linux kernel add alsa

Start the Linux Kernel Configuration tool:

make ARCH=arm CROSS_COMPILE=arm-hisiv300-linux- menuconfig

Select Device Drivers from the main menu.

    ...
    ...
    Power management options --->
    [ ] Networking support --->
    Device Drivers --->
    File systems --->
    Kernel hacking --->
    ...
    ...

Select Sound card support as shown here

    ...
    ...
    Graphics support  --->
    <*> Sound card support  --->
    [*] HID Devices  --->
    [*] USB support  --->
    ...

Select "Advanced Linux Sound Architecture" as shown here

    ...
    ...
    --- Sound card support
    <*>   Advanced Linux Sound Architecture  --->
    < >   Open Sound System (DEPRECATED)  --->

select USB sound devices as shown here

    ...
    ...
    [ ]   SPI sound devices  --->
    [*]   USB sound devices  --->
    <*>   ALSA for SoC audio support  --->
    ... 
    ...

Select USB Audio/MIDI driver as shown here

    ...
    ...
    --- USB sound devices
    <*>   USB Audio/MIDI driver
    < >   Edirol UA-101/UA-1000 driver
    ...
    ...

This is all required for adding USB host audio support in kernel.