1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Helper code to detect 360 degree hinges (yoga) style 2-in-1 devices using 2 accelerometers 4 * 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 undocumented 7 * 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 in 9 * 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 reported 12 * by various drivers/platform/x86 drivers is incorrect. These drivers use the detection 13 * code in this file to disable SW_TABLET_MODE reporting to avoid reporting broken info 14 * (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 20 static 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 36 static 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