| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 | 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 | |
| 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 | |
| 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"); |