drivers/hid/hid-primax.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * HID driver for primax and similar keyboards with in-band modifiers
   4  *
   5  * Copyright 2011 Google Inc. All Rights Reserved
   6  *
   7  * Author:
   8  *      Terry Lambert <tlambert@google.com>
   9  */
  10
  11 #include <linux/device.h>
  12 #include <linux/hid.h>
  13 #include <linux/module.h>
  14
  15 #include "hid-ids.h"
  16
  17 static int px_raw_event(struct hid_device *hid, struct hid_report *report,
  18          u8 *data, int size)
  19 {
  20         int idx = size;
  21
  22         switch (report->id) {
  23         case 0:         /* keyboard input */
  24                 /*
  25                  * Convert in-band modifier key values into out of band
  26                  * modifier bits and pull the key strokes from the report.
  27                  * Thus a report data set which looked like:
  28                  *
  29                  * [00][00][E0][30][00][00][00][00]
  30                  * (no modifier bits + "Left Shift" key + "1" key)
  31                  *
  32                  * Would be converted to:
  33                  *
  34                  * [01][00][00][30][00][00][00][00]
  35                  * (Left Shift modifier bit + "1" key)
  36                  *
  37                  * As long as it's in the size range, the upper level
  38                  * drivers don't particularly care if there are in-band
  39                  * 0-valued keys, so they don't stop parsing.
  40                  */
  41                 while (--idx > 1) {
  42                         if (data[idx] < 0xE0 || data[idx] > 0xE7)
  43                                 continue;
  44                         data[0] |= (1 << (data[idx] - 0xE0));
  45                         data[idx] = 0;
  46                 }
  47                 hid_report_raw_event(hid, HID_INPUT_REPORT, data, size, 0);
  48                 return 1;
  49
  50         default:        /* unknown report */
  51                 /* Unknown report type; pass upstream */
  52                 hid_info(hid, "unknown report type %d\n", report->id);
  53                 break;
  54         }
  55
  56         return 0;
  57 }
  58
  59 static const struct hid_device_id px_devices[] = {
  60         { HID_USB_DEVICE(USB_VENDOR_ID_PRIMAX, USB_DEVICE_ID_PRIMAX_KEYBOARD) },
  61         { }
  62 };
  63 MODULE_DEVICE_TABLE(hid, px_devices);
  64
  65 static struct hid_driver px_driver = {
  66         .name = "primax",
  67         .id_table = px_devices,
  68         .raw_event = px_raw_event,
  69 };
  70 module_hid_driver(px_driver);
  71
  72 MODULE_AUTHOR("Terry Lambert <tlambert@google.com>");
  73 MODULE_LICENSE("GPL");