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 */ 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