Re: [PATCH 5/9] ARM: dts: Add GPMC node for OMAP2, OMAP4 and OMAP5

[Jon Hunter <jon-hunter@ti.com>]

On 03/08/2013 02:25 PM, Javier Martinez Canillas wrote:
> On Fri, Mar 8, 2013 at 6:27 PM, Jon Hunter <jon-hunter@ti.com> wrote:
>> Add the device-tree node for GPMC on OMAP2, OMAP4 and OMAP5 devices.
>>
>> Signed-off-by: Jon Hunter <jon-hunter@ti.com>
>> ---
>>  arch/arm/boot/dts/omap2420.dtsi |   11 +++++++++++
>>  arch/arm/boot/dts/omap2430.dtsi |   11 +++++++++++
>>  arch/arm/boot/dts/omap4.dtsi    |   11 +++++++++++
>>  arch/arm/boot/dts/omap5.dtsi    |   11 +++++++++++
>>  4 files changed, 44 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/omap2420.dtsi b/arch/arm/boot/dts/omap2420.dtsi
>> index af65609..d4ce6c2 100644
>> --- a/arch/arm/boot/dts/omap2420.dtsi
>> +++ b/arch/arm/boot/dts/omap2420.dtsi
>> @@ -29,6 +29,17 @@
>>                         pinctrl-single,function-mask = <0x3f>;
>>                 };
>>
>> +               gpmc: gpmc@6800a000 {
>> +                       compatible = "ti,omap2420-gpmc";
>> +                       reg = <0x6800a000 0x1000>;
>> +                       #address-cells = <2>;
>> +                       #size-cells = <1>;
>> +                       interrupts = <20>;
>> +                       gpmc,num-cs = <8>;
>> +                       gpmc,num-waitpins = <4>;
>> +                       ti,hwmods = "gpmc";
>> +               };
>> +
>>                 mcbsp1: mcbsp@48074000 {
>>                         compatible = "ti,omap2420-mcbsp";
>>                         reg = <0x48074000 0xff>;
>> diff --git a/arch/arm/boot/dts/omap2430.dtsi b/arch/arm/boot/dts/omap2430.dtsi
>> index c392445..832f184 100644
>> --- a/arch/arm/boot/dts/omap2430.dtsi
>> +++ b/arch/arm/boot/dts/omap2430.dtsi
>> @@ -29,6 +29,17 @@
>>                         pinctrl-single,function-mask = <0x3f>;
>>                 };
>>
>> +               gpmc: gpmc@6e000000 {
>> +                       compatible = "ti,omap2430-gpmc";
>> +                       reg = <0x6e000000 0x1000>;
>> +                       #address-cells = <2>;
>> +                       #size-cells = <1>;
>> +                       interrupts = <20>;
>> +                       gpmc,num-cs = <8>;
>> +                       gpmc,num-waitpins = <4>;
>> +                       ti,hwmods = "gpmc";
>> +               };
>> +
>>                 mcbsp1: mcbsp@48074000 {
>>                         compatible = "ti,omap2430-mcbsp";
>>                         reg = <0x48074000 0xff>;
>> diff --git a/arch/arm/boot/dts/omap4.dtsi b/arch/arm/boot/dts/omap4.dtsi
>> index 827f6f3..726ef11 100644
>> --- a/arch/arm/boot/dts/omap4.dtsi
>> +++ b/arch/arm/boot/dts/omap4.dtsi
>> @@ -196,6 +196,17 @@
>>                         #interrupt-cells = <1>;
>>                 };
>>
>> +               gpmc: gpmc@50000000 {
>> +                       compatible = "ti,omap4430-gpmc";
>> +                       reg = <0x50000000 0x1000>;
> 
> Hi Jon,
> 
> By looking at the GPMC Register Summary from both the OMAP4460 and OMAP OMAP35x
> Technical Reference Manuals I see that the GPMC register address space
> is only 720 bytes length. From base address + 0x0 to base address +
> 0x02d0.
> 
> So shouldn't the regs property be <0x50000000 0x2d0> instead?
> 
> Of course are only a few kilobytes but still I wonder if it makes
> sense to map them when they are not going to be used.

Yes you are correct. In general, I have been trying to stay some-what
consistent with what hwmod was doing as this was being auto-generated by
some hardware design specs and I believe they wanted to eventually get
to the point where DT files would be auto-generated too for OMAP.
Furthermore my understanding is that the smallest page that can be
mapped by the kernel for ARM is 4kB. So if you declare it as 0x2d0 or
0x1000 it will map a 4kB page (I could be wrong here).

I don't have any strong feelings here but will do what the consensus
prefers.

Cheers
Jon