leds: Add ktd2692 flash LED driver

This patch adds a driver to support the ktd2692 flash LEDs.
ktd2692 can control flash current by ExpressWire interface.
Signed-off-by: Ingi Kim <ingi2.kim@samsung.com>
Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Reviewed-by: Varka Bhadram <varkabhadram@gmail.com>
Acked-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/Kconfig

@@ -532,6 +532,15 @@ config LEDS_MENF21BMC
 	  This driver can also be built as a module. If so the module
 	  will be called leds-menf21bmc.
 
+config LEDS_KTD2692
+	tristate "LED support for KTD2692 flash LED controller"
+	depends on LEDS_CLASS_FLASH && GPIOLIB && OF
+	help
+	  This option enables support for KTD2692 LED flash connected
+	  through ExpressWire interface.
+
+	  Say Y to enable this driver.
+
 comment "LED driver for blink(1) USB RGB LED is under Special HID drivers (HID_THINGM)"
 
 config LEDS_BLINKM

drivers/leds/Makefile

@@ -63,6 +63,7 @@ obj-$(CONFIG_LEDS_SYSCON)		+= leds-syscon.o
 obj-$(CONFIG_LEDS_VERSATILE)		+= leds-versatile.o
 obj-$(CONFIG_LEDS_MENF21BMC)		+= leds-menf21bmc.o
 obj-$(CONFIG_LEDS_PM8941_WLED)		+= leds-pm8941-wled.o
+obj-$(CONFIG_LEDS_KTD2692)		+= leds-ktd2692.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o

