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STMicroelectronics STM32 Serial Audio Interface (SAI).
The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
The SAI contains two independent audio sub-blocks. Each sub-block has
its own clock generator and I/O lines controller.
Required properties:
- compatible: Should be "st,stm32f4-sai"
- reg: Base address and size of SAI common register set.
- clocks: Must contain phandle and clock specifier pairs for each entry
in clock-names.
- clock-names: Must contain "x8k" and "x11k"
"x8k": SAI parent clock for sampling rates multiple of 8kHz.
"x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
- interrupts: cpu DAI interrupt line shared by SAI sub-blocks
Optional properties:
- resets: Reference to a reset controller asserting the SAI
SAI subnodes:
Two subnodes corresponding to SAI sub-block instances A et B can be defined.
Subnode can be omitted for unsused sub-block.
SAI subnodes required properties:
- compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
for SAI sub-block A or B respectively.
- reg: Base address and size of SAI sub-block register set.
- clocks: Must contain one phandle and clock specifier pair
for sai_ck which feeds the internal clock generator.
- clock-names: Must contain "sai_ck".
- dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
- dma-names: identifier string for each DMA request line
"tx": if sai sub-block is configured as playback DAI
"rx": if sai sub-block is configured as capture DAI
- pinctrl-names: should contain only value "default"
- pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
Example:
sound_card {
compatible = "audio-graph-card";
dais = <&sai1b_port>;
};
sai1: sai1@40015800 {
compatible = "st,stm32f4-sai";
#address-cells = <1>;
#size-cells = <1>;
ranges;
reg = <0x40015800 0x4>;
clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
clock-names = "x8k", "x11k";
interrupts = <87>;
sai1b: audio-controller@40015824 {
#sound-dai-cells = <0>;
compatible = "st,stm32-sai-sub-b";
reg = <0x40015824 0x1C>;
clocks = <&rcc 1 CLK_SAI2>;
clock-names = "sai_ck";
dmas = <&dma2 5 0 0x400 0x0>;
dma-names = "tx";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sai1b>;
ports {
#address-cells = <1>;
#size-cells = <0>;
sai1b_port: port@0 {
reg = <0>;
cpu_endpoint: endpoint {
remote-endpoint = <&codec_endpoint>;
audio-graph-card,format = "i2s";
audio-graph-card,bitclock-master = <&codec_endpoint>;
audio-graph-card,frame-master = <&codec_endpoint>;
};
};
};
};
};
audio-codec {
codec_port: port {
codec_endpoint: endpoint {
remote-endpoint = <&cpu_endpoint>;
};
};
};