// SPDX-License-Identifier: GPL-2.0-only

  /*
   * HID driver for primax and similar keyboards with in-band modifiers
   *
   * Copyright 2011 Google Inc. All Rights Reserved
   *
   * Author:
   *	Terry Lambert <tlambert@google.com>

   */
  
  #include <linux/device.h>
  #include <linux/hid.h>
  #include <linux/module.h>
  
  #include "hid-ids.h"
  
  static int px_raw_event(struct hid_device *hid, struct hid_report *report,
  	 u8 *data, int size)
  {
  	int idx = size;
  
  	switch (report->id) {
  	case 0:		/* keyboard input */
  		/*
  		 * Convert in-band modifier key values into out of band
  		 * modifier bits and pull the key strokes from the report.
  		 * Thus a report data set which looked like:
  		 *
  		 * [00][00][E0][30][00][00][00][00]
  		 * (no modifier bits + "Left Shift" key + "1" key)
  		 *
  		 * Would be converted to:
  		 *
  		 * [01][00][00][30][00][00][00][00]
  		 * (Left Shift modifier bit + "1" key)
  		 *
  		 * As long as it's in the size range, the upper level
  		 * drivers don't particularly care if there are in-band
  		 * 0-valued keys, so they don't stop parsing.
  		 */
  		while (--idx > 1) {
  			if (data[idx] < 0xE0 || data[idx] > 0xE7)
  				continue;
  			data[0] |= (1 << (data[idx] - 0xE0));
  			data[idx] = 0;
  		}
  		hid_report_raw_event(hid, HID_INPUT_REPORT, data, size, 0);
  		return 1;
  
  	default:	/* unknown report */
  		/* Unknown report type; pass upstream */
  		hid_info(hid, "unknown report type %d
  ", report->id);
  		break;
  	}
  
  	return 0;
  }

  static const struct hid_device_id px_devices[] = {
  	{ HID_USB_DEVICE(USB_VENDOR_ID_PRIMAX, USB_DEVICE_ID_PRIMAX_KEYBOARD) },
  	{ }
  };
  MODULE_DEVICE_TABLE(hid, px_devices);
  
  static struct hid_driver px_driver = {
  	.name = "primax",
  	.id_table = px_devices,
  	.raw_event = px_raw_event,

  };

  module_hid_driver(px_driver);

  MODULE_AUTHOR("Terry Lambert <tlambert@google.com>");
  MODULE_LICENSE("GPL");