drivers/leds/leds-ktd2692.c

+/*
+ * LED driver : leds-ktd2692.c
+ *
+ * Copyright (C) 2015 Samsung Electronics
+ * Ingi Kim <ingi2.kim@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/workqueue.h>
+
+/* Value related the movie mode */
+#define KTD2692_MOVIE_MODE_CURRENT_LEVELS	16
+#define KTD2692_MM_TO_FL_RATIO(x)		((x) / 3)
+#define KTD2962_MM_MIN_CURR_THRESHOLD_SCALE	8
+
+/* Value related the flash mode */
+#define KTD2692_FLASH_MODE_TIMEOUT_LEVELS	8
+#define KTD2692_FLASH_MODE_TIMEOUT_DISABLE	0
+#define KTD2692_FLASH_MODE_CURR_PERCENT(x)	(((x) * 16) / 100)
+
+/* Macro for getting offset of flash timeout */
+#define GET_TIMEOUT_OFFSET(timeout, step)	((timeout) / (step))
+
+/* Base register address */
+#define KTD2692_REG_LVP_BASE			0x00
+#define KTD2692_REG_FLASH_TIMEOUT_BASE		0x20
+#define KTD2692_REG_MM_MIN_CURR_THRESHOLD_BASE	0x40
+#define KTD2692_REG_MOVIE_CURRENT_BASE		0x60
+#define KTD2692_REG_FLASH_CURRENT_BASE		0x80
+#define KTD2692_REG_MODE_BASE			0xA0
+
+/* Set bit coding time for expresswire interface */
+#define KTD2692_TIME_RESET_US			700
+#define KTD2692_TIME_DATA_START_TIME_US		10
+#define KTD2692_TIME_HIGH_END_OF_DATA_US	350
+#define KTD2692_TIME_LOW_END_OF_DATA_US		10
+#define KTD2692_TIME_SHORT_BITSET_US		4
+#define KTD2692_TIME_LONG_BITSET_US		12
+
+/* KTD2692 default length of name */
+#define KTD2692_NAME_LENGTH			20
+
+enum ktd2692_bitset {
+	KTD2692_LOW = 0,
+	KTD2692_HIGH,
+};
+
+/* Movie / Flash Mode Control */
+enum ktd2692_led_mode {
+	KTD2692_MODE_DISABLE = 0,	/* default */
+	KTD2692_MODE_MOVIE,
+	KTD2692_MODE_FLASH,
+};
+
+struct ktd2692_led_config_data {
+	/* maximum LED current in movie mode */
+	u32 movie_max_microamp;
+	/* maximum LED current in flash mode */
+	u32 flash_max_microamp;
+	/* maximum flash timeout */
+	u32 flash_max_timeout;
+	/* max LED brightness level */
+	enum led_brightness max_brightness;
+};
+
+struct ktd2692_context {
+	/* Related LED Flash class device */
+	struct led_classdev_flash fled_cdev;
+
+	/* secures access to the device */
+	struct mutex lock;
+	struct regulator *regulator;
+	struct work_struct work_brightness_set;
+
+	struct gpio_desc *aux_gpio;
+	struct gpio_desc *ctrl_gpio;
+
+	enum ktd2692_led_mode mode;
+	enum led_brightness torch_brightness;
+};
+
+static struct ktd2692_context *fled_cdev_to_led(
+				struct led_classdev_flash *fled_cdev)
+{
+	return container_of(fled_cdev, struct ktd2692_context, fled_cdev);
+}
+
+static void ktd2692_expresswire_start(struct ktd2692_context *led)
+{
+	gpiod_direction_output(led->ctrl_gpio, KTD2692_HIGH);
+	udelay(KTD2692_TIME_DATA_START_TIME_US);
+}
+
+static void ktd2692_expresswire_reset(struct ktd2692_context *led)
+{
+	gpiod_direction_output(led->ctrl_gpio, KTD2692_LOW);
+	udelay(KTD2692_TIME_RESET_US);
+}
+
+static void ktd2692_expresswire_end(struct ktd2692_context *led)
+{
+	gpiod_direction_output(led->ctrl_gpio, KTD2692_LOW);
+	udelay(KTD2692_TIME_LOW_END_OF_DATA_US);
+	gpiod_direction_output(led->ctrl_gpio, KTD2692_HIGH);
+	udelay(KTD2692_TIME_HIGH_END_OF_DATA_US);
+}
+
+static void ktd2692_expresswire_set_bit(struct ktd2692_context *led, bool bit)
+{
+	/*
+	 * The Low Bit(0) and High Bit(1) is based on a time detection
+	 * algorithm between time low and time high
+	 * Time_(L_LB) : Low time of the Low Bit(0)
+	 * Time_(H_LB) : High time of the LOW Bit(0)
+	 * Time_(L_HB) : Low time of the High Bit(1)
+	 * Time_(H_HB) : High time of the High Bit(1)
+	 *
+	 * It can be simplified to:
+	 * Low Bit(0) : 2 * Time_(H_LB) < Time_(L_LB)
+	 * High Bit(1) : 2 * Time_(L_HB) < Time_(H_HB)
+	 * HIGH  ___           ____    _..     _________    ___
+	 *          |_________|    |_..  |____|         |__|
+	 * LOW        <L_LB>  <H_LB>     <L_HB>  <H_HB>
+	 *          [  Low Bit (0) ]     [  High Bit(1) ]
+	 */
+	if (bit) {
+		gpiod_direction_output(led->ctrl_gpio, KTD2692_LOW);
+		udelay(KTD2692_TIME_SHORT_BITSET_US);
+		gpiod_direction_output(led->ctrl_gpio, KTD2692_HIGH);
+		udelay(KTD2692_TIME_LONG_BITSET_US);
+	} else {
