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 26 struct led_pwm_data { 27 struct led_classdev cdev; 28 struct pwm_device *pwm; 29 unsigned int active_low; 30 unsigned int period; 31 int duty; 32 bool can_sleep; 33 }; 34 35 struct led_pwm_priv { 36 int num_leds; 37 struct led_pwm_data leds[0]; 38 }; 39 40 static void __led_pwm_set(struct led_pwm_data *led_dat) 41 { 42 int new_duty = led_dat->duty; 43 44 pwm_config(led_dat->pwm, new_duty, led_dat->period); 45 46 if (new_duty == 0) 47 pwm_disable(led_dat->pwm); 48 else 49 pwm_enable(led_dat->pwm); 50 } 51 52 static void led_pwm_set(struct led_classdev *led_cdev, 53 enum led_brightness brightness) 54 { 55 struct led_pwm_data *led_dat = 56 container_of(led_cdev, struct led_pwm_data, cdev); 57 unsigned int max = led_dat->cdev.max_brightness; 58 unsigned long long duty = led_dat->period; 59 60 duty *= brightness; 61 do_div(duty, max); 62 63 if (led_dat->active_low) 64 duty = led_dat->period - duty; 65 66 led_dat->duty = duty; 67 68 __led_pwm_set(led_dat); 69 } 70 71 static int led_pwm_set_blocking(struct led_classdev *led_cdev, 72 enum led_brightness brightness) 73 { 74 led_pwm_set(led_cdev, brightness); 75 return 0; 76 } 77 78 static inline size_t sizeof_pwm_leds_priv(int num_leds) 79 { 80 return sizeof(struct led_pwm_priv) + 81 (sizeof(struct led_pwm_data) * num_leds); 82 } 83 84 static void led_pwm_cleanup(struct led_pwm_priv *priv) 85 { 86 while (priv->num_leds--) 87 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 88 } 89 90 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 91 struct led_pwm *led, struct device_node *child) 92 { 93 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 94 struct pwm_args pargs; 95 int ret; 96 97 led_data->active_low = led->active_low; 98 led_data->cdev.name = led->name; 99 led_data->cdev.default_trigger = led->default_trigger; 100 led_data->cdev.brightness = LED_OFF; 101 led_data->cdev.max_brightness = led->max_brightness; 102 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 103 104 if (child) 105 led_data->pwm = devm_of_pwm_get(dev, child, NULL); 106 else 107 led_data->pwm = devm_pwm_get(dev, led->name); 108 if (IS_ERR(led_data->pwm)) { 109 ret = PTR_ERR(led_data->pwm); 110 dev_err(dev, "unable to request PWM for %s: %d\n", 111 led->name, ret); 112 return ret; 113 } 114 115 led_data->can_sleep = pwm_can_sleep(led_data->pwm); 116 if (!led_data->can_sleep) 117 led_data->cdev.brightness_set = led_pwm_set; 118 else 119 led_data->cdev.brightness_set_blocking = led_pwm_set_blocking; 120 121 /* 122 * FIXME: pwm_apply_args() should be removed when switching to the 123 * atomic PWM API. 124 */ 125 pwm_apply_args(led_data->pwm); 126 127 pwm_get_args(led_data->pwm, &pargs); 128 129 led_data->period = pargs.period; 130 if (!led_data->period && (led->pwm_period_ns > 0)) 131 led_data->period = led->pwm_period_ns; 132 133 ret = led_classdev_register(dev, &led_data->cdev); 134 if (ret == 0) { 135 priv->num_leds++; 136 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 137 } else { 138 dev_err(dev, "failed to register PWM led for %s: %d\n", 139 led->name, ret); 140 } 141 142 return ret; 143 } 144 145 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 146 { 147 struct device_node *child; 148 struct led_pwm led; 149 int ret = 0; 150 151 memset(&led, 0, sizeof(led)); 152 153 for_each_child_of_node(dev->of_node, child) { 154 led.name = of_get_property(child, "label", NULL) ? : 155 child->name; 156 157 led.default_trigger = of_get_property(child, 158 "linux,default-trigger", NULL); 159 led.active_low = of_property_read_bool(child, "active-low"); 160 of_property_read_u32(child, "max-brightness", 161 &led.max_brightness); 162 163 ret = led_pwm_add(dev, priv, &led, child); 164 if (ret) { 165 of_node_put(child); 166 break; 167 } 168 } 169 170 return ret; 171 } 172 173 static int led_pwm_probe(struct platform_device *pdev) 174 { 175 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 176 struct led_pwm_priv *priv; 177 int count, i; 178 int ret = 0; 179 180 if (pdata) 181 count = pdata->num_leds; 182 else 183 count = of_get_child_count(pdev->dev.of_node); 184 185 if (!count) 186 return -EINVAL; 187 188 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 189 GFP_KERNEL); 190 if (!priv) 191 return -ENOMEM; 192 193 if (pdata) { 194 for (i = 0; i < count; i++) { 195 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 196 NULL); 197 if (ret) 198 break; 199 } 200 } else { 201 ret = led_pwm_create_of(&pdev->dev, priv); 202 } 203 204 if (ret) { 205 led_pwm_cleanup(priv); 206 return ret; 207 } 208 209 platform_set_drvdata(pdev, priv); 210 211 return 0; 212 } 213 214 static int led_pwm_remove(struct platform_device *pdev) 215 { 216 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 217 218 led_pwm_cleanup(priv); 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 .of_match_table = of_pwm_leds_match, 235 }, 236 }; 237 238 module_platform_driver(led_pwm_driver); 239 240 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 241 MODULE_DESCRIPTION("generic PWM LED driver"); 242 MODULE_LICENSE("GPL v2"); 243 MODULE_ALIAS("platform:leds-pwm"); 244