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	acpi_pm_wakeup_event(&adev->dev);
 51	switch (event) {
 52	case 0x80:
 53		chromeos_tbmc_query_switch(adev, adev->driver_data);
 54		break;
 55	default:
 56		dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);
 57	}
 58}
 59
 60static int chromeos_tbmc_open(struct input_dev *idev)
 61{
 62	struct acpi_device *adev = input_get_drvdata(idev);
 63
 64	return chromeos_tbmc_query_switch(adev, idev);
 65}
 66
 67static int chromeos_tbmc_add(struct acpi_device *adev)
 68{
 69	struct input_dev *idev;
 70	struct device *dev = &adev->dev;
 71	int ret;
 72
 73	idev = devm_input_allocate_device(dev);
 74	if (!idev)
 75		return -ENOMEM;
 76
 77	idev->name = "Tablet Mode Switch";
 78	idev->phys = acpi_device_hid(adev);
 79
 80	idev->id.bustype = BUS_HOST;
 81	idev->id.version = 1;
 82	idev->id.product = 0;
 83	idev->open = chromeos_tbmc_open;
 84
 85	input_set_drvdata(idev, adev);
 86	adev->driver_data = idev;
 87
 88	input_set_capability(idev, EV_SW, SW_TABLET_MODE);
 89	ret = input_register_device(idev);
 90	if (ret) {
 91		dev_err(dev, "cannot register input device\n");
 92		return ret;
 93	}
 94	device_init_wakeup(dev, true);
 95	return 0;
 96}
 97
 98static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
 99	{ ACPI_DRV_NAME, 0 },
100	{ }
101};
102MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
103
104static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
105		chromeos_tbmc_resume);
106
107static struct acpi_driver chromeos_tbmc_driver = {
108	.name = DRV_NAME,
109	.class = DRV_NAME,
110	.ids = chromeos_tbmc_acpi_device_ids,
111	.ops = {
112		.add = chromeos_tbmc_add,
113		.notify = chromeos_tbmc_notify,
114	},
115	.drv.pm = &chromeos_tbmc_pm_ops,
116};
117
118module_acpi_driver(chromeos_tbmc_driver);
119
120MODULE_LICENSE("GPL v2");
121MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");