Blackfin arch: Fix BUG -- BF533 + 0.5 silicon + MPU + UART PIO -> crash

Apply ANOMALY_05000283 & ANOMALY_05000315
Workaround also to the EXCEPTION path.

Cover evt_ivhw also with ANOMALY_05000315
The Workaround needs to be prior to accesses (either read or write) to
any system MMR.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

arch/blackfin/mach-common/entry.S

@@ -484,6 +484,15 @@ ENTRY(_trap) /* Exception: 4th entry into system event table(supervisor mode)*/
 	[--sp] = ASTAT;
 	[--sp] = (R7:6,P5:4);
 
+#if ANOMALY_05000283 || ANOMALY_05000315
+	cc = r7 == r7;
+	p5.h = HI(CHIPID);
+	p5.l = LO(CHIPID);
+	if cc jump 1f;
+	r7.l = W[p5];
+1:
+#endif
+
 #ifdef CONFIG_DEBUG_DOUBLEFAULT
 	/*
 	 * Save these registers, as they are only valid in exception context
@@ -1020,6 +1029,15 @@ ENTRY(_early_trap)
 	SAVE_ALL_SYS
 	trace_buffer_stop(p0,r0);
 
+#if ANOMALY_05000283 || ANOMALY_05000315
+	cc = r5 == r5;
+	p4.h = HI(CHIPID);
+	p4.l = LO(CHIPID);
+	if cc jump 1f;
+	r5.l = W[p4];
+1:
+#endif
+
 	/* Turn caches off, to ensure we don't get double exceptions */
 
 	P4.L = LO(IMEM_CONTROL);

arch/blackfin/mach-common/interrupt.S

@@ -143,7 +143,7 @@ ENTRY(_evt_ivhw)
 	fp = 0;
 #endif
 
-#if ANOMALY_05000283
+#if ANOMALY_05000283 || ANOMALY_05000315
 	cc = r7 == r7;
 	p5.h = HI(CHIPID);
 	p5.l = LO(CHIPID);