# How to use the SPI ports

<abstract>
This article illustrates how to use the SPI ports on Acme Systems Road Runner SOM based on Microchip
SAMA5D27 MPU
</abstract>

## Pinout of SPI ports

The SPI bus lines are located on the following pins:

	| Signal     | Per A | Per B | Per C | Per D | Per E | Per F 
	|------------|-------|-------|-------|-------|-------|-------
	| SPI0 MOSI  | PA15  |       | PB0   |       |       |       
	| SPI0 MISO  | PA16  |       | PA31  |       |       |       
	| SPI0 SCLK  | PA14  |       | PB1   |       |       |       
	| SPI0 CS0   | PA17  |       | PA30  |       |       |      
	| SPI0 CS1   | PA18  |       | PA29  |       |       |      
	| SPI0 CS2 	 | PA19  |       | PA27  |       |       |      
	| SPI0 CS3   | PA20  |       | PA28  |       |       |       
	!------------|-------|-------|-------|-------|-------|-------
	| SPI1 MOSI  | PD26  |       |       | PC2   | PA23  |       
	| SPI1 MISO  | PD27  |       |       | PC3   | PA24  |       
	| SPI1 SCLK  | PD25  |       |       | PC1   | PA25  |       
	| SPI1 CS0   | PD28  |       |       | PC4   | PA22  |       
	| SPI1 CS1   | PD29  |       |       | PC5   | PA26  |       
	| SPI1 CS2   | PD30  |       |       | PC6   | PA27  |       
	| SPI1 CS3   |       |       |       | PC7   | PA28  |       
	|------------|-------|-------|-------|-------|-------|-------

* [Roadrunner pinout](/pinout_roadrunner)

## Kernel configuration

	Device Drivers  --->
	  [*] SPI support  ---> 
	    <*>   Atmel SPI Controller 
	    <*>   User mode SPI device driver support

## Device tree
	
	/****************/		
	/* Enable SPI 0 */
	/****************/		
	
	spi0: spi@f8000000 {
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_spi0_default>;
		status = "okay";

	    spidev@0 {
           compatible = "linux,spidev";
           spi-max-frequency = <10000000>;
           reg = <0>;
	    };
	};

	/* Pin definition Peripheral A */

	pinctrl_spi0_default: spi0_default {
		pinmux = <PIN_PA14__SPI0_SPCK>,
				<PIN_PA15__SPI0_MOSI>,
				<PIN_PA16__SPI0_MISO>,
				<PIN_PA17__SPI0_NPCS0>,
				<PIN_PA18__SPI0_NPCS1>,
				<PIN_PA19__SPI0_NPCS2>,
				<PIN_PA20__SPI0_NPCS3>;
		bias-disable;
	};
	
	/****************/		
	/* Enable SPI 1 */
	/****************/		
	
	spi1: spi@fc000000 {
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_spi1_default>;
		status = "okay";

	    spidev@0 {
           compatible = "linux,spidev";
           spi-max-frequency = <10000000>;
           reg = <0>;
	    };

	};

	/* Pin definition Peripheral D */

	pinctrl_spi1_default: spi1_default {
		pinmux = <PIN_PC1__SPI1_SPCK>,
		<PIN_PC2__SPI1_MOSI>,
		<PIN_PC3__SPI1_MISO>,
		<PIN_PC4__SPI1_NPCS0>;
		bias-disable;
	};

## Links

* [Microchip SAMA5D2 Series datasheet](http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf)
* @article='roadrunner_fbtft'
* [Overview of Linux kernel SPI support](https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/Documentation/spi/spi-summary?h=v4.19.78)
* [Intro to the userspace API for spi devices](https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/Documentation/spi/spidev?h=v4.19.78)
* [Example of Device Tree](https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts?h=v4.19.78)

@include='adv_roadrunner'