projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 9f986a8c DB |
1 | What: /sys/class/gpio/ |
| 2 | Date: July 2008 | |
| 3 | KernelVersion: 2.6.27 | |
| 4 | Contact: David Brownell <dbrownell@users.sourceforge.net> | |
| 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 | |
| 14 | the range 0..INT_MAX. See Documentation/gpio.txt for more information. | |
| 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 | |
| 19 | /gpioN ... for each exported GPIO #N | |
| 20 | /value ... always readable, writes fail for input GPIOs | |
| 21 | /direction ... r/w as: in, out (default low); write: high, low | |
| ff77c352 | 22 | /edge ... r/w as: none, falling, rising, both |
| 9f986a8c DB |
23 | /gpiochipN ... for each gpiochip; #N is its first GPIO |
| 24 | /base ... (r/o) same as N | |
| 25 | /label ... (r/o) descriptive, not necessarily unique | |
| 26 | /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) | |
| 27 |