avr32: add ATAG_BOARDINFO

The ATAG_BOARDINFO is intended to hand over the information
bd->bi_board_number from u-boot to the kernel.

This piece of information can be used to implement some kind of board
identification while booting the kernel. Therefore it is placed in .initdata
section and can be accessed via the new symbol board_number only while
initializing the kernel.
Signed-off-by: Andreas Bießmann <biessmann@corscience.de>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>

arch/avr32/include/asm/setup.h

@@ -94,6 +94,13 @@ struct tag_ethernet {
 
 #define ETH_INVALID_PHY	0xff
 
+/* board information */
+#define ATAG_BOARDINFO	0x54410008
+
+struct tag_boardinfo {
+	u32	board_number;
+};
+
 struct tag {
 	struct tag_header hdr;
 	union {
@@ -102,6 +109,7 @@ struct tag {
 		struct tag_cmdline cmdline;
 		struct tag_clock clock;
 		struct tag_ethernet ethernet;
+		struct tag_boardinfo boardinfo;
 	} u;
 };
 
@@ -128,6 +136,7 @@ extern struct tag *bootloader_tags;
 
 extern resource_size_t fbmem_start;
 extern resource_size_t fbmem_size;
+extern u32 board_number;
 
 void setup_processor(void);
 

arch/avr32/kernel/setup.c

@@ -390,6 +390,21 @@ static int __init parse_tag_clock(struct tag *tag)
 }
 __tagtable(ATAG_CLOCK, parse_tag_clock);
 
+/*
+ * The board_number correspond to the bd->bi_board_number in U-Boot. This
+ * parameter is only available during initialisation and can be used in some
+ * kind of board identification.
+ */
+u32 __initdata board_number;
+
+static int __init parse_tag_boardinfo(struct tag *tag)
+{
+	board_number = tag->u.boardinfo.board_number;
+
+	return 0;
+}
+__tagtable(ATAG_BOARDINFO, parse_tag_boardinfo);
+
 /*
  * Scan the tag table for this tag, and call its parse function. The
  * tag table is built by the linker from all the __tagtable