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 if (ret != -EPROBE_DEFER) 104 dev_err(dev, "unable to request PWM for %s: %d\n", 105 led->name, ret); 106 return ret; 107 } 108 109 led_data->cdev.brightness_set_blocking = led_pwm_set; 110 111 /* 112 * FIXME: pwm_apply_args() should be removed when switching to the 113 * atomic PWM API. 114 */ 115 pwm_apply_args(led_data->pwm); 116 117 pwm_get_args(led_data->pwm, &pargs); 118 119 led_data->period = pargs.period; 120 if (!led_data->period && (led->pwm_period_ns > 0)) 121 led_data->period = led->pwm_period_ns; 122 123 ret = led_classdev_register(dev, &led_data->cdev); 124 if (ret == 0) { 125 priv->num_leds++; 126 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 127 } else { 128 dev_err(dev, "failed to register PWM led for %s: %d\n", 129 led->name, ret); 130 } 131 132 return ret; 133 } 134 135 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 136 { 137 struct device_node *child; 138 struct led_pwm led; 139 int ret = 0; 140 141 memset(&led, 0, sizeof(led)); 142 143 for_each_child_of_node(dev->of_node, child) { 144 led.name = of_get_property(child, "label", NULL) ? : 145 child->name; 146 147 led.default_trigger = of_get_property(child, 148 "linux,default-trigger", NULL); 149 led.active_low = of_property_read_bool(child, "active-low"); 150 of_property_read_u32(child, "max-brightness", 151 &led.max_brightness); 152 153 ret = led_pwm_add(dev, priv, &led, child); 154 if (ret) { 155 of_node_put(child); 156 break; 157 } 158 } 159 160 return ret; 161 } 162 163 static int led_pwm_probe(struct platform_device *pdev) 164 { 165 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 166 struct led_pwm_priv *priv; 167 int count, i; 168 int ret = 0; 169 170 if (pdata) 171 count = pdata->num_leds; 172 else 173 count = of_get_child_count(pdev->dev.of_node); 174 175 if (!count) 176 return -EINVAL; 177 178 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 179 GFP_KERNEL); 180 if (!priv) 181 return -ENOMEM; 182 183 if (pdata) { 184 for (i = 0; i < count; i++) { 185 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 186 NULL); 187 if (ret) 188 break; 189 } 190 } else { 191 ret = led_pwm_create_of(&pdev->dev, priv); 192 } 193 194 if (ret) { 195 led_pwm_cleanup(priv); 196 return ret; 197 } 198 199 platform_set_drvdata(pdev, priv); 200 201 return 0; 202 } 203 204 static int led_pwm_remove(struct platform_device *pdev) 205 { 206 struct led_pwm_priv *priv = platform_get_drvdata(pdev); 207 208 led_pwm_cleanup(priv); 209 210 return 0; 211 } 212 213 static const struct of_device_id of_pwm_leds_match[] = { 214 { .compatible = "pwm-leds", }, 215 {}, 216 }; 217 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 218 219 static struct platform_driver led_pwm_driver = { 220 .probe = led_pwm_probe, 221 .remove = led_pwm_remove, 222 .driver = { 223 .name = "leds_pwm", 224 .of_match_table = of_pwm_leds_match, 225 }, 226 }; 227 228 module_platform_driver(led_pwm_driver); 229 230 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 231 MODULE_DESCRIPTION("generic PWM LED driver"); 232 MODULE_LICENSE("GPL v2"); 233 MODULE_ALIAS("platform:leds-pwm"); 234