[RFC] leds: add sgm3140 driver

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 4b68520ac251..7c391af8b380 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -836,6 +836,15 @@  config LEDS_LM36274
 	  Say Y to enable the LM36274 LED driver for TI LMU devices.
 	  This supports the LED device LM36274.
 
+config LEDS_SGM3140
+	tristate "LED support for the SGM3140"
+	depends on LEDS_CLASS_FLASH
+	depends on V4L2_FLASH_LED_CLASS || !V4L2_FLASH_LED_CLASS
+	depends on OF
+	help
+	  This option enables support for the SGM3140 500mA Buck/Boost Charge
+	  Pump LED Driver. It has supports flash and torch mode.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 2da39e896ce8..38d57dd53e4b 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -85,6 +85,7 @@  obj-$(CONFIG_LEDS_LM3601X)		+= leds-lm3601x.o
 obj-$(CONFIG_LEDS_TI_LMU_COMMON)	+= leds-ti-lmu-common.o
 obj-$(CONFIG_LEDS_LM3697)		+= leds-lm3697.o
 obj-$(CONFIG_LEDS_LM36274)		+= leds-lm36274.o
+obj-$(CONFIG_LEDS_SGM3140)		+= leds-sgm3140.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o
diff --git a/drivers/leds/leds-sgm3140.c b/drivers/leds/leds-sgm3140.c
new file mode 100644
index 000000000000..9e91392f0343
--- /dev/null
+++ b/drivers/leds/leds-sgm3140.c
@@ -0,0 +1,210 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 Luca Weiss <luca@z3ntu.xyz>
+
+#include <linux/gpio/consumer.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include <media/v4l2-flash-led-class.h>
+
+#define SGM3140_NAME "sgm3140"
+
+struct sgm3140 {
+	struct gpio_desc *flash_gpio;
+	struct gpio_desc *enable_gpio;
+
+	struct led_classdev_flash fled_cdev;
+	struct v4l2_flash *v4l2_flash;
+
+	struct timer_list powerdown_timer;
+};
+
+static struct sgm3140 *flcdev_to_sgm3140(struct led_classdev_flash *flcdev)
+{
+	return container_of(flcdev, struct sgm3140, fled_cdev);
+}
+
+int sgm3140_strobe_set(struct led_classdev_flash *fled_cdev, bool state)
+{
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+
+	if (state) {
+		gpiod_set_value_cansleep(priv->flash_gpio, 1);
+		gpiod_set_value_cansleep(priv->enable_gpio, 1);
+		mod_timer(&priv->powerdown_timer,
+			  jiffies + msecs_to_jiffies(250));
+	} else {
+		gpiod_set_value_cansleep(priv->enable_gpio, 0);
+		gpiod_set_value_cansleep(priv->flash_gpio, 0);
+		del_timer_sync(&priv->powerdown_timer);
+	}
+
+	return 0;
+}
+
+struct led_flash_ops sgm3140_flash_ops = {
+	.strobe_set = sgm3140_strobe_set,
+};
+
+int sgm3140_brightness_set(struct led_classdev *led_cdev,
+			   enum led_brightness brightness)
+{
+	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+	struct sgm3140 *priv = flcdev_to_sgm3140(fled_cdev);
+
+	if (brightness == LED_OFF)
+		gpiod_set_value_cansleep(priv->enable_gpio, 0);
+	else
+		gpiod_set_value_cansleep(priv->enable_gpio, 1);
+
+	return 0;
+}
+
+static void sgm3140_powerdown_timer(struct timer_list *t)
+{
+	struct sgm3140 *priv = from_timer(priv, t, powerdown_timer);
+
+	gpiod_set_value_cansleep(priv->enable_gpio, 0);
+	gpiod_set_value_cansleep(priv->flash_gpio, 0);
+}
+
+#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
+static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
+					   struct v4l2_flash_config *v4l2_sd_cfg)
+{
+	struct led_classdev *led_cdev = &priv->fled_cdev.led_cdev;
+	struct led_flash_setting *s;
