AM335x DMA data transfer from memory to register

Hi All,

System : Linux 4.1 Beaglebone black

I'm working on data transfer using DMA on timer trigger. I want to update TMAR(offset = 0x4C) register after every trigger in order to change a time period for next transfer. For this purpose, I have configured DMA in A-sync mode and set SRCBIDX,SRCCIDX to zero. I'm using APIs from EDMA.C and EDMA.h.

When I assigned destination address by edma_set_dest (dma_ch, (unsigned long)(TMAR_address), INCR, W32BIT);

where TMAR_address is calculated using 

Timer_base = ioremap(0x48044000,4*1024);

TMAR_address = Timer_base + (offset)/4; (since Timer_base is 4 byte pointer)

I saw garbage value being transferred.

My question is

1) How to assign address of peripheral register to DMA using  edma_set_dest. Since edma_set_dest accepts data in dma_addr_t. 

2) Is memory mapping used by DMA and CPU is different? In that case, can someone shed light on how to calculate  register address that can be fed to DMA as destination address? I have verified that memory to memory transfer is working but not device to memory.  Therefore the problem is related to destination address only.

 Regards,

Satish