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 led_dat->duty = duty; 73 74 if (led_dat->can_sleep) 75 schedule_work(&led_dat->work); 76 else 77 __led_pwm_set(led_dat); 78 } 79 80 static inline size_t sizeof_pwm_leds_priv(int num_leds) 81 { 82 return sizeof(struct led_pwm_priv) + 83 (sizeof(struct led_pwm_data) * num_leds); 84 } 85 86 static void led_pwm_cleanup(struct led_pwm_priv *priv) 87 { 88 while (priv->num_leds--) { 89 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 90 if (priv->leds[priv->num_leds].can_sleep) 91 cancel_work_sync(&priv->leds[priv->num_leds].work); 92 } 93 } 94 95 static int led_pwm_create_of(struct platform_device *pdev, 96 struct led_pwm_priv *priv) 97 { 98 struct device_node *child; 99 int ret; 100 101 for_each_child_of_node(pdev->dev.of_node, child) { 102 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds]; 103 104 led_dat->cdev.name = of_get_property(child, "label", 105 NULL) ? : child->name; 106 107 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL); 108 if (IS_ERR(led_dat->pwm)) { 109 dev_err(&pdev->dev, "unable to request PWM for %s\n", 110 led_dat->cdev.name); 111 ret = PTR_ERR(led_dat->pwm); 112 goto err; 113 } 114 /* Get the period from PWM core when n*/ 115 led_dat->period = pwm_get_period(led_dat->pwm); 116 117 led_dat->cdev.default_trigger = of_get_property(child, 118 "linux,default-trigger", NULL); 119 of_property_read_u32(child, "max-brightness", 120 &led_dat->cdev.max_brightness); 121 122 led_dat->cdev.brightness_set = led_pwm_set; 123 led_dat->cdev.brightness = LED_OFF; 124 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 125 126 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm); 127 if (led_dat->can_sleep) 128 INIT_WORK(&led_dat->work, led_pwm_work); 129 130 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 131 if (ret < 0) { 132 dev_err(&pdev->dev, "failed to register for %s\n", 133 led_dat->cdev.name); 134 of_node_put(child); 135 goto err; 136 } 137 priv->num_leds++; 138 } 139 140 return 0; 141 err: 142 led_pwm_cleanup(priv); 143 144 return ret; 145 } 146 147 static int led_pwm_probe(struct platform_device *pdev) 148 { 149 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 150 struct led_pwm_priv *priv; 151 int count, i; 152 int ret = 0; 153 154 if (pdata) 155 count = pdata->num_leds; 156 else 157 count = of_get_child_count(pdev->dev.of_node); 158 159 if (!count) 160 return -EINVAL; 161 162 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 163 GFP_KERNEL); 164 if (!priv) 165 return -ENOMEM; 166 167 if (pdata) { 168 for (i = 0; i < count; i++) { 169 struct led_pwm *cur_led = &pdata->leds[i]; 170 struct led_pwm_data *led_dat = &priv->leds[i]; 171 172 led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name); 173 if (IS_ERR(led_dat->pwm)) { 174 ret = PTR_ERR(led_dat->pwm); 175 dev_err(&pdev->dev, 176 "unable to request PWM for %s\n", 177 cur_led->name); 178 goto err; 179 } 180 181 led_dat->cdev.name = cur_led->name; 182 led_dat->cdev.default_trigger = cur_led->default_trigger; 183 led_dat->active_low = cur_led->active_low; 184 led_dat->period = cur_led->pwm_period_ns; 185 led_dat->cdev.brightness_set = led_pwm_set; 186 led_dat->cdev.brightness = LED_OFF; 187 led_dat->cdev.max_brightness = cur_led->max_brightness; 188 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 189 190 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm); 191 if (led_dat->can_sleep) 192 INIT_WORK(&led_dat->work, led_pwm_work); 193 194 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 195 if (ret < 0) 196 goto err; 197 } 198 priv->num_leds = count; 199 } else { 200 ret = led_pwm_create_of(pdev, priv); 201 if (ret) 202 return ret; 203 } 204 205 platform_set_drvdata(pdev, priv); 206 207 return 0; 208 209 err: 210 priv->num_leds = i; 211 led_pwm_cleanup(priv); 212 213 return ret; 214 } 215 216 static int led_pwm_remove(struct platform_device *pdev) 217 { 218 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 219 220 led_pwm_cleanup(priv); 221 222 return 0; 223 } 224 225 static const struct of_device_id of_pwm_leds_match[] = { 226 { .compatible = "pwm-leds", }, 227 {}, 228 }; 229 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 230 231 static struct platform_driver led_pwm_driver = { 232 .probe = led_pwm_probe, 233 .remove = led_pwm_remove, 234 .driver = { 235 .name = "leds_pwm", 236 .owner = THIS_MODULE, 237 .of_match_table = of_pwm_leds_match, 238 }, 239 }; 240 241 module_platform_driver(led_pwm_driver); 242 243 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 244 MODULE_DESCRIPTION("PWM LED driver for PXA"); 245 MODULE_LICENSE("GPL"); 246 MODULE_ALIAS("platform:leds-pwm"); 247