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