mfd: wm831x: Feed the device UUID into device_add_randomness()

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@opensource.wolfsonmicro.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/mfd/wm831x-otp.c b/drivers/mfd/wm831x-otp.c
index f742745ff35..b90f3e06b6c 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);
 
+        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;
 }