1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/drivers/leds-pwm.c 4 * 5 * simple PWM based LED control 6 * 7 * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de) 8 * 9 * based on leds-gpio.c by Raphael Assenat <raph@8d.com> 10 */ 11 12 #include <linux/module.h> 13 #include <linux/kernel.h> 14 #include <linux/platform_device.h> 15 #include <linux/of_platform.h> 16 #include <linux/leds.h> 17 #include <linux/err.h> 18 #include <linux/pwm.h> 19 #include <linux/leds_pwm.h> 20 #include <linux/slab.h> 21 22 struct led_pwm_data { 23 struct led_classdev cdev; 24 struct pwm_device *pwm; 25 unsigned int active_low; 26 unsigned int period; 27 int duty; 28 }; 29 30 struct led_pwm_priv { 31 int num_leds; 32 struct led_pwm_data leds[0]; 33 }; 34 35 static void __led_pwm_set(struct led_pwm_data *led_dat) 36 { 37 int new_duty = led_dat->duty; 38 39 pwm_config(led_dat->pwm, new_duty, led_dat->period); 40 41 if (new_duty == 0) 42 pwm_disable(led_dat->pwm); 43 else 44 pwm_enable(led_dat->pwm); 45 } 46 47 static int led_pwm_set(struct led_classdev *led_cdev, 48 enum led_brightness brightness) 49 { 50 struct led_pwm_data *led_dat = 51 container_of(led_cdev, struct led_pwm_data, cdev); 52 unsigned int max = led_dat->cdev.max_brightness; 53 unsigned long long duty = led_dat->period; 54 55 duty *= brightness; 56 do_div(duty, max); 57 58 if (led_dat->active_low) 59 duty = led_dat->period - duty; 60 61 led_dat->duty = duty; 62 63 __led_pwm_set(led_dat); 64 65 return 0; 66 } 67 68 static inline size_t sizeof_pwm_leds_priv(int num_leds) 69 { 70 return sizeof(struct led_pwm_priv) + 71 (sizeof(struct led_pwm_data) * num_leds); 72 } 73 74 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 75 struct led_pwm *led, struct device_node *child) 76 { 77 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 78 struct pwm_args pargs; 79 int ret; 80 81 led_data->active_low = led->active_low; 82 led_data->cdev.name = led->name; 83 led_data->cdev.default_trigger = led->default_trigger; 84 led_data->cdev.brightness = LED_OFF; 85 led_data->cdev.max_brightness = led->max_brightness; 86 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 87 88 if (child) 89 led_data->pwm = devm_of_pwm_get(dev, child, NULL); 90 else 91 led_data->pwm = devm_pwm_get(dev, led->name); 92 if (IS_ERR(led_data->pwm)) { 93 ret = PTR_ERR(led_data->pwm); 94 if (ret != -EPROBE_DEFER) 95 dev_err(dev, "unable to request PWM for %s: %d\n", 96 led->name, ret); 97 return ret; 98 } 99 100 led_data->cdev.brightness_set_blocking = led_pwm_set; 101 102 /* 103 * FIXME: pwm_apply_args() should be removed when switching to the 104 * atomic PWM API. 105 */ 106 pwm_apply_args(led_data->pwm); 107 108 pwm_get_args(led_data->pwm, &pargs); 109 110 led_data->period = pargs.period; 111 if (!led_data->period && (led->pwm_period_ns > 0)) 112 led_data->period = led->pwm_period_ns; 113 114 ret = devm_of_led_classdev_register(dev, child, &led_data->cdev); 115 if (ret == 0) { 116 priv->num_leds++; 117 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 118 } else { 119 dev_err(dev, "failed to register PWM led for %s: %d\n", 120 led->name, ret); 121 } 122 123 return ret; 124 } 125 126 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv) 127 { 128 struct device_node *child; 129 struct led_pwm led; 130 int ret = 0; 131 132 memset(&led, 0, sizeof(led)); 133 134 for_each_child_of_node(dev->of_node, child) { 135 led.name = of_get_property(child, "label", NULL) ? : 136 child->name; 137 138 led.default_trigger = of_get_property(child, 139 "linux,default-trigger", NULL); 140 led.active_low = of_property_read_bool(child, "active-low"); 141 of_property_read_u32(child, "max-brightness", 142 &led.max_brightness); 143 144 ret = led_pwm_add(dev, priv, &led, child); 145 if (ret) { 146 of_node_put(child); 147 break; 148 } 149 } 150 151 return ret; 152 } 153 154 static int led_pwm_probe(struct platform_device *pdev) 155 { 156 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 157 struct led_pwm_priv *priv; 158 int count, i; 159 int ret = 0; 160 161 if (pdata) 162 count = pdata->num_leds; 163 else 164 count = of_get_child_count(pdev->dev.of_node); 165 166 if (!count) 167 return -EINVAL; 168 169 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 170 GFP_KERNEL); 171 if (!priv) 172 return -ENOMEM; 173 174 if (pdata) { 175 for (i = 0; i < count; i++) { 176 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 177 NULL); 178 if (ret) 179 break; 180 } 181 } else { 182 ret = led_pwm_create_of(&pdev->dev, priv); 183 } 184 185 if (ret) 186 return ret; 187 188 platform_set_drvdata(pdev, priv); 189 190 return 0; 191 } 192 193 static const struct of_device_id of_pwm_leds_match[] = { 194 { .compatible = "pwm-leds", }, 195 {}, 196 }; 197 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 198 199 static struct platform_driver led_pwm_driver = { 200 .probe = led_pwm_probe, 201 .driver = { 202 .name = "leds_pwm", 203 .of_match_table = of_pwm_leds_match, 204 }, 205 }; 206 207 module_platform_driver(led_pwm_driver); 208 209 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 210 MODULE_DESCRIPTION("generic PWM LED driver"); 211 MODULE_LICENSE("GPL v2"); 212 MODULE_ALIAS("platform:leds-pwm"); 213