DMA length is from 1 byte to 32MB for AST2600 and AST10x0
and DMA length is from 4 bytes to 32MB for AST2500.
In other words, if "R_DMA_LEN" is 0, it should move at least 1 byte
data for AST2600 and AST10x0 and 4 bytes data for AST2500.
To support all ASPEED SOCs, adds dma_start_length parameter to store
the start length, add helper routines function to compute the dma length
and update DMA_LENGTH mask to "1FFFFFF" to support dma 1 byte
length unit for AST2600 and AST1030.
Currently, only supports dma length 4 bytes aligned.
Signed-off-by: Troy Lee <troy_lee@aspeedtech.com>
Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>