linux-imx

// SPDX-License-Identifier: GPL-2.0

// Driver to detect Tablet Mode for ChromeOS convertible.

//

// Copyright (C) 2017 Google, Inc.

// Author: Gwendal Grignou <gwendal@chromium.org>

//

// On Chromebook using ACPI, this device listens for notification

// from GOOG0006 and issue method TBMC to retrieve the status.

//

// GOOG0006 issues the notification when it receives EC_HOST_EVENT_MODE_CHANGE

// from the EC.

// Method TBMC reads EC_ACPI_MEM_DEVICE_ORIENTATION byte from the shared

// memory region.

​

#include <linux/acpi.h>

#include <linux/input.h>

#include <linux/io.h>

#include <linux/module.h>

#include <linux/printk.h>

​

#define DRV_NAME "chromeos_tbmc"

#define ACPI_DRV_NAME "GOOG0006"

​

static int chromeos_tbmc_query_switch(struct acpi_device *adev,

                     struct input_dev *idev)

{

    unsigned long long state;

    acpi_status status;

​

    status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);

    if (ACPI_FAILURE(status))

        return -ENODEV;

​

    /* input layer checks if event is redundant */

    input_report_switch(idev, SW_TABLET_MODE, state);

    input_sync(idev);

​

    return 0;

}

​

static __maybe_unused int chromeos_tbmc_resume(struct device *dev)

{

    struct acpi_device *adev = to_acpi_device(dev);

​

    return chromeos_tbmc_query_switch(adev, adev->driver_data);

}

​

static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)

{

    switch (event) {

    case 0x80:

        chromeos_tbmc_query_switch(adev, adev->driver_data);

        break;

    default:

        dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);

    }

}

​

static int chromeos_tbmc_open(struct input_dev *idev)

{

    struct acpi_device *adev = input_get_drvdata(idev);

​

    return chromeos_tbmc_query_switch(adev, idev);

}

​

static int chromeos_tbmc_add(struct acpi_device *adev)

{

    struct input_dev *idev;

    struct device *dev = &adev->dev;

    int ret;

​

    idev = devm_input_allocate_device(dev);

    if (!idev)

        return -ENOMEM;

​

    idev->name = "Tablet Mode Switch";

    idev->phys = acpi_device_hid(adev);

​

    idev->id.bustype = BUS_HOST;

    idev->id.version = 1;

    idev->id.product = 0;

    idev->open = chromeos_tbmc_open;

​

    input_set_drvdata(idev, adev);

    adev->driver_data = idev;

​

    input_set_capability(idev, EV_SW, SW_TABLET_MODE);

    ret = input_register_device(idev);

    if (ret) {

        dev_err(dev, "cannot register input device\n");

        return ret;

    }