// SPDX-License-Identifier: GPL-2.0
/*
 * Apple Touch Bar Backlight Driver
 *
 * Copyright (c) 2017-2018 Ronald Tschalär
 * Copyright (c) 2022-2023 Kerem Karabay <kekrby@gmail.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/hid.h>
#include <linux/backlight.h>
#include <linux/device.h>

#include "hid-ids.h"

#define APPLETB_BL_ON   1
#define APPLETB_BL_DIM   3
#define APPLETB_BL_OFF   4

#define HID_UP_APPLEVENDOR_TB_BL 0xff120000

#define HID_VD_APPLE_TB_BRIGHTNESS 0xff120001
#define HID_USAGE_AUX1   0xff120020
#define HID_USAGE_BRIGHTNESS  0xff120021

static int appletb_bl_def_brightness = 2;
module_param_named(brightness, appletb_bl_def_brightness, int, 0444);
MODULE_PARM_DESC(brightness, "Default brightness:\n"
    "    0 - Touchbar is off\n"
    "    1 - Dim brightness\n"
    "    [2] - Full brightness");

struct appletb_bl {
 struct hid_field *aux1_field, *brightness_field;
 struct backlight_device *bdev;

 bool full_on;
};

static const u8 appletb_bl_brightness_map[] = {
 APPLETB_BL_OFF,
 APPLETB_BL_DIM,
 APPLETB_BL_ON,
};

static int appletb_bl_set_brightness(struct appletb_bl *bl, u8 brightness)
{
 struct hid_report *report = bl->brightness_field->report;
 struct hid_device *hdev = report->device;
 int ret;

 ret = hid_set_field(bl->aux1_field, 0, 1);
 if (ret) {
  hid_err(hdev, "Failed to set auxiliary field (%pe)\n", ERR_PTR(ret));
  return ret;
 }

 ret = hid_set_field(bl->brightness_field, 0, brightness);
 if (ret) {
  hid_err(hdev, "Failed to set brightness field (%pe)\n", ERR_PTR(ret));
  return ret;
 }

 if (!bl->full_on) {
  ret = hid_hw_power(hdev, PM_HINT_FULLON);
  if (ret < 0) {
   hid_err(hdev, "Device didn't power on (%pe)\n", ERR_PTR(ret));
   return ret;
  }

  bl->full_on = true;
 }

 hid_hw_request(hdev, report, HID_REQ_SET_REPORT);

 if (brightness == APPLETB_BL_OFF) {
  hid_hw_power(hdev, PM_HINT_NORMAL);
  bl->full_on = false;
 }

 return 0;
}

static int appletb_bl_update_status(struct backlight_device *bdev)
{
 struct appletb_bl *bl = bl_get_data(bdev);
 u8 brightness;

 if (backlight_is_blank(bdev))
  brightness = APPLETB_BL_OFF;
 else
  brightness = appletb_bl_brightness_map[backlight_get_brightness(bdev)];

 return appletb_bl_set_brightness(bl, brightness);
}

static const struct backlight_ops appletb_bl_backlight_ops = {
 .options = BL_CORE_SUSPENDRESUME,
 .update_status = appletb_bl_update_status,
};

static int appletb_bl_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
 struct hid_field *aux1_field, *brightness_field;
 struct backlight_properties bl_props = { 0 };
 struct device *dev = &hdev->dev;
 struct appletb_bl *bl;
 int ret;

 ret = hid_parse(hdev);
 if (ret)
  return dev_err_probe(dev, ret, "HID parse failed\n");

 aux1_field = hid_find_field(hdev, HID_FEATURE_REPORT,
        HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_AUX1);

 brightness_field = hid_find_field(hdev, HID_FEATURE_REPORT,
       HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_BRIGHTNESS);

 if (!aux1_field || !brightness_field)
  return -ENODEV;

 if (aux1_field->report != brightness_field->report)
  return dev_err_probe(dev, -ENODEV, "Encountered unexpected report structure\n");

 bl = devm_kzalloc(dev, sizeof(*bl), GFP_KERNEL);
 if (!bl)
  return -ENOMEM;

 ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
 if (ret)
  return dev_err_probe(dev, ret, "HID hardware start failed\n");

 ret = hid_hw_open(hdev);
 if (ret) {
  dev_err_probe(dev, ret, "HID hardware open failed\n");
  goto stop_hw;
 }

 bl->aux1_field = aux1_field;
 bl->brightness_field = brightness_field;

 ret = appletb_bl_set_brightness(bl,
  appletb_bl_brightness_map[(appletb_bl_def_brightness > 2) ? 2 : appletb_bl_def_brightness]);

 if (ret) {
  dev_err_probe(dev, ret, "Failed to set default touch bar brightness to %d\n",
         appletb_bl_def_brightness);
  goto close_hw;
 }

 bl_props.type = BACKLIGHT_RAW;
 bl_props.max_brightness = ARRAY_SIZE(appletb_bl_brightness_map) - 1;

 bl->bdev = devm_backlight_device_register(dev, "appletb_backlight", dev, bl,
        &appletb_bl_backlight_ops, &bl_props);
 if (IS_ERR(bl->bdev)) {
  ret = PTR_ERR(bl->bdev);
  dev_err_probe(dev, ret, "Failed to register backlight device\n");
  goto close_hw;
 }

 hid_set_drvdata(hdev, bl);

 return 0;

close_hw:
 hid_hw_close(hdev);
stop_hw:
 hid_hw_stop(hdev);

 return ret;
}

static void appletb_bl_remove(struct hid_device *hdev)
{
 struct appletb_bl *bl = hid_get_drvdata(hdev);

 appletb_bl_set_brightness(bl, APPLETB_BL_OFF);

 hid_hw_close(hdev);
 hid_hw_stop(hdev);
}

static const struct hid_device_id appletb_bl_hid_ids[] = {
 /* MacBook Pro's 2018, 2019, with T2 chip: iBridge DFR Brightness */
 { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
 { }
};
MODULE_DEVICE_TABLE(hid, appletb_bl_hid_ids);

static struct hid_driver appletb_bl_hid_driver = {
 .name = "hid-appletb-bl",
 .id_table = appletb_bl_hid_ids,
 .probe = appletb_bl_probe,
 .remove = appletb_bl_remove,
};
module_hid_driver(appletb_bl_hid_driver);

MODULE_AUTHOR("Ronald Tschalär");
MODULE_AUTHOR("Kerem Karabay <kekrby@gmail.com>");
MODULE_DESCRIPTION("MacBook Pro Touch Bar Backlight driver");
MODULE_LICENSE("GPL");