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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Datasheet:4 * https://www.kinet-ic.com/uploads/web/KTD2801/KTD2801-04b.pdf5 */6#include <linux/backlight.h>7#include <linux/gpio/consumer.h>8#include <linux/leds-expresswire.h>9#include <linux/platform_device.h>10#include <linux/property.h>11 12#define KTD2801_DEFAULT_BRIGHTNESS 10013#define KTD2801_MAX_BRIGHTNESS 25514 15/* These values have been extracted from Samsung's driver. */16static const struct expresswire_timing ktd2801_timing = {17 .poweroff_us = 2600,18 .detect_delay_us = 150,19 .detect_us = 270,20 .data_start_us = 5,21 .short_bitset_us = 5,22 .long_bitset_us = 15,23 .end_of_data_low_us = 10,24 .end_of_data_high_us = 35025};26 27struct ktd2801_backlight {28 struct expresswire_common_props props;29 struct backlight_device *bd;30 bool was_on;31};32 33static int ktd2801_update_status(struct backlight_device *bd)34{35 struct ktd2801_backlight *ktd2801 = bl_get_data(bd);36 u8 brightness = (u8) backlight_get_brightness(bd);37 38 if (backlight_is_blank(bd)) {39 expresswire_power_off(&ktd2801->props);40 ktd2801->was_on = false;41 return 0;42 }43 44 if (!ktd2801->was_on) {45 expresswire_enable(&ktd2801->props);46 ktd2801->was_on = true;47 }48 49 expresswire_write_u8(&ktd2801->props, brightness);50 51 return 0;52}53 54static const struct backlight_ops ktd2801_backlight_ops = {55 .update_status = ktd2801_update_status,56};57 58static int ktd2801_backlight_probe(struct platform_device *pdev)59{60 struct device *dev = &pdev->dev;61 struct backlight_device *bd;62 struct ktd2801_backlight *ktd2801;63 u32 brightness, max_brightness;64 int ret;65 66 ktd2801 = devm_kzalloc(dev, sizeof(*ktd2801), GFP_KERNEL);67 if (!ktd2801)68 return -ENOMEM;69 ktd2801->was_on = true;70 ktd2801->props.timing = ktd2801_timing;71 72 ret = device_property_read_u32(dev, "max-brightness", &max_brightness);73 if (ret)74 max_brightness = KTD2801_MAX_BRIGHTNESS;75 if (max_brightness > KTD2801_MAX_BRIGHTNESS) {76 dev_err(dev, "illegal max brightness specified\n");77 max_brightness = KTD2801_MAX_BRIGHTNESS;78 }79 80 ret = device_property_read_u32(dev, "default-brightness", &brightness);81 if (ret)82 brightness = KTD2801_DEFAULT_BRIGHTNESS;83 if (brightness > max_brightness) {84 dev_err(dev, "default brightness exceeds max\n");85 brightness = max_brightness;86 }87 88 ktd2801->props.ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);89 if (IS_ERR(ktd2801->props.ctrl_gpio))90 return dev_err_probe(dev, PTR_ERR(ktd2801->props.ctrl_gpio),91 "failed to get backlight GPIO");92 gpiod_set_consumer_name(ktd2801->props.ctrl_gpio, dev_name(dev));93 94 bd = devm_backlight_device_register(dev, dev_name(dev), dev, ktd2801,95 &ktd2801_backlight_ops, NULL);96 if (IS_ERR(bd))97 return dev_err_probe(dev, PTR_ERR(bd),98 "failed to register backlight");99 100 bd->props.max_brightness = max_brightness;101 bd->props.brightness = brightness;102 103 ktd2801->bd = bd;104 platform_set_drvdata(pdev, bd);105 backlight_update_status(bd);106 107 return 0;108}109 110static const struct of_device_id ktd2801_of_match[] = {111 { .compatible = "kinetic,ktd2801" },112 { }113};114MODULE_DEVICE_TABLE(of, ktd2801_of_match);115 116static struct platform_driver ktd2801_backlight_driver = {117 .driver = {118 .name = "ktd2801-backlight",119 .of_match_table = ktd2801_of_match,120 },121 .probe = ktd2801_backlight_probe,122};123module_platform_driver(ktd2801_backlight_driver);124 125MODULE_IMPORT_NS(EXPRESSWIRE);126MODULE_AUTHOR("Duje Mihanović <duje.mihanovic@skole.hr>");127MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver");128MODULE_LICENSE("GPL");129