Re: [PATCHv9 03/18] TEMP: OMAP3xxx: hwmod data: add PRM hwmod

[Cousson, Benoit]

On 10/13/2011 6:51 PM, Paul Walmsley wrote:
> On Thu, 13 Oct 2011, Paul Walmsley wrote:
>
> > On Wed, 12 Oct 2011, Cousson, Benoit wrote:
> >
> > > On 10/11/2011 1:26 AM, Paul Walmsley wrote:
> > > > On Tue, 11 Oct 2011, Cousson, Benoit wrote:
> > > >
> > > > > In fact the device name does not have to match the hwmod name. So we
> > > > > can just create an "omap2_prm" omap_device for OMAP2, "omap3_prm"
> > > > > omap_device for OMAP3... That will allow the relevant PRM driver to
> > > > > be bound to the proper device.
> > > >
> > > > Incidentally, given that we would be using the hwmod name and the version
> > > > number to determine the appropriate omap_device name, what IP version
> > > > numbers should we assign to these PRM IP blocks for different SoCs?
> > >
> > > It can just be 1, 2 and 3... The idea is just to differentiate the IP for each
> > > OMAP.
> >
> > So those are basically arbitrary?  Something is not clear here.
> >
> > In the current hwmod design, IP blocks with different interfaces were
> > intended to be uniquely identified by the hwmod name alone.  That is why
> > omap_hwmod_lookup() only takes a 'name' parameter.
> >
> > If I understand what you want to do, you wish to change this to uniquely
> > identify them by a (name, interface version number) tuple.
> >
> > I don't have a problem with this in theory, but it implies some changes to
> > the existing model.  Specifically:
> >
> > - we'll need to add an interface version number to the struct omap_hwmod
> >
> > - we'll need to modify omap_hwmod_lookup() to take an interface version
> > number
> >
> > - the "ti,hwmod" DT binding that you proposed earlier will need to include
> > an interface version number
>
> Hmm, reflecting on this further, is your intention to bind drivers to
> hwmods by the struct omap_hwmod_class instead?

Well, somehow, the class was added for that purpose, to allow one timer 
driver to bind to 2 different hwmods. But in that case the device name 
was the same.

> If we define that "rev" field as the interface version number, that should
> probably work.
>
> So then in C struct format, in a platform_device system, the mapping table
> would basically become
>
> struct omap_hwmod_driver_map {
> 	const char *class_name;
> 	const u32 class_rev;
> 	const char *platform_device_name;
> }

This is needed if and only if you want to have a different driver for 
the same IP.

In the case of the timer, we do have only one device name and one driver:
class=timer, rev=1, device=omap_timer
class=timer, rev=2, device=omap_timer

Regards,
Benoit
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