platform/chrome/chromeos_tbmc.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // Driver to detect Tablet Mode for ChromeOS convertible.
0003 //
0004 // Copyright (C) 2017 Google, Inc.
0005 // Author: Gwendal Grignou <gwendal@chromium.org>
0006 //
0007 // On Chromebook using ACPI, this device listens for notification
0008 // from GOOG0006 and issue method TBMC to retrieve the status.
0009 //
0010 // GOOG0006 issues the notification when it receives EC_HOST_EVENT_MODE_CHANGE
0011 // from the EC.
0012 // Method TBMC reads EC_ACPI_MEM_DEVICE_ORIENTATION byte from the shared
0013 // memory region.
0014
0015 #include <linux/acpi.h>
0016 #include <linux/input.h>
0017 #include <linux/io.h>
0018 #include <linux/module.h>
0019 #include <linux/printk.h>
0020
0021 #define DRV_NAME "chromeos_tbmc"
0022 #define ACPI_DRV_NAME "GOOG0006"
0023
0024 static int chromeos_tbmc_query_switch(struct acpi_device *adev,
0025                      struct input_dev *idev)
0026 {
0027     unsigned long long state;
0028     acpi_status status;
0029
0030     status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);
0031     if (ACPI_FAILURE(status))
0032         return -ENODEV;
0033
0034     /* input layer checks if event is redundant */
0035     input_report_switch(idev, SW_TABLET_MODE, state);
0036     input_sync(idev);
0037
0038     return 0;
0039 }
0040
0041 static __maybe_unused int chromeos_tbmc_resume(struct device *dev)
0042 {
0043     struct acpi_device *adev = to_acpi_device(dev);
0044
0045     return chromeos_tbmc_query_switch(adev, adev->driver_data);
0046 }
0047
0048 static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)
0049 {
0050     acpi_pm_wakeup_event(&adev->dev);
0051     switch (event) {
0052     case 0x80:
0053         chromeos_tbmc_query_switch(adev, adev->driver_data);
0054         break;
0055     default:
0056         dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);
0057     }
0058 }
0059
0060 static int chromeos_tbmc_open(struct input_dev *idev)
0061 {
0062     struct acpi_device *adev = input_get_drvdata(idev);
0063
0064     return chromeos_tbmc_query_switch(adev, idev);
0065 }
0066
0067 static int chromeos_tbmc_add(struct acpi_device *adev)
0068 {
0069     struct input_dev *idev;
0070     struct device *dev = &adev->dev;
0071     int ret;
0072
0073     idev = devm_input_allocate_device(dev);
0074     if (!idev)
0075         return -ENOMEM;
0076
0077     idev->name = "Tablet Mode Switch";
0078     idev->phys = acpi_device_hid(adev);
0079
0080     idev->id.bustype = BUS_HOST;
0081     idev->id.version = 1;
0082     idev->id.product = 0;
0083     idev->open = chromeos_tbmc_open;
0084
0085     input_set_drvdata(idev, adev);
0086     adev->driver_data = idev;
0087
0088     input_set_capability(idev, EV_SW, SW_TABLET_MODE);
0089     ret = input_register_device(idev);
0090     if (ret) {
0091         dev_err(dev, "cannot register input device\n");
0092         return ret;
0093     }
0094     device_init_wakeup(dev, true);
0095     return 0;
0096 }
0097
0098 static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {
0099     { ACPI_DRV_NAME, 0 },
0100     { }
0101 };
0102 MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);
0103
0104 static SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
0105         chromeos_tbmc_resume);
0106
0107 static struct acpi_driver chromeos_tbmc_driver = {
0108     .name = DRV_NAME,
0109     .class = DRV_NAME,
0110     .ids = chromeos_tbmc_acpi_device_ids,
0111     .ops = {
0112         .add = chromeos_tbmc_add,
0113         .notify = chromeos_tbmc_notify,
0114     },
0115     .drv.pm = &chromeos_tbmc_pm_ops,
0116 };
0117
0118 module_acpi_driver(chromeos_tbmc_driver);
0119
0120 MODULE_LICENSE("GPL v2");
0121 MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");