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  */
iio_read_acpi_mount_matrix(struct device * dev,struct iio_mount_matrix * orientation,char * acpi_method)26 bool 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 
81 out_free_buffer:
82 	kfree(buffer.pointer);
83 	return ret;
84 }
85 EXPORT_SYMBOL_GPL(iio_read_acpi_mount_matrix);
86