+		gpiod_direction_output(led->ctrl_gpio, KTD2692_LOW);
+		udelay(KTD2692_TIME_LONG_BITSET_US);
+		gpiod_direction_output(led->ctrl_gpio, KTD2692_HIGH);
+		udelay(KTD2692_TIME_SHORT_BITSET_US);
+	}
+}
+
+static void ktd2692_expresswire_write(struct ktd2692_context *led, u8 value)
+{
+	int i;
+
+	ktd2692_expresswire_start(led);
+	for (i = 7; i >= 0; i--)
+		ktd2692_expresswire_set_bit(led, value & BIT(i));
+	ktd2692_expresswire_end(led);
+}
+
+static void ktd2692_brightness_set(struct ktd2692_context *led,
+				   enum led_brightness brightness)
+{
+	mutex_lock(&led->lock);
+
+	if (brightness == LED_OFF) {
+		led->mode = KTD2692_MODE_DISABLE;
+		gpiod_direction_output(led->aux_gpio, KTD2692_LOW);
+	} else {
+		ktd2692_expresswire_write(led, brightness |
+					KTD2692_REG_MOVIE_CURRENT_BASE);
+		led->mode = KTD2692_MODE_MOVIE;
+	}
+
+	ktd2692_expresswire_write(led, led->mode | KTD2692_REG_MODE_BASE);
+	mutex_unlock(&led->lock);
+}
+
+static void ktd2692_brightness_set_work(struct work_struct *work)
+{
+	struct ktd2692_context *led =
+		container_of(work, struct ktd2692_context, work_brightness_set);
+
+	ktd2692_brightness_set(led, led->torch_brightness);
+}
+
+static void ktd2692_led_brightness_set(struct led_classdev *led_cdev,
+				       enum led_brightness brightness)
+{
+	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+	struct ktd2692_context *led = fled_cdev_to_led(fled_cdev);
+
+	led->torch_brightness = brightness;
+	schedule_work(&led->work_brightness_set);
+}
+
+static int ktd2692_led_brightness_set_sync(struct led_classdev *led_cdev,
+					   enum led_brightness brightness)
+{
+	struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+	struct ktd2692_context *led = fled_cdev_to_led(fled_cdev);
+
+	ktd2692_brightness_set(led, brightness);
+
+	return 0;
+}
+
+static int ktd2692_led_flash_strobe_set(struct led_classdev_flash *fled_cdev,
+					bool state)
+{
+	struct ktd2692_context *led = fled_cdev_to_led(fled_cdev);
+	struct led_flash_setting *timeout = &fled_cdev->timeout;
+	u32 flash_tm_reg;
+
+	mutex_lock(&led->lock);
+
+	if (state) {
+		flash_tm_reg = GET_TIMEOUT_OFFSET(timeout->val, timeout->step);
+		ktd2692_expresswire_write(led, flash_tm_reg
+				| KTD2692_REG_FLASH_TIMEOUT_BASE);
+
+		led->mode = KTD2692_MODE_FLASH;
+		gpiod_direction_output(led->aux_gpio, KTD2692_HIGH);
+	} else {
+		led->mode = KTD2692_MODE_DISABLE;
+		gpiod_direction_output(led->aux_gpio, KTD2692_LOW);
+	}
+
+	ktd2692_expresswire_write(led, led->mode | KTD2692_REG_MODE_BASE);
+
+	fled_cdev->led_cdev.brightness = LED_OFF;
+	led->mode = KTD2692_MODE_DISABLE;
+
+	mutex_unlock(&led->lock);
+
+	return 0;
+}
+
+static int ktd2692_led_flash_timeout_set(struct led_classdev_flash *fled_cdev,
+					 u32 timeout)
+{
+	return 0;
+}
+
+static void ktd2692_init_movie_current_max(struct ktd2692_led_config_data *cfg)
+{
+	u32 offset, step;
+	u32 movie_current_microamp;
+
+	offset = KTD2692_MOVIE_MODE_CURRENT_LEVELS;
+	step = KTD2692_MM_TO_FL_RATIO(cfg->flash_max_microamp)
+		/ KTD2692_MOVIE_MODE_CURRENT_LEVELS;
+
+	do {
+		movie_current_microamp = step * offset;
+		offset--;
+	} while ((movie_current_microamp > cfg->movie_max_microamp) &&
+		(offset > 0));
+
+	cfg->max_brightness = offset;
+}
+
+static void ktd2692_init_flash_timeout(struct led_classdev_flash *fled_cdev,
+				       struct ktd2692_led_config_data *cfg)
+{
+	struct led_flash_setting *setting;
+
+	setting = &fled_cdev->timeout;
+	setting->min = KTD2692_FLASH_MODE_TIMEOUT_DISABLE;
+	setting->max = cfg->flash_max_timeout;
+	setting->step = cfg->flash_max_timeout
+			/ (KTD2692_FLASH_MODE_TIMEOUT_LEVELS - 1);
+	setting->val = cfg->flash_max_timeout;
+}
+
+static void ktd2692_setup(struct ktd2692_context *led)
+{
+	led->mode = KTD2692_MODE_DISABLE;
+	ktd2692_expresswire_reset(led);
+	gpiod_direction_output(led->aux_gpio, KTD2692_LOW);
+
+	ktd2692_expresswire_write(led, (KTD2962_MM_MIN_CURR_THRESHOLD_SCALE - 1)
+				 | KTD2692_REG_MM_MIN_CURR_THRESHOLD_BASE);
+	ktd2692_expresswire_write(led, KTD2692_FLASH_MODE_CURR_PERCENT(45)
