[PATCH] target/m68k: only change valid bits in CACR

[Laurent Vivier <laurent@vivier.eu>]

This is used by netBSD (and MacOS ROM) to detect the MMU type

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target/m68k/cpu.c    | 28 ++++++++++++++++++++++------
 target/m68k/cpu.h    |  4 ++++
 target/m68k/helper.c | 16 ++++++++++++++--
 3 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index e6596de29c..1d202cec49 100644
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -114,11 +114,8 @@ static void m68000_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
 
-static void m68020_cpu_initfn(Object *obj)
+static void m680x0_cpu_common(CPUM68KState *env)
 {
-    M68kCPU *cpu = M68K_CPU(obj);
-    CPUM68KState *env = &cpu->env;
-
     m68k_set_feature(env, M68K_FEATURE_M68000);
     m68k_set_feature(env, M68K_FEATURE_USP);
     m68k_set_feature(env, M68K_FEATURE_WORD_INDEX);
@@ -136,14 +133,32 @@ static void m68020_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_CHK2);
     m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
-#define m68030_cpu_initfn m68020_cpu_initfn
+
+static void m68020_cpu_initfn(Object *obj)
+{
+    M68kCPU *cpu = M68K_CPU(obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_MMU68851);
+}
+
+static void m68030_cpu_initfn(Object *obj)
+{
+    M68kCPU *cpu = M68K_CPU(obj);
+    CPUM68KState *env = &cpu->env;
+
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_MMU68030);
+}
 
 static void m68040_cpu_initfn(Object *obj)
 {
     M68kCPU *cpu = M68K_CPU(obj);
     CPUM68KState *env = &cpu->env;
 
-    m68020_cpu_initfn(obj);
+    m680x0_cpu_common(env);
+    m68k_set_feature(env, M68K_FEATURE_MMU68040);
     m68k_set_feature(env, M68K_FEATURE_M68040);
 }
 
@@ -166,6 +181,7 @@ static void m68060_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_BKPT);
     m68k_set_feature(env, M68K_FEATURE_RTD);
     m68k_set_feature(env, M68K_FEATURE_CHK2);
+    m68k_set_feature(env, M68K_FEATURE_MMU68060);
 }
 
 static void m5208_cpu_initfn(Object *obj)
diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 20de3c379a..36e4353b44 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -483,6 +483,10 @@ enum m68k_features {
     M68K_FEATURE_CHK2,
     M68K_FEATURE_M68040, /* instructions specific to MC68040 */
     M68K_FEATURE_MOVEP,
+    M68K_FEATURE_MMU68851,
+    M68K_FEATURE_MMU68030,
+    M68K_FEATURE_MMU68040,
+    M68K_FEATURE_MMU68060,
 };
 
 static inline int m68k_feature(CPUM68KState *env, int feature)
diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index ae766a6cb0..b5758bbd7d 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -205,7 +205,13 @@ void HELPER(m68k_movec_to)(CPUM68KState *env, uint32_t reg, uint32_t val)
         return;
     /* MC680[234]0 */
     case M68K_CR_CACR:
-        env->cacr = val;
+        if (m68k_feature(env, M68K_FEATURE_MMU68040)) {
+            env->cacr = val & 0x80008000;
+        } else if (m68k_feature(env, M68K_FEATURE_MMU68030)) {
+            env->cacr = val & 0x00003fff;
+        } else if (m68k_feature(env, M68K_FEATURE_MMU68851)) {
+            env->cacr = val & 0x0000000f;
+        }
         m68k_switch_sp(env);
         return;
     /* MC680[34]0 */
@@ -261,7 +267,13 @@ uint32_t HELPER(m68k_movec_from)(CPUM68KState *env, uint32_t reg)
         return env->vbr;
     /* MC680[234]0 */
     case M68K_CR_CACR:
-        return env->cacr;
+        if (m68k_feature(env, M68K_FEATURE_MMU68040)) {
+            return env->cacr & 0x80008000;
+        } else if (m68k_feature(env, M68K_FEATURE_MMU68030)) {
+            return env->cacr & 0x00003fff;
+        } else if (m68k_feature(env, M68K_FEATURE_MMU68851)) {
+            return env->cacr & 0x0000000f;
+        }
     /* MC680[34]0 */
     case M68K_CR_TC:
         return env->mmu.tcr;
-- 
2.23.0