// SPDX-License-Identifier: GPL-2.0
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// Driver to detect Tablet Mode for ChromeOS convertible.
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//
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// Copyright (C) 2017 Google, Inc.
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// Author: Gwendal Grignou <gwendal@chromium.org>
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//
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// On Chromebook using ACPI, this device listens for notification
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// from GOOG0006 and issue method TBMC to retrieve the status.
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//
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// GOOG0006 issues the notification when it receives EC_HOST_EVENT_MODE_CHANGE
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// from the EC.
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// Method TBMC reads EC_ACPI_MEM_DEVICE_ORIENTATION byte from the shared
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// memory region.
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#include <linux/acpi.h>
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#include <linux/input.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/printk.h>
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#define DRV_NAME "chromeos_tbmc"
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#define ACPI_DRV_NAME "GOOG0006"
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static int chromeos_tbmc_query_switch(struct acpi_device *adev,
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struct input_dev *idev)
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{
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unsigned long long state;
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acpi_status status;
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status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);
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if (ACPI_FAILURE(status))
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return -ENODEV;
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/* input layer checks if event is redundant */
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input_report_switch(idev, SW_TABLET_MODE, state);
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input_sync(idev);
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return 0;
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}
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static __maybe_unused int chromeos_tbmc_resume(struct device *dev)
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{
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struct acpi_device *adev = to_acpi_device(dev);
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return chromeos_tbmc_query_switch(adev, adev->driver_data);
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}
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static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)
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{
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acpi_pm_wakeup_event(&adev->dev);
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switch (event) {
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case 0x80:
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chromeos_tbmc_query_switch(adev, adev->driver_data);
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break;
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default:
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dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);
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}
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}
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static int chromeos_tbmc_open(struct input_dev *idev)
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{
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struct acpi_device *adev = input_get_drvdata(idev);
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return chromeos_tbmc_query_switch(adev, idev);
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}
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static int chromeos_tbmc_add(struct acpi_device *adev)
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{
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struct input_dev *idev;
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struct device *dev = &adev->dev;
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int ret;
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idev = devm_input_allocate_device(dev);
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if (!idev)
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return -ENOMEM;
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idev->name = "Tablet Mode Switch";
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idev->phys = acpi_device_hid(adev);
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idev->id.bustype = BUS_HOST;
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idev->id.version = 1;
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idev->id.product = 0;
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idev->open = chromeos_tbmc_open;
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input_set_drvdata(idev, adev);
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adev->driver_data = idev;
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input_set_capability(idev, EV_SW, SW_TABLET_MODE);
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ret = input_register_device(idev);
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if (ret) {
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dev_err(dev, "cannot register input device\n");
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return ret;
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}
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device_init_wakeup(dev, true);
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return 0;
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}
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static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
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{ ACPI_DRV_NAME, 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
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static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
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chromeos_tbmc_resume);
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static struct acpi_driver chromeos_tbmc_driver = {
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.name = DRV_NAME,
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.class = DRV_NAME,
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.ids = chromeos_tbmc_acpi_device_ids,
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.ops = {
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.add = chromeos_tbmc_add,
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.notify = chromeos_tbmc_notify,
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},
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.drv.pm = &chromeos_tbmc_pm_ops,
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};
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module_acpi_driver(chromeos_tbmc_driver);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");
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