[FAQ] PCMD3180: Is there a Linux Driver for the PCMD3180 devices?

Hello,

The PCMD3180 Linux driver is shared with the TLV320ADCx140 driver and is upstreamed at the Linux kernel website:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/sound/soc/codecs/tlv320adcx140.c?h=v5.9.6

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/sound/soc/codecs/tlv320adcx140.h?h=v5.9.6

 You can find the documentation for the device tree is at:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/sound/tlv320adcx140.yaml

There were a few patches applied to the upstream, so make sure to download the patches and apply them.

For PCMD3180, you will need to setup some registers to map the PDM inputs and PDM clocks to pin in the DTS:

ti,mic-bias-source  => If not present, sets 0x75 ADCX140_PWR_CFG to 0x60, MICBIAS_PDZ bitfield

Sets MicBias source, not used in your application

ti,pdm-edge-select = <1 1 0 0>;  => 0x20 ADCX140_PDM_CFG Register

Sets the PDMCLK edge to latch the data. 

ti,gpi-config = <4 5 0 0 >;           => 0x2B ADCX140_GPIO_CFG0  and 0x2C ADCX140_GPI_CFG1 Registers

Sets the GPI input for a channel

ti,gpo-config-1 = <4 1>;              => 0x22 ADCX140_GPO_CFG0 Register 

Sets the PDM Clock output

ti,slot-mapping = <0 1 2 3>;              => 0x0B ADCX140_ASI_CH1, 0x0C ADCX140_ASI_CH2, 0x0D ADCX140_ASI_CH3, and 0x0E ADCX140_ASI_CH4

Maps the TDM bus slot to a channel

ti,asi-tx-drive = <1>;              => 0x07 ADCX140_ASI_CFG0, TX_FILL

Setting to one tri-states the TDM bus when PCMD3180 is not driving it.

Some other PCMD3180 setup is performed through alsamixer commands. For example, alsamixer commands set the following registers

## CHx_ASI_EN to On

amixer cset numid=29,iface=MIXER,name='CH1_ASI_EN Switch’ On

amixer cset numid=30,iface=MIXER,name='CH2_ASI_EN Switch' On

amixer cset numid=31,iface=MIXER,name='CH3_ASI_EN Switch' On   => 0x74, ADCX140_ASI_OUT_CH_EN, determines which channels are enabled

## MICxM Input Mux to Digital

amixer cset numid=25,iface=MIXER,name='MIC1M Input Mux’ 2      => 0x3C, ADCX140_CH1_CFG0, sets the channel 1 to a digital microphone input

amixer cset numid=26,iface=MIXER,name='MIC2M Input Mux' 2      => 0x41, ADCX140_CH2_CFG0, sets the channel 2 to a digital microphone input

amixer cset numid=27,iface=MIXER,name='MIC3M Input Mux' 2      => 0x46, ADCX140_CH3_CFG0, sets the channel 3 to a digital microphone input

## PDM CLk Div Select to 2.8224MHz

amixer cset numid=46,iface=MIXER,name='PDM Clk Div Select’ 0     => 0x1F, PDMCLK_CFG, sets the clock rate for the PDM clock output