1// SPDX-License-Identifier: GPL-2.0-only
2/* IIO ACPI helper functions */
3
4#include <linux/acpi.h>
5#include <linux/dev_printk.h>
6#include <linux/iio/iio.h>
7#include <linux/sprintf.h>
8
9/**
10 * iio_read_acpi_mount_matrix() - Read accelerometer mount matrix info from ACPI
11 * @dev:		Device structure
12 * @orientation:	iio_mount_matrix struct to fill
13 * @acpi_method:	ACPI method name to read the matrix from, usually "ROTM"
14 *
15 * Try to read the mount-matrix by calling the specified method on the device's
16 * ACPI firmware-node. If the device has no ACPI firmware-node; or the method
17 * does not exist then this will fail silently. This expects the method to
18 * return data in the ACPI "ROTM" format defined by Microsoft:
19 * https://learn.microsoft.com/en-us/windows-hardware/drivers/sensors/sensors-acpi-entries
20 * This is a Microsoft extension and not part of the official ACPI spec.
21 * The method name is configurable because some dual-accel setups define 2 mount
22 * matrices in a single ACPI device using separate "ROMK" and "ROMS" methods.
23 *
24 * Returns: true if the matrix was successfully, false otherwise.
25 */
26bool iio_read_acpi_mount_matrix(struct device *dev,
27				struct iio_mount_matrix *orientation,
28				char *acpi_method)
29{
30	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
31	struct acpi_device *adev = ACPI_COMPANION(dev);
32	char *str;
33	union acpi_object *obj, *elements;
34	acpi_status status;
35	int i, j, val[3];
36	bool ret = false;
37
38	if (!adev || !acpi_has_method(adev->handle, acpi_method))
39		return false;
40
41	status = acpi_evaluate_object(adev->handle, acpi_method, NULL, &buffer);
42	if (ACPI_FAILURE(status)) {
43		dev_err(dev, "Failed to get ACPI mount matrix: %d\n", status);
44		return false;
45	}
46
47	obj = buffer.pointer;
48	if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 3) {
49		dev_err(dev, "Unknown ACPI mount matrix package format\n");
50		goto out_free_buffer;
51	}
52
53	elements = obj->package.elements;
54	for (i = 0; i < 3; i++) {
55		if (elements[i].type != ACPI_TYPE_STRING) {
56			dev_err(dev, "Unknown ACPI mount matrix element format\n");
57			goto out_free_buffer;
58		}
59
60		str = elements[i].string.pointer;
61		if (sscanf(str, "%d %d %d", &val[0], &val[1], &val[2]) != 3) {
62			dev_err(dev, "Incorrect ACPI mount matrix string format\n");
63			goto out_free_buffer;
64		}
65
66		for (j = 0; j < 3; j++) {
67			switch (val[j]) {
68			case -1: str = "-1"; break;
69			case 0:  str = "0";  break;
70			case 1:  str = "1";  break;
71			default:
72				dev_err(dev, "Invalid value in ACPI mount matrix: %d\n", val[j]);
73				goto out_free_buffer;
74			}
75			orientation->rotation[i * 3 + j] = str;
76		}
77	}
78
79	ret = true;
80
81out_free_buffer:
82	kfree(buffer.pointer);
83	return ret;
84}
85EXPORT_SYMBOL_GPL(iio_read_acpi_mount_matrix);
86