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 #include <linux/workqueue.h> 27 28 struct led_pwm_data { 29 struct led_classdev cdev; 30 struct pwm_device *pwm; 31 struct work_struct work; 32 unsigned int active_low; 33 unsigned int period; 34 int duty; 35 bool can_sleep; 36 }; 37 38 struct led_pwm_priv { 39 int num_leds; 40 struct led_pwm_data leds[0]; 41 }; 42 43 static void __led_pwm_set(struct led_pwm_data *led_dat) 44 { 45 int new_duty = led_dat->duty; 46 47 pwm_config(led_dat->pwm, new_duty, led_dat->period); 48 49 if (new_duty == 0) 50 pwm_disable(led_dat->pwm); 51 else 52 pwm_enable(led_dat->pwm); 53 } 54 55 static void led_pwm_work(struct work_struct *work) 56 { 57 struct led_pwm_data *led_dat = 58 container_of(work, struct led_pwm_data, work); 59 60 __led_pwm_set(led_dat); 61 } 62 63 static void led_pwm_set(struct led_classdev *led_cdev, 64 enum led_brightness brightness) 65 { 66 struct led_pwm_data *led_dat = 67 container_of(led_cdev, struct led_pwm_data, cdev); 68 unsigned int max = led_dat->cdev.max_brightness; 69 unsigned int period = led_dat->period; 70 71 led_dat->duty = brightness * period / max; 72 73 if (led_dat->can_sleep) 74 schedule_work(&led_dat->work); 75 else 76 __led_pwm_set(led_dat); 77 } 78 79 static inline size_t sizeof_pwm_leds_priv(int num_leds) 80 { 81 return sizeof(struct led_pwm_priv) + 82 (sizeof(struct led_pwm_data) * num_leds); 83 } 84 85 static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev) 86 { 87 struct device_node *node = pdev->dev.of_node; 88 struct device_node *child; 89 struct led_pwm_priv *priv; 90 int count, ret; 91 92 /* count LEDs in this device, so we know how much to allocate */ 93 count = of_get_child_count(node); 94 if (!count) 95 return NULL; 96 97 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 98 GFP_KERNEL); 99 if (!priv) 100 return NULL; 101 102 for_each_child_of_node(node, child) { 103 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds]; 104 105 led_dat->cdev.name = of_get_property(child, "label", 106 NULL) ? : child->name; 107 108 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL); 109 if (IS_ERR(led_dat->pwm)) { 110 dev_err(&pdev->dev, "unable to request PWM for %s\n", 111 led_dat->cdev.name); 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 priv; 141 err: 142 while (priv->num_leds--) 143 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 144 145 return NULL; 146 } 147 148 static int led_pwm_probe(struct platform_device *pdev) 149 { 150 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 151 struct led_pwm_priv *priv; 152 int i, ret = 0; 153 154 if (pdata && pdata->num_leds) { 155 priv = devm_kzalloc(&pdev->dev, 156 sizeof_pwm_leds_priv(pdata->num_leds), 157 GFP_KERNEL); 158 if (!priv) 159 return -ENOMEM; 160 161 for (i = 0; i < pdata->num_leds; i++) { 162 struct led_pwm *cur_led = &pdata->leds[i]; 163 struct led_pwm_data *led_dat = &priv->leds[i]; 164 165 led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name); 166 if (IS_ERR(led_dat->pwm)) { 167 ret = PTR_ERR(led_dat->pwm); 168 dev_err(&pdev->dev, 169 "unable to request PWM for %s\n", 170 cur_led->name); 171 goto err; 172 } 173 174 led_dat->cdev.name = cur_led->name; 175 led_dat->cdev.default_trigger = cur_led->default_trigger; 176 led_dat->active_low = cur_led->active_low; 177 led_dat->period = cur_led->pwm_period_ns; 178 led_dat->cdev.brightness_set = led_pwm_set; 179 led_dat->cdev.brightness = LED_OFF; 180 led_dat->cdev.max_brightness = cur_led->max_brightness; 181 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; 182 183 led_dat->can_sleep = pwm_can_sleep(led_dat->pwm); 184 if (led_dat->can_sleep) 185 INIT_WORK(&led_dat->work, led_pwm_work); 186 187 ret = led_classdev_register(&pdev->dev, &led_dat->cdev); 188 if (ret < 0) 189 goto err; 190 } 191 priv->num_leds = pdata->num_leds; 192 } else { 193 priv = led_pwm_create_of(pdev); 194 if (!priv) 195 return -ENODEV; 196 } 197 198 platform_set_drvdata(pdev, priv); 199 200 return 0; 201 202 err: 203 while (i--) 204 led_classdev_unregister(&priv->leds[i].cdev); 205 206 return ret; 207 } 208 209 static int led_pwm_remove(struct platform_device *pdev) 210 { 211 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 212 int i; 213 214 for (i = 0; i < priv->num_leds; i++) { 215 led_classdev_unregister(&priv->leds[i].cdev); 216 if (priv->leds[i].can_sleep) 217 cancel_work_sync(&priv->leds[i].work); 218 } 219 220 return 0; 221 } 222 223 static const struct of_device_id of_pwm_leds_match[] = { 224 { .compatible = "pwm-leds", }, 225 {}, 226 }; 227 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 228 229 static struct platform_driver led_pwm_driver = { 230 .probe = led_pwm_probe, 231 .remove = led_pwm_remove, 232 .driver = { 233 .name = "leds_pwm", 234 .owner = THIS_MODULE, 235 .of_match_table = of_match_ptr(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