1 files changed, 130 insertions, 0 deletions
diff --git a/drivers/leds/leds-lt3593.c b/drivers/leds/leds-lt3593.c
new file mode 100644
index 000000000..7dab08773
--- /dev/null
+++ b/drivers/leds/leds-lt3593.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#define LED_LT3593_NAME "lt3593"
+
+struct lt3593_led_data {
+	struct led_classdev cdev;
+	struct gpio_desc *gpiod;
+};
+
+static int lt3593_led_set(struct led_classdev *led_cdev,
+			   enum led_brightness value)
+{
+	struct lt3593_led_data *led_dat =
+		container_of(led_cdev, struct lt3593_led_data, cdev);
+	int pulses;
+
+	/*
+	 * The LT3593 resets its internal current level register to the maximum
+	 * level on the first falling edge on the control pin. Each following
+	 * falling edge decreases the current level by 625uA. Up to 32 pulses
+	 * can be sent, so the maximum power reduction is 20mA.
+	 * After a timeout of 128us, the value is taken from the register and
+	 * applied is to the output driver.
+	 */
+
+	if (value == 0) {
+		gpiod_set_value_cansleep(led_dat->gpiod, 0);
+		return 0;
+	}
+
+	pulses = 32 - (value * 32) / 255;
+
+	if (pulses == 0) {
+		gpiod_set_value_cansleep(led_dat->gpiod, 0);
+		mdelay(1);
+		gpiod_set_value_cansleep(led_dat->gpiod, 1);
+		return 0;
+	}
+
+	gpiod_set_value_cansleep(led_dat->gpiod, 1);
+
+	while (pulses--) {
+		gpiod_set_value_cansleep(led_dat->gpiod, 0);
+		udelay(1);
+		gpiod_set_value_cansleep(led_dat->gpiod, 1);
+		udelay(1);
+	}
+
+	return 0;
+}
+
+static int lt3593_led_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct lt3593_led_data *led_data;
+	struct fwnode_handle *child;
+	int ret, state = LEDS_GPIO_DEFSTATE_OFF;
+	struct led_init_data init_data = {};
+	const char *tmp;
+
+	if (!dev_of_node(dev))
+		return -ENODEV;
+
+	led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
+	if (!led_data)
+		return -ENOMEM;
+
+	if (device_get_child_node_count(dev) != 1) {
+		dev_err(dev, "Device must have exactly one LED sub-node.");
+		return -EINVAL;
+	}
+
+	led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
+	if (IS_ERR(led_data->gpiod))
+		return PTR_ERR(led_data->gpiod);
+
+	child = device_get_next_child_node(dev, NULL);
+
+	if (!fwnode_property_read_string(child, "default-state", &tmp)) {
+		if (!strcmp(tmp, "on"))
+			state = LEDS_GPIO_DEFSTATE_ON;
+	}
+
+	led_data->cdev.brightness_set_blocking = lt3593_led_set;
+	led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
+
+	init_data.fwnode = child;
+	init_data.devicename = LED_LT3593_NAME;
+	init_data.default_label = ":";
+
+	ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
+	fwnode_handle_put(child);
+	if (ret < 0)
+		return ret;
+
+	platform_set_drvdata(pdev, led_data);
+
+	return 0;
+}
+
+static const struct of_device_id of_lt3593_leds_match[] = {
+	{ .compatible = "lltc,lt3593", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
+
+static struct platform_driver lt3593_led_driver = {
+	.probe		= lt3593_led_probe,
+	.driver		= {
+		.name	= "leds-lt3593",
+		.of_match_table = of_match_ptr(of_lt3593_leds_match),
+	},
+};
+
+module_platform_driver(lt3593_led_driver);
+
+MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
+MODULE_DESCRIPTION("LED driver for LT3593 controllers");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-lt3593");