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Diffstat (limited to 'Documentation/driver-api/gpio/legacy.rst')
| -rw-r--r-- | Documentation/driver-api/gpio/legacy.rst | 21 |
1 files changed, 0 insertions, 21 deletions
diff --git a/Documentation/driver-api/gpio/legacy.rst b/Documentation/driver-api/gpio/legacy.rst index e0306e78e34b..78372853c6d4 100644 --- a/Documentation/driver-api/gpio/legacy.rst +++ b/Documentation/driver-api/gpio/legacy.rst @@ -714,27 +714,6 @@ gpiochip nodes (possibly in conjunction with schematics) to determine 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():: - - /* export the GPIO to userspace */ - int gpio_export(unsigned gpio, bool direction_may_change); - - /* reverse gpio_export() */ - void gpio_unexport(); - -After a kernel driver requests a GPIO, it may only be made available in -the sysfs interface by gpio_export(). The driver can control whether the -signal direction may change. This helps drivers prevent userspace code -from accidentally clobbering important system state. - -This explicit exporting can help with debugging (by making some kinds -of experiments easier), or can provide an always-there interface that's -suitable for documenting as part of a board support package. - - API Reference ============= |