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