Subject: [PATCH 2/4] ARM: rockchip: add sram dt nodes and documentation

From: [email-masked] (Heiko Stübner)
Date: Tue, 18 Jun 2013 03:17:42 +0200

Am Dienstag, 18. Juni 2013, 01:41:27 schrieb Rob Herring:
> On 06/17/2013 05:44 PM, Heiko St?bner wrote:
> > The Rockchip SoCs need a special part of their sram for bringup
> > of additional cores. Therefore the mapped area should be split
> > into a special area for the smp code and a generic area that gets
> > handled by mmio-sram.
> > 
> > Signed-off-by: Heiko Stuebner <[email-masked]>
> > ---
> > 
> >  .../devicetree/bindings/arm/rockchip/smp-sram.txt  |   29
> >  ++++++++++++++++++++ arch/arm/boot/dts/rk3066a.dtsi                    
> >  |   14 ++++++++++ 2 files changed, 43 insertions(+)
> >  create mode 100644
> >  Documentation/devicetree/bindings/arm/rockchip/smp-sram.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/rockchip/smp-sram.txt
> > b/Documentation/devicetree/bindings/arm/rockchip/smp-sram.txt new file
> > mode 100644
> > index 0000000..9c81fac
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/rockchip/smp-sram.txt
> > @@ -0,0 +1,29 @@
> > +Rockchip SRAM for smp bringup:
> > +------------------------------
> > +
> > +Rockchip smp-capable SoCs use the first part of the sram for the bringup
> > +of the cores. Once the core gets powered up it executes the code that is
> > +residing at the very beginning of the sram.
> > +
> > +While the suspend also needs to have code in the sram that can be
> > realized +with the generic mmio-sram driver and only the smp specific
> > part needs to +be mapped specially in the smp code.
> > +
> > +Therefore split the sram mapping in a smp-specific part that gets used
> > +by the smp code exclusively and a bigger generic part for mmio-sram
> > +
> > +Required node properties:
> > +- compatible value : = "rockchip,rk3066-smp-sram";
> > +- reg : physical base address and the size of the registers window
> > +
> > +Example:
> > +
> > +	sram at 10080000 {
> > +		compatible = "rockchip,rk3066-smp-sram";
> > +		reg = <0x10080000 0x100>;
> > +	};
> > +
> > +	sram: sram at 10080100 {
> > +		compatible = "mmio-sram";
> > +		reg = <0x10080100 0x9900>;
> 
> I think a better way would be to specify some portion of the sram as
> reserved rather than defining the s/w use of the sram in DT.
> Something like this:
> 
> mmio-sram-reserved = <base size base size>;
> 
> where base values are relative to reg property base.

hmm, but I don't see how to get then access to the reserved part. As can be 
seen in patch 4 [which I've forgotton to cc you in, sorry] the smp-trampoline 
gets copied into this area for the core to execute after poweron, so I need to 
get the mapped representation of the reserved area.

Or do you mean

- let mmio-sram only allocate the non-reserved spaces for itself
- grab mmio-sram node in the smp code and map the necessary reserved space

This might actually work.

Thanks
Heiko

> > +	};
> > diff --git a/arch/arm/boot/dts/rk3066a.dtsi
> > b/arch/arm/boot/dts/rk3066a.dtsi index 26c4311..44eabd2 100644
> > --- a/arch/arm/boot/dts/rk3066a.dtsi
> > +++ b/arch/arm/boot/dts/rk3066a.dtsi
> > @@ -53,6 +53,20 @@
> > 
> >  			reg = <0x1013c000 0x100>;
> >  		
> >  		};
> > 
> > +		/*
> > +		 * the first part of the sram is needed for the smp
> > +		 * trampoline code during cpu bringup
> > +		 */
> > +		sram at 10080000 {
> > +			compatible = "rockchip,rk3066-smp-sram";
> > +			reg = <0x10080000 0x100>;
> > +		};
> > +
> > +		sram: sram at 10080100 {
> > +			compatible = "mmio-sram";
> > +			reg = <0x10080100 0x9900>;
> > +		};
> > +
> > 
> >  		gic: interrupt-controller at 1013d000 {
> >  		
> >  			compatible = "arm,cortex-a9-gic";
> >  			interrupt-controller;