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Commit | Line | Data |
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9f986a8c DB |
1 | What: /sys/class/gpio/ |
2 | Date: July 2008 | |
3 | KernelVersion: 2.6.27 | |
fe95046e | 4 | Contact: Linus Walleij <linusw@kernel.org> |
9f986a8c DB |
5 | Description: |
6 | ||
7 | As a Kconfig option, individual GPIO signals may be accessed from | |
8 | userspace. GPIOs are only made available to userspace by an explicit | |
9 | "export" operation. If a given GPIO is not claimed for use by | |
10 | kernel code, it may be exported by userspace (and unexported later). | |
11 | Kernel code may export it for complete or partial access. | |
12 | ||
13 | GPIOs are identified as they are inside the kernel, using integers in | |
ec15872d | 14 | the range 0..INT_MAX. See Documentation/gpio for more information. |
9f986a8c DB |
15 | |
16 | /sys/class/gpio | |
17 | /export ... asks the kernel to export a GPIO to userspace | |
18 | /unexport ... to return a GPIO to the kernel | |
77a775b7 LW |
19 | /gpioN ... for each exported GPIO #N OR |
20 | /<LINE-NAME> ... for a properly named GPIO line | |
9f986a8c DB |
21 | /value ... always readable, writes fail for input GPIOs |
22 | /direction ... r/w as: in, out (default low); write: high, low | |
ff77c352 | 23 | /edge ... r/w as: none, falling, rising, both |
9f986a8c DB |
24 | /gpiochipN ... for each gpiochip; #N is its first GPIO |
25 | /base ... (r/o) same as N | |
26 | /label ... (r/o) descriptive, not necessarily unique | |
27 | /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) | |
28 | ||
fe95046e LW |
29 | This ABI is deprecated and will be removed after 2020. It is |
30 | replaced with the GPIO character device. |