ARM: bcm2835: Set Serial number and Revision

The VideoCore bootloader passes in Serial number and
Revision number through Device Tree. Make these available to
userspace through /proc/cpuinfo.

Mainline status:

There is a commit in linux-next that standardize passing the serial
number through Device Tree (string: /serial-number):
ARM: 8355/1: arch: Show the serial number from devicetree in cpuinfo

There was an attempt to do the same with the revision number, but it
didn't get in:
[PATCH v2 1/2] arm: devtree: Set system_rev from DT revision

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>

Author: notro

arch/arm/mach-bcm/board_bcm2835.c

@@ -18,6 +18,7 @@
 #include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/clk/bcm2835.h>
+#include <asm/system_info.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
@@ -107,6 +108,9 @@ static void __init bcm2835_map_io(void)
 
 static void __init bcm2835_init(void)
 {
+	struct device_node *np = of_find_node_by_path("/system");
+	u32 val;
+	u64 val64;
 	int ret;
 
 	bcm2835_setup_restart();
@@ -121,6 +125,11 @@ static void __init bcm2835_init(void)
 		pr_err("of_platform_populate failed: %d\n", ret);
 		BUG();
 	}
+
+	if (!of_property_read_u32(np, "linux,revision", &val))
+		system_rev = val;
+	if (!of_property_read_u64(np, "linux,serial", &val64))
+		system_serial_low = val64;
 }
 
 static const char * const bcm2835_compat[] = {