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