1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org> 3 4 #include <linux/kernel.h> 5 #include <linux/platform_device.h> 6 #include <linux/leds.h> 7 #include <linux/delay.h> 8 #include <linux/gpio/consumer.h> 9 #include <linux/slab.h> 10 #include <linux/mod_devicetable.h> 11 #include <linux/module.h> 12 #include <linux/property.h> 13 14 #define LED_LT3593_NAME "lt3593" 15 16 struct lt3593_led_data { 17 struct led_classdev cdev; 18 struct gpio_desc *gpiod; 19 }; 20 21 static int lt3593_led_set(struct led_classdev *led_cdev, 22 enum led_brightness value) 23 { 24 struct lt3593_led_data *led_dat = 25 container_of(led_cdev, struct lt3593_led_data, cdev); 26 int pulses; 27 28 /* 29 * The LT3593 resets its internal current level register to the maximum 30 * level on the first falling edge on the control pin. Each following 31 * falling edge decreases the current level by 625uA. Up to 32 pulses 32 * can be sent, so the maximum power reduction is 20mA. 33 * After a timeout of 128us, the value is taken from the register and 34 * applied is to the output driver. 35 */ 36 37 if (value == 0) { 38 gpiod_set_value_cansleep(led_dat->gpiod, 0); 39 return 0; 40 } 41 42 pulses = 32 - (value * 32) / 255; 43 44 if (pulses == 0) { 45 gpiod_set_value_cansleep(led_dat->gpiod, 0); 46 mdelay(1); 47 gpiod_set_value_cansleep(led_dat->gpiod, 1); 48 return 0; 49 } 50 51 gpiod_set_value_cansleep(led_dat->gpiod, 1); 52 53 while (pulses--) { 54 gpiod_set_value_cansleep(led_dat->gpiod, 0); 55 udelay(1); 56 gpiod_set_value_cansleep(led_dat->gpiod, 1); 57 udelay(1); 58 } 59 60 return 0; 61 } 62 63 static int lt3593_led_probe(struct platform_device *pdev) 64 { 65 struct device *dev = &pdev->dev; 66 struct lt3593_led_data *led_data; 67 struct fwnode_handle *child; 68 int ret, state = LEDS_GPIO_DEFSTATE_OFF; 69 struct led_init_data init_data = {}; 70 const char *tmp; 71 72 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL); 73 if (!led_data) 74 return -ENOMEM; 75 76 if (device_get_child_node_count(dev) != 1) { 77 dev_err(dev, "Device must have exactly one LED sub-node."); 78 return -EINVAL; 79 } 80 81 led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0); 82 if (IS_ERR(led_data->gpiod)) 83 return PTR_ERR(led_data->gpiod); 84 85 child = device_get_next_child_node(dev, NULL); 86 87 if (!fwnode_property_read_string(child, "default-state", &tmp)) { 88 if (!strcmp(tmp, "on")) 89 state = LEDS_GPIO_DEFSTATE_ON; 90 } 91 92 led_data->cdev.brightness_set_blocking = lt3593_led_set; 93 led_data->cdev.brightness = state ? LED_FULL : LED_OFF; 94 95 init_data.fwnode = child; 96 init_data.devicename = LED_LT3593_NAME; 97 init_data.default_label = ":"; 98 99 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data); 100 fwnode_handle_put(child); 101 if (ret < 0) 102 return ret; 103 104 platform_set_drvdata(pdev, led_data); 105 106 return 0; 107 } 108 109 static const struct of_device_id of_lt3593_leds_match[] = { 110 { .compatible = "lltc,lt3593", }, 111 {}, 112 }; 113 MODULE_DEVICE_TABLE(of, of_lt3593_leds_match); 114 115 static struct platform_driver lt3593_led_driver = { 116 .probe = lt3593_led_probe, 117 .driver = { 118 .name = "leds-lt3593", 119 .of_match_table = of_lt3593_leds_match, 120 }, 121 }; 122 123 module_platform_driver(lt3593_led_driver); 124 125 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>"); 126 MODULE_DESCRIPTION("LED driver for LT3593 controllers"); 127 MODULE_LICENSE("GPL v2"); 128 MODULE_ALIAS("platform:leds-lt3593"); 129