How to implement non interleaved mmap (direct) access mode in Alsa for live streaming from SRAM? - mmap

Question

I have a buffer in SRAM of size 4096 bytes which gets updated with new raw audio data periodically:
----------------------------------------
| 2048 bytes of L | 2048 bytes of right|
----------------------------------------
^ ^
|A |B
NOTE: A and B are pointers to the start addresses.
As shown, the data is non-interleaved stereo (16 bit samples, 44100Hz sampling rate) and since it is in memory already, I prefer to use MMAP'ed access instead of RW (and as far as my understanding of alsa goes, it should not use a separate buffer for copying data into from this buffer).
The starting address for this buffer is fixed (say 0x3f000000 physical address) and I am MMAPing this buffer to get a virtual address pointer.
Now, how do I send data to alsa for playback and what should be my configuration?
My current unsuccessful way is:
Resample ON
Rate 44100
SND_PCM_ACCESS_MMAP_NONINTERLEAVED
channels 2
format SND_PCM_FORMAT_S16_LE
period near 1024 frames
buffer near 2*1024 frames
void* ptr[2];
ptr[0] = A // Points to mmaped virtual address of A
ptr[1] = B // Points to mmaped virtual address of B
while(1)
{
wait_for_new_data_in_buffer();
snd_pcm_mmap_writen(handle, &ptr, period_size);
}
Extra info:
1. I am using an embedded board with arm cores and running basic linux on it.
2. This is a proprietary work related project and hence the vague-ness of this question.
3. I already know that directly MMAPing a physical address is not recommended so do not waste your time commenting about it.
Thanks in advance.