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 #include "leds.h" 21 22 struct led_pwm { 23 const char *name; 24 u8 active_low; 25 u8 default_state; 26 unsigned int max_brightness; 27 }; 28 29 struct led_pwm_data { 30 struct led_classdev cdev; 31 struct pwm_device *pwm; 32 struct pwm_state pwmstate; 33 unsigned int active_low; 34 }; 35 36 struct led_pwm_priv { 37 int num_leds; 38 struct led_pwm_data leds[]; 39 }; 40 41 static int led_pwm_set(struct led_classdev *led_cdev, 42 enum led_brightness brightness) 43 { 44 struct led_pwm_data *led_dat = 45 container_of(led_cdev, struct led_pwm_data, cdev); 46 unsigned int max = led_dat->cdev.max_brightness; 47 unsigned long long duty = led_dat->pwmstate.period; 48 49 duty *= brightness; 50 do_div(duty, max); 51 52 if (led_dat->active_low) 53 duty = led_dat->pwmstate.period - duty; 54 55 led_dat->pwmstate.duty_cycle = duty; 56 led_dat->pwmstate.enabled = duty > 0; 57 return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate); 58 } 59 60 __attribute__((nonnull)) 61 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 62 struct led_pwm *led, struct fwnode_handle *fwnode) 63 { 64 struct led_pwm_data *led_data = &priv->leds[priv->num_leds]; 65 struct led_init_data init_data = { .fwnode = fwnode }; 66 int ret; 67 68 led_data->active_low = led->active_low; 69 led_data->cdev.name = led->name; 70 led_data->cdev.brightness = LED_OFF; 71 led_data->cdev.max_brightness = led->max_brightness; 72 led_data->cdev.flags = LED_CORE_SUSPENDRESUME; 73 74 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL); 75 if (IS_ERR(led_data->pwm)) 76 return dev_err_probe(dev, PTR_ERR(led_data->pwm), 77 "unable to request PWM for %s\n", 78 led->name); 79 80 led_data->cdev.brightness_set_blocking = led_pwm_set; 81 82 /* init PWM state */ 83 switch (led->default_state) { 84 case LEDS_DEFSTATE_KEEP: 85 pwm_get_state(led_data->pwm, &led_data->pwmstate); 86 if (led_data->pwmstate.period) 87 break; 88 led->default_state = LEDS_DEFSTATE_OFF; 89 dev_warn(dev, 90 "failed to read period for %s, default to off", 91 led->name); 92 fallthrough; 93 default: 94 pwm_init_state(led_data->pwm, &led_data->pwmstate); 95 break; 96 } 97 98 /* set brightness */ 99 switch (led->default_state) { 100 case LEDS_DEFSTATE_ON: 101 led_data->cdev.brightness = led->max_brightness; 102 break; 103 case LEDS_DEFSTATE_KEEP: 104 { 105 uint64_t brightness; 106 107 brightness = led->max_brightness; 108 brightness *= led_data->pwmstate.duty_cycle; 109 do_div(brightness, led_data->pwmstate.period); 110 led_data->cdev.brightness = brightness; 111 } 112 break; 113 } 114 115 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data); 116 if (ret) { 117 dev_err(dev, "failed to register PWM led for %s: %d\n", 118 led->name, ret); 119 return ret; 120 } 121 122 if (led->default_state != LEDS_DEFSTATE_KEEP) { 123 ret = led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 124 if (ret) { 125 dev_err(dev, "failed to set led PWM value for %s: %d", 126 led->name, ret); 127 return ret; 128 } 129 } 130 131 priv->num_leds++; 132 return 0; 133 } 134 135 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) 136 { 137 struct fwnode_handle *fwnode; 138 struct led_pwm led; 139 int ret; 140 141 memset(&led, 0, sizeof(led)); 142 143 device_for_each_child_node(dev, fwnode) { 144 ret = fwnode_property_read_string(fwnode, "label", &led.name); 145 if (ret && is_of_node(fwnode)) 146 led.name = to_of_node(fwnode)->name; 147 148 if (!led.name) { 149 ret = EINVAL; 150 goto err_child_out; 151 } 152 153 led.active_low = fwnode_property_read_bool(fwnode, 154 "active-low"); 155 fwnode_property_read_u32(fwnode, "max-brightness", 156 &led.max_brightness); 157 158 led.default_state = led_init_default_state_get(fwnode); 159 160 ret = led_pwm_add(dev, priv, &led, fwnode); 161 if (ret) 162 goto err_child_out; 163 } 164 165 return 0; 166 167 err_child_out: 168 fwnode_handle_put(fwnode); 169 return ret; 170 } 171 172 static int led_pwm_probe(struct platform_device *pdev) 173 { 174 struct led_pwm_priv *priv; 175 int ret = 0; 176 int count; 177 178 count = device_get_child_node_count(&pdev->dev); 179 180 if (!count) 181 return -EINVAL; 182 183 priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count), 184 GFP_KERNEL); 185 if (!priv) 186 return -ENOMEM; 187 188 ret = led_pwm_create_fwnode(&pdev->dev, priv); 189 190 if (ret) 191 return ret; 192 193 platform_set_drvdata(pdev, priv); 194 195 return 0; 196 } 197 198 static const struct of_device_id of_pwm_leds_match[] = { 199 { .compatible = "pwm-leds", }, 200 {}, 201 }; 202 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 203 204 static struct platform_driver led_pwm_driver = { 205 .probe = led_pwm_probe, 206 .driver = { 207 .name = "leds_pwm", 208 .of_match_table = of_pwm_leds_match, 209 }, 210 }; 211 212 module_platform_driver(led_pwm_driver); 213 214 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 215 MODULE_DESCRIPTION("generic PWM LED driver"); 216 MODULE_LICENSE("GPL v2"); 217 MODULE_ALIAS("platform:leds-pwm"); 218