Re: [PATCH V2 2/9] Documentation: devicetree: Add DT bindings for UFS host controller

[Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org>]

On Wed, May 15, 2013 at 12:51:12PM +0530, Sujit Reddy Thumma wrote:
> On 5/14/2013 11:38 PM, Olof Johansson wrote:
> >On Tue, May 14, 2013 at 12:08 AM, Dolev Raviv <draviv-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> wrote:
> >>Compatible list is used in commit 03b1781 but is not documented.
> >>Add necessary device tree bindings to describe on-chip UFS host
> >>controllers.
> >>
> >>Signed-off-by: Sujit Reddy Thumma <sthumma-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> >>
> >>diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> >>new file mode 100644
> >>index 0000000..20468b2
> >>--- /dev/null
> >>+++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> >>@@ -0,0 +1,16 @@
> >>+* Universal Flash Storage (UFS) Host Controller
> >>+
> >>+UFSHC nodes are defined to describe on-chip UFS host controllers.
> >>+Each UFS controller instance should have its own node.
> >>+
> >>+Required properties:
> >>+- compatible        : compatible list, contains "jedec,ufs-1.1"
> >>+- interrupts        : <interrupt mapping for UFS host controller IRQ>
> >>+- reg               : <registers mapping>
> >>+
> >>+Example:
> >>+       ufshc@0xfc598000 {
> >>+               compatible = "jedec,ufs-1.1";
> >
> >Hmm.
> >
> >Does jedec really specify the programming interface of this type of
> >device, register layout and meaning? It seems to be more about the
> >command set and electrical/connectivity specifications, no?
> 
> That's true with UFS device specification. For UFS Host Controller
> specification Jedec indeed standardized the hardware registers,
> memory structures and register programming sequence to talk to UFS
> device.

Ok, fair enough. However, I think "jedec,ufshc-1.1" would be more
appropriate to avoid ambiguities. Compare to SD where "sdhci" is the
only compatible string used for the standard interface.


-Olof