Re: UIO device name

[Paul Mundt <lethal@linux-sh.org>]

On Wed, Sep 24, 2008 at 11:57:59AM +0200, Joakim Tjernlund wrote:
> On Wed, 2008-09-24 at 18:35 +0900, Paul Mundt wrote:
> > On Wed, Sep 24, 2008 at 11:21:33AM +0200, Joakim Tjernlund wrote:
> > > As far as I can see there isn't a way to name the /dev/uio%d device file
> > > to something more useful, is that so?
> > > I would like to name the device file from within the kernel so I can
> > > find the correct device from userspace.
> > > The very least is to control the minor(%d) number.
> > > 
> > You have a couple of options for this:
> > 
> > 	- the 'name' sysfs entry for each of the uio devices, which
> > 	  corresponds to the uio device name.
> > 	- extracting the relevant data from things like 'lsuio'.
> > 	- hooking in the pretty mame through udev to create an alias.
> 
> Right, but I want to do it from within the kernel when I create the
> device because that the only place I truly know what HW the uio maps to.
> 
> I found that this works:
>  struct uio_info *info,
>  struct uio_device *idev;
> 
>  idev = info->uio_dev;
>  device_rename(idev->dev, "irq4");
> 
> but then I have to copy the private uio_device struct from uio.c
> Is there a better way to get at idev->dev?
> 
I fail to see what this will buy you that you can't already do with udev
(or a set of scripts that look at sysfs) today. "the only place I truly
know what HW the uio maps to" doesn't make any sense, the name is fully
preserved and exposed. If you can't figure out your device from looking
at /sys/class/uio/uio?/name, I'm not sure how a rename is going to make
any difference.

If you need to poke at uio private data, you are almost certainly doing
something wrong.