Add a mailbox controller driver for the Microchip Inter-processor
Communication (IPC), which is used to send and receive data between
processors.
The driver uses the RISC-V Supervisor Binary Interface (SBI) to
communicate with software running in machine mode (M-mode) to access
the IPC hardware block.
Additional details on the Microchip vendor extension and the IPC
function IDs described in the driver can be found in the following
documentation:
https://github.com/linux4microchip/microchip-sbi-ecall-extension
This SBI interface in this driver is compatible with the Mi-V Inter-hart
Communication (IHC) IP.
Transmitting and receiving data through the mailbox framework is done
through struct mchp_ipc_msg.
Signed-off-by: Valentina Fernandez <valentina.fernandezalanis@microchip.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
