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(handle: adev->handle, pathname: "TBMC", NULL, data: &state);
31 if (ACPI_FAILURE(status))
32 return -ENODEV;
33
34 /* input layer checks if event is redundant */
35 input_report_switch(dev: idev, SW_TABLET_MODE, value: state);
36 input_sync(dev: 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, idev: adev->driver_data);
46}
47
48static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)
49{
50 acpi_pm_wakeup_event(dev: &adev->dev);
51 switch (event) {
52 case 0x80:
53 chromeos_tbmc_query_switch(adev, idev: 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(dev: 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(device: 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(dev: idev, data: adev);
86 adev->driver_data = idev;
87
88 input_set_capability(dev: 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, enable: 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");
122

source code of linux/drivers/platform/chrome/chromeos_tbmc.c