Blackfin: implement bootcount support

The default storage location for bootcount is EVT0.  This version uses
one 32bit value and combines the magic/count value in the upper/lower
16bits.  If there is demand for more, should be easy to do.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/cpu/Makefile

@@ -17,6 +17,7 @@ EXTRA    :=
 CEXTRA   := initcode.o
 SEXTRA   := start.o
 SOBJS    := interrupt.o cache.o
+COBJS-$(CONFIG_BOOTCOUNT_LIMIT) += bootcount.o
 COBJS-y  += cpu.o
 COBJS-y  += interrupts.o
 COBJS-$(CONFIG_JTAG_CONSOLE) += jtag-console.o

arch/blackfin/cpu/bootcount.c

@@ -0,0 +1,34 @@
+/*
+ * functions for handling bootcount support
+ *
+ * Copyright (c) 2010 Analog Devices Inc.
+ *
+ * Licensed under the 2-clause BSD.
+ */
+
+/* This version uses one 32bit storage and combines the magic/count */
+
+#include <common.h>
+
+/* We abuse the EVT0 MMR for bootcount storage by default */
+#ifndef CONFIG_SYS_BOOTCOUNT_ADDR
+# define CONFIG_SYS_BOOTCOUNT_ADDR EVT0
+#endif
+
+#define MAGIC_MASK 0xffff0000
+#define COUNT_MASK 0x0000ffff
+
+void bootcount_store(ulong cnt)
+{
+	ulong magic = (BOOTCOUNT_MAGIC & MAGIC_MASK) | (cnt & COUNT_MASK);
+	bfin_write32(CONFIG_SYS_BOOTCOUNT_ADDR, magic);
+}
+
+ulong bootcount_load(void)
+{
+	ulong magic = bfin_read32(CONFIG_SYS_BOOTCOUNT_ADDR);
+	if ((magic & MAGIC_MASK) == (BOOTCOUNT_MAGIC & MAGIC_MASK))
+		return magic & COUNT_MASK;
+	else
+		return 0;
+}