riscv_coprocessor interface makes it possible for RISC-V
processors to read and write Control and Status Registers (CSRs) like
mtime
SIM_INTERFACE(riscv_coprocessor) {
uint64 (*read_register)(conf_object_t *obj, uint64 number);
void (*write_register)(conf_object_t *obj, uint64 number, uint64 value);
};
#define RISCV_COPROCESSOR_INTERFACE "riscv_coprocessor"