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"); 122