linux-zen-server/drivers/leds/flash/leds-rt8515.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * LED driver for Richtek RT8515 flash/torch white LEDs
 * found on some Samsung mobile phones.
 *
 * This is a 1.5A Boost dual channel driver produced around 2011.
 *
 * The component lacks a datasheet, but in the schematic picture
 * from the LG P970 service manual you can see the connections
 * from the RT8515 to the LED, with two resistors connected
 * from the pins "RFS" and "RTS" to ground.
 *
 * On the LG P970:
 * RFS (resistance flash setting?) is 20 kOhm
 * RTS (resistance torch setting?) is 39 kOhm
 *
 * Some sleuthing finds us the RT9387A which we have a datasheet for:
 * https://static5.arrow.com/pdfs/2014/7/27/8/21/12/794/rtt_/manual/94download_ds.jspprt9387a.jspprt9387a.pdf
 * This apparently works the same way so in theory this driver
 * should cover RT9387A as well. This has not been tested, please
 * update the compatibles if you add RT9387A support.
 *
 * Linus Walleij <linus.walleij@linaro.org>
 */
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/led-class-flash.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>

#include <media/v4l2-flash-led-class.h>

/* We can provide 15-700 mA out to the LED */
#define RT8515_MIN_IOUT_MA	15
#define RT8515_MAX_IOUT_MA	700
/* The maximum intensity is 1-16 for flash and 1-100 for torch */
#define RT8515_FLASH_MAX	16
#define RT8515_TORCH_MAX	100

#define RT8515_TIMEOUT_US	250000U
#define RT8515_MAX_TIMEOUT_US	300000U

struct rt8515 {
	struct led_classdev_flash fled;
	struct device *dev;
	struct v4l2_flash *v4l2_flash;
	struct mutex lock;
	struct regulator *reg;
	struct gpio_desc *enable_torch;
	struct gpio_desc *enable_flash;
	struct timer_list powerdown_timer;
	u32 max_timeout; /* Flash max timeout */
	int flash_max_intensity;
	int torch_max_intensity;
};

static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
{
	return container_of(fled, struct rt8515, fled);
}

static void rt8515_gpio_led_off(struct rt8515 *rt)
{
	gpiod_set_value(rt->enable_flash, 0);
	gpiod_set_value(rt->enable_torch, 0);
}

static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
					  int brightness)
{
	int i;

	/*
	 * Toggling a GPIO line with a small delay increases the
	 * brightness one step at a time.
	 */
	for (i = 0; i < brightness; i++) {
		gpiod_set_value(gpiod, 0);
		udelay(1);
		gpiod_set_value(gpiod, 1);
		udelay(1);
	}
}

/* This is setting the torch light level */
static int rt8515_led_brightness_set(struct led_classdev *led,
				     enum led_brightness brightness)
{
	struct led_classdev_flash *fled = lcdev_to_flcdev(led);
	struct rt8515 *rt = to_rt8515(fled);

	mutex_lock(&rt->lock);

	if (brightness == LED_OFF) {
		/* Off */
		rt8515_gpio_led_off(rt);
	} else if (brightness < RT8515_TORCH_MAX) {
		/* Step it up to movie mode brightness using the flash pin */
		rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
	} else {
		/* Max torch brightness requested */
		gpiod_set_value(rt->enable_torch, 1);
	}

	mutex_unlock(&rt->lock);

	return 0;
}

static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
				       bool state)
{
	struct rt8515 *rt = to_rt8515(fled);
	struct led_flash_setting *timeout = &fled->timeout;
	int brightness = rt->flash_max_intensity;

	mutex_lock(&rt->lock);

	if (state) {
		/* Enable LED flash mode and set brightness */
		rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
		/* Set timeout */
		mod_timer(&rt->powerdown_timer,
			  jiffies + usecs_to_jiffies(timeout->val));
	} else {
		del_timer_sync(&rt->powerdown_timer);
		/* Turn the LED off */
		rt8515_gpio_led_off(rt);
	}

	fled->led_cdev.brightness = LED_OFF;
	/* After this the torch LED will be disabled */

	mutex_unlock(&rt->lock);

	return 0;
}

static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
				       bool *state)
{
	struct rt8515 *rt = to_rt8515(fled);

