linux-kernel - Re: [PATCH v3 3/3] riscv: dts: spacemit: define a SPI controller node

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Message-ID: <ED4C67FD136DEB19+aNINJJVYbNnT87va@LT-Guozexi>
Date: Tue, 23 Sep 2025 10:59:48 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Yixun Lan <dlan@...too.org>, Alex Elder <elder@...cstar.com>
Cc: broonie@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, ziyao@...root.org, linux-spi@...r.kernel.org,
	devicetree@...r.kernel.org, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, alex@...ti.fr,
	p.zabel@...gutronix.de, spacemit@...ts.linux.dev,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: Re: [PATCH v3 3/3] riscv: dts: spacemit: define a SPI controller node

On Tue, Sep 23, 2025 at 08:19:30AM +0800, Yixun Lan wrote:
> Hi Alex,
> 
> On 11:17 Mon 22 Sep     , Alex Elder wrote:
> > Define a node for the fourth SoC SPI controller (number 3) on
> > the SpacemiT K1 SoC.
> > 
> > Enable it on the Banana Pi BPI-F3 board, which exposes this feature
> > via its GPIO block:
> >   GPIO PIN 19:  MOSI
> >   GPIO PIN 21:  MISO
> >   GPIO PIN 23:  SCLK
> >   GPIO PIN 24:  SS (inverted)
> > 
> > Define pincontrol configurations for the pins as used on that board.
> > 
> > (This was tested using a GigaDevice GD25Q64E SPI NOR chip.)
> > 
> > Signed-off-by: Alex Elder <elder@...cstar.com>
> > ---
> > v3: - Moved the SPI controller into the dma-bus memory region
> > 
> >  .../boot/dts/spacemit/k1-bananapi-f3.dts      |  7 +++++++
> >  arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi  | 20 +++++++++++++++++++
> >  arch/riscv/boot/dts/spacemit/k1.dtsi          | 16 +++++++++++++++
> >  3 files changed, 43 insertions(+)
> > 
> > diff --git a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > index 2aaaff77831e1..d9d865fbe320e 100644
> > --- a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > +++ b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > @@ -14,6 +14,7 @@ aliases {
> >  		ethernet0 = &eth0;
> >  		ethernet1 = &eth1;
> >  		serial0 = &uart0;
> > +		spi3 = &spi3;
> >  	};
> >  
> >  	chosen {
> > @@ -92,6 +93,12 @@ &pdma {
> >  	status = "okay";
> >  };
> >  
> > +&spi3 {
> > +	pinctrl-0 = <&ssp3_0_cfg>;
> > +	pinctrl-names = "default";
> > +	status = "okay";
> > +};
> > +
> >  &uart0 {
> >  	pinctrl-names = "default";
> >  	pinctrl-0 = <&uart0_2_cfg>;
> > diff --git a/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi b/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi
> > index aff19c86d5ff3..205c201a3005c 100644
> > --- a/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi
> > +++ b/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi
> > @@ -76,4 +76,24 @@ pwm14-1-pins {
> >  			drive-strength = <32>;
> >  		};
> >  	};
> > +
> > +	ssp3_0_cfg: ssp3-0-cfg {
> ..
> > +		ssp3-0-no-pull-pins {
> I'd prefer not to enforce "pull" info inside the name, you can't embed
> all property info, besides, what's if you want to change/override later?
> 
> how about just name it as ssp3-0-defaul-pins or simply ssp3-0-pins?
uart: uart0_2_cfg and function is 2.
pwm: pwm14_1_cfg and function is 4
spi: ssp3_0_cfg and function is 2

I’m a bit confused about the meaning of the second number here.
Is it intended to be an index, or the function number?

If it’s an index, should it start from 0 or 1?
The starting point seems inconsistent across pwm/spi/uart.
If it’s supposed to be the function number,
then the spi and pwm parts look incorrect.

Could you clarify this? Yixun.

                - Troy
> 
> > +			pinmux = <K1_PADCONF(75, 2)>,	/* SCLK */
> > +				 <K1_PADCONF(77, 2)>,	/* MOSI  */
> > +				 <K1_PADCONF(78, 2)>;	/* MISO */
> > +
> > +			bias-disable;
> > +			drive-strength = <19>;
> > +			power-source = <3300>;
> > +		};
> > +
> > +		ssp3-0-frm-pins {
> > +			pinmux = <K1_PADCONF(76, 2)>;	/* FRM (frame) */
> > +
> > +			bias-pull-up = <0>;
> > +			drive-strength = <19>;
> > +			power-source = <3300>;
> > +		};
> > +	};
> >  };
> > diff --git a/arch/riscv/boot/dts/spacemit/k1.dtsi b/arch/riscv/boot/dts/spacemit/k1.dtsi
> > index 6cdcd80a7c83b..eb8a14dd72ea4 100644
> > --- a/arch/riscv/boot/dts/spacemit/k1.dtsi
> > +++ b/arch/riscv/boot/dts/spacemit/k1.dtsi
> > @@ -797,6 +797,22 @@ uart9: serial@...17800 {
> >  				status = "disabled";
> >  			};
> >  
> > +			spi3: spi@...1c000 {
> > +				compatible = "spacemit,k1-spi";
> > +				reg = <0x0 0xd401c000 0x0 0x30>;
> > +				#address-cells = <1>;
> > +				#size-cells = <0>;
> > +				clocks = <&syscon_apbc CLK_SSP3>,
> > +					 <&syscon_apbc CLK_SSP3_BUS>;
> > +				clock-names = "core", "bus";
> > +				resets = <&syscon_apbc RESET_SSP3>;
> > +				interrupts = <55>;
> ..
> > +				dmas = <&pdma 20>,
> > +				       <&pdma 19>;
> can we also squash the dmas into one line? but, do split if there are too many..
> 
> yes, it's simply a style change that I'd like to keep them consistent at DT level,
> besides you might also want to adjust dt-binding examples to align with them here..
> 
> thanks
> 
> > +				dma-names = "rx", "tx";
> > +				status = "disabled";
> > +			};
> > +
> >  			/* sec_uart1: 0xf0612000, not available from Linux */
> >  		};
> >  
> > -- 
> > 2.48.1
> > 
> > 
> 
> -- 
> Yixun Lan (dlan)
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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