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

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Message-ID: <5956e320-7cbb-4d9a-95a7-720cfa6b9654@riscstar.com>
Date: Thu, 18 Sep 2025 08:51:24 -0500
From: Alex Elder <elder@...cstar.com>
To: Yixun Lan <dlan@...too.org>
Cc: broonie@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.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
Subject: Re: [PATCH 3/3] riscv: dts: spacemit: define a SPI controller node

On 9/18/25 8:32 AM, Yixun Lan wrote:
> Hi Alex,
> 
> On 17:07 Wed 17 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>
>> ---
>>   .../boot/dts/spacemit/k1-bananapi-f3.dts      |  6 ++++++
>>   arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi  | 20 +++++++++++++++++++
>>   arch/riscv/boot/dts/spacemit/k1.dtsi          | 19 ++++++++++++++++++
>>   3 files changed, 45 insertions(+)
>>
>> diff --git a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
>> index 6013be2585428..380d475d2f3f3 100644
>> --- a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
>> +++ b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
>> @@ -44,6 +44,12 @@ &pdma {
>>   	status = "okay";
>>   };
>>   
>> +&spi3 {
> ..
>> +	pinctrl-names = "default";
>> +	pinctrl-0 = <&ssp3_0_cfg>;
> Can you swap the order of these two pinctrl properties?
> Yes, we currently have some inconsistency in tree, I plan to fix during next cycle

Sure, I'll do that.

>> +	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 3810557374228..16c953eca2aaa 100644
>> --- a/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi
>> +++ b/arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi
>> @@ -28,4 +28,24 @@ pwm14-1-pins {
>>   			drive-strength = <32>;
>>   		};
>>   	};
>> +
>> +	ssp3_0_cfg: ssp3-0-cfg {
>> +		ssp3-0-no-pull-pins {
>> +			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 66b33a9110ccd..a826cc1ac83d5 100644
>> --- a/arch/riscv/boot/dts/spacemit/k1.dtsi
>> +++ b/arch/riscv/boot/dts/spacemit/k1.dtsi
>> @@ -834,6 +834,25 @@ storage-bus {
>>   			#size-cells = <2>;
>>   			dma-ranges = <0x0 0x00000000 0x0 0x00000000 0x0 0x80000000>;
>>   
>> +			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";
> can you simply put them together in one line? it's kind of tedious to split..

Sure I can do that.  I've seen it both ways.

>> +				resets = <&syscon_apbc RESET_SSP3>;
>> +				interrupts-extended = <&plic 55>;
> why use interrupts-extended?

Because it specifies both the controller and interrupt number
explicitly.  Why *not* use interrupts-extended?

>> +				spacemit,k1-ssp-id = <3>;
>> +				dmas = <&pdma 20>,
>> +				       <&pdma 19>;
> .. em, so the SPI will use pdma, then probably you should also adjust Kconfig to
> select PDMA driver?

You're right.  Thanks for catching that.

					-Alex

> 
>> +				dma-names = "rx",
>> +					    "tx";
>> +				status = "disabled";
>> +			};
>> +
>>   			emmc: mmc@...81000 {
>>   				compatible = "spacemit,k1-sdhci";
>>   				reg = <0x0 0xd4281000 0x0 0x200>;
>> -- 
>> 2.48.1
>>
>>
>