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 int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 69 struct led_pwm *led, struct fwnode_handle *fwnode) 70 { 71 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 72 struct pwm_args pargs; 73 int ret; 74 75 led_data->active_low = led->active_low; 76 led_data->cdev.name = led->name; 77 led_data->cdev.default_trigger = led->default_trigger; 78 led_data->cdev.brightness = LED_OFF; 79 led_data->cdev.max_brightness = led->max_brightness; 80 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 81 82 if (fwnode) 83 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL); 84 else 85 led_data->pwm = devm_pwm_get(dev, led->name); 86 if (IS_ERR(led_data->pwm)) { 87 ret = PTR_ERR(led_data->pwm); 88 if (ret != -EPROBE_DEFER) 89 dev_err(dev, "unable to request PWM for %s: %d\n", 90 led->name, ret); 91 return ret; 92 } 93 94 led_data->cdev.brightness_set_blocking = led_pwm_set; 95 96 /* 97 * FIXME: pwm_apply_args() should be removed when switching to the 98 * atomic PWM API. 99 */ 100 pwm_apply_args(led_data->pwm); 101 102 pwm_get_args(led_data->pwm, &pargs); 103 104 led_data->period = pargs.period; 105 if (!led_data->period && (led->pwm_period_ns > 0)) 106 led_data->period = led->pwm_period_ns; 107 108 ret = devm_led_classdev_register(dev, &led_data->cdev); 109 if (ret == 0) { 110 priv->num_leds++; 111 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 112 } else { 113 dev_err(dev, "failed to register PWM led for %s: %d\n", 114 led->name, ret); 115 } 116 117 return ret; 118 } 119 120 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) 121 { 122 struct fwnode_handle *fwnode; 123 struct led_pwm led; 124 int ret = 0; 125 126 memset(&led, 0, sizeof(led)); 127 128 device_for_each_child_node(dev, fwnode) { 129 ret = fwnode_property_read_string(fwnode, "label", &led.name); 130 if (ret && is_of_node(fwnode)) 131 led.name = to_of_node(fwnode)->name; 132 133 if (!led.name) { 134 fwnode_handle_put(fwnode); 135 return -EINVAL; 136 } 137 138 fwnode_property_read_string(fwnode, "linux,default-trigger", 139 &led.default_trigger); 140 141 led.active_low = fwnode_property_read_bool(fwnode, 142 "active-low"); 143 fwnode_property_read_u32(fwnode, "max-brightness", 144 &led.max_brightness); 145 146 ret = led_pwm_add(dev, priv, &led, fwnode); 147 if (ret) { 148 fwnode_handle_put(fwnode); 149 break; 150 } 151 } 152 153 return ret; 154 } 155 156 static int led_pwm_probe(struct platform_device *pdev) 157 { 158 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 159 struct led_pwm_priv *priv; 160 int count, i; 161 int ret = 0; 162 163 if (pdata) 164 count = pdata->num_leds; 165 else 166 count = device_get_child_node_count(&pdev->dev); 167 168 if (!count) 169 return -EINVAL; 170 171 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count), 172 GFP_KERNEL); 173 if (!priv) 174 return -ENOMEM; 175 176 if (pdata) { 177 for (i = 0; i < count; i++) { 178 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 179 NULL); 180 if (ret) 181 break; 182 } 183 } else { 184 ret = led_pwm_create_fwnode(&pdev->dev, priv); 185 } 186 187 if (ret) 188 return ret; 189 190 platform_set_drvdata(pdev, priv); 191 192 return 0; 193 } 194 195 static const struct of_device_id of_pwm_leds_match[] = { 196 { .compatible = "pwm-leds", }, 197 {}, 198 }; 199 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 200 201 static struct platform_driver led_pwm_driver = { 202 .probe = led_pwm_probe, 203 .driver = { 204 .name = "leds_pwm", 205 .of_match_table = of_pwm_leds_match, 206 }, 207 }; 208 209 module_platform_driver(led_pwm_driver); 210 211 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 212 MODULE_DESCRIPTION("generic PWM LED driver"); 213 MODULE_LICENSE("GPL v2"); 214 MODULE_ALIAS("platform:leds-pwm"); 215