Hi Geert, On Wed, Jan 15, 2020 at 07:15:18PM +0100, Geert Uytterhoeven wrote: > Hi all, > > GPIO controllers are exported to userspace using /dev/gpiochip* > character devices. Access control to these devices is provided by > standard UNIX file system permissions, on an all-or-nothing basis: > either a GPIO controller is accessible for a user, or it is not. > Currently no mechanism exists to control access to individual GPIOs. > > Hence this adds a GPIO driver to aggregate existing GPIOs, and expose > them as a new gpiochip. This is useful for implementing access control, > and assigning a set of GPIOs to a specific user. Furthermore, this > simplifies and hardens exporting GPIOs to a virtual machine, as the VM > can just grab the full GPIO controller, and no longer needs to care > about which GPIOs to grab and which not, reducing the attack surface. > > Recently, other use cases have been discovered[1]: > - Describing simple GPIO-operated devices in DT, and using the GPIO > Aggregator as a generic GPIO driver for userspace, which is useful > for industrial control. As per comments and test results in [*] (accidentally attached to v3): Reviewed-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> Tested-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> [*] https://lore.kernel.org/linux-renesas-soc/20200120121439.GA24951@xxxxxxxxxxxxxxxxxxxx/ ("Re: [PATCH v3 0/7] gpio: Add GPIO Aggregator/Repeater") -- Best Regards, Eugeniu Rosca
