The 1.4.9 Integrated flash controller in ls1046a Reference Manual shows that NOR and GPCM support 256MB.
However, the IFC Address only exists from 0 to 27, and when calculated, it is confirmed that only 32MByte can be set.
How do I design it to set 256MByte that is confirmed in the Reference Manual?
The number of address lines in a system determines the maximum addressable memory space of that system. With 28 address lines, the IFC can address up to 2^28 (268,435,456) unique memory locations. In the case of NOR flash, each memory location typically consists of 1 byte (8 bits).
Therefore, the maximum memory space that can be addressed by the IFC is 268,435,456 bytes (or 256 megabytes).
If I use 16-bit NOR-flash, is Address[27] unused?
Calculated in 16-bit NOR-flash, the maximum is 512 Mbyte, but LS1046A data sheet checks indicate that it supports up to 256 Mbyte.
As stated in the reference manual, an IFC with 28 address lines and a data bus width of 16 bits supports memory banks of up to 256 MB for NOR and GPCM.
If you use 16-bit NOR flash, then in that case, the address line A[0] will be masked.