LXR linux/drivers/platform/chrome/chromeos

   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// On Chromebook using ACPI, this device listens for notification
   8// from GOOG0006 and issue method TBMC to retrieve the status.
   9//
  10// GOOG0006 issues the notification when it receives EC_HOST_EVENT_MODE_CHANGE
  11// from the EC.
  12// Method TBMC reads EC_ACPI_MEM_DEVICE_ORIENTATION byte from the shared
  13// memory region.
  14
  15#include <linux/acpi.h>
  16#include <linux/input.h>
  17#include <linux/io.h>
  18#include <linux/module.h>
  19#include <linux/printk.h>
  20
  21#define DRV_NAME "chromeos_tbmc"
  22#define ACPI_DRV_NAME "GOOG0006"
  23
  24static int chromeos_tbmc_query_switch(struct acpi_device *adev,
  25                                     struct input_dev *idev)
  26{
  27        unsigned long long state;
  28        acpi_status status;
  29
  30        status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);
  31        if (ACPI_FAILURE(status))
  32                return -ENODEV;
  33
  34        /* input layer checks if event is redundant */
  35        input_report_switch(idev, SW_TABLET_MODE, state);
  36        input_sync(idev);
  37
  38        return 0;
  39}
  40
  41static __maybe_unused int chromeos_tbmc_resume(struct device *dev)
  42{
  43        struct acpi_device *adev = to_acpi_device(dev);
  44
  45        return chromeos_tbmc_query_switch(adev, adev->driver_data);
  46}
  47
  48static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)
  49{
  50        switch (event) {
  51        case 0x80:
  52                chromeos_tbmc_query_switch(adev, adev->driver_data);
  53                break;
  54        default:
  55                dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);
  56        }
  57}
  58
  59static int chromeos_tbmc_open(struct input_dev *idev)
  60{
  61        struct acpi_device *adev = input_get_drvdata(idev);
  62
  63        return chromeos_tbmc_query_switch(adev, idev);
  64}
  65
  66static int chromeos_tbmc_add(struct acpi_device *adev)
  67{
  68        struct input_dev *idev;
  69        struct device *dev = &adev->dev;
  70        int ret;
  71
  72        idev = devm_input_allocate_device(dev);
  73        if (!idev)
  74                return -ENOMEM;
  75
  76        idev->name = "Tablet Mode Switch";
  77        idev->phys = acpi_device_hid(adev);
  78
  79        idev->id.bustype = BUS_HOST;
  80        idev->id.version = 1;
  81        idev->id.product = 0;
  82        idev->open = chromeos_tbmc_open;
  83
  84        input_set_drvdata(idev, adev);
  85        adev->driver_data = idev;
  86
  87        input_set_capability(idev, EV_SW, SW_TABLET_MODE);
  88        ret = input_register_device(idev);
  89        if (ret) {
  90                dev_err(dev, "cannot register input device\n");
  91                return ret;
  92        }
  93        return 0;
  94}
  95
  96static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
  97        { ACPI_DRV_NAME, 0 },
  98        { }
  99};
 100MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
 101
 102static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
 103                chromeos_tbmc_resume);
 104
 105static struct acpi_driver chromeos_tbmc_driver = {
 106        .name = DRV_NAME,
 107        .class = DRV_NAME,
 108        .ids = chromeos_tbmc_acpi_device_ids,
 109        .ops = {
 110                .add = chromeos_tbmc_add,
 111                .notify = chromeos_tbmc_notify,
 112        },
 113        .drv.pm = &chromeos_tbmc_pm_ops,
 114};
 115
 116module_acpi_driver(chromeos_tbmc_driver);
 117
 118MODULE_LICENSE("GPL v2");
 119MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");
 120