linux-kernel - Re: [PATCH v2 08/10] riscv: dts: add initial SpacemiT K1 SoC device tree

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Date: Tue, 2 Jul 2024 01:28:47 +0000
From: Yixun Lan <dlan@...too.org>
To: Emil Renner Berthing <emil.renner.berthing@...onical.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Conor Dooley <conor@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Samuel Holland <samuel.holland@...ive.com>,
	Anup Patel <anup@...infault.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>, Lubomir Rintel <lkundrak@...sk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Palmer Dabbelt <palmer@...ive.com>, linux-riscv@...ts.infradead.org,
	linux-serial@...r.kernel.org, Inochi Amaoto <inochiama@...look.com>,
	Meng Zhang <zhangmeng.kevin@...cemit.com>,
	Yangyu Chen <cyy@...self.name>
Subject: Re: [PATCH v2 08/10] riscv: dts: add initial SpacemiT K1 SoC device
 tree

On 12:49 Mon 01 Jul     , Emil Renner Berthing wrote:
> Yixun Lan wrote:
> > From: Yangyu Chen <cyy@...self.name>
> >
> > Banana Pi BPI-F3 motherboard is powered by SpacemiT K1[1].
> >
> > Key features:
> > - 4 cores per cluster, 2 clusters on chip
> > - UART IP is Intel XScale UART
> >
> > Some key considerations:
> > - ISA string is inferred from vendor documentation[2]
> > - Cluster topology is inferred from datasheet[1] and L2 in vendor dts[3]
> > - No coherent DMA on this board
> >     Inferred by taking vendor ethernet and MMC drivers to the mainline
> >     kernel. Without dma-noncoherent in soc node, the driver fails.
> > - No cache nodes now
> >     The parameters from vendor dts are likely to be wrong. It has 512
> >     sets for a 32KiB L1 Cache. In this case, each set is 64B in size.
> >     When the size of the cache line is 64B, it is a directly mapped
> >     cache rather than a set-associative cache, the latter is commonly
> >     used. Thus, I didn't use the parameters from vendor dts.
> >
> > Currently only support booting into console with only uart, other
> > features will be added soon later.
> >
...

> > +		clint: timer@...00000 {
> > +			compatible = "spacemit,k1-clint", "sifive,clint0";
> > +			reg = <0x0 0xe4000000 0x0 0x10000>;
> > +			interrupts-extended = <&cpu0_intc 3>, <&cpu0_intc 7>,
> > +					      <&cpu1_intc 3>, <&cpu1_intc 7>,
> > +					      <&cpu2_intc 3>, <&cpu2_intc 7>,
> > +					      <&cpu3_intc 3>, <&cpu3_intc 7>,
> > +					      <&cpu4_intc 3>, <&cpu4_intc 7>,
> > +					      <&cpu5_intc 3>, <&cpu5_intc 7>,
> > +					      <&cpu6_intc 3>, <&cpu6_intc 7>,
> > +					      <&cpu7_intc 3>, <&cpu7_intc 7>;
> > +		};
> > +
> > +		uart0: serial@...17000 {
> > +			compatible = "spacemit,k1-uart", "intel,xscale-uart";
> > +			reg = <0x0 0xd4017000 0x0 0x100>;
> > +			interrupts = <42>;
> > +			clock-frequency = <14857000>;
> > +			reg-shift = <2>;
> > +			reg-io-width = <4>;
> > +			status = "disabled";
> > +		};
> > +
> > +		/* note: uart1 skipped */
> 
> The datasheet page you link to above says "-UART (×10)", but here you're
> skipping one of them. Why? I can see the vendor tree does the same, but it
> would be nice with an explanation of what's going on.
> 
/* note: uart1 in 0xf0612000, reserved for TEE usage */
I would put something like this, does this sound ok to you?

more detail, iomem range from 0xf000,0000 - 0xf080,0000 are dedicated for TEE purpose,
It won't be exposed to Linux once TEE feature is enabled..

skipping uart1 may make people confused but we are trying to follow datasheet..


-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55