drivers/iio/industrialio-acpi.c

   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);