target/avr: Add instruction translation - MCU Control Instructions

This includes:
    - BREAK
    - NOP
    - SLEEP
    - WDR

Signed-off-by: Michael Rolnik <mrolnik@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Aleksandar Markovic <aleksandar.m.mail@gmail.com>
Reviewed-by: Aleksandar Markovic <aleksandar.m.mail@gmail.com>
Signed-off-by: Thomas Huth <huth@tuxfamily.org>
Message-Id: <20200705140315.260514-16-huth@tuxfamily.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

target/avr/insn.decode

@@ -177,3 +177,11 @@ BST             1111 101 rd:5 0 bit:3
 BLD             1111 100 rd:5 0 bit:3
 BSET            1001 0100 0 bit:3 1000
 BCLR            1001 0100 1 bit:3 1000
+
+#
+# MCU Control Instructions
+#
+BREAK           1001 0101 1001 1000
+NOP             0000 0000 0000 0000
+SLEEP           1001 0101 1000 1000
+WDR             1001 0101 1010 1000

target/avr/translate.c

@@ -2740,3 +2740,68 @@ static bool trans_BCLR(DisasContext *ctx, arg_BCLR *a)
 
     return true;
 }
+
+/*
+ * MCU Control Instructions
+ */
+
+/*
+ *  The BREAK instruction is used by the On-chip Debug system, and is
+ *  normally not used in the application software. When the BREAK instruction is
+ *  executed, the AVR CPU is set in the Stopped Mode. This gives the On-chip
+ *  Debugger access to internal resources.  If any Lock bits are set, or either
+ *  the JTAGEN or OCDEN Fuses are unprogrammed, the CPU will treat the BREAK
+ *  instruction as a NOP and will not enter the Stopped mode.  This instruction
+ *  is not available in all devices. Refer to the device specific instruction
+ *  set summary.
+ */
+static bool trans_BREAK(DisasContext *ctx, arg_BREAK *a)
+{
+    if (!avr_have_feature(ctx, AVR_FEATURE_BREAK)) {
+        return true;
+    }
+
+#ifdef BREAKPOINT_ON_BREAK
+    tcg_gen_movi_tl(cpu_pc, ctx->npc - 1);
+    gen_helper_debug(cpu_env);
+    ctx->bstate = DISAS_EXIT;
+#else
+    /* NOP */
+#endif
+
+    return true;
+}
+
+/*
+ *  This instruction performs a single cycle No Operation.
+ */
+static bool trans_NOP(DisasContext *ctx, arg_NOP *a)
+{
+
+    /* NOP */
+
+    return true;
+}
+
+/*
+ *  This instruction sets the circuit in sleep mode defined by the MCU
+ *  Control Register.
+ */
+static bool trans_SLEEP(DisasContext *ctx, arg_SLEEP *a)
+{
+    gen_helper_sleep(cpu_env);
+    ctx->bstate = DISAS_NORETURN;
+    return true;
+}
+
+/*
+ *  This instruction resets the Watchdog Timer. This instruction must be
+ *  executed within a limited time given by the WD prescaler. See the Watchdog
+ *  Timer hardware specification.
+ */
+static bool trans_WDR(DisasContext *ctx, arg_WDR *a)
+{
+    gen_helper_wdr(cpu_env);
+
+    return true;
+}