65219.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define TPS65219_GPIO0_DIR_MASK		BIT(3)
+#define TPS65219_GPIO0_OFFSET		2
+#define TPS65219_GPIO0_IDX		0
+#define TPS65219_GPIO_DIR_IN		1
+#define TPS65219_GPIO_DIR_OUT		0
+
+struct tps65219_gpio {
+	struct gpio_chip gpio_chip;
+	struct tps65219 *tps;
+};
+
+static int tps65219_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct tps65219_gpio *gpio = gpiochip_get_data(gc);
+	int ret, val;
+
+	if (offset != TPS65219_GPIO0_IDX)
+		return GPIO_LINE_DIRECTION_OUT;
+
+	ret = regmap_read(gpio->tps->regmap, TPS65219_REG_MFP_1_CONFIG, &val);
+	if (ret)
+		return ret;
+
+	return !!(val & TPS65219_GPIO0_DIR_MASK);
+}
+
+static int tps65219_gpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct tps65219_gpio *gpio = gpiochip_get_data(gc);
+	struct device *dev = gpio->tps->dev;
+	int ret, val;
+
+	if (offset != TPS65219_GPIO0_IDX) {
+		dev_err(dev, "GPIO%d is output only, cannot get\n", offset);
+		return -ENOTSUPP;
+	}
+
+	ret = regmap_read(gpio->tps->regmap, TPS65219_REG_MFP_CTRL, &val);
+	if (ret)
+		return ret;
+
+	ret = !!(val & BIT(TPS65219_MFP_GPIO_STATUS_MASK));
+	dev_warn(dev, "GPIO%d = %d, MULTI_DEVICE_ENABLE, not a standard GPIO\n", offset, ret);
+
+	/*
+	 * Depending on NVM config, return an error if direction is output, otherwise the GPIO0
+	 * status bit.
+	 */
+
+	if (tps65219_gpio_get_direction(gc, offset) == TPS65219_GPIO_DIR_OUT)
+		return -ENOTSUPP;
+
+	return ret;
+}
+
+static void tps65219_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	struct tps65219_gpio *gpio = gpiochip_get_data(gc);
+	struct device *dev = gpio->tps->dev;
+	int v, mask, bit;
+
+	bit = (offset == TPS65219_GPIO0_IDX) ? TPS65219_GPIO0_OFFSET : offset - 1;
+
+	mask = BIT(bit);
+	v = value ? mask : 0;
+
+	if (regmap_update_bits(gpio->tps->regmap, TPS65219_REG_GENERAL_CONFIG, mask, v))
+		dev_err(dev, "GPIO%d, set to value %d failed.\n", offset, value);
+}
+
+static int tps65219_gpio_change_direction(struct gpio_chip *gc, unsigned int offset,
+					  unsigned int direction)
+{
+	struct tps65219_gpio *gpio = gpiochip_get_data(gc);
+	struct device *dev = gpio->tps->dev;
+
+	/*
+	 * Documentation is stating that GPIO0 direction must not be changed in Linux:
+	 * Table 8-34. MFP_1_CONFIG(3): MULTI_DEVICE_ENABLE, should only be changed in INITIALIZE
+	 * state (prior to ON Request).
+	 * Set statically by NVM, changing direction in application can cause a hang.
+	 * Below can be used for test purpose only.
+	 */
+
+	if (IS_ENABLED(CONFIG_DEBUG_GPIO)) {
+		int ret = regmap_update_bits(gpio->tps->regmap, TPS65219_REG_MFP_1_CONFIG,
+					     TPS65219_GPIO0_DIR_MASK, direction);
+		if (ret) {
+			dev_err(dev,
+				"GPIO DEBUG enabled: Fail to change direction to %u for GPIO%d.\n",
+				direction, offset);
+			return ret;
+		}
+	}
+
+	dev_err(dev,
+		"GPIO%d direction set by NVM, change to %u failed, not allowed by specification\n",
+		 offset, direction);
+
+	return -ENOTSUPP;
+}
+
+static int tps65219_gpio_direction_input(struct gpio_chip *gc, unsigned int offset)
+{
+	struct tps65219_gpio *gpio = gpiochip_get_data(gc);
+	struct device *dev = gpio->tps->dev;
+
+	if (offset != TPS65219_GPIO0_IDX) {
+		dev_err(dev, "GPIO%d is output only, cannot change to input\n", offset);
+		return -ENOTSUPP;
+	}
+
+	if (tps65219_gpio_get_direction(gc, offset) == TPS65219_GPIO_DIR_IN)
+		return 0;
+
+	return tps65219_gpio_change_direction(gc, offset, TPS65219_GPIO_DIR_IN);
+}
+
+static int tps65219_gpio_direction_output(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	tps65219_gpio_set(gc, offset, value);
+	if (offset != TPS65219_GPIO0_IDX)
+		return 0;
+
+	if (tps65219_gpio_get_direction(gc, offset) == TPS65219_GPIO_DIR_OUT)
+		return 0;
+
+	return tps65219_gpio_change_direction(gc, offset, TPS65219_GPIO_DIR_OUT);
+}
+
+static const struct gpio_chip tps65219_template_chip = {
+	.label			= "tps65219-gpio",
+	.owner			= THIS_MODULE,
+	.get_direction		= tps65219_gpio_get_direction,
+	.direction_input	= tps65219_gpio_direction_input,
+	.direction_output	= tps65219_gpio_direction_output,
+	.get			= tps65219_gpio_get,
+	.set			= tps65219_gpio_set,
+	.base			= -1,
+	.ngpio			= 3,
+	.can_sleep		= true,
+};
+
+static int tps65219_gpio_probe(struct platform_device *pdev)
+{
+	struct tps65219 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct tps65219_gpio *gpio;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->tps = tps;
+	gpio->gpio_chip = tps65219_template_chip;
+	gpio->gpio_chip.parent = tps->dev;
+
+	return devm_gpiochip_add_data(&pdev->dev, &gpio->gpio_chip, gpio);
+}
+
+static struct platform_driver tps65219_gpio_driver = {
+	.driver = {
+		.name = "tps65219-gpio",
+	},
+	.probe = tps65219_gpio_probe,
+};
+module_platform_driver(tps65219_gpio_driver);
+
+MODULE_ALIAS("platform:tps65219-gpio");
+MODULE_AUTHOR("Jonathan Cormier <jcormier@criticallink.com>");
+MODULE_DESCRIPTION("TPS65219 GPIO driver");
+MODULE_LICENSE("GPL");