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1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>3 4#include <linux/kernel.h>5#include <linux/platform_device.h>6#include <linux/leds.h>7#include <linux/delay.h>8#include <linux/gpio/consumer.h>9#include <linux/slab.h>10#include <linux/mod_devicetable.h>11#include <linux/module.h>12#include <linux/property.h>13 14#define LED_LT3593_NAME "lt3593"15 16struct lt3593_led_data {17 struct led_classdev cdev;18 struct gpio_desc *gpiod;19};20 21static int lt3593_led_set(struct led_classdev *led_cdev,22 enum led_brightness value)23{24 struct lt3593_led_data *led_dat =25 container_of(led_cdev, struct lt3593_led_data, cdev);26 int pulses;27 28 /*29 * The LT3593 resets its internal current level register to the maximum30 * level on the first falling edge on the control pin. Each following31 * falling edge decreases the current level by 625uA. Up to 32 pulses32 * can be sent, so the maximum power reduction is 20mA.33 * After a timeout of 128us, the value is taken from the register and34 * applied is to the output driver.35 */36 37 if (value == 0) {38 gpiod_set_value_cansleep(led_dat->gpiod, 0);39 return 0;40 }41 42 pulses = 32 - (value * 32) / 255;43 44 if (pulses == 0) {45 gpiod_set_value_cansleep(led_dat->gpiod, 0);46 mdelay(1);47 gpiod_set_value_cansleep(led_dat->gpiod, 1);48 return 0;49 }50 51 gpiod_set_value_cansleep(led_dat->gpiod, 1);52 53 while (pulses--) {54 gpiod_set_value_cansleep(led_dat->gpiod, 0);55 udelay(1);56 gpiod_set_value_cansleep(led_dat->gpiod, 1);57 udelay(1);58 }59 60 return 0;61}62 63static int lt3593_led_probe(struct platform_device *pdev)64{65 struct device *dev = &pdev->dev;66 struct lt3593_led_data *led_data;67 struct fwnode_handle *child;68 int ret, state = LEDS_GPIO_DEFSTATE_OFF;69 struct led_init_data init_data = {};70 const char *tmp;71 72 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);73 if (!led_data)74 return -ENOMEM;75 76 if (device_get_child_node_count(dev) != 1) {77 dev_err(dev, "Device must have exactly one LED sub-node.");78 return -EINVAL;79 }80 81 led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);82 if (IS_ERR(led_data->gpiod))83 return PTR_ERR(led_data->gpiod);84 85 child = device_get_next_child_node(dev, NULL);86 87 if (!fwnode_property_read_string(child, "default-state", &tmp)) {88 if (!strcmp(tmp, "on"))89 state = LEDS_GPIO_DEFSTATE_ON;90 }91 92 led_data->cdev.brightness_set_blocking = lt3593_led_set;93 led_data->cdev.brightness = state ? LED_FULL : LED_OFF;94 95 init_data.fwnode = child;96 init_data.devicename = LED_LT3593_NAME;97 init_data.default_label = ":";98 99 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);100 fwnode_handle_put(child);101 if (ret < 0)102 return ret;103 104 platform_set_drvdata(pdev, led_data);105 106 return 0;107}108 109static const struct of_device_id of_lt3593_leds_match[] = {110 { .compatible = "lltc,lt3593", },111 {},112};113MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);114 115static struct platform_driver lt3593_led_driver = {116 .probe = lt3593_led_probe,117 .driver = {118 .name = "leds-lt3593",119 .of_match_table = of_lt3593_leds_match,120 },121};122 123module_platform_driver(lt3593_led_driver);124 125MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");126MODULE_DESCRIPTION("LED driver for LT3593 controllers");127MODULE_LICENSE("GPL v2");128MODULE_ALIAS("platform:leds-lt3593");129