Re: RFC: gpio attachment for ppbus

[Hans Rosenfeld <rosenfeld%grumpf.hope-2000.org@localhost>]

On Mon, Apr 28, 2008 at 05:59:24PM -0400, der Mouse wrote:
> One thing I would suggest is that you document which order the data
> pins and the control pins are written in, when changing both.  (Or does
> the scaffolding allow userland to control that order?  I don't know
> gpiobus.)

The current gpio API does not allow changing more than one pin at a
time, so you are forced to implement the order yourself. There is also
no distinction between data pins, status pins and control pins, they are
all just gpio pins. 

For some future extension of the gpio driver, I thought about adding an
ioctl() to specify a sequence of operations to perform, complete with
timing information. The actual operations would still be carried out
sequentially by the gpio driver, but you wouldn't need an ioctl() for
every read or write of a pin. But this still needs some more thought.


-- 
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