mpc83xx: Add support for the display of reset status

83xx processor family has many reset sources, such as
power on reset, software hard reset, software soft reset,
JTAG, bus monitor, software watchdog, check stop reset,
external hard reset, external software reset.
sometimes, to figure out the fault of system, we need to
know the cause of reset early before the prompt of
u-boot present.

Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>

cpu/mpc83xx/cpu_init.c

@@ -257,3 +257,39 @@ int cpu_init_r (void)
 #endif
 	return 0;
 }
+
+/*
+ * Figure out the cause of the reset
+ */
+int prt_83xx_rsr(void)
+{
+	static struct {
+		ulong mask;
+		char *desc;
+	} bits[] = {
+		{
+		RSR_SWSR, "Software Soft"}, {
+		RSR_SWHR, "Software Hard"}, {
+		RSR_JSRS, "JTAG Soft"}, {
+		RSR_CSHR, "Check Stop"}, {
+		RSR_SWRS, "Software Watchdog"}, {
+		RSR_BMRS, "Bus Monitor"}, {
+		RSR_SRS,  "External/Internal Soft"}, {
+		RSR_HRS,  "External/Internal Hard"}
+	};
+	static int n = sizeof bits / sizeof bits[0];
+	ulong rsr = gd->reset_status;
+	int i;
+	char *sep;
+
+	puts("Reset Status:");
+
+	sep = " ";
+	for (i = 0; i < n; i++)
+		if (rsr & bits[i].mask) {
+			printf("%s%s", sep, bits[i].desc);
+			sep = ", ";
+		}
+	puts("\n\n");
+	return 0;
+}