1 .. SPDX-License-Identifier: GPL-2.0-only
2
3 GPIO Testing Driver
4 ===================
5
6 .. note::
7
8 This module has been obsoleted by the more
9 New developments should use that API and ex
10 encouraged to migrate as soon as possible.
11 This module will continue to be maintained
12 added.
13
14 The GPIO Testing Driver (gpio-mockup) provides
15 chips for testing purposes. The lines exposed
16 using the standard GPIO character device inter
17 using the dedicated debugfs directory structur
18
19 Creating simulated chips using module params
20 --------------------------------------------
21
22 When loading the gpio-mockup driver a number o
23 module.
24
25 gpio_mockup_ranges
26
27 This parameter takes an argument in th
28 pairs. Each pair defines the base GPIO
29 and the first number after the last of
30 is -1, the gpiolib will assign it auto
31 parameter is the number of lines expos
32
33 Example: gpio_mockup_ranges=-1,8,-1,16
34
35 The line above creates three chips. Th
36 the second 16 and the third 4. The bas
37 to 405 while for two first chips it wi
38
39 gpio_mockup_named_lines
40
41 This parameter doesn't take any argume
42 GPIO lines exposed by it should be nam
43
44 The name format is: gpio-mockup-X-Y wh
45 and Y is the line offset.
46
47 Manipulating simulated lines
48 ----------------------------
49
50 Each mockup chip creates its own subdirectory
51 The directory is named after the chip's label.
52 after the chip's name, which points to the lab
53
54 Inside each subdirectory, there's a separate a
55 name of the attribute represents the line's of
56
57 Reading from a line attribute returns the curr
58 changes the configuration of the simulated pul
59 (1 - pull-up, 0 - pull-down).
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