hw/ssi: Allwinner A10 SPI emulation

hw/ssi: Allwinner A10 SPI emulation

This patch implements Allwinner A10 SPI controller emulation.
Only master-mode functionality is implemented.

Since U-Boot and Linux SPI drivers for Allwinner A10 perform only
byte-wide CPU access (no DMA) to the transmit and receive registers of
the peripheral, the emulated controller does not implement DMA control,
and supports only byte-wide access to transmit and receive registers
(half-word and word accesses will be treated as byte accesses).

Signed-off-by: Strahinja Jankovic <strahinja.p.jankovic@gmail.com>
Message-id: 20241001221349.8319-2-strahinja.p.jankovic@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>