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