	*state = timer_pending(&rt->powerdown_timer);

	return 0;
}

static int rt8515_led_flash_timeout_set(struct led_classdev_flash *fled,
					u32 timeout)
{
	/* The timeout is stored in the led-class-flash core */
	return 0;
}

static const struct led_flash_ops rt8515_flash_ops = {
	.strobe_set = rt8515_led_flash_strobe_set,
	.strobe_get = rt8515_led_flash_strobe_get,
	.timeout_set = rt8515_led_flash_timeout_set,
};

static void rt8515_powerdown_timer(struct timer_list *t)
{
	struct rt8515 *rt = from_timer(rt, t, powerdown_timer);

	/* Turn the LED off */
	rt8515_gpio_led_off(rt);
}

static void rt8515_init_flash_timeout(struct rt8515 *rt)
{
	struct led_classdev_flash *fled = &rt->fled;
	struct led_flash_setting *s;

	/* Init flash timeout setting */
	s = &fled->timeout;
	s->min = 1;
	s->max = rt->max_timeout;
	s->step = 1;
	/*
	 * Set default timeout to RT8515_TIMEOUT_US except if
	 * max_timeout from DT is lower.
	 */
	s->val = min(rt->max_timeout, RT8515_TIMEOUT_US);
}

#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
/* Configure the V2L2 flash subdevice */
static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
					  struct v4l2_flash_config *v4l2_sd_cfg)
{
	struct led_classdev *led = &rt->fled.led_cdev;
	struct led_flash_setting *s;

	strscpy(v4l2_sd_cfg->dev_name, led->dev->kobj.name,
		sizeof(v4l2_sd_cfg->dev_name));

	/*
	 * Init flash intensity setting: this is a linear scale
	 * capped from the device tree max intensity setting
	 * 1..flash_max_intensity
	 */
	s = &v4l2_sd_cfg->intensity;
	s->min = 1;
	s->max = rt->flash_max_intensity;
	s->step = 1;
	s->val = s->max;
}

static void rt8515_v4l2_flash_release(struct rt8515 *rt)
{
	v4l2_flash_release(rt->v4l2_flash);
}

#else
static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
					  struct v4l2_flash_config *v4l2_sd_cfg)
{
}

static void rt8515_v4l2_flash_release(struct rt8515 *rt)
{
}
#endif

static void rt8515_determine_max_intensity(struct rt8515 *rt,
					   struct fwnode_handle *led,
					   const char *resistance,
					   const char *max_ua_prop, int hw_max,
					   int *max_intensity_setting)
{
	u32 res = 0; /* Can't be 0 so 0 is undefined */
	u32 ua;
	u32 max_ma;
	int max_intensity;
	int ret;

	fwnode_property_read_u32(rt->dev->fwnode, resistance, &res);
	ret = fwnode_property_read_u32(led, max_ua_prop, &ua);

	/* Missing info in DT, OK go with hardware maxima */
	if (ret || res == 0) {
		dev_err(rt->dev,
			"either %s or %s missing from DT, using HW max\n",
			resistance, max_ua_prop);
		max_ma = RT8515_MAX_IOUT_MA;
		max_intensity = hw_max;
		goto out_assign_max;
	}

	/*
	 * Formula from the datasheet, this is the maximum current
	 * defined by the hardware.
	 */
	max_ma = (5500 * 1000) / res;
	/*
	 * Calculate max intensity (linear scaling)
	 * Formula is ((ua / 1000) / max_ma) * 100, then simplified
	 */
	max_intensity = (ua / 10) / max_ma;

	dev_info(rt->dev,
		 "current restricted from %u to %u mA, max intensity %d/100\n",
		 max_ma, (ua / 1000), max_intensity);

out_assign_max:
	dev_info(rt->dev, "max intensity %d/%d = %d mA\n",
		 max_intensity, hw_max, max_ma);
	*max_intensity_setting = max_intensity;
}