+				 | KTD2692_REG_FLASH_CURRENT_BASE);
+}
+
+static int ktd2692_parse_dt(struct ktd2692_context *led, struct device *dev,
+			    struct ktd2692_led_config_data *cfg)
+{
+	struct device_node *np = dev->of_node;
+	struct device_node *child_node;
+	int ret;
+
+	if (!dev->of_node)
+		return -ENXIO;
+
+	led->ctrl_gpio = devm_gpiod_get(dev, "ctrl");
+	if (IS_ERR(led->ctrl_gpio)) {
+		ret = PTR_ERR(led->ctrl_gpio);
+		dev_err(dev, "cannot get ctrl-gpios %d\n", ret);
+		return ret;
+	}
+
+	led->aux_gpio = devm_gpiod_get(dev, "aux");
+	if (IS_ERR(led->aux_gpio)) {
+		ret = PTR_ERR(led->aux_gpio);
+		dev_err(dev, "cannot get aux-gpios %d\n", ret);
+		return ret;
+	}
+
+	led->regulator = devm_regulator_get(dev, "vin");
+	if (IS_ERR(led->regulator))
+		led->regulator = NULL;
+
+	if (led->regulator) {
+		ret = regulator_enable(led->regulator);
+		if (ret)
+			dev_err(dev, "Failed to enable supply: %d\n", ret);
+	}
+
+	child_node = of_get_next_available_child(np, NULL);
+	if (!child_node) {
+		dev_err(dev, "No DT child node found for connected LED.\n");
+		return -EINVAL;
+	}
+
+	led->fled_cdev.led_cdev.name =
+		of_get_property(child_node, "label", NULL) ? : child_node->name;
+
+	ret = of_property_read_u32(child_node, "led-max-microamp",
+				   &cfg->movie_max_microamp);
+	if (ret) {
+		dev_err(dev, "failed to parse led-max-microamp\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(child_node, "flash-max-microamp",
+				   &cfg->flash_max_microamp);
+	if (ret) {
+		dev_err(dev, "failed to parse flash-max-microamp\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(child_node, "flash-max-timeout-us",
+				   &cfg->flash_max_timeout);
+	if (ret)
+		dev_err(dev, "failed to parse flash-max-timeout-us\n");
+
+	of_node_put(child_node);
+	return ret;
+}
+
+static const struct led_flash_ops flash_ops = {
+	.strobe_set = ktd2692_led_flash_strobe_set,
+	.timeout_set = ktd2692_led_flash_timeout_set,
+};
+
+static int ktd2692_probe(struct platform_device *pdev)
+{
+	struct ktd2692_context *led;
+	struct led_classdev *led_cdev;
+	struct led_classdev_flash *fled_cdev;
+	struct ktd2692_led_config_data led_cfg;
+	int ret;
+
+	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	fled_cdev = &led->fled_cdev;
+	led_cdev = &fled_cdev->led_cdev;
+
+	ret = ktd2692_parse_dt(led, &pdev->dev, &led_cfg);
+	if (ret)
+		return ret;
+
+	ktd2692_init_flash_timeout(fled_cdev, &led_cfg);
+	ktd2692_init_movie_current_max(&led_cfg);
+
+	fled_cdev->ops = &flash_ops;
+
+	led_cdev->max_brightness = led_cfg.max_brightness;
+	led_cdev->brightness_set = ktd2692_led_brightness_set;
+	led_cdev->brightness_set_sync = ktd2692_led_brightness_set_sync;
+	led_cdev->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
+
+	mutex_init(&led->lock);
+	INIT_WORK(&led->work_brightness_set, ktd2692_brightness_set_work);
+
+	platform_set_drvdata(pdev, led);
+
+	ret = led_classdev_flash_register(&pdev->dev, fled_cdev);
+	if (ret) {
+		dev_err(&pdev->dev, "can't register LED %s\n", led_cdev->name);
+		mutex_destroy(&led->lock);
+		return ret;
+	}
+
+	ktd2692_setup(led);
+
+	return 0;
+}
+
+static int ktd2692_remove(struct platform_device *pdev)
+{
+	struct ktd2692_context *led = platform_get_drvdata(pdev);
+	int ret;
+
+	led_classdev_flash_unregister(&led->fled_cdev);
+	cancel_work_sync(&led->work_brightness_set);
+
+	if (led->regulator) {
+		ret = regulator_disable(led->regulator);
+		if (ret)
+			dev_err(&pdev->dev,
+				"Failed to disable supply: %d\n", ret);
+	}
+
+	mutex_destroy(&led->lock);
+
+	return 0;
+}
+
+static const struct of_device_id ktd2692_match[] = {
+	{ .compatible = "kinetic,ktd2692", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver ktd2692_driver = {
+	.driver = {
+		.name  = "ktd2692",
+		.of_match_table = ktd2692_match,
+	},
+	.probe  = ktd2692_probe,
+	.remove = ktd2692_remove,
+};
+
+module_platform_driver(ktd2692_driver);
+
+MODULE_AUTHOR("Ingi Kim <ingi2.kim@samsung.com>");
+MODULE_DESCRIPTION("Kinetic KTD2692 LED driver");
+MODULE_LICENSE("GPL v2");