[PATCH] mfd: wm831x: Feed the device UUID into device_add_randomness()

From: Mark Brown
Date: Thu Jul 05 2012 - 16:23:18 EST

wm831x devices contain a unique ID value. Feed this into the newly added
device_add_randomness() to add some per device seed data to the pool.

Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

add_device_randomness() has only just been added in -next, this will
need to either wait until after the merge window or be merged along with
the patch adding it.

drivers/mfd/wm831x-otp.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/mfd/wm831x-otp.c b/drivers/mfd/wm831x-otp.c
index f742745..b90f3e0 100644
--- a/drivers/mfd/wm831x-otp.c
+++ b/drivers/mfd/wm831x-otp.c
@@ -18,6 +18,7 @@
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/mfd/core.h>
+#include <linux/random.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/otp.h>
@@ -66,6 +67,7 @@ static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL);

int wm831x_otp_init(struct wm831x *wm831x)
+ char uuid[WM831X_UNIQUE_ID_LEN];
int ret;

ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
@@ -73,6 +75,12 @@ int wm831x_otp_init(struct wm831x *wm831x)
dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",

+ ret = wm831x_unique_id_read(wm831x, uuid);
+ if (ret == 0)
+ add_device_randomness(uuid, sizeof(uuid));
+ else
+ dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret);
return ret;


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