ARM: OMAP2+: Set system_rev from ATAGS for n900

This fixed a regression with DT boot compared to legacy boot.
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
[tony@atomide.com: edited patch subject to follow standard]
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/board-generic.c

@@ -18,6 +18,7 @@
 
 #include <asm/setup.h>
 #include <asm/mach/arch.h>
+#include <asm/system_info.h>
 
 #include "common.h"
 
@@ -77,12 +78,31 @@ static const char *const n900_boards_compat[] __initconst = {
 	NULL,
 };
 
+/* Set system_rev from atags */
+static void __init rx51_set_system_rev(const struct tag *tags)
+{
+	const struct tag *tag;
+
+	if (tags->hdr.tag != ATAG_CORE)
+		return;
+
+	for_each_tag(tag, tags) {
+		if (tag->hdr.tag == ATAG_REVISION) {
+			system_rev = tag->u.revision.rev;
+			break;
+		}
+	}
+}
+
 /* Legacy userspace on Nokia N900 needs ATAGS exported in /proc/atags,
  * save them while the data is still not overwritten
  */
 static void __init rx51_reserve(void)
 {
-	save_atags((const struct tag *)(PAGE_OFFSET + 0x100));
+	const struct tag *tags = (const struct tag *)(PAGE_OFFSET + 0x100);
+
+	save_atags(tags);
+	rx51_set_system_rev(tags);
 	omap_reserve();
 }