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/platform_device.h> 18 #include <linux/of_platform.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 #include <linux/workqueue.h> 26 27 struct led_pwm_data { 28 struct led_classdev cdev; 29 struct pwm_device *pwm; 30 struct work_struct work; 31 unsigned int active_low; 32 unsigned int period; 33 int duty; 34 bool can_sleep; 35 }; 36 37 struct led_pwm_priv { 38 int num_leds; 39 struct led_pwm_data leds[0]; 40 }; 41 42 static void __led_pwm_set(struct led_pwm_data *led_dat) 43 { 44 int new_duty = led_dat->duty; 45 46 pwm_config(led_dat->pwm, new_duty, led_dat->period); 47 48 if (new_duty == 0) 49 pwm_disable(led_dat->pwm); 50 else 51 pwm_enable(led_dat->pwm); 52 } 53 54 static void led_pwm_work(struct work_struct *work) 55 { 56 struct led_pwm_data *led_dat = 57 container_of(work, struct led_pwm_data, work); 58 59 __led_pwm_set(led_dat); 60 } 61 62 static void led_pwm_set(struct led_classdev *led_cdev, 63 enum led_brightness brightness) 64 { 65 struct led_pwm_data *led_dat = 66 container_of(led_cdev, struct led_pwm_data, cdev); 67 unsigned int max = led_dat->cdev.max_brightness; 68 unsigned long long duty = led_dat->period; 69 70 duty *= brightness; 71 do_div(duty, max); 72 73 if (led_dat->active_low) 74 duty = led_dat->period - duty; 75 76 led_dat->duty = duty; 77 78 if (led_dat->can_sleep) 79 schedule_work(&led_dat->work); 80 else 81 __led_pwm_set(led_dat); 82 } 83 84 static inline size_t sizeof_pwm_leds_priv(int num_leds) 85 { 86 return sizeof(struct led_pwm_priv) + 87 (sizeof(struct led_pwm_data) * num_leds); 88 } 89 90 static void led_pwm_cleanup(struct led_pwm_priv *priv) 91 { 92 while (priv->num_leds--) { 93 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 94 if (priv->leds[priv->num_leds].can_sleep) 95 cancel_work_sync(&priv->leds[priv->num_leds].work); 96 } 97 } 98 99 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 100 struct led_pwm *led, struct device_node *child) 101 { 102 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 103 int ret; 104 105 led_data->active_low = led->active_low; 106 led_data->cdev.name = led->name; 107 led_data->cdev.default_trigger = led->default_trigger; 108 led_data->cdev.brightness_set = led_pwm_set; 109 led_data->cdev.brightness = LED_OFF; 110 led_data->cdev.max_brightness = led->max_brightness; 111 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 112 113 if (child) 114 led_data->pwm = devm_of_pwm_get(dev, child, NULL); 115 else 116 led_data->pwm = devm_pwm_get(dev, led->name); 117 if (IS_ERR(led_data->pwm)) { 118 ret = PTR_ERR(led_data->pwm); 119 dev_err(dev, "unable to request PWM for %s: %d\n", 120 led->name, ret); 121 return ret; 122 } 123 124 if (child) 125 led_data->period = pwm_get_period(led_data->pwm); 126 127 led_data->can_sleep = pwm_can_sleep(led_data->pwm); 128 if (led_data->can_sleep) 129 INIT_WORK(&led_data->work, led_pwm_work); 130 131 led_data->period = pwm_get_period(led_data->pwm); 132 if (!led_data->period && (led->pwm_period_ns > 0)) 133 led_data->period = led->pwm_period_ns; 134 135 ret = led_classdev_register(dev, &led_data->cdev); 136 if (ret == 0) { 137 priv->num_leds++; 138 } else { 139 dev_err(dev, "failed to register PWM led for %s: %d\n", 140 led->name, ret); 141 } 142 143 return ret; 144 } 145 146 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 147 { 148 struct device_node *child; 149 struct led_pwm led; 150 int ret = 0; 151 152 memset(&led, 0, sizeof(led)); 153 154 for_each_child_of_node(dev->of_node, child) { 155 led.name = of_get_property(child, "label", NULL) ? : 156 child->name; 157 158 led.default_trigger = of_get_property(child, 159 "linux,default-trigger", NULL); 160 led.active_low = of_property_read_bool(child, "active-low"); 161 of_property_read_u32(child, "max-brightness", 162 &led.max_brightness); 163 164 ret = led_pwm_add(dev, priv, &led, child); 165 if (ret) { 166 of_node_put(child); 167 break; 168 } 169 } 170 171 return ret; 172 } 173 174 static int led_pwm_probe(struct platform_device *pdev) 175 { 176 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 177 struct led_pwm_priv *priv; 178 int count, i; 179 int ret = 0; 180 181 if (pdata) 182 count = pdata->num_leds; 183 else 184 count = of_get_child_count(pdev->dev.of_node); 185 186 if (!count) 187 return -EINVAL; 188 189 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 190 GFP_KERNEL); 191 if (!priv) 192 return -ENOMEM; 193 194 if (pdata) { 195 for (i = 0; i < count; i++) { 196 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 197 NULL); 198 if (ret) 199 break; 200 } 201 } else { 202 ret = led_pwm_create_of(&pdev->dev, priv); 203 } 204 205 if (ret) { 206 led_pwm_cleanup(priv); 207 return ret; 208 } 209 210 platform_set_drvdata(pdev, priv); 211 212 return 0; 213 } 214 215 static int led_pwm_remove(struct platform_device *pdev) 216 { 217 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 218 219 led_pwm_cleanup(priv); 220 221 return 0; 222 } 223 224 static const struct of_device_id of_pwm_leds_match[] = { 225 { .compatible = "pwm-leds", }, 226 {}, 227 }; 228 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 229 230 static struct platform_driver led_pwm_driver = { 231 .probe = led_pwm_probe, 232 .remove = led_pwm_remove, 233 .driver = { 234 .name = "leds_pwm", 235 .of_match_table = of_pwm_leds_match, 236 }, 237 }; 238 239 module_platform_driver(led_pwm_driver); 240 241 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 242 MODULE_DESCRIPTION("PWM LED driver for PXA"); 243 MODULE_LICENSE("GPL"); 244 MODULE_ALIAS("platform:leds-pwm"); 245