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/of_platform.h> 20 #include <linux/fb.h> 21 #include <linux/leds.h> 22 #include <linux/err.h> 23 #include <linux/pwm.h> 24 #include <linux/leds_pwm.h> 25 #include <linux/slab.h> 26 27 struct led_pwm_data { 28 struct led_classdev cdev; 29 struct pwm_device *pwm; 30 unsigned int active_low; 31 unsigned int period; 32 }; 33 34 struct led_pwm_priv { 35 int num_leds; 36 struct led_pwm_data leds[0]; 37 }; 38 39 static void led_pwm_set(struct led_classdev *led_cdev, 40 enum led_brightness brightness) 41 { 42 struct led_pwm_data *led_dat = 43 container_of(led_cdev, struct led_pwm_data, cdev); 44 unsigned int max = led_dat->cdev.max_brightness; 45 unsigned int period = led_dat->period; 46 47 if (brightness == 0) { 48 pwm_config(led_dat->pwm, 0, period); 49 pwm_disable(led_dat->pwm); 50 } else { 51 pwm_config(led_dat->pwm, brightness * period / max, period); 52 pwm_enable(led_dat->pwm); 53 } 54 } 55 56 static inline size_t sizeof_pwm_leds_priv(int num_leds) 57 { 58 return sizeof(struct led_pwm_priv) + 59 (sizeof(struct led_pwm_data) * num_leds); 60 } 61 62 static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev) 63 { 64 struct device_node *node = pdev->dev.of_node; 65 struct device_node *child; 66 struct led_pwm_priv *priv; 67 int count, ret; 68 69 /* count LEDs in this device, so we know how much to allocate */ 70 count = of_get_child_count(node); 71 if (!count) 72 return NULL; 73 74 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 75 GFP_KERNEL); 76 if (!priv) 77 return NULL; 78 79 for_each_child_of_node(node, child) { 80 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds]; 81 82 led_dat->cdev.name = of_get_property(child, "label", 83 NULL) ? : child->name; 84 85 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL); 86 if (IS_ERR(led_dat->pwm)) { 87 dev_err(&pdev->dev, "unable to request PWM for %s\n", 88 led_dat->cdev.name); 89 goto err; 90 } 91 /* Get the period from PWM core when n*/ 92 led_dat->period = pwm_get_period(led_dat->pwm); 93 94 led_dat->cdev.default_trigger = of_get_property(child, 95 "linux,default-trigger", NULL); 96 of_property_read_u32(child, "max-brightness", 97 &led_dat->cdev.max_brightness); 98 99 led_dat->cdev.brightness_set = led_pwm_set; 100 led_dat->cdev.brightness = LED_OFF; 101 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 102 103 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 104 if (ret < 0) { 105 dev_err(&pdev->dev, "failed to register for %s\n", 106 led_dat->cdev.name); 107 of_node_put(child); 108 goto err; 109 } 110 priv->num_leds++; 111 } 112 113 return priv; 114 err: 115 while (priv->num_leds--) 116 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 117 118 return NULL; 119 } 120 121 static int led_pwm_probe(struct platform_device *pdev) 122 { 123 struct led_pwm_platform_data *pdata = pdev->dev.platform_data; 124 struct led_pwm_priv *priv; 125 int i, ret = 0; 126 127 if (pdata && pdata->num_leds) { 128 priv = devm_kzalloc(&pdev->dev, 129 sizeof_pwm_leds_priv(pdata->num_leds), 130 GFP_KERNEL); 131 if (!priv) 132 return -ENOMEM; 133 134 for (i = 0; i < pdata->num_leds; i++) { 135 struct led_pwm *cur_led = &pdata->leds[i]; 136 struct led_pwm_data *led_dat = &priv->leds[i]; 137 138 led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name); 139 if (IS_ERR(led_dat->pwm)) { 140 ret = PTR_ERR(led_dat->pwm); 141 dev_err(&pdev->dev, 142 "unable to request PWM for %s\n", 143 cur_led->name); 144 goto err; 145 } 146 147 led_dat->cdev.name = cur_led->name; 148 led_dat->cdev.default_trigger = cur_led->default_trigger; 149 led_dat->active_low = cur_led->active_low; 150 led_dat->period = cur_led->pwm_period_ns; 151 led_dat->cdev.brightness_set = led_pwm_set; 152 led_dat->cdev.brightness = LED_OFF; 153 led_dat->cdev.max_brightness = cur_led->max_brightness; 154 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 155 156 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 157 if (ret < 0) 158 goto err; 159 } 160 priv->num_leds = pdata->num_leds; 161 } else { 162 priv = led_pwm_create_of(pdev); 163 if (!priv) 164 return -ENODEV; 165 } 166 167 platform_set_drvdata(pdev, priv); 168 169 return 0; 170 171 err: 172 while (i--) 173 led_classdev_unregister(&priv->leds[i].cdev); 174 175 return ret; 176 } 177 178 static int led_pwm_remove(struct platform_device *pdev) 179 { 180 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 181 int i; 182 183 for (i = 0; i < priv->num_leds; i++) 184 led_classdev_unregister(&priv->leds[i].cdev); 185 186 return 0; 187 } 188 189 static const struct of_device_id of_pwm_leds_match[] = { 190 { .compatible = "pwm-leds", }, 191 {}, 192 }; 193 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 194 195 static struct platform_driver led_pwm_driver = { 196 .probe = led_pwm_probe, 197 .remove = led_pwm_remove, 198 .driver = { 199 .name = "leds_pwm", 200 .owner = THIS_MODULE, 201 .of_match_table = of_match_ptr(of_pwm_leds_match), 202 }, 203 }; 204 205 module_platform_driver(led_pwm_driver); 206 207 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 208 MODULE_DESCRIPTION("PWM LED driver for PXA"); 209 MODULE_LICENSE("GPL"); 210 MODULE_ALIAS("platform:leds-pwm"); 211