leds-pwm.c 4.0 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * linux/drivers/leds-pwm.c
  4. *
  5. * simple PWM based LED control
  6. *
  7. * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
  8. *
  9. * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
  10. */
  11. #include <linux/module.h>
  12. #include <linux/kernel.h>
  13. #include <linux/platform_device.h>
  14. #include <linux/of_platform.h>
  15. #include <linux/leds.h>
  16. #include <linux/err.h>
  17. #include <linux/pwm.h>
  18. #include <linux/slab.h>
  19. struct led_pwm {
  20. const char *name;
  21. u8 active_low;
  22. unsigned int max_brightness;
  23. };
  24. struct led_pwm_data {
  25. struct led_classdev cdev;
  26. struct pwm_device *pwm;
  27. struct pwm_state pwmstate;
  28. unsigned int active_low;
  29. };
  30. struct led_pwm_priv {
  31. int num_leds;
  32. struct led_pwm_data leds[];
  33. };
  34. static int led_pwm_set(struct led_classdev *led_cdev,
  35. enum led_brightness brightness)
  36. {
  37. struct led_pwm_data *led_dat =
  38. container_of(led_cdev, struct led_pwm_data, cdev);
  39. unsigned int max = led_dat->cdev.max_brightness;
  40. unsigned long long duty = led_dat->pwmstate.period;
  41. duty *= brightness;
  42. do_div(duty, max);
  43. if (led_dat->active_low)
  44. duty = led_dat->pwmstate.period - duty;
  45. led_dat->pwmstate.duty_cycle = duty;
  46. led_dat->pwmstate.enabled = duty > 0;
  47. return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
  48. }
  49. __attribute__((nonnull))
  50. static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
  51. struct led_pwm *led, struct fwnode_handle *fwnode)
  52. {
  53. struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
  54. struct led_init_data init_data = { .fwnode = fwnode };
  55. int ret;
  56. led_data->active_low = led->active_low;
  57. led_data->cdev.name = led->name;
  58. led_data->cdev.brightness = LED_OFF;
  59. led_data->cdev.max_brightness = led->max_brightness;
  60. led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
  61. led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
  62. if (IS_ERR(led_data->pwm))
  63. return dev_err_probe(dev, PTR_ERR(led_data->pwm),
  64. "unable to request PWM for %s\n",
  65. led->name);
  66. led_data->cdev.brightness_set_blocking = led_pwm_set;
  67. pwm_init_state(led_data->pwm, &led_data->pwmstate);
  68. ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
  69. if (ret) {
  70. dev_err(dev, "failed to register PWM led for %s: %d\n",
  71. led->name, ret);
  72. return ret;
  73. }
  74. ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
  75. if (ret) {
  76. dev_err(dev, "failed to set led PWM value for %s: %d",
  77. led->name, ret);
  78. return ret;
  79. }
  80. priv->num_leds++;
  81. return 0;
  82. }
  83. static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
  84. {
  85. struct fwnode_handle *fwnode;
  86. struct led_pwm led;
  87. int ret = 0;
  88. memset(&led, 0, sizeof(led));
  89. device_for_each_child_node(dev, fwnode) {
  90. ret = fwnode_property_read_string(fwnode, "label", &led.name);
  91. if (ret && is_of_node(fwnode))
  92. led.name = to_of_node(fwnode)->name;
  93. if (!led.name) {
  94. fwnode_handle_put(fwnode);
  95. return -EINVAL;
  96. }
  97. led.active_low = fwnode_property_read_bool(fwnode,
  98. "active-low");
  99. fwnode_property_read_u32(fwnode, "max-brightness",
  100. &led.max_brightness);
  101. ret = led_pwm_add(dev, priv, &led, fwnode);
  102. if (ret) {
  103. fwnode_handle_put(fwnode);
  104. break;
  105. }
  106. }
  107. return ret;
  108. }
  109. static int led_pwm_probe(struct platform_device *pdev)
  110. {
  111. struct led_pwm_priv *priv;
  112. int ret = 0;
  113. int count;
  114. count = device_get_child_node_count(&pdev->dev);
  115. if (!count)
  116. return -EINVAL;
  117. priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
  118. GFP_KERNEL);
  119. if (!priv)
  120. return -ENOMEM;
  121. ret = led_pwm_create_fwnode(&pdev->dev, priv);
  122. if (ret)
  123. return ret;
  124. platform_set_drvdata(pdev, priv);
  125. return 0;
  126. }
  127. static const struct of_device_id of_pwm_leds_match[] = {
  128. { .compatible = "pwm-leds", },
  129. {},
  130. };
  131. MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
  132. static struct platform_driver led_pwm_driver = {
  133. .probe = led_pwm_probe,
  134. .driver = {
  135. .name = "leds_pwm",
  136. .of_match_table = of_pwm_leds_match,
  137. },
  138. };
  139. module_platform_driver(led_pwm_driver);
  140. MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
  141. MODULE_DESCRIPTION("generic PWM LED driver");
  142. MODULE_LICENSE("GPL v2");
  143. MODULE_ALIAS("platform:leds-pwm");