drivers/hid/hid-google-hammer.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  HID driver for Google Hammer device.
   4  *
   5  *  Copyright (c) 2017 Google Inc.
   6  *  Author: Wei-Ning Huang <wnhuang@google.com>
   7  */
   8
   9 /*
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  */
  15
  16 #include <linux/hid.h>
  17 #include <linux/leds.h>
  18 #include <linux/module.h>
  19
  20 #include "hid-ids.h"
  21
  22 #define MAX_BRIGHTNESS 100
  23
  24 /* HID usage for keyboard backlight (Alphanumeric display brightness) */
  25 #define HID_AD_BRIGHTNESS 0x00140046
  26
  27 struct hammer_kbd_leds {
  28         struct led_classdev cdev;
  29         struct hid_device *hdev;
  30         u8 buf[2] ____cacheline_aligned;
  31 };
  32
  33 static int hammer_kbd_brightness_set_blocking(struct led_classdev *cdev,
  34                 enum led_brightness br)
  35 {
  36         struct hammer_kbd_leds *led = container_of(cdev,
  37                                                    struct hammer_kbd_leds,
  38                                                    cdev);
  39         int ret;
  40
  41         led->buf[0] = 0;
  42         led->buf[1] = br;
  43
  44         /*
  45          * Request USB HID device to be in Full On mode, so that sending
  46          * hardware output report and hardware raw request won't fail.
  47          */
  48         ret = hid_hw_power(led->hdev, PM_HINT_FULLON);
  49         if (ret < 0) {
  50                 hid_err(led->hdev, "failed: device not resumed %d\n", ret);
  51                 return ret;
  52         }
  53
  54         ret = hid_hw_output_report(led->hdev, led->buf, sizeof(led->buf));
  55         if (ret == -ENOSYS)
  56                 ret = hid_hw_raw_request(led->hdev, 0, led->buf,
  57                                          sizeof(led->buf),
  58                                          HID_OUTPUT_REPORT,
  59                                          HID_REQ_SET_REPORT);
  60         if (ret < 0)
  61                 hid_err(led->hdev, "failed to set keyboard backlight: %d\n",
  62                         ret);
  63
  64         /* Request USB HID device back to Normal Mode. */
  65         hid_hw_power(led->hdev, PM_HINT_NORMAL);
  66
  67         return ret;
  68 }
  69
  70 static int hammer_register_leds(struct hid_device *hdev)
  71 {
  72         struct hammer_kbd_leds *kbd_backlight;
  73
  74         kbd_backlight = devm_kzalloc(&hdev->dev,
  75                                      sizeof(*kbd_backlight),
  76                                      GFP_KERNEL);
  77         if (!kbd_backlight)
  78                 return -ENOMEM;
  79
  80         kbd_backlight->hdev = hdev;
  81         kbd_backlight->cdev.name = "hammer::kbd_backlight";
  82         kbd_backlight->cdev.max_brightness = MAX_BRIGHTNESS;
  83         kbd_backlight->cdev.brightness_set_blocking =
  84                 hammer_kbd_brightness_set_blocking;
  85         kbd_backlight->cdev.flags = LED_HW_PLUGGABLE;
  86
  87         /* Set backlight to 0% initially. */
  88         hammer_kbd_brightness_set_blocking(&kbd_backlight->cdev, 0);
  89
  90         return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
  91 }
  92
  93 static int hammer_input_configured(struct hid_device *hdev,
  94                                    struct hid_input *hi)
  95 {
  96         struct list_head *report_list =
  97                 &hdev->report_enum[HID_OUTPUT_REPORT].report_list;
  98         struct hid_report *report;
  99
 100         if (list_empty(report_list))
 101                 return 0;
 102
 103         report = list_first_entry(report_list, struct hid_report, list);
 104
 105         if (report->maxfield == 1 &&
 106             report->field[0]->application == HID_GD_KEYBOARD &&
 107             report->field[0]->maxusage == 1 &&
 108             report->field[0]->usage[0].hid == HID_AD_BRIGHTNESS) {
 109                 int err = hammer_register_leds(hdev);
 110
 111                 if (err)
 112                         hid_warn(hdev,
 113                                 "Failed to register keyboard backlight: %d\n",
 114                                 err);
 115         }
 116
 117         return 0;
 118 }
 119
 120 static const struct hid_device_id hammer_devices[] = {
 121         { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
 122                      USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
 123         { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
 124                      USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STAFF) },
 125         { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
 126                      USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WAND) },
 127         { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
 128                      USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WHISKERS) },
 129         { }
 130 };
 131 MODULE_DEVICE_TABLE(hid, hammer_devices);
 132
 133 static struct hid_driver hammer_driver = {
 134         .name = "hammer",
 135         .id_table = hammer_devices,
 136         .input_configured = hammer_input_configured,
 137 };
 138 module_hid_driver(hammer_driver);
 139
 140 MODULE_LICENSE("GPL");