On Wed, 31 Oct 2012 18:04:09 +0900, Alex Courbot <acour...@nvidia.com> wrote: > Hi, > > Would anyone be opposed to having a gpio_get() function that works similarly > to e.g. regulator_get() and clk_get()? > > I can see some good reasons to have this: > > - Less platform data to pass to drivers, > - Consistency between different subsystems. Regulator, clock, PWM, ... all > use > this scheme. > - The "device-specific indirection" could make some DT structures more > reusable. Right now the only way to address a GPIO through the DT is via a > phandle that includes the GPIO number - thus hard-coded. > > The implementation would be rather simple, and the function would just return > the right GPIO number (acquired through gpio_request).
I've got no problem with it, but the devil is in the API details. Draft something up (unless you already have and I just haven't seen it yet... I'll get to it). :-) BTW, I would prefer a system that resolves the gpio at .probe() time instead of at registration time. That makes deferred probing easier. g. > > Rationale for this: I would like to be able to share power sequences between > devices, e.g. to completely extract the per-device resources from the > sequence. Every power sequence step references either a regulator, PWM, or > GPIO. For regulators and PWMs separation is easy because their subsystems > provide regulator_get() and pwm_get() which allow the resource to be > referenced by name in the sequence, and resolved to different instances > depending on the device. GPIOs, on the other hand, can only be referenced by > number - and that makes it necessary to duplicate the sequence's structure in > memory for every device that may use it. It if was possible to reference > GPIOs > by names that resolve to different GPIO numbers according to the device, then > the problem would be solved. > > There are probably other use-cases that would benefit from this, if you know > of > one please feel free to share. > > Thanks, > Alex. > -- Grant Likely, B.Sc, P.Eng. Secret Lab Technologies, Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
