sdio
====
Probes all SDIO devices listed in the sysfs ``/sys/bus/sdio/devices/``.

Function Arguments
------------------
.. list-table::
   :widths: 20 10 60
   :header-rows: 1
   :align: left

   * - Name
     - Type
     - Description

   * - dir_path
     - str, None
     - (optional; default: ``None``) The path used to search for device sysfs data. First all symlinks are resolved, to the the "real" path. Then iteratively search toward parent folder until the remaining path contains the relevent data fields.

Description
-----------
This function goes through ``/sys/bus/sdio/devices/`` to read attributes of
each SDIO device listed there.  Each result should contain these fields:

- ``device_path``: Pathname of the sysfs directory.
- ``vendor``
- ``device``

Examples
--------
Let's say the Chromebook has two SDIO devices.  One of which
(at ``/sys/bus/sdio/devices/mmc1:0001:1``) has the attributes:

- ``vendor=0x0123``
- ``device=0x4567``

And the other one (at ``/sys/bus/sdio/devices/mmc1:0002:1``) has the
attributes:

- ``vendor=0x0246``
- ``device=0x1357``


Then the probe statement::

  {
    "eval": "sdio"
  }

will have the corresponding probed result::

  [
    {
      "bus_type": "sdio",
      "vendor": "0123",
      "device": "4567"
    },
    {
      "bus_type": "sdio",
      "vendor": "0246",
      "device": "1357"
    }
  ]

To verify if the Chromebook has SDIO device which ``vendor`` is ``0x0246``,
you can write a probe statement like::

  {
    "eval": "sdio",
    "expect": {
      "vendor": "0246"
    }
  }

The corresponding probed result will be empty if and only if there's no
SDIO device which ``vendor`` is ``0x0246`` found.