LXR linux/drivers/leds/leds-lt3593.c

   1// SPDX-License-Identifier: GPL-2.0
   2// 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 maximum
  30         * level on the first falling edge on the control pin. Each following
  31         * falling edge decreases the current level by 625uA. Up to 32 pulses
  32         * can be sent, so the maximum power reduction is 20mA.
  33         * After a timeout of 128us, the value is taken from the register and
  34         * 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