// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *  Force feedback support for Holtek On Line Grip based gamepads
   *
   *  These include at least a Brazilian "Clone Joypad Super Power Fire"
   *  which uses vendor ID 0x1241 and identifies as "HOLTEK On Line Grip".
   *
   *  Copyright (c) 2011 Anssi Hannula <anssi.hannula@iki.fi>
   */
  
  /*

   */
  
  #include <linux/hid.h>
  #include <linux/input.h>

  #include <linux/module.h>

  #include <linux/slab.h>

  
  #include "hid-ids.h"
  
  #ifdef CONFIG_HOLTEK_FF

  /*
   * These commands and parameters are currently known:
   *
   * byte 0: command id:
   * 	01  set effect parameters
   * 	02  play specified effect
   * 	03  stop specified effect
   * 	04  stop all effects
   * 	06  stop all effects
   * 	(the difference between 04 and 06 isn't known; win driver
   * 	 sends 06,04 on application init, and 06 otherwise)
   * 
   * Commands 01 and 02 need to be sent as pairs, i.e. you need to send 01
   * before each 02.
   *
   * The rest of the bytes are parameters. Command 01 takes all of them, and
   * commands 02,03 take only the effect id.
   *
   * byte 1:
   *	bits 0-3: effect id:
   * 		1: very strong rumble
   * 		2: periodic rumble, short intervals
   * 		3: very strong rumble
   * 		4: periodic rumble, long intervals
   * 		5: weak periodic rumble, long intervals
   * 		6: weak periodic rumble, short intervals
   * 		7: periodic rumble, short intervals
   * 		8: strong periodic rumble, short intervals
   * 		9: very strong rumble
   * 		a: causes an error
   * 		b: very strong periodic rumble, very short intervals
   * 		c-f: nothing
   *	bit 6: right (weak) motor enabled
   *	bit 7: left (strong) motor enabled
   *
   * bytes 2-3:  time in milliseconds, big-endian
   * bytes 5-6:  unknown (win driver seems to use at least 10e0 with effect 1
   * 		       and 0014 with effect 6)
   * byte 7:
   *	bits 0-3: effect magnitude
   */
  
  #define HOLTEKFF_MSG_LENGTH     7
  
  static const u8 start_effect_1[] = { 0x02, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00 };
  static const u8 stop_all4[] =	   { 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  static const u8 stop_all6[] =	   { 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  
  struct holtekff_device {
  	struct hid_field *field;
  };
  
  static void holtekff_send(struct holtekff_device *holtekff,
  			  struct hid_device *hid,
  			  const u8 data[HOLTEKFF_MSG_LENGTH])
  {
  	int i;
  
  	for (i = 0; i < HOLTEKFF_MSG_LENGTH; i++) {
  		holtekff->field->value[i] = data[i];
  	}

  	dbg_hid("sending %7ph
  ", data);

  	hid_hw_request(hid, holtekff->field->report, HID_REQ_SET_REPORT);

  }
  
  static int holtekff_play(struct input_dev *dev, void *data,
  			 struct ff_effect *effect)
  {
  	struct hid_device *hid = input_get_drvdata(dev);
  	struct holtekff_device *holtekff = data;
  	int left, right;
  	/* effect type 1, length 65535 msec */
  	u8 buf[HOLTEKFF_MSG_LENGTH] =
  		{ 0x01, 0x01, 0xff, 0xff, 0x10, 0xe0, 0x00 };
  
  	left = effect->u.rumble.strong_magnitude;
  	right = effect->u.rumble.weak_magnitude;
  	dbg_hid("called with 0x%04x 0x%04x
  ", left, right);
  
  	if (!left && !right) {
  		holtekff_send(holtekff, hid, stop_all6);
  		return 0;
  	}
  
  	if (left)
  		buf[1] |= 0x80;
  	if (right)
  		buf[1] |= 0x40;
  
  	/* The device takes a single magnitude, so we just sum them up. */
  	buf[6] = min(0xf, (left >> 12) + (right >> 12));
  
  	holtekff_send(holtekff, hid, buf);
  	holtekff_send(holtekff, hid, start_effect_1);
  
  	return 0;
  }
  
  static int holtekff_init(struct hid_device *hid)
  {
  	struct holtekff_device *holtekff;
  	struct hid_report *report;

  	struct hid_input *hidinput;

  	struct list_head *report_list =
  			&hid->report_enum[HID_OUTPUT_REPORT].report_list;

  	struct input_dev *dev;

  	int error;

  	if (list_empty(&hid->inputs)) {
  		hid_err(hid, "no inputs found
  ");
  		return -ENODEV;
  	}
  	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
  	dev = hidinput->input;

  	if (list_empty(report_list)) {
  		hid_err(hid, "no output report found
  ");
  		return -ENODEV;
  	}
  
  	report = list_entry(report_list->next, struct hid_report, list);
  
  	if (report->maxfield < 1 || report->field[0]->report_count != 7) {
  		hid_err(hid, "unexpected output report layout
  ");
  		return -ENODEV;
  	}
  
  	holtekff = kzalloc(sizeof(*holtekff), GFP_KERNEL);
  	if (!holtekff)
  		return -ENOMEM;
  
  	set_bit(FF_RUMBLE, dev->ffbit);
  
  	holtekff->field = report->field[0];
  
  	/* initialize the same way as win driver does */
  	holtekff_send(holtekff, hid, stop_all4);
  	holtekff_send(holtekff, hid, stop_all6);
  
  	error = input_ff_create_memless(dev, holtekff, holtekff_play);
  	if (error) {
  		kfree(holtekff);
  		return error;
  	}
  
  	hid_info(hid, "Force feedback for Holtek On Line Grip based devices by Anssi Hannula <anssi.hannula@iki.fi>
  ");
  
  	return 0;
  }
  #else
  static inline int holtekff_init(struct hid_device *hid)
  {
  	return 0;
  }
  #endif
  
  static int holtek_probe(struct hid_device *hdev, const struct hid_device_id *id)
  {
  	int ret;
  
  	ret = hid_parse(hdev);
  	if (ret) {
  		hid_err(hdev, "parse failed
  ");
  		goto err;
  	}
  
  	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
  	if (ret) {
  		hid_err(hdev, "hw start failed
  ");
  		goto err;
  	}
  
  	holtekff_init(hdev);
  
  	return 0;
  err:
  	return ret;
  }
  
  static const struct hid_device_id holtek_devices[] = {
  	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK, USB_DEVICE_ID_HOLTEK_ON_LINE_GRIP) },
  	{ }
  };
  MODULE_DEVICE_TABLE(hid, holtek_devices);
  
  static struct hid_driver holtek_driver = {
  	.name = "holtek",
  	.id_table = holtek_devices,
  	.probe = holtek_probe,
  };

  module_hid_driver(holtek_driver);

  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Anssi Hannula <anssi.hannula@iki.fi>");
  MODULE_DESCRIPTION("Force feedback support for Holtek On Line Grip based devices");