leds-lt3593.c 3.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. // Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
  3. #include <linux/kernel.h>
  4. #include <linux/platform_device.h>
  5. #include <linux/leds.h>
  6. #include <linux/delay.h>
  7. #include <linux/gpio/consumer.h>
  8. #include <linux/slab.h>
  9. #include <linux/module.h>
  10. #include <linux/of.h>
  11. #define LED_LT3593_NAME "lt3593"
  12. struct lt3593_led_data {
  13. struct led_classdev cdev;
  14. struct gpio_desc *gpiod;
  15. };
  16. static int lt3593_led_set(struct led_classdev *led_cdev,
  17. enum led_brightness value)
  18. {
  19. struct lt3593_led_data *led_dat =
  20. container_of(led_cdev, struct lt3593_led_data, cdev);
  21. int pulses;
  22. /*
  23. * The LT3593 resets its internal current level register to the maximum
  24. * level on the first falling edge on the control pin. Each following
  25. * falling edge decreases the current level by 625uA. Up to 32 pulses
  26. * can be sent, so the maximum power reduction is 20mA.
  27. * After a timeout of 128us, the value is taken from the register and
  28. * applied is to the output driver.
  29. */
  30. if (value == 0) {
  31. gpiod_set_value_cansleep(led_dat->gpiod, 0);
  32. return 0;
  33. }
  34. pulses = 32 - (value * 32) / 255;
  35. if (pulses == 0) {
  36. gpiod_set_value_cansleep(led_dat->gpiod, 0);
  37. mdelay(1);
  38. gpiod_set_value_cansleep(led_dat->gpiod, 1);
  39. return 0;
  40. }
  41. gpiod_set_value_cansleep(led_dat->gpiod, 1);
  42. while (pulses--) {
  43. gpiod_set_value_cansleep(led_dat->gpiod, 0);
  44. udelay(1);
  45. gpiod_set_value_cansleep(led_dat->gpiod, 1);
  46. udelay(1);
  47. }
  48. return 0;
  49. }
  50. static int lt3593_led_probe(struct platform_device *pdev)
  51. {
  52. struct device *dev = &pdev->dev;
  53. struct lt3593_led_data *led_data;
  54. struct fwnode_handle *child;
  55. int ret, state = LEDS_GPIO_DEFSTATE_OFF;
  56. struct led_init_data init_data = {};
  57. const char *tmp;
  58. if (!dev_of_node(dev))
  59. return -ENODEV;
  60. led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
  61. if (!led_data)
  62. return -ENOMEM;
  63. if (device_get_child_node_count(dev) != 1) {
  64. dev_err(dev, "Device must have exactly one LED sub-node.");
  65. return -EINVAL;
  66. }
  67. led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
  68. if (IS_ERR(led_data->gpiod))
  69. return PTR_ERR(led_data->gpiod);
  70. child = device_get_next_child_node(dev, NULL);
  71. if (!fwnode_property_read_string(child, "default-state", &tmp)) {
  72. if (!strcmp(tmp, "on"))
  73. state = LEDS_GPIO_DEFSTATE_ON;
  74. }
  75. led_data->cdev.brightness_set_blocking = lt3593_led_set;
  76. led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
  77. init_data.fwnode = child;
  78. init_data.devicename = LED_LT3593_NAME;
  79. init_data.default_label = ":";
  80. ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
  81. fwnode_handle_put(child);
  82. if (ret < 0)
  83. return ret;
  84. platform_set_drvdata(pdev, led_data);
  85. return 0;
  86. }
  87. static const struct of_device_id of_lt3593_leds_match[] = {
  88. { .compatible = "lltc,lt3593", },
  89. {},
  90. };
  91. MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
  92. static struct platform_driver lt3593_led_driver = {
  93. .probe = lt3593_led_probe,
  94. .driver = {
  95. .name = "leds-lt3593",
  96. .of_match_table = of_match_ptr(of_lt3593_leds_match),
  97. },
  98. };
  99. module_platform_driver(lt3593_led_driver);
  100. MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
  101. MODULE_DESCRIPTION("LED driver for LT3593 controllers");
  102. MODULE_LICENSE("GPL v2");
  103. MODULE_ALIAS("platform:leds-lt3593");