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Diffstat (limited to 'Documentation/devicetree/bindings/mfd/atmel-usart.txt')
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diff --git a/Documentation/devicetree/bindings/mfd/atmel-usart.txt b/Documentation/devicetree/bindings/mfd/atmel-usart.txt new file mode 100644 index 000000000..a09133066 --- /dev/null +++ b/Documentation/devicetree/bindings/mfd/atmel-usart.txt @@ -0,0 +1,98 @@ +* Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART) + +Required properties for USART: +- compatible: Should be one of the following: + - "atmel,at91rm9200-usart" + - "atmel,at91sam9260-usart" + - "microchip,sam9x60-usart" + - "atmel,at91rm9200-dbgu", "atmel,at91rm9200-usart" + - "atmel,at91sam9260-dbgu", "atmel,at91sam9260-usart" + - "microchip,sam9x60-dbgu", "microchip,sam9x60-usart" +- reg: Should contain registers location and length +- interrupts: Should contain interrupt +- clock-names: tuple listing input clock names. + Required elements: "usart" +- clocks: phandles to input clocks. + +Required properties for USART in SPI mode: +- #size-cells : Must be <0> +- #address-cells : Must be <1> +- cs-gpios: chipselects (internal cs not supported) +- atmel,usart-mode : Must be <AT91_USART_MODE_SPI> (found in dt-bindings/mfd/at91-usart.h) + +Optional properties in serial and SPI mode: +- dma bindings for dma transfer: + - dmas: DMA specifier, consisting of a phandle to DMA controller node, + memory peripheral interface and USART DMA channel ID, FIFO configuration. + The order of DMA channels is fixed. The first DMA channel must be TX + associated channel and the second one must be RX associated channel. + Refer to dma.txt and atmel-dma.txt for details. + - dma-names: "tx" for TX channel. + "rx" for RX channel. + The order of dma-names is also fixed. The first name must be "tx" + and the second one must be "rx" as in the examples below. + +Optional properties in serial mode: +- atmel,use-dma-rx: use of PDC or DMA for receiving data +- atmel,use-dma-tx: use of PDC or DMA for transmitting data +- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD line respectively. + It will use specified PIO instead of the peripheral function pin for the USART feature. + If unsure, don't specify this property. +- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO + capable USARTs. +- rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt + +<chip> compatible description: +- at91rm9200: legacy USART support +- at91sam9260: generic USART implementation for SAM9 SoCs + +Example: +- use PDC: + usart0: serial@fff8c000 { + compatible = "atmel,at91sam9260-usart"; + reg = <0xfff8c000 0x4000>; + interrupts = <7>; + clocks = <&usart0_clk>; + clock-names = "usart"; + atmel,use-dma-rx; + atmel,use-dma-tx; + rts-gpios = <&pioD 15 GPIO_ACTIVE_LOW>; + cts-gpios = <&pioD 16 GPIO_ACTIVE_LOW>; + dtr-gpios = <&pioD 17 GPIO_ACTIVE_LOW>; + dsr-gpios = <&pioD 18 GPIO_ACTIVE_LOW>; + dcd-gpios = <&pioD 20 GPIO_ACTIVE_LOW>; + rng-gpios = <&pioD 19 GPIO_ACTIVE_LOW>; + }; + +- use DMA: + usart0: serial@f001c000 { + compatible = "atmel,at91sam9260-usart"; + reg = <0xf001c000 0x100>; + interrupts = <12 4 5>; + clocks = <&usart0_clk>; + clock-names = "usart"; + atmel,use-dma-rx; + atmel,use-dma-tx; + dmas = <&dma0 2 0x3>, + <&dma0 2 0x204>; + dma-names = "tx", "rx"; + atmel,fifo-size = <32>; + }; + +- SPI mode: + #include <dt-bindings/mfd/at91-usart.h> + + spi0: spi@f001c000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "atmel,at91rm9200-usart", "atmel,at91sam9260-usart"; + atmel,usart-mode = <AT91_USART_MODE_SPI>; + reg = <0xf001c000 0x100>; + interrupts = <12 IRQ_TYPE_LEVEL_HIGH 5>; + clocks = <&usart0_clk>; + clock-names = "usart"; + dmas = <&dma0 2 AT91_DMA_CFG_PER_ID(3)>, + <&dma0 2 (AT91_DMA_CFG_PER_ID(4) | AT91_DMA_CFG_FIFOCFG_ASAP)>; + dma-names = "tx", "rx"; + cs-gpios = <&pioB 3 0>; + }; |