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"); 120