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/device.h>
   6 #include <linux/export.h>
   7 #include <linux/iio/iio.h>
   8 #include <linux/sprintf.h>
   9
  10 /**
  11  * iio_read_acpi_mount_matrix() - Read accelerometer mount matrix info from ACPI
  12  * @dev:                Device structure
  13  * @orientation:        iio_mount_matrix struct to fill
  14  * @acpi_method:        ACPI method name to read the matrix from, usually "ROTM"
  15  *
  16  * Try to read the mount-matrix by calling the specified method on the device's
  17  * ACPI firmware-node. If the device has no ACPI firmware-node; or the method
  18  * does not exist then this will fail silently. This expects the method to
  19  * return data in the ACPI "ROTM" format defined by Microsoft:
  20  * https://learn.microsoft.com/en-us/windows-hardware/drivers/sensors/sensors-acpi-entries
  21  * This is a Microsoft extension and not part of the official ACPI spec.
  22  * The method name is configurable because some dual-accel setups define 2 mount
  23  * matrices in a single ACPI device using separate "ROMK" and "ROMS" methods.
  24  *
  25  * Returns: true if the matrix was successfully, false otherwise.
  26  */
  27 bool iio_read_acpi_mount_matrix(struct device *dev,
  28                                 struct iio_mount_matrix *orientation,
  29                                 char *acpi_method)
  30 {
  31         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  32         char *str;
  33         union acpi_object *obj, *elements;
  34         acpi_handle handle;
  35         acpi_status status;
  36         int i, j, val[3];
  37         bool ret = false;
  38
  39         handle = ACPI_HANDLE(dev);
  40         if (!handle)
  41                 return false;
  42
  43         if (!acpi_has_method(handle, acpi_method))
  44                 return false;
  45
  46         status = acpi_evaluate_object(handle, acpi_method, NULL, &buffer);
  47         if (ACPI_FAILURE(status)) {
  48                 dev_err(dev, "Failed to get ACPI mount matrix: %d\n", status);
  49                 return false;
  50         }
  51
  52         obj = buffer.pointer;
  53         if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 3) {
  54                 dev_err(dev, "Unknown ACPI mount matrix package format\n");
  55                 goto out_free_buffer;
  56         }
  57
  58         elements = obj->package.elements;
  59         for (i = 0; i < 3; i++) {
  60                 if (elements[i].type != ACPI_TYPE_STRING) {
  61                         dev_err(dev, "Unknown ACPI mount matrix element format\n");
  62                         goto out_free_buffer;
  63                 }
  64
  65                 str = elements[i].string.pointer;
  66                 if (sscanf(str, "%d %d %d", &val[0], &val[1], &val[2]) != 3) {
  67                         dev_err(dev, "Incorrect ACPI mount matrix string format\n");
  68                         goto out_free_buffer;
  69                 }
  70
  71                 for (j = 0; j < 3; j++) {
  72                         switch (val[j]) {
  73                         case -1: str = "-1"; break;
  74                         case 0:  str = "0";  break;
  75                         case 1:  str = "1";  break;
  76                         default:
  77                                 dev_err(dev, "Invalid value in ACPI mount matrix: %d\n", val[j]);
  78                                 goto out_free_buffer;
  79                         }
  80                         orientation->rotation[i * 3 + j] = str;
  81                 }
  82         }
  83
  84         ret = true;
  85
  86 out_free_buffer:
  87         kfree(buffer.pointer);
  88         return ret;
  89 }
  90 EXPORT_SYMBOL_GPL(iio_read_acpi_mount_matrix);
  91
  92 /**
  93  * iio_get_acpi_device_name_and_data() - Return ACPI device instance name and driver data
  94  * @dev:                Device structure
  95  * @data:               Optional pointer to return driver data
  96  *
  97  * When device was enumerated by ACPI ID matching, the user might
  98  * want to set description for the physical chip. In such cases
  99  * the ACPI device instance name might be used. This call may be
 100  * performed to retrieve this information.
 101  *
 102  * NOTE: This helper function exists only for backward compatibility,
 103  * do not use in a new code!
 104  *
 105  * Returns: ACPI device instance name or %NULL.
 106  */
 107 const char *iio_get_acpi_device_name_and_data(struct device *dev, const void **data)
 108 {
 109         const struct acpi_device_id *id;
 110         acpi_handle handle;
 111
 112         handle = ACPI_HANDLE(dev);
 113         if (!handle)
 114                 return NULL;
 115
 116         id = acpi_match_device(dev->driver->acpi_match_table, dev);
 117         if (!id)
 118                 return NULL;
 119
 120         if (data)
 121                 *data = (const void *)id->driver_data;
 122
 123         return dev_name(dev);
 124 }
 125 EXPORT_SYMBOL_GPL(iio_get_acpi_device_name_and_data);