linux/drivers/iio/industrialio-acpi.c
Hans de Goede 02eae0bb95 iio: core: Add iio_read_acpi_mount_matrix() helper function
The ACPI "ROTM" rotation matrix parsing code atm is already duplicated
between bmc150-accel-core.c and kxcjk-1013.c and a third user of this
is coming.

Add an iio_read_acpi_mount_matrix() helper function for this.
The 2 existing copies of the code are identical, except that
the kxcjk-1013.c has slightly better error logging.

To new helper is a 1:1 copy of the kxcjk-1013.c version, the only change
is the addition of a "char *acpi_method" parameter since some bmc150
dual-accel setups (360° hinges with 1 accel in kbd/base + 1 in display)
declare both accels in a single ACPI device with 2 different method names
for the 2 matrices. This new acpi_method parameter is not "const char *"
because the pathname parameter to acpi_evaluate_object() is not const.

The 2 existing copies of this function will be removed in further patches
in this series.

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240425125754.76010-2-hdegoede@redhat.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2024-04-29 20:53:25 +01:00

86 lines
2.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/* IIO ACPI helper functions */
#include <linux/acpi.h>
#include <linux/dev_printk.h>
#include <linux/iio/iio.h>
#include <linux/sprintf.h>
/**
* iio_read_acpi_mount_matrix() - Read accelerometer mount matrix info from ACPI
* @dev: Device structure
* @orientation: iio_mount_matrix struct to fill
* @acpi_method: ACPI method name to read the matrix from, usually "ROTM"
*
* Try to read the mount-matrix by calling the specified method on the device's
* ACPI firmware-node. If the device has no ACPI firmware-node; or the method
* does not exist then this will fail silently. This expects the method to
* return data in the ACPI "ROTM" format defined by Microsoft:
* https://learn.microsoft.com/en-us/windows-hardware/drivers/sensors/sensors-acpi-entries
* This is a Microsoft extension and not part of the official ACPI spec.
* The method name is configurable because some dual-accel setups define 2 mount
* matrices in a single ACPI device using separate "ROMK" and "ROMS" methods.
*
* Returns: true if the matrix was successfully, false otherwise.
*/
bool iio_read_acpi_mount_matrix(struct device *dev,
struct iio_mount_matrix *orientation,
char *acpi_method)
{
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_device *adev = ACPI_COMPANION(dev);
char *str;
union acpi_object *obj, *elements;
acpi_status status;
int i, j, val[3];
bool ret = false;
if (!adev || !acpi_has_method(adev->handle, acpi_method))
return false;
status = acpi_evaluate_object(adev->handle, acpi_method, NULL, &buffer);
if (ACPI_FAILURE(status)) {
dev_err(dev, "Failed to get ACPI mount matrix: %d\n", status);
return false;
}
obj = buffer.pointer;
if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 3) {
dev_err(dev, "Unknown ACPI mount matrix package format\n");
goto out_free_buffer;
}
elements = obj->package.elements;
for (i = 0; i < 3; i++) {
if (elements[i].type != ACPI_TYPE_STRING) {
dev_err(dev, "Unknown ACPI mount matrix element format\n");
goto out_free_buffer;
}
str = elements[i].string.pointer;
if (sscanf(str, "%d %d %d", &val[0], &val[1], &val[2]) != 3) {
dev_err(dev, "Incorrect ACPI mount matrix string format\n");
goto out_free_buffer;
}
for (j = 0; j < 3; j++) {
switch (val[j]) {
case -1: str = "-1"; break;
case 0: str = "0"; break;
case 1: str = "1"; break;
default:
dev_err(dev, "Invalid value in ACPI mount matrix: %d\n", val[j]);
goto out_free_buffer;
}
orientation->rotation[i * 3 + j] = str;
}
}
ret = true;
out_free_buffer:
kfree(buffer.pointer);
return ret;
}
EXPORT_SYMBOL_GPL(iio_read_acpi_mount_matrix);