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 fwnode_handle *fwnode) 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 (fwnode) 89 led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, 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, to_of_node(fwnode), 115 &led_data->cdev); 116 if (ret == 0) { 117 priv->num_leds++; 118 led_pwm_set(&led_data->cdev, led_data->cdev.brightness); 119 } else { 120 dev_err(dev, "failed to register PWM led for %s: %d\n", 121 led->name, ret); 122 } 123 124 return ret; 125 } 126 127 static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) 128 { 129 struct fwnode_handle *fwnode; 130 struct led_pwm led; 131 int ret = 0; 132 133 memset(&led, 0, sizeof(led)); 134 135 device_for_each_child_node(dev, fwnode) { 136 ret = fwnode_property_read_string(fwnode, "label", &led.name); 137 if (ret && is_of_node(fwnode)) 138 led.name = to_of_node(fwnode)->name; 139 140 if (!led.name) { 141 fwnode_handle_put(fwnode); 142 return -EINVAL; 143 } 144 145 fwnode_property_read_string(fwnode, "linux,default-trigger", 146 &led.default_trigger); 147 148 led.active_low = fwnode_property_read_bool(fwnode, 149 "active-low"); 150 fwnode_property_read_u32(fwnode, "max-brightness", 151 &led.max_brightness); 152 153 ret = led_pwm_add(dev, priv, &led, fwnode); 154 if (ret) { 155 fwnode_handle_put(fwnode); 156 break; 157 } 158 } 159 160 return ret; 161 } 162 163 static int led_pwm_probe(struct platform_device *pdev) 164 { 165 struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev); 166 struct led_pwm_priv *priv; 167 int count, i; 168 int ret = 0; 169 170 if (pdata) 171 count = pdata->num_leds; 172 else 173 count = device_get_child_node_count(&pdev->dev); 174 175 if (!count) 176 return -EINVAL; 177 178 priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count), 179 GFP_KERNEL); 180 if (!priv) 181 return -ENOMEM; 182 183 if (pdata) { 184 for (i = 0; i < count; i++) { 185 ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i], 186 NULL); 187 if (ret) 188 break; 189 } 190 } else { 191 ret = led_pwm_create_fwnode(&pdev->dev, priv); 192 } 193 194 if (ret) 195 return ret; 196 197 platform_set_drvdata(pdev, priv); 198 199 return 0; 200 } 201 202 static const struct of_device_id of_pwm_leds_match[] = { 203 { .compatible = "pwm-leds", }, 204 {}, 205 }; 206 MODULE_DEVICE_TABLE(of, of_pwm_leds_match); 207 208 static struct platform_driver led_pwm_driver = { 209 .probe = led_pwm_probe, 210 .driver = { 211 .name = "leds_pwm", 212 .of_match_table = of_pwm_leds_match, 213 }, 214 }; 215 216 module_platform_driver(led_pwm_driver); 217 218 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>"); 219 MODULE_DESCRIPTION("generic PWM LED driver"); 220 MODULE_LICENSE("GPL v2"); 221 MODULE_ALIAS("platform:leds-pwm"); 222