platform/x86/dual_accel_detect.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * Helper code to detect 360 degree hinges (yoga) style 2-in-1 devices using 2 accelerometers
0004  * to allow the OS to determine the angle between the display and the base of the device.
0005  *
0006  * On Windows these are read by a special HingeAngleService process which calls undocumented
0007  * ACPI methods, to let the firmware know if the 2-in-1 is in tablet- or laptop-mode.
0008  * The firmware may use this to disable the kbd and touchpad to avoid spurious input in
0009  * tablet-mode as well as to report SW_TABLET_MODE info to the OS.
0010  *
0011  * Since Linux does not call these undocumented methods, the SW_TABLET_MODE info reported
0012  * by various drivers/platform/x86 drivers is incorrect. These drivers use the detection
0013  * code in this file to disable SW_TABLET_MODE reporting to avoid reporting broken info
0014  * (instead userspace can derive the status itself by directly reading the 2 accels).
0015  */
0016
0017 #include <linux/acpi.h>
0018 #include <linux/i2c.h>
0019
0020 static bool dual_accel_detect_bosc0200(void)
0021 {
0022     struct acpi_device *adev;
0023     int count;
0024
0025     adev = acpi_dev_get_first_match_dev("BOSC0200", NULL, -1);
0026     if (!adev)
0027         return false;
0028
0029     count = i2c_acpi_client_count(adev);
0030
0031     acpi_dev_put(adev);
0032
0033     return count == 2;
0034 }
0035
0036 static bool dual_accel_detect(void)
0037 {
0038     /* Systems which use a pair of accels with KIOX010A / KIOX020A ACPI ids */
0039     if (acpi_dev_present("KIOX010A", NULL, -1) &&
0040         acpi_dev_present("KIOX020A", NULL, -1))
0041         return true;
0042
0043     /* Systems which use a single DUAL250E ACPI device to model 2 accels */
0044     if (acpi_dev_present("DUAL250E", NULL, -1))
0045         return true;
0046
0047     /* Systems which use a single BOSC0200 ACPI device to model 2 accels */
0048     if (dual_accel_detect_bosc0200())
0049         return true;
0050
0051     return false;
0052 }