53 lines · c
1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * Helper code to detect 360 degree hinges (yoga) style 2-in-1 devices using 2 accelerometers4 * to allow the OS to determine the angle between the display and the base of the device.5 *6 * On Windows these are read by a special HingeAngleService process which calls undocumented7 * ACPI methods, to let the firmware know if the 2-in-1 is in tablet- or laptop-mode.8 * The firmware may use this to disable the kbd and touchpad to avoid spurious input in9 * tablet-mode as well as to report SW_TABLET_MODE info to the OS.10 *11 * Since Linux does not call these undocumented methods, the SW_TABLET_MODE info reported12 * by various drivers/platform/x86 drivers is incorrect. These drivers use the detection13 * code in this file to disable SW_TABLET_MODE reporting to avoid reporting broken info14 * (instead userspace can derive the status itself by directly reading the 2 accels).15 */16 17#include <linux/acpi.h>18#include <linux/i2c.h>19 20static bool dual_accel_detect_bosc0200(void)21{22 struct acpi_device *adev;23 int count;24 25 adev = acpi_dev_get_first_match_dev("BOSC0200", NULL, -1);26 if (!adev)27 return false;28 29 count = i2c_acpi_client_count(adev);30 31 acpi_dev_put(adev);32 33 return count == 2;34}35 36static bool dual_accel_detect(void)37{38 /* Systems which use a pair of accels with KIOX010A / KIOX020A ACPI ids */39 if (acpi_dev_present("KIOX010A", NULL, -1) &&40 acpi_dev_present("KIOX020A", NULL, -1))41 return true;42 43 /* Systems which use a single DUAL250E ACPI device to model 2 accels */44 if (acpi_dev_present("DUAL250E", NULL, -1))45 return true;46 47 /* Systems which use a single BOSC0200 ACPI device to model 2 accels */48 if (dual_accel_detect_bosc0200())49 return true;50 51 return false;52}53