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 | |
24 | static 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 | |
41 | static __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 | |
48 | static 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 | |
60 | static 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 | |
67 | static 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 | |
98 | static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = { |
99 | { ACPI_DRV_NAME, 0 }, |
100 | { } |
101 | }; |
102 | MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids); |
103 | |
104 | static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL, |
105 | chromeos_tbmc_resume); |
106 | |
107 | static 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 | |
118 | module_acpi_driver(chromeos_tbmc_driver); |
119 | |
120 | MODULE_LICENSE("GPL v2" ); |
121 | MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver" ); |
122 | |