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/slab.h> 20 21 struct led_pwm { 22 const char *name; 23 const char *default_trigger; 24 u8 active_low; 25 unsigned int max_brightness; 26 }; 27 28 struct led_pwm_platform_data { 29 int num_leds; 30 struct led_pwm *leds; 31 }; 32 33 struct led_pwm_data { 34 struct led_classdev cdev; 35 struct pwm_device *pwm; 36 struct pwm_state pwmstate; 37 unsigned int active_low; 38 }; 39 40 struct led_pwm_priv { 41 int num_leds; 42 struct led_pwm_data leds[]; 43 }; 44 45 static int led_pwm_set(struct led_classdev *led_cdev, 46 enum led_brightness brightness) 47 { 48 struct led_pwm_data *led_dat = 49 container_of(led_cdev, struct led_pwm_data, cdev); 50 unsigned int max = led_dat->cdev.max_brightness; 51 unsigned long long duty = led_dat->pwmstate.period; 52 53 duty *= brightness; 54 do_div(duty, max); 55 56 if (led_dat->active_low) 57 duty = led_dat->pwmstate.period - duty; 58 59 led_dat->pwmstate.duty_cycle = duty; 60 led_dat->pwmstate.enabled = duty > 0; 61 return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate); 62 } 63 64 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 65 struct led_pwm *led, struct fwnode_handle *fwnode) 66 { 67 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 68 int ret; 69 70 led_data->active_low = led->active_low; 71 led_data->cdev.name = led->name; 72 led_data->cdev.default_trigger = led->default_trigger; 73 led_data->cdev.brightness = LED_OFF; 74 led_data->cdev.max_brightness = led->max_brightness; 75 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 76 77 if (fwnode) 78 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL); 79 else 80 led_data->pwm = devm_pwm_get(dev, led->name); 81 if (IS_ERR(led_data->pwm)) { 82 ret = PTR_ERR(led_data->pwm); 83 if (ret != -EPROBE_DEFER) 84 dev_err(dev, "unable to request PWM for %s: %d\n", 85 led->name, ret); 86 return ret; 87 } 88 89 led_data->cdev.brightness_set_blocking = led_pwm_set; 90 91 pwm_init_state(led_data->pwm, &led_data->pwmstate); 92 93 ret = devm_led_classdev_register(dev, &led_data->cdev); 94 if (ret) { 95 dev_err(dev, "failed to register PWM led for %s: %d\n", 96 led->name, ret); 97 return ret; 98 } 99 100 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 101 if (ret) { 102 dev_err(dev, "failed to set led PWM value for %s: %d", 103 led->name, ret); 104 return ret; 105 } 106 107 priv->num_leds++; 108 return 0; 109 } 110 111 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) 112 { 113 struct fwnode_handle *fwnode; 114 struct led_pwm led; 115 int ret = 0; 116 117 memset(&led, 0, sizeof(led)); 118 119 device_for_each_child_node(dev, fwnode) { 120 ret = fwnode_property_read_string(fwnode, "label", &led.name); 121 if (ret && is_of_node(fwnode)) 122 led.name = to_of_node(fwnode)->name; 123 124 if (!led.name) { 125 fwnode_handle_put(fwnode); 126 return -EINVAL; 127 } 128 129 fwnode_property_read_string(fwnode, "linux,default-trigger", 130 &led.default_trigger); 131 132 led.active_low = fwnode_property_read_bool(fwnode, 133 "active-low"); 134 fwnode_property_read_u32(fwnode, "max-brightness", 135 &led.max_brightness); 136 137 ret = led_pwm_add(dev, priv, &led, fwnode); 138 if (ret) { 139 fwnode_handle_put(fwnode); 140 break; 141 } 142 } 143 144 return ret; 145 } 146 147 static int led_pwm_probe(struct platform_device *pdev) 148 { 149 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 150 struct led_pwm_priv *priv; 151 int count, i; 152 int ret = 0; 153 154 if (pdata) 155 count = pdata->num_leds; 156 else 157 count = device_get_child_node_count(&pdev->dev); 158 159 if (!count) 160 return -EINVAL; 161 162 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count), 163 GFP_KERNEL); 164 if (!priv) 165 return -ENOMEM; 166 167 if (pdata) { 168 for (i = 0; i < count; i++) { 169 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 170 NULL); 171 if (ret) 172 break; 173 } 174 } else { 175 ret = led_pwm_create_fwnode(&pdev->dev, priv); 176 } 177 178 if (ret) 179 return ret; 180 181 platform_set_drvdata(pdev, priv); 182 183 return 0; 184 } 185 186 static const struct of_device_id of_pwm_leds_match[] = { 187 { .compatible = "pwm-leds", }, 188 {}, 189 }; 190 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 191 192 static struct platform_driver led_pwm_driver = { 193 .probe = led_pwm_probe, 194 .driver = { 195 .name = "leds_pwm", 196 .of_match_table = of_pwm_leds_match, 197 }, 198 }; 199 200 module_platform_driver(led_pwm_driver); 201 202 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 203 MODULE_DESCRIPTION("generic PWM LED driver"); 204 MODULE_LICENSE("GPL v2"); 205 MODULE_ALIAS("platform:leds-pwm"); 206