| 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"); |