Merge tag 'platform-drivers-x86-v4.20-1' of git://git.infradead.org/linux-platform...
[sfrench/cifs-2.6.git] / drivers / platform / chrome / chromeos_tbmc.c
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(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
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
48 static 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
59 static 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
66 static 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
96 static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
97         { ACPI_DRV_NAME, 0 },
98         { }
99 };
100 MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
101
102 static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
103                 chromeos_tbmc_resume);
104
105 static 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
116 module_acpi_driver(chromeos_tbmc_driver);
117
118 MODULE_LICENSE("GPL v2");
119 MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");