Re: [PATCH v2 2/2] ARM: dts: am33xx: Move wkup_m3 node to soc node and add ranges

[Tony Lindgren]

* Dave Gerlach <d-gerlach@xxxxxx> [150310 12:55]:
> Tony,
> On 03/10/2015 11:09 AM, Tony Lindgren wrote:
> > * Suman Anna <s-anna@xxxxxx> [150309 16:59]:
> >> On 03/05/2015 10:57 AM, Tony Lindgren wrote:
> >>> * Suman Anna <s-anna@xxxxxx> [150305 08:47]:
> >>>> On 03/05/2015 09:40 AM, Tony Lindgren wrote:
> >>>>> * Dave Gerlach <d-gerlach@xxxxxx> [150304 20:14]:
> >>>> Dave,
> >>>>
> >>>> Looks like the commit message disappeared during your patch preparation.
> >>>>
> >>>>>> Signed-off-by: Suman Anna <s-anna@xxxxxx>
> >>>>>> Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> >>>>>> ---
> >>>>>>  arch/arm/boot/dts/am33xx.dtsi | 21 +++++++++++++--------
> >>>>>>  1 file changed, 13 insertions(+), 8 deletions(-)
> >>>>>>
> >>>>>> diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi
> >>>>>> index acd3705..086415c 100644
> >>>>>> --- a/arch/arm/boot/dts/am33xx.dtsi
> >>>>>> +++ b/arch/arm/boot/dts/am33xx.dtsi
> >>>>>> @@ -77,10 +77,23 @@
> >>>>>>  	 */
> >>>>>>  	soc {
> >>>>>>  		compatible = "ti,omap-infra";
> >>>>>> +		#address-cells = <1>;
> >>>>>> +		#size-cells = <1>;
> >>>>>> +		ranges = <0x0     0x44d00000 0x4000>,
> >>>>>> +			 <0x80000 0x44d80000 0x2000>;
> >>>>>> +
> >>>>>
> >>>>> I think putting the ranges here will cause issues for adding
> >>>>> ranges for anything else.
> >>>>>
> >>>>> How about do something like this instead (untested):
> >>>>>
> >>>>> ocp {
> >>>>> 	l4_wkup: l4_wkup@44c00000 {
> >>>>> 		compatible = "am335-l4-wkup", "simple-bus";
> >>>>> 		ranges = <0 0x44c00000 0x3fffff>;
> >>>>>
> >>>>> 		wkup_m3: wkup_m3@44d00000 {
> >>>>> 			compatible = "ti,am3353-wkup-m3";
> >>>>> 			reg = <0x1000000     0x4000>,	/* M3 UMEM */
> >>>>> 			      <0x180000	     0x2000>;	/* M3 DMEM */
> >>>>> 			ti,hwmods = "wkup_m3";
> >>>>> 			ti,pm-firmware = "am335x-pm-firmware.elf";
> >>>>> 		};
> >>>>>
> >>>>> 		...
> >>>>> 	};
> >>>>> };
> >>>>>
> >>>>> That way we can start moving also the other l4_wkup components there
> >>>>> eventuallly without having to redo the ranges again for wkup_m3.
> >>>>>
> >>>>> You can also look at how the scm_conf was done for dm816x.dtsi for an
> >>>>> example, and the recent large set of patches posted by Tero.
> >>
> >> I have taken a look at both the above. The L4_WKUP range includes the
> >> PRCM, Control Module, as well as a few peripherals like DMTimer0, UART0
> >> etc. What all do we want to move here eventually?
> > 
> > Well eventually all the children of L4_WKUP, but that can be done
> > slowly as some of the drivers have weird hacks and may not work
> > properly if moved around.
> > 
> > For example, anything with reg entries for something like SCM area will
> > break as that's not going to be in the L4_WKUP area ny longer :p And
> > that's actually good as it will protect us from spaghetti code
> > automatically later on for new code.
> > 
> >> Depending on that, we may have to use 2 address cells like in Tero's
> >> PRCM cleanup series rather than the single cell translation used by
> >> you in dm816x.dtsi so that we can retain the relative addresses
> >> w.r.t the existing node bases in the derivative child nodes.
> > 
> > Hmm OK, care to paste a dts snippet example for that?
> 
> Suman and I have been looking at this together, so I can comment here. An
> implementation like this is what Suman is referring to:
> 
> +               l4_wkup: l4_wkup@44c00000 {
> +                       compatible = "am335-l4-wkup", "simple-bus";
> +                       #address-cells = <2>;
> +                       #size-cells = <1>;
> +                       ranges = <0 0           0x44c00000 0x100000>,
> +                                <1 0x0         0x44d00000 0x4000>,
> +                                <2 0x80000     0x44d80000 0x2000>;
> +
> +                       wkup_m3: wkup_m3@1,0 {
> +                               compatible = "ti,am3353-wkup-m3";
> +                               reg = <1 0x0     0x4000>,       /* M3 UMEM */
> +                                     <2 0x80000 0x2000>;       /* M3 DMEM */
> +
> +                               ti,hwmods = "wkup_m3";
> +                               ti,pm-firmware = "am335x-pm-firmware.elf";
> +                       };
> +               };
> +
> 
> The of_* layer automatically translates everything so the pdata-quirks can still
> match based on wkup_m3@44d00000. The existing wkup_m3_rproc driver works almost
> entirely as is with this, all cpu addresses are read and mapped correctly but
> the driver no longer will read the actual device addresses correctly which we
> need for understanding where to load the firmware sections.

OK. I still don't quite understand how these additional ranges make sense
for other drivers connected to the l4_wkup. For wkup_m3, it makes sense if
it allows you to translate directly to the m3 address space, but is that
really the case here? Maybe you should have the ranges in wkup_m3 instead
if you want addresses for the m3?

> These device addresses are being read directly using of_get_address, which reads
> the first value in the reg entries which is 1 and 2 now for UMEM and DMEM. We
> would need some sort of change there also to get the proper 0x0 and 0x80000
> device address values. Just advancing the pointer returned by of_get_address
> does the trick but this doesn't seem like the cleanest solution.

I'd assume we have similar uses of range already.. Maybe look at some pcie
examples and how they use ranges for the bus address translation? 

Regards,

Tony
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