diff options
-rw-r--r-- | Documentation/gpio/index.rst | 17 | ||||
-rw-r--r-- | Documentation/gpio/sysfs.rst (renamed from Documentation/gpio/sysfs.txt) | 39 |
2 files changed, 42 insertions, 14 deletions
diff --git a/Documentation/gpio/index.rst b/Documentation/gpio/index.rst new file mode 100644 index 000000000000..09a4a553f434 --- /dev/null +++ b/Documentation/gpio/index.rst @@ -0,0 +1,17 @@ +:orphan: + +==== +gpio +==== + +.. toctree:: + :maxdepth: 1 + + sysfs + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.rst index 58eeab81f349..ec09ffd983e7 100644 --- a/Documentation/gpio/sysfs.txt +++ b/Documentation/gpio/sysfs.rst @@ -1,10 +1,12 @@ GPIO Sysfs Interface for Userspace ================================== -THIS ABI IS DEPRECATED, THE ABI DOCUMENTATION HAS BEEN MOVED TO -Documentation/ABI/obsolete/sysfs-gpio AND NEW USERSPACE CONSUMERS -ARE SUPPOSED TO USE THE CHARACTER DEVICE ABI. THIS OLD SYSFS ABI WILL -NOT BE DEVELOPED (NO NEW FEATURES), IT WILL JUST BE MAINTAINED. +.. warning:: + + THIS ABI IS DEPRECATED, THE ABI DOCUMENTATION HAS BEEN MOVED TO + Documentation/ABI/obsolete/sysfs-gpio AND NEW USERSPACE CONSUMERS + ARE SUPPOSED TO USE THE CHARACTER DEVICE ABI. THIS OLD SYSFS ABI WILL + NOT BE DEVELOPED (NO NEW FEATURES), IT WILL JUST BE MAINTAINED. Refer to the examples in tools/gpio/* for an introduction to the new character device ABI. Also see the userspace header in @@ -51,13 +53,15 @@ The control interfaces are write-only: /sys/class/gpio/ - "export" ... Userspace may ask the kernel to export control of + "export" ... + Userspace may ask the kernel to export control of a GPIO to userspace by writing its number to this file. Example: "echo 19 > export" will create a "gpio19" node for GPIO #19, if that's not requested by kernel code. - "unexport" ... Reverses the effect of exporting to userspace. + "unexport" ... + Reverses the effect of exporting to userspace. Example: "echo 19 > unexport" will remove a "gpio19" node exported using the "export" file. @@ -67,7 +71,8 @@ and have the following read/write attributes: /sys/class/gpio/gpioN/ - "direction" ... reads as either "in" or "out". This value may + "direction" ... + reads as either "in" or "out". This value may normally be written. Writing as "out" defaults to initializing the value as low. To ensure glitch free operation, values "low" and "high" may be written to @@ -78,7 +83,8 @@ and have the following read/write attributes: it was exported by kernel code that didn't explicitly allow userspace to reconfigure this GPIO's direction. - "value" ... reads as either 0 (low) or 1 (high). If the GPIO + "value" ... + reads as either 0 (low) or 1 (high). If the GPIO is configured as an output, this value may be written; any nonzero value is treated as high. @@ -92,14 +98,16 @@ and have the following read/write attributes: file and read the new value or close the file and re-open it to read the value. - "edge" ... reads as either "none", "rising", "falling", or + "edge" ... + reads as either "none", "rising", "falling", or "both". Write these strings to select the signal edge(s) that will make poll(2) on the "value" file return. This file exists only if the pin can be configured as an interrupt generating input pin. - "active_low" ... reads as either 0 (false) or 1 (true). Write + "active_low" ... + reads as either 0 (false) or 1 (true). Write any nonzero value to invert the value attribute both for reading and writing. Existing and subsequent poll(2) support configuration via the edge attribute @@ -112,11 +120,14 @@ read-only attributes: /sys/class/gpio/gpiochipN/ - "base" ... same as N, the first GPIO managed by this chip + "base" ... + same as N, the first GPIO managed by this chip - "label" ... provided for diagnostics (not always unique) + "label" ... + provided for diagnostics (not always unique) - "ngpio" ... how many GPIOs this manages (N to N + ngpio - 1) + "ngpio" ... + how many GPIOs this manages (N to N + ngpio - 1) Board documentation should in most cases cover what GPIOs are used for what purposes. However, those numbers are not always stable; GPIOs on @@ -129,7 +140,7 @@ the correct GPIO number to use for a given signal. Exporting from Kernel code -------------------------- Kernel code can explicitly manage exports of GPIOs which have already been -requested using gpio_request(): +requested using gpio_request():: /* export the GPIO to userspace */ int gpiod_export(struct gpio_desc *desc, bool direction_may_change); |