static int rt8515_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct fwnode_handle *child;
	struct rt8515 *rt;
	struct led_classdev *led;
	struct led_classdev_flash *fled;
	struct led_init_data init_data = {};
	struct v4l2_flash_config v4l2_sd_cfg = {};
	int ret;

	rt = devm_kzalloc(dev, sizeof(*rt), GFP_KERNEL);
	if (!rt)
		return -ENOMEM;

	rt->dev = dev;
	fled = &rt->fled;
	led = &fled->led_cdev;

	/* ENF - Enable Flash line */
	rt->enable_flash = devm_gpiod_get(dev, "enf", GPIOD_OUT_LOW);
	if (IS_ERR(rt->enable_flash))
		return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
				     "cannot get ENF (enable flash) GPIO\n");

	/* ENT - Enable Torch line */
	rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
	if (IS_ERR(rt->enable_torch))
		return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
				     "cannot get ENT (enable torch) GPIO\n");

	child = fwnode_get_next_available_child_node(dev->fwnode, NULL);
	if (!child) {
		dev_err(dev,
			"No fwnode child node found for connected LED.\n");
		return -EINVAL;
	}
	init_data.fwnode = child;

	rt8515_determine_max_intensity(rt, child, "richtek,rfs-ohms",
				       "flash-max-microamp",
				       RT8515_FLASH_MAX,
				       &rt->flash_max_intensity);
	rt8515_determine_max_intensity(rt, child, "richtek,rts-ohms",
				       "led-max-microamp",
				       RT8515_TORCH_MAX,
				       &rt->torch_max_intensity);

	ret = fwnode_property_read_u32(child, "flash-max-timeout-us",
				       &rt->max_timeout);
	if (ret) {
		rt->max_timeout = RT8515_MAX_TIMEOUT_US;
		dev_warn(dev,
			 "flash-max-timeout-us property missing\n");
	}
	timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0);
	rt8515_init_flash_timeout(rt);

	fled->ops = &rt8515_flash_ops;

	led->max_brightness = rt->torch_max_intensity;
	led->brightness_set_blocking = rt8515_led_brightness_set;
	led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;

	mutex_init(&rt->lock);

	platform_set_drvdata(pdev, rt);

	ret = devm_led_classdev_flash_register_ext(dev, fled, &init_data);
	if (ret) {
		fwnode_handle_put(child);
		mutex_destroy(&rt->lock);
		dev_err(dev, "can't register LED %s\n", led->name);
		return ret;
	}

	rt8515_init_v4l2_flash_config(rt, &v4l2_sd_cfg);

	/* Create a V4L2 Flash device if V4L2 flash is enabled */
	rt->v4l2_flash = v4l2_flash_init(dev, child, fled, NULL, &v4l2_sd_cfg);
	if (IS_ERR(rt->v4l2_flash)) {
		ret = PTR_ERR(rt->v4l2_flash);
		dev_err(dev, "failed to register V4L2 flash device (%d)\n",
			ret);
		/*
		 * Continue without the V4L2 flash
		 * (we still have the classdev)
		 */
	}

	fwnode_handle_put(child);
	return 0;
}

static int rt8515_remove(struct platform_device *pdev)
{
	struct rt8515 *rt = platform_get_drvdata(pdev);

	rt8515_v4l2_flash_release(rt);
	del_timer_sync(&rt->powerdown_timer);
	mutex_destroy(&rt->lock);

	return 0;
}

static const struct of_device_id rt8515_match[] = {
	{ .compatible = "richtek,rt8515", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rt8515_match);

static struct platform_driver rt8515_driver = {
	.driver = {
		.name  = "rt8515",
		.of_match_table = rt8515_match,
	},
	.probe  = rt8515_probe,
	.remove = rt8515_remove,
};
module_platform_driver(rt8515_driver);

MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
MODULE_DESCRIPTION("Richtek RT8515 LED driver");
MODULE_LICENSE("GPL");