I/O Access Abstractions
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Quoted 2 lines · Russell King
They _ARE_ different, because people connect these chips in many different ways. For example:
Also hence the mess in serial.c. On the board I'm currently dealing with, the PC16550 chip is connected to the memory space with registers at 4-byte intervals because the chip is an 8-bit chip connected to a 32-bit data bus (and so ignored addr lines A0 and A1). Whereas on the PC, various serial register sets appear generally in I/O port space at 1-byte intervals from some base address.
This could be greatly simplified with the method I'm proposing. The resource access function could make the address space for that device to be eight consecutive registers regardless of the reality.
David