1 /* 2 * linux/drivers/leds-pwm.c 3 * 4 * simple PWM based LED control 5 * 6 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de) 7 * 8 * based on leds-gpio.c by Raphael Assenat <raph@8d.com> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 15 #include <linux/module.h> 16 #include <linux/kernel.h> 17 #include <linux/init.h> 18 #include <linux/platform_device.h> 19 #include <linux/fb.h> 20 #include <linux/leds.h> 21 #include <linux/err.h> 22 #include <linux/pwm.h> 23 #include <linux/leds_pwm.h> 24 #include <linux/slab.h> 25 26 struct led_pwm_data { 27 struct led_classdev cdev; 28 struct pwm_device *pwm; 29 unsigned int active_low; 30 unsigned int period; 31 }; 32 33 static void led_pwm_set(struct led_classdev *led_cdev, 34 enum led_brightness brightness) 35 { 36 struct led_pwm_data *led_dat = 37 container_of(led_cdev, struct led_pwm_data, cdev); 38 unsigned int max = led_dat->cdev.max_brightness; 39 unsigned int period = led_dat->period; 40 41 if (brightness == 0) { 42 pwm_config(led_dat->pwm, 0, period); 43 pwm_disable(led_dat->pwm); 44 } else { 45 pwm_config(led_dat->pwm, brightness * period / max, period); 46 pwm_enable(led_dat->pwm); 47 } 48 } 49 50 static int led_pwm_probe(struct platform_device *pdev) 51 { 52 struct led_pwm_platform_data *pdata = pdev->dev.platform_data; 53 struct led_pwm *cur_led; 54 struct led_pwm_data *leds_data, *led_dat; 55 int i, ret = 0; 56 57 if (!pdata) 58 return -EBUSY; 59 60 leds_data = devm_kzalloc(&pdev->dev, 61 sizeof(struct led_pwm_data) * pdata->num_leds, 62 GFP_KERNEL); 63 if (!leds_data) 64 return -ENOMEM; 65 66 for (i = 0; i < pdata->num_leds; i++) { 67 cur_led = &pdata->leds[i]; 68 led_dat = &leds_data[i]; 69 70 led_dat->pwm = pwm_request(cur_led->pwm_id, 71 cur_led->name); 72 if (IS_ERR(led_dat->pwm)) { 73 ret = PTR_ERR(led_dat->pwm); 74 dev_err(&pdev->dev, "unable to request PWM %d\n", 75 cur_led->pwm_id); 76 goto err; 77 } 78 79 led_dat->cdev.name = cur_led->name; 80 led_dat->cdev.default_trigger = cur_led->default_trigger; 81 led_dat->active_low = cur_led->active_low; 82 led_dat->period = cur_led->pwm_period_ns; 83 led_dat->cdev.brightness_set = led_pwm_set; 84 led_dat->cdev.brightness = LED_OFF; 85 led_dat->cdev.max_brightness = cur_led->max_brightness; 86 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 87 88 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 89 if (ret < 0) { 90 pwm_free(led_dat->pwm); 91 goto err; 92 } 93 } 94 95 platform_set_drvdata(pdev, leds_data); 96 97 return 0; 98 99 err: 100 if (i > 0) { 101 for (i = i - 1; i >= 0; i--) { 102 led_classdev_unregister(&leds_data[i].cdev); 103 pwm_free(leds_data[i].pwm); 104 } 105 } 106 107 return ret; 108 } 109 110 static int led_pwm_remove(struct platform_device *pdev) 111 { 112 int i; 113 struct led_pwm_platform_data *pdata = pdev->dev.platform_data; 114 struct led_pwm_data *leds_data; 115 116 leds_data = platform_get_drvdata(pdev); 117 118 for (i = 0; i < pdata->num_leds; i++) { 119 led_classdev_unregister(&leds_data[i].cdev); 120 pwm_free(leds_data[i].pwm); 121 } 122 123 return 0; 124 } 125 126 static struct platform_driver led_pwm_driver = { 127 .probe = led_pwm_probe, 128 .remove = led_pwm_remove, 129 .driver = { 130 .name = "leds_pwm", 131 .owner = THIS_MODULE, 132 }, 133 }; 134 135 module_platform_driver(led_pwm_driver); 136 137 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 138 MODULE_DESCRIPTION("PWM LED driver for PXA"); 139 MODULE_LICENSE("GPL"); 140 MODULE_ALIAS("platform:leds-pwm"); 141