4.4 UART DMA

For the ATWILC3000 only, the user must ensure that the Direct Memory Access (DMA) is enabled in the Universal Synchronous/Asynchronous Receiver/Transmitter (USART).

For example, the SAMA5D4’s sama5d4.dtsi file in the kernel_tree/arch/arm/boot/dts path is modified as shown below.

usart4: serial@fc010000 {
	compatible = "atmel,at91sam9260-usart";
	reg = <0xfc010000 0x100>;
	interrupts = <31 IRQ_TYPE_LEVEL_HIGH 5>;
	dmas = <&dma1
		(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1)
		| AT91_XDMAC_DT_PERID(20))>,
			<&dma1
		(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1)
		| AT91_XDMAC_DT_PERID(21))>;
	dma-names = "tx", "rx";
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_usart4>;
	clocks = <&pmc PMC_TYPE_PERIPHERAL 31>;
	clock-names = "usart";
	status = "disabled"
};

Note: SDIO/SPI DMA may be enabled for Wi-Fi depending on the application requirements.