Re: [PATCH v3 18/26] arm64: dts: rockchip: rk3399: add crypto node

[LABBE Corentin]

Le Tue, Mar 22, 2022 at 12:00:06PM +0000, Robin Murphy a écrit :
> On 2022-03-21 20:07, Corentin Labbe wrote:
> > The rk3399 has a crypto IP handled by the rk3288 crypto driver so adds a
> > node for it.
> > 
> > Signed-off-by: Corentin Labbe <clabbe@xxxxxxxxxxxx>
> > ---
> >   arch/arm64/boot/dts/rockchip/rk3399.dtsi | 12 ++++++++++++
> >   1 file changed, 12 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > index 88f26d89eea1..ca2c658371a5 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > @@ -573,6 +573,18 @@ saradc: saradc@ff100000 {
> >   		status = "disabled";
> >   	};
> >   
> > +	crypto0: crypto@ff8b0000 {
> > +		compatible = "rockchip,rk3399-crypto";
> > +		reg = <0x0 0xff8b0000 0x0 0x4000>,
> > +		      <0x0 0xff8b8000 0x0 0x4000>;
> > +		interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH 0>,
> > +			     <GIC_SPI 135 IRQ_TYPE_LEVEL_HIGH 0>;
> > +		clocks = <&cru SCLK_CRYPTO0>, <&cru HCLK_M_CRYPTO0>, <&cru HCLK_S_CRYPTO0>,
> > +			 <&cru SCLK_CRYPTO1>, <&cru HCLK_M_CRYPTO1>, <&cru HCLK_S_CRYPTO1>;
> > +		resets = <&cru SRST_CRYPTO0>, <&cru SRST_CRYPTO0_S>, <&cru SRST_CRYPTO0_M>,
> > +			 <&cru SRST_CRYPTO1>, <&cru SRST_CRYPTO1_S>, <&cru SRST_CRYPTO1_M>;
> > +	};
> 
> What's going on here? If these are simply two instances of the same IP 
> block as the evidence suggests, why are they crammed into a single DT 
> node rather than simply being described as two separate instances? I was 
> rather wondering what all the confusing mess in patch #16 was about, 
> until I got here.
> 
> If there's something in the crypto API that means the driver can't 
> simply naively register itself multiple times, there should be any 
> number of ways for the probe routine to keep track of whether it's 
> already registered something and associate any subsequent devices with 
> the first one internally if need be. Linux implementation details should 
> not leak out as non-standard DT weirdness.
> 
> I know the Rockchip IOMMU driver does this, but in that case the two 
> IOMMU instances are closely coupled and sharing work such that they 
> effectively need to be programmed identically at all times, so it was a 
> bit more justifiable. I don't know the full story here, but it certainly 
> looks like rk_get_engine_number() is just a means to schedule work on 
> any available unit independently, so looks like it wouldn't take much to 
> select between distinct devices at that point, and actually end up a lot 
> simpler and cleaner overall.

Yes rk3399 has 2 instances of the same IP (Exception: crypto1 does not have RSA).

The problem is that only one drivername (like rk-md5) could exists.
If crypto0 and crypto1 register with different drivername (rk-md5-0/rk-md5-1), only one will be used anyway.
So I merged them into only one instance.
I think this way will be easier, but you are right, this is not pretty.

I found another way with 2 nodes:
You could preview it at https://github.com/montjoie/linux/tree/cryptorockchipv4
Basicly the crypto0 is a normal instance, and crypto1 "registers" itself against crypto0.
So if crypto0 know another instance exists it will load balance requests.

Regards