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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Helper code to detect 360 degree hinges (yoga) style 2-in-1 devices using 2 accelerometers
* to allow the OS to determine the angle between the display and the base of the device.
*
* On Windows these are read by a special HingeAngleService process which calls undocumented
* ACPI methods, to let the firmware know if the 2-in-1 is in tablet- or laptop-mode.
* The firmware may use this to disable the kbd and touchpad to avoid spurious input in
* tablet-mode as well as to report SW_TABLET_MODE info to the OS.
*
* Since Linux does not call these undocumented methods, the SW_TABLET_MODE info reported
* by various drivers/platform/x86 drivers is incorrect. These drivers use the detection
* code in this file to disable SW_TABLET_MODE reporting to avoid reporting broken info
* (instead userspace can derive the status itself by directly reading the 2 accels).
*/
#include <linux/acpi.h>
#include <linux/i2c.h>
static int dual_accel_i2c_resource_count(struct acpi_resource *ares, void *data)
{
struct acpi_resource_i2c_serialbus *sb;
int *count = data;
if (i2c_acpi_get_i2c_resource(ares, &sb))
*count = *count + 1;
return 1;
}
static int dual_accel_i2c_client_count(struct acpi_device *adev)
{
int ret, count = 0;
LIST_HEAD(r);
ret = acpi_dev_get_resources(adev, &r, dual_accel_i2c_resource_count, &count);
if (ret < 0)
return ret;
acpi_dev_free_resource_list(&r);
return count;
}
static bool dual_accel_detect_bosc0200(void)
{
struct acpi_device *adev;
int count;
adev = acpi_dev_get_first_match_dev("BOSC0200", NULL, -1);
if (!adev)
return false;
count = dual_accel_i2c_client_count(adev);
acpi_dev_put(adev);
return count == 2;
}
static bool dual_accel_detect(void)
{
/* Systems which use a pair of accels with KIOX010A / KIOX020A ACPI ids */
if (acpi_dev_present("KIOX010A", NULL, -1) &&
acpi_dev_present("KIOX020A", NULL, -1))
return true;
/* Systems which use a single DUAL250E ACPI device to model 2 accels */
if (acpi_dev_present("DUAL250E", NULL, -1))
return true;
/* Systems which use a single BOSC0200 ACPI device to model 2 accels */
if (dual_accel_detect_bosc0200())
return true;
return false;
}
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