1.. SPDX-License-Identifier: GPL-2.0
 2
 3.. _gpio_errors:
 4
 5*******************
 6GPIO Error Codes
 7*******************
 8
 9.. _gpio-errors:
10
11.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
12
13.. flat-table:: Common GPIO error codes
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17
18    -  -  ``EAGAIN`` (aka ``EWOULDBLOCK``)
19
20       -  The device was opened in non-blocking mode and a read can't
21          be performed as there is no data available.
22
23    -  -  ``EBADF``
24
25       -  The file descriptor is not valid.
26
27    -  -  ``EBUSY``
28
29       -  The ioctl can't be handled because the device is busy. Typically
30          returned when an ioctl attempts something that would require the
31          usage of a resource that was already allocated. The ioctl must not
32          be retried without performing another action to fix the problem
33          first.
34
35    -  -  ``EFAULT``
36
37       -  There was a failure while copying data from/to userspace, probably
38	  caused by an invalid pointer reference.
39
40    -  -  ``EINVAL``
41
42       -  One or more of the ioctl parameters are invalid or out of the
43          allowed range. This is a widely used error code.
44
45    -  -  ``ENODEV``
46
47       -  Device not found or was removed.
48
49    -  -  ``ENOMEM``
50
51       -  There's not enough memory to handle the desired operation.
52
53    -  -  ``EPERM``
54
55       -  Permission denied. Typically returned in response to an attempt
56          to perform an action incompatible with the current line
57          configuration.
58
59    -  -  ``EIO``
60
61       -  I/O error. Typically returned when there are problems communicating
62          with a hardware device or requesting features that hardware does not
63          support. This could indicate broken or flaky hardware.
64          It's a 'Something is wrong, I give up!' type of error.
65
66    -  - ``ENXIO``
67
68       -  Typically returned when a feature requiring interrupt support was
69          requested, but the line does not support interrupts.
70
71.. note::
72
73  #. This list is not exhaustive; ioctls may return other error codes.
74     Since errors may have side effects such as a driver reset,
75     applications should abort on unexpected errors, or otherwise
76     assume that the device is in a bad state.
77
78  #. Request-specific error codes are listed in the individual
79     requests descriptions.