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HDL AXI I2S Linux Driver

Supported Devices

  • HDL AXI I2S

Source Code

Status

Source Mainlined?
git git

Files

Function File
driver sound/soc/adi/axi-i2s.c

Example device initialization

The AXI I2S driver is a platform driver and can currently only be instantiated via device tree.

Required devicetree properties:

  • compatible : Must be “adi,axi-i2s-1.00.a”
  • reg : Must contain I2S registers location and length
  • clocks : Clock specifier providing a handle to the controllers clocks. The controller expects two clocks, the clock used for the AXI interface and the clock used for the sample rate base frequency.
  • clock-names : “axi” for the clock to the AXI interface, “i2s” for the sample rate base clock.
  • dma : Specifiers for the DMA channels that are used by the core.
  • dma-names : “tx” for the transmit channel, “rx” for the receive channel.

Example:

    axi_i2s_0: axi-i2s@77600000 {
		compatible = "adi,axi-i2s-1.00.a";
		reg = <0x77600000 0x1000>;                                                                                                      
		clocks = <&fpga_clock &audio_clock>;                                                                                            
		clock-names = "axi", "ref";
		dmas = <&ps7_dma 0 &ps7_dma 1>;                                                                                                 
		dma-names = "tx", "rx";      
    };

DAI configuration

The driver will register one CPU-DAI named after the device itself.

Supported DAI formats

Name Supported by driver Description
SND_SOC_DAIFMT_I2S yes I2S mode
SND_SOC_DAIFMT_RIGHT_J no Right Justified mode
SND_SOC_DAIFMT_LEFT_J no Left Justified mode
SND_SOC_DAIFMT_DSP_A no data MSB after FRM LRC
SND_SOC_DAIFMT_DSP_B no data MSB during FRM LRC
SND_SOC_DAIFMT_AC97 no AC97 mode
SND_SOC_DAIFMT_PDM no Pulse density modulation
SND_SOC_DAIFMT_SPDIF no SPDIF mode
SND_SOC_DAIFMT_NB_NF yes Normal bit- and frameclock
SND_SOC_DAIFMT_NB_IF no Normal bitclock, inverted frameclock
SND_SOC_DAIFMT_IB_NF no Inverted frameclock, normal bitclock
SND_SOC_DAIFMT_IB_IF no Inverted bit- and frameclock
SND_SOC_DAIFMT_CBM_CFM no Codec bit- and frameclock master
SND_SOC_DAIFMT_CBS_CFM no Codec bitclock slave, frameclock master
SND_SOC_DAIFMT_CBM_CFS no Codec bitclock master, frameclock slave
SND_SOC_DAIFMT_CBS_CFS yes Codec bit- and frameclock slave

Example DAI configuration

static struct snd_soc_dai_link zed_adau1761_dai_link = {
	.name = "adau1761",
	.stream_name = "adau1761",
	.codec_dai_name = "adau-hifi",
	.dai_fmt = SND_SOC_DAIFMT_I2S |
			SND_SOC_DAIFMT_NB_NF |
			SND_SOC_DAIFMT_CBS_CFS,
	.ops = &zed_adau1761_ops,
};
 
static struct snd_soc_card zed_adau1761_card = {
	.name = "ZED ADAU161",
	.owner = THIS_MODULE,
	.dai_link = &zed_adau1761_dai_link,
	.num_links = 1,
	.dapm_widgets = zed_adau1761_widgets,
	.num_dapm_widgets = ARRAY_SIZE(zed_adau1761_widgets),
	.dapm_routes = zed_adau1761_routes,
	.num_dapm_routes = ARRAY_SIZE(zed_adau1761_routes),
	.fully_routed = true,
};

I2S + ADAU1761 ZED board driver

The HDL I2S SPDIF driver is currently used in conjunction with the ADAU1761 audio codec on the ZED board. For this platform there exist a ASoC board driver which provides the necessary information on how both device are interconnected, so that a ALSA sound card can be instantiated.

Source

Status

Source Mainlined?
git In progress

Files

Function File
driver sound/soc/adi/zed_adau1761.c

Kernel configuration

Enable ALSA SoC evaluation board driver:

Device Drivers  --->
<*> Sound card support  --->
<*>   Advanced Linux Sound Architecture  --->
<*>     ALSA for SoC audio support  --->
<*>       Audio support for Analog Devices reference designs
<*>         ZED board sound support

Example device initialization

The ZED board ADAU1761 sound board driver is a platform driver and can currently only be instantiated via device tree.

Required devicetree properties:

  • compatible: Should always be “adv7511-hdmi-snd”
  • audio-codec: Phandle to the ADAU1761 device devicetree entry
  • cpu-dai: Phandle to the I2S device devicetree entry

Example:

	axi_iic_0: i2c@41600000 {
		compatible = "xlnx,axi-iic-1.01.b", "xlnx,xps-iic-2.00.a";
		interrupt-parent = <&gic>;
		interrupts = <0 57 0x4>;
		reg = <0x41600000 0x10000>;

		#size-cells = <0>;
		#address-cells = <1>;

		adau1761: adau1761@3b {
			compatible = "adi,adau1761";
			reg = <0x3b>;
		};
	};

	axi_i2s: axi-i2s@0x77600000 {
		compatible = "adi,axi-i2s-1.00.a";
		reg = <0x77600000 0x1000>;                                                                                                      
		clocks = <&fpga_clock &audio_clock>;                                                                                            
		clock-names = "axi", "ref";
		dmas = <&ps7_dma 0 &ps7_dma 1>;                                                                                                 
		dma-names = "tx", "rx";                                                                                                         
	}; 

	zed_adau1761_snd: zed_adau1761_snd {
		compatible = "zed-adau1761-snd";
		audio-codec = <&adau1761>;
		cpu-dai = <&axi_i2s>;
	};

Driver testing

Make sure the sound card is properly instantiated.

This specifies any shell prompt running on the target

root:/> aplay -l
card 0: ...

To test audio playback you can use the speaker test utility, which allows to playback several different test patterns. For a extensive description on the speaker-test utility and the different options it supports please refer to the speaker-test man page.

This specifies any shell prompt running on the target

root:/> speakertest -c 2
speaker-test 1.0.24.2

Playback device is default
Stream parameters are 48000Hz, S32_LE, 2 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 512 to 2097152
Period size range from 256 to 262143
Requested buffer time 20000 us
Periods = 4
was set period_size = 320
was set buffer_size = 960
 0 - Front Left
 1 - Front Right
....

To test audio record you can use the arecord utility. arecord will record the incoming audio signal and write it to a wav file.

This specifies any shell prompt running on the target

root:/> arecord -f S32 -r 48000 -c 2 > test.wav
...

To playback a wav file you can use the aplay utility. You can also create a audio loop-back by sending the output of arecord to aplay. This will send the incoming audio stream back via the outgoing audio stream.

This specifies any shell prompt running on the target

root:/> arecord -f S32 -r 48000 -c 2 | aplay
...

For more information on the the aplay and arecord utilities please refer to the aplay and arecord man page.

More information

31 Jul 2012 17:53 · larsc
/srv/wiki.analog.com/data/pages/resources/tools-software/linux-drivers/sound/hdl-axi-i2s.txt · Last modified: 26 Sep 2018 02:13 by gerardms