target/loongarch: Add LoongArch IOCSR instruction

This includes:
- IOCSR{RD/WR}.{B/H/W/D}

Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220606124333.2060567-27-yangxiaojuan@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/loongarch/cpu.h

@@ -12,6 +12,27 @@
 #include "fpu/softfloat-types.h"
 #include "hw/registerfields.h"
 #include "qemu/timer.h"
+#include "exec/memory.h"
+#include "hw/sysbus.h"
+
+#define IOCSRF_TEMP             0
+#define IOCSRF_NODECNT          1
+#define IOCSRF_MSI              2
+#define IOCSRF_EXTIOI           3
+#define IOCSRF_CSRIPI           4
+#define IOCSRF_FREQCSR          5
+#define IOCSRF_FREQSCALE        6
+#define IOCSRF_DVFSV1           7
+#define IOCSRF_GMOD             9
+#define IOCSRF_VM               11
+
+#define FEATURE_REG             0x8
+#define VENDOR_REG              0x10
+#define CPUNAME_REG             0x20
+#define MISC_FUNC_REG           0x420
+#define IOCSRM_EXTIOI_EN        48
+
+#define IOCSR_MEM_SIZE          0x428
 
 #define TCG_GUEST_DEFAULT_MO (0)
 
@@ -283,6 +304,10 @@ typedef struct CPUArchState {
     uint64_t CSR_DSAVE;
 
     LoongArchTLB  tlb[LOONGARCH_TLB_MAX];
+
+    AddressSpace address_space_iocsr;
+    MemoryRegion system_iocsr;
+    MemoryRegion iocsr_mem;
 } CPULoongArchState;
 
 /**