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 led_data->can_sleep = pwm_can_sleep(led_data->pwm); 125 if (led_data->can_sleep) 126 INIT_WORK(&led_data->work, led_pwm_work); 127 128 led_data->period = pwm_get_period(led_data->pwm); 129 if (!led_data->period && (led->pwm_period_ns > 0)) 130 led_data->period = led->pwm_period_ns; 131 132 ret = led_classdev_register(dev, &led_data->cdev); 133 if (ret == 0) { 134 priv->num_leds++; 135 } else { 136 dev_err(dev, "failed to register PWM led for %s: %d\n", 137 led->name, ret); 138 } 139 140 return ret; 141 } 142 143 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 144 { 145 struct device_node *child; 146 struct led_pwm led; 147 int ret = 0; 148 149 memset(&led, 0, sizeof(led)); 150 151 for_each_child_of_node(dev->of_node, child) { 152 led.name = of_get_property(child, "label", NULL) ? : 153 child->name; 154 155 led.default_trigger = of_get_property(child, 156 "linux,default-trigger", NULL); 157 led.active_low = of_property_read_bool(child, "active-low"); 158 of_property_read_u32(child, "max-brightness", 159 &led.max_brightness); 160 161 ret = led_pwm_add(dev, priv, &led, child); 162 if (ret) { 163 of_node_put(child); 164 break; 165 } 166 } 167 168 return ret; 169 } 170 171 static int led_pwm_probe(struct platform_device *pdev) 172 { 173 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 174 struct led_pwm_priv *priv; 175 int count, i; 176 int ret = 0; 177 178 if (pdata) 179 count = pdata->num_leds; 180 else 181 count = of_get_child_count(pdev->dev.of_node); 182 183 if (!count) 184 return -EINVAL; 185 186 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 187 GFP_KERNEL); 188 if (!priv) 189 return -ENOMEM; 190 191 if (pdata) { 192 for (i = 0; i < count; i++) { 193 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 194 NULL); 195 if (ret) 196 break; 197 } 198 } else { 199 ret = led_pwm_create_of(&pdev->dev, priv); 200 } 201 202 if (ret) { 203 led_pwm_cleanup(priv); 204 return ret; 205 } 206 207 platform_set_drvdata(pdev, priv); 208 209 return 0; 210 } 211 212 static int led_pwm_remove(struct platform_device *pdev) 213 { 214 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 215 216 led_pwm_cleanup(priv); 217 218 return 0; 219 } 220 221 static const struct of_device_id of_pwm_leds_match[] = { 222 { .compatible = "pwm-leds", }, 223 {}, 224 }; 225 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 226 227 static struct platform_driver led_pwm_driver = { 228 .probe = led_pwm_probe, 229 .remove = led_pwm_remove, 230 .driver = { 231 .name = "leds_pwm", 232 .of_match_table = of_pwm_leds_match, 233 }, 234 }; 235 236 module_platform_driver(led_pwm_driver); 237 238 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 239 MODULE_DESCRIPTION("PWM LED driver for PXA"); 240 MODULE_LICENSE("GPL"); 241 MODULE_ALIAS("platform:leds-pwm"); 242