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// 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;
}
return 0;
}
static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
{ ACPI_DRV_NAME, 0 },
{ }
};
MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
chromeos_tbmc_resume);
static struct acpi_driver chromeos_tbmc_driver = {
.name = DRV_NAME,
.class = DRV_NAME,
.ids = chromeos_tbmc_acpi_device_ids,
.ops = {
.add = chromeos_tbmc_add,
.notify = chromeos_tbmc_notify,
},
.drv.pm = &chromeos_tbmc_pm_ops,
};
module_acpi_driver(chromeos_tbmc_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");
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