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/leds.h> 20 #include <linux/err.h> 21 #include <linux/pwm.h> 22 #include <linux/leds_pwm.h> 23 #include <linux/slab.h> 24 25 struct led_pwm_data { 26 struct led_classdev cdev; 27 struct pwm_device *pwm; 28 unsigned int active_low; 29 unsigned int period; 30 int duty; 31 }; 32 33 struct led_pwm_priv { 34 int num_leds; 35 struct led_pwm_data leds[0]; 36 }; 37 38 static void __led_pwm_set(struct led_pwm_data *led_dat) 39 { 40 int new_duty = led_dat->duty; 41 42 pwm_config(led_dat->pwm, new_duty, led_dat->period); 43 44 if (new_duty == 0) 45 pwm_disable(led_dat->pwm); 46 else 47 pwm_enable(led_dat->pwm); 48 } 49 50 static int led_pwm_set(struct led_classdev *led_cdev, 51 enum led_brightness brightness) 52 { 53 struct led_pwm_data *led_dat = 54 container_of(led_cdev, struct led_pwm_data, cdev); 55 unsigned int max = led_dat->cdev.max_brightness; 56 unsigned long long duty = led_dat->period; 57 58 duty *= brightness; 59 do_div(duty, max); 60 61 if (led_dat->active_low) 62 duty = led_dat->period - duty; 63 64 led_dat->duty = duty; 65 66 __led_pwm_set(led_dat); 67 68 return 0; 69 } 70 71 static inline size_t sizeof_pwm_leds_priv(int num_leds) 72 { 73 return sizeof(struct led_pwm_priv) + 74 (sizeof(struct led_pwm_data) * num_leds); 75 } 76 77 static void led_pwm_cleanup(struct led_pwm_priv *priv) 78 { 79 while (priv->num_leds--) 80 led_classdev_unregister(&priv->leds[priv->num_leds].cdev); 81 } 82 83 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 84 struct led_pwm *led, struct device_node *child) 85 { 86 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 87 struct pwm_args pargs; 88 int ret; 89 90 led_data->active_low = led->active_low; 91 led_data->cdev.name = led->name; 92 led_data->cdev.default_trigger = led->default_trigger; 93 led_data->cdev.brightness = LED_OFF; 94 led_data->cdev.max_brightness = led->max_brightness; 95 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 96 97 if (child) 98 led_data->pwm = devm_of_pwm_get(dev, child, NULL); 99 else 100 led_data->pwm = devm_pwm_get(dev, led->name); 101 if (IS_ERR(led_data->pwm)) { 102 ret = PTR_ERR(led_data->pwm); 103 dev_err(dev, "unable to request PWM for %s: %d\n", 104 led->name, ret); 105 return ret; 106 } 107 108 led_data->cdev.brightness_set_blocking = led_pwm_set; 109 110 /* 111 * FIXME: pwm_apply_args() should be removed when switching to the 112 * atomic PWM API. 113 */ 114 pwm_apply_args(led_data->pwm); 115 116 pwm_get_args(led_data->pwm, &pargs); 117 118 led_data->period = pargs.period; 119 if (!led_data->period && (led->pwm_period_ns > 0)) 120 led_data->period = led->pwm_period_ns; 121 122 ret = led_classdev_register(dev, &led_data->cdev); 123 if (ret == 0) { 124 priv->num_leds++; 125 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 126 } else { 127 dev_err(dev, "failed to register PWM led for %s: %d\n", 128 led->name, ret); 129 } 130 131 return ret; 132 } 133 134 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 135 { 136 struct device_node *child; 137 struct led_pwm led; 138 int ret = 0; 139 140 memset(&led, 0, sizeof(led)); 141 142 for_each_child_of_node(dev->of_node, child) { 143 led.name = of_get_property(child, "label", NULL) ? : 144 child->name; 145 146 led.default_trigger = of_get_property(child, 147 "linux,default-trigger", NULL); 148 led.active_low = of_property_read_bool(child, "active-low"); 149 of_property_read_u32(child, "max-brightness", 150 &led.max_brightness); 151 152 ret = led_pwm_add(dev, priv, &led, child); 153 if (ret) { 154 of_node_put(child); 155 break; 156 } 157 } 158 159 return ret; 160 } 161 162 static int led_pwm_probe(struct platform_device *pdev) 163 { 164 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 165 struct led_pwm_priv *priv; 166 int count, i; 167 int ret = 0; 168 169 if (pdata) 170 count = pdata->num_leds; 171 else 172 count = of_get_child_count(pdev->dev.of_node); 173 174 if (!count) 175 return -EINVAL; 176 177 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 178 GFP_KERNEL); 179 if (!priv) 180 return -ENOMEM; 181 182 if (pdata) { 183 for (i = 0; i < count; i++) { 184 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 185 NULL); 186 if (ret) 187 break; 188 } 189 } else { 190 ret = led_pwm_create_of(&pdev->dev, priv); 191 } 192 193 if (ret) { 194 led_pwm_cleanup(priv); 195 return ret; 196 } 197 198 platform_set_drvdata(pdev, priv); 199 200 return 0; 201 } 202 203 static int led_pwm_remove(struct platform_device *pdev) 204 { 205 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 206 207 led_pwm_cleanup(priv); 208 209 return 0; 210 } 211 212 static const struct of_device_id of_pwm_leds_match[] = { 213 { .compatible = "pwm-leds", }, 214 {}, 215 }; 216 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 217 218 static struct platform_driver led_pwm_driver = { 219 .probe = led_pwm_probe, 220 .remove = led_pwm_remove, 221 .driver = { 222 .name = "leds_pwm", 223 .of_match_table = of_pwm_leds_match, 224 }, 225 }; 226 227 module_platform_driver(led_pwm_driver); 228 229 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 230 MODULE_DESCRIPTION("generic PWM LED driver"); 231 MODULE_LICENSE("GPL v2"); 232 MODULE_ALIAS("platform:leds-pwm"); 233