drivers/platform/x86/dual_accel_detect.h

   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 }