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