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
chromeos_tbmc_query_switch(struct acpi_device * adev,struct input_dev * idev)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(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
chromeos_tbmc_resume(struct device * dev)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, adev->driver_data);
46 }
47
chromeos_tbmc_notify(struct acpi_device * adev,u32 event)48 static 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
chromeos_tbmc_open(struct input_dev * idev)60 static 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
chromeos_tbmc_add(struct acpi_device * adev)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(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
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