diff options
Diffstat (limited to 'drivers/video/backlight/ktd2801-backlight.c')
| -rw-r--r-- | drivers/video/backlight/ktd2801-backlight.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/drivers/video/backlight/ktd2801-backlight.c b/drivers/video/backlight/ktd2801-backlight.c new file mode 100644 index 0000000000..d295c27660 --- /dev/null +++ b/drivers/video/backlight/ktd2801-backlight.c @@ -0,0 +1,128 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Datasheet: + * https://www.kinet-ic.com/uploads/web/KTD2801/KTD2801-04b.pdf + */ +#include <linux/backlight.h> +#include <linux/gpio/consumer.h> +#include <linux/leds-expresswire.h> +#include <linux/platform_device.h> +#include <linux/property.h> + +#define KTD2801_DEFAULT_BRIGHTNESS 100 +#define KTD2801_MAX_BRIGHTNESS 255 + +/* These values have been extracted from Samsung's driver. */ +static const struct expresswire_timing ktd2801_timing = { + .poweroff_us = 2600, + .detect_delay_us = 150, + .detect_us = 270, + .data_start_us = 5, + .short_bitset_us = 5, + .long_bitset_us = 15, + .end_of_data_low_us = 10, + .end_of_data_high_us = 350 +}; + +struct ktd2801_backlight { + struct expresswire_common_props props; + struct backlight_device *bd; + bool was_on; +}; + +static int ktd2801_update_status(struct backlight_device *bd) +{ + struct ktd2801_backlight *ktd2801 = bl_get_data(bd); + u8 brightness = (u8) backlight_get_brightness(bd); + + if (backlight_is_blank(bd)) { + expresswire_power_off(&ktd2801->props); + ktd2801->was_on = false; + return 0; + } + + if (!ktd2801->was_on) { + expresswire_enable(&ktd2801->props); + ktd2801->was_on = true; + } + + expresswire_write_u8(&ktd2801->props, brightness); + + return 0; +} + +static const struct backlight_ops ktd2801_backlight_ops = { + .update_status = ktd2801_update_status, +}; + +static int ktd2801_backlight_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct backlight_device *bd; + struct ktd2801_backlight *ktd2801; + u32 brightness, max_brightness; + int ret; + + ktd2801 = devm_kzalloc(dev, sizeof(*ktd2801), GFP_KERNEL); + if (!ktd2801) + return -ENOMEM; + ktd2801->was_on = true; + ktd2801->props.timing = ktd2801_timing; + + ret = device_property_read_u32(dev, "max-brightness", &max_brightness); + if (ret) + max_brightness = KTD2801_MAX_BRIGHTNESS; + if (max_brightness > KTD2801_MAX_BRIGHTNESS) { + dev_err(dev, "illegal max brightness specified\n"); + max_brightness = KTD2801_MAX_BRIGHTNESS; + } + + ret = device_property_read_u32(dev, "default-brightness", &brightness); + if (ret) + brightness = KTD2801_DEFAULT_BRIGHTNESS; + if (brightness > max_brightness) { + dev_err(dev, "default brightness exceeds max\n"); + brightness = max_brightness; + } + + ktd2801->props.ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH); + if (IS_ERR(ktd2801->props.ctrl_gpio)) + return dev_err_probe(dev, PTR_ERR(ktd2801->props.ctrl_gpio), + "failed to get backlight GPIO"); + gpiod_set_consumer_name(ktd2801->props.ctrl_gpio, dev_name(dev)); + + bd = devm_backlight_device_register(dev, dev_name(dev), dev, ktd2801, + &ktd2801_backlight_ops, NULL); + if (IS_ERR(bd)) + return dev_err_probe(dev, PTR_ERR(bd), + "failed to register backlight"); + + bd->props.max_brightness = max_brightness; + bd->props.brightness = brightness; + + ktd2801->bd = bd; + platform_set_drvdata(pdev, bd); + backlight_update_status(bd); + + return 0; +} + +static const struct of_device_id ktd2801_of_match[] = { + { .compatible = "kinetic,ktd2801" }, + { } +}; +MODULE_DEVICE_TABLE(of, ktd2801_of_match); + +static struct platform_driver ktd2801_backlight_driver = { + .driver = { + .name = "ktd2801-backlight", + .of_match_table = ktd2801_of_match, + }, + .probe = ktd2801_backlight_probe, +}; +module_platform_driver(ktd2801_backlight_driver); + +MODULE_IMPORT_NS(EXPRESSWIRE); +MODULE_AUTHOR("Duje Mihanović <duje.mihanovic@skole.hr>"); +MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver"); +MODULE_LICENSE("GPL"); |