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.h>
   9 #include <linux/gpio/consumer.h>
  10 #include <linux/slab.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <uapi/linux/uleds.h>
  14
  15 struct lt3593_led_data {
  16         char name[LED_MAX_NAME_SIZE];
  17         struct led_classdev cdev;
  18         struct gpio_desc *gpiod;
  19 };
  20
  21 static 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
  63 static struct lt3593_led_data *lt3593_led_probe_pdata(struct device *dev)
  64 {
  65         struct gpio_led_platform_data *pdata = dev_get_platdata(dev);
  66         const struct gpio_led *template = &pdata->leds[0];
  67         struct lt3593_led_data *led_data;
  68         int ret, state;
  69
  70         if (pdata->num_leds != 1)
  71                 return ERR_PTR(-EINVAL);
  72
  73         led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
  74         if (!led_data)
  75                 return ERR_PTR(-ENOMEM);
  76
  77         led_data->cdev.name = template->name;
  78         led_data->cdev.default_trigger = template->default_trigger;
  79         led_data->cdev.brightness_set_blocking = lt3593_led_set;
  80
  81         state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
  82         led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
  83
  84         if (!template->retain_state_suspended)
  85                 led_data->cdev.flags |= LED_CORE_SUSPENDRESUME;
  86
  87         ret = devm_gpio_request_one(dev, template->gpio, state ?
  88                                     GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
  89                                     template->name);
  90         if (ret < 0)
  91                 return ERR_PTR(ret);
  92
  93         led_data->gpiod = gpio_to_desc(template->gpio);
  94         if (!led_data->gpiod)
  95                 return ERR_PTR(-EPROBE_DEFER);
  96
  97         ret = devm_led_classdev_register(dev, &led_data->cdev);
  98         if (ret < 0)
  99                 return ERR_PTR(ret);
 100
 101         dev_info(dev, "registered LT3593 LED '%s' at GPIO %d\n",
 102                  template->name, template->gpio);
 103
 104         return led_data;
 105 }
 106
 107 static int lt3593_led_probe(struct platform_device *pdev)
 108 {
 109         struct device *dev = &pdev->dev;
 110         struct lt3593_led_data *led_data;
 111         struct fwnode_handle *child;
 112         int ret, state = LEDS_GPIO_DEFSTATE_OFF;
 113         enum gpiod_flags flags = GPIOD_OUT_LOW;
 114         const char *tmp;
 115
 116         if (dev_get_platdata(dev)) {
 117                 led_data = lt3593_led_probe_pdata(dev);
 118                 if (IS_ERR(led_data))
 119                         return PTR_ERR(led_data);
 120
 121                 goto out;
 122         }
 123
 124         if (!dev->of_node)
 125                 return -ENODEV;
 126
 127         led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
 128         if (!led_data)
 129                 return -ENOMEM;
 130
 131         if (device_get_child_node_count(dev) != 1) {
 132                 dev_err(dev, "Device must have exactly one LED sub-node.");
 133                 return -EINVAL;
 134         }
 135
 136         led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
 137         if (IS_ERR(led_data->gpiod))
 138                 return PTR_ERR(led_data->gpiod);
 139
 140         child = device_get_next_child_node(dev, NULL);
 141
 142         ret = fwnode_property_read_string(child, "label", &tmp);
 143         if (ret < 0)
 144                 snprintf(led_data->name, sizeof(led_data->name),
 145                          "lt3593::");
 146         else
 147                 snprintf(led_data->name, sizeof(led_data->name),
 148                          "lt3593:%s", tmp);
 149
 150         fwnode_property_read_string(child, "linux,default-trigger",
 151                                     &led_data->cdev.default_trigger);
 152
 153         if (!fwnode_property_read_string(child, "default-state", &tmp)) {
 154                 if (!strcmp(tmp, "keep")) {
 155                         state = LEDS_GPIO_DEFSTATE_KEEP;
 156                         flags = GPIOD_ASIS;
 157                 } else if (!strcmp(tmp, "on")) {
 158                         state = LEDS_GPIO_DEFSTATE_ON;
 159                         flags = GPIOD_OUT_HIGH;
 160                 }
 161         }
 162
 163         led_data->cdev.name = led_data->name;
 164         led_data->cdev.brightness_set_blocking = lt3593_led_set;
 165         led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
 166
 167         ret = devm_led_classdev_register(dev, &led_data->cdev);
 168         if (ret < 0) {
 169                 fwnode_handle_put(child);
 170                 return ret;
 171         }
 172
 173         led_data->cdev.dev->of_node = dev->of_node;
 174
 175 out:
 176         platform_set_drvdata(pdev, led_data);
 177
 178         return 0;
 179 }
 180
 181 #ifdef CONFIG_OF
 182 static const struct of_device_id of_lt3593_leds_match[] = {
 183         { .compatible = "lltc,lt3593", },
 184         {},
 185 };
 186 MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
 187 #endif
 188
 189 static struct platform_driver lt3593_led_driver = {
 190         .probe          = lt3593_led_probe,
 191         .driver         = {
 192                 .name   = "leds-lt3593",
 193                 .of_match_table = of_match_ptr(of_lt3593_leds_match),
 194         },
 195 };
 196
 197 module_platform_driver(lt3593_led_driver);
 198
 199 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
 200 MODULE_DESCRIPTION("LED driver for LT3593 controllers");
 201 MODULE_LICENSE("GPL v2");
 202 MODULE_ALIAS("platform:leds-lt3593");