ARM: ux500: add DB serial number to entropy pool

This throws the DB (digital baseband, ASIC) serial number, process
type etc into the entropy pool by way of the device_add_randomness()
call. This should make every device have a unique pool state upon
boot.

Cc: Theodore Tso <tytso@mit.edu>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ux500/cpu-db8500.c

@@ -17,6 +17,8 @@
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/mfd/abx500/ab8500.h>
+#include <linux/platform_data/usb-musb-ux500.h>
+#include <linux/random.h>
 
 #include <asm/pmu.h>
 #include <asm/mach/map.h>
@@ -24,7 +26,6 @@
 #include <mach/hardware.h>
 #include <mach/setup.h>
 #include <mach/devices.h>
-#include <linux/platform_data/usb-musb-ux500.h>
 #include <mach/db8500-regs.h>
 
 #include "devices-db8500.h"
@@ -187,6 +188,8 @@ static const char *db8500_read_soc_id(void)
 {
 	void __iomem *uid = __io_address(U8500_BB_UID_BASE);
 
+	/* Throw these device-specific numbers into the entropy pool */
+	add_device_randomness(uid, 0x14);
 	return kasprintf(GFP_KERNEL, "%08x%08x%08x%08x%08x",
 			 readl((u32 *)uid+1),
 			 readl((u32 *)uid+1), readl((u32 *)uid+2),