Re: [patch/rfc 2/4] pcf875x I2C GPIO expander driver

[Trent Piepho]

On Fri, 30 Nov 2007, David Brownell wrote:
> On Friday 30 November 2007, Jean Delvare wrote:
> > So the user-space interface would be part of the generic GPIO
> > infrastructure? I like the idea.
>
> I thought that would make sense too! :)  Someone would need to
> write the code though.  Having such a mechanism would provide
> another "carrot" to migrate folk towards the gpiolib core.

Here's some code to do this.  It's not entirely perfect yet, but it is
usable.  I create a directory in sysfs (class/gpio/<name>:<num>) for each
gpio line.  The are files in this directory to allow reading/setting the
gpio value and direction.  One can also see the label associated with the
gpio if gpiolib is keeping track of labels (i.e.  debugfs is on).  sysfs
also creates a gpio directory under the device associated with the gpio
lines (this is a new thing one needs to add) with that device's gpios. 
Actually, think these are "real" sysfs directories, and the ones in
/sys/class are copies made by sysfs.

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