+
+	strlcpy(v4l2_sd_cfg->dev_name, led_cdev->dev->kobj.name,
+		sizeof(v4l2_sd_cfg->dev_name));
+
+	s = &v4l2_sd_cfg->intensity;
+	s->min = 0;
+	s->max = 1;
+	s->step = 1;
+	s->val = 1;
+}
+
+#else
+static void sgm3140_init_v4l2_flash_config(struct sgm3140 *priv,
+					   struct v4l2_flash_config *v4l2_sd_cfg)
+{
+}
+#endif
+
+static int sgm3140_probe(struct platform_device *pdev)
+{
+	struct sgm3140 *priv;
+	struct led_classdev *led_cdev;
+	struct led_classdev_flash *fled_cdev;
+	struct led_init_data init_data = {};
+	struct device_node *child_node;
+	struct v4l2_flash_config v4l2_sd_cfg;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->flash_gpio = devm_gpiod_get(&pdev->dev, "flash", GPIOD_OUT_LOW);
+	ret = PTR_ERR_OR_ZERO(priv->flash_gpio);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "Failed to request flash gpio: %d\n",
+				ret);
+		return ret;
+	}
+
+	priv->enable_gpio = devm_gpiod_get(&pdev->dev, "enable", GPIOD_OUT_LOW);
+	ret = PTR_ERR_OR_ZERO(priv->enable_gpio);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "Failed to request enable gpio: %d\n",
+				ret);
+		return ret;
+	}
+
+	child_node = of_get_next_available_child(pdev->dev.of_node, NULL);
+	if (!child_node) {
+		dev_err(&pdev->dev, "No DT child node found for connected LED.\n");
+		return -EINVAL;
+	}
+
+	timer_setup(&priv->powerdown_timer, sgm3140_powerdown_timer, 0);
+
+	fled_cdev = &priv->fled_cdev;
+	led_cdev = &fled_cdev->led_cdev;
+
+	fled_cdev->ops = &sgm3140_flash_ops;
+
+	led_cdev->brightness_set_blocking = sgm3140_brightness_set;
+	led_cdev->max_brightness = LED_ON;
+	led_cdev->flags |= LED_DEV_CAP_FLASH;
+
+	init_data.fwnode = of_fwnode_handle(child_node);
+	init_data.devicename = SGM3140_NAME;
+
+	platform_set_drvdata(pdev, priv);
+
+	/* Register in the LED subsystem */
+	ret = led_classdev_flash_register_ext(&pdev->dev, fled_cdev, &init_data);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register flash device: %d\n",
+			ret);
+		goto err_flash_register;
+	}
+
+	sgm3140_init_v4l2_flash_config(priv, &v4l2_sd_cfg);
+
+	/* Create V4L2 Flash subdev */
+	priv->v4l2_flash = v4l2_flash_init(&pdev->dev, of_fwnode_handle(child_node),
+					   fled_cdev, NULL,
+					   &v4l2_sd_cfg);
+	if (IS_ERR(priv->v4l2_flash)) {
+		ret = PTR_ERR(priv->v4l2_flash);
+		goto err_v4l2_flash_init;
+	}
+
+	return 0;
+
+err_v4l2_flash_init:
+	led_classdev_flash_unregister(fled_cdev);
+err_flash_register:
+	of_node_put(child_node);
+	return ret;
+}
+
+static int sgm3140_remove(struct platform_device *pdev)
+{
+	struct sgm3140 *priv = platform_get_drvdata(pdev);
+
+	del_timer_sync(&priv->powerdown_timer);
+
+	v4l2_flash_release(priv->v4l2_flash);
+	led_classdev_flash_unregister(&priv->fled_cdev);
+
+	return 0;
+}
+
+static const struct of_device_id sgm3140_dt_match[] = {
+	{ .compatible = "sgmicro,sgm3140" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sgm3140_dt_match);
+
+static struct platform_driver sgm3140_driver = {
+	.probe	= sgm3140_probe,
+	.remove	= sgm3140_remove,
+	.driver	= {
+		.name	= "sgm3140",
+		.of_match_table = sgm3140_dt_match,
+	},
+};
+
+module_platform_driver(sgm3140_driver);
+
+MODULE_AUTHOR("Luca Weiss <luca@z3ntu.xyz>");
+MODULE_DESCRIPTION("SG Micro SGM3140 charge pump led driver");
+MODULE_LICENSE("GPL v2");