drivers/platform/chrome/chromeos_tbmc.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 // Driver to detect Tablet Mode for ChromeOS convertible.
   3 //
   4 // Copyright (C) 2017 Google, Inc.
   5 // Author: Gwendal Grignou <gwendal@chromium.org>
   6
   7 #include <linux/acpi.h>
   8 #include <linux/input.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/printk.h>
  12
  13 #define DRV_NAME "chromeos_tbmc"
  14 #define ACPI_DRV_NAME "GOOG0006"
  15
  16 static int chromeos_tbmc_query_switch(struct acpi_device *adev,
  17                                      struct input_dev *idev)
  18 {
  19         unsigned long long state;
  20         acpi_status status;
  21
  22         status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);
  23         if (ACPI_FAILURE(status))
  24                 return -ENODEV;
  25
  26         /* input layer checks if event is redundant */
  27         input_report_switch(idev, SW_TABLET_MODE, state);
  28         input_sync(idev);
  29
  30         return 0;
  31 }
  32
  33 static __maybe_unused int chromeos_tbmc_resume(struct device *dev)
  34 {
  35         struct acpi_device *adev = to_acpi_device(dev);
  36
  37         return chromeos_tbmc_query_switch(adev, adev->driver_data);
  38 }
  39
  40 static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)
  41 {
  42         switch (event) {
  43         case 0x80:
  44                 chromeos_tbmc_query_switch(adev, adev->driver_data);
  45                 break;
  46         default:
  47                 dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);
  48         }
  49 }
  50
  51 static int chromeos_tbmc_open(struct input_dev *idev)
  52 {
  53         struct acpi_device *adev = input_get_drvdata(idev);
  54
  55         return chromeos_tbmc_query_switch(adev, idev);
  56 }
  57
  58 static int chromeos_tbmc_add(struct acpi_device *adev)
  59 {
  60         struct input_dev *idev;
  61         struct device *dev = &adev->dev;
  62         int ret;
  63
  64         idev = devm_input_allocate_device(dev);
  65         if (!idev)
  66                 return -ENOMEM;
  67
  68         idev->name = "Tablet Mode Switch";
  69         idev->phys = acpi_device_hid(adev);
  70
  71         idev->id.bustype = BUS_HOST;
  72         idev->id.version = 1;
  73         idev->id.product = 0;
  74         idev->open = chromeos_tbmc_open;
  75
  76         input_set_drvdata(idev, adev);
  77         adev->driver_data = idev;
  78
  79         input_set_capability(idev, EV_SW, SW_TABLET_MODE);
  80         ret = input_register_device(idev);
  81         if (ret) {
  82                 dev_err(dev, "cannot register input device\n");
  83                 return ret;
  84         }
  85         return 0;
  86 }
  87
  88 static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
  89         { ACPI_DRV_NAME, 0 },
  90         { }
  91 };
  92 MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
  93
  94 static const SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
  95                 chromeos_tbmc_resume);
  96
  97 static struct acpi_driver chromeos_tbmc_driver = {
  98         .name = DRV_NAME,
  99         .class = DRV_NAME,
 100         .ids = chromeos_tbmc_acpi_device_ids,
 101         .ops = {
 102                 .add = chromeos_tbmc_add,
 103                 .notify = chromeos_tbmc_notify,
 104         },
 105         .drv.pm = &chromeos_tbmc_pm_ops,
 106 };
 107
 108 module_acpi_driver(chromeos_tbmc_driver);
 109
 110 MODULE_LICENSE("GPL v2");
 111 MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");