xref: /linux/drivers/platform/x86/dual_accel_detect.h (revision 762f99f4f3cb41a775b5157dd761217beba65873)
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  
dual_accel_detect_bosc0200(void)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  
dual_accel_detect(void)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