---

yaml --- r: 320722 b: refs/heads/master c: 9dccf55 h: refs/heads/master v: v3
git-mirror · Jul 19, 2012 · 13ca131 · 13ca131
1 parent 04e8f52
commit 13ca131
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Showing 2 changed files with 24 additions and 2 deletions.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 330e0a01d54c2b8606c56816f99af6ebc58ec92c
+refs/heads/master: 9dccf55f4cb011a7552a8a2749a580662f5ed8ed
diff --git a/trunk/drivers/rtc/rtc-wm831x.c b/trunk/drivers/rtc/rtc-wm831x.c
@@ -24,7 +24,7 @@
 #include <linux/mfd/wm831x/core.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
-
+#include <linux/random.h>
 
 /*
  * R16416 (0x4020) - RTC Write Counter
@@ -96,6 +96,26 @@ struct wm831x_rtc {
 	unsigned int alarm_enabled:1;
 };
 
+static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
+{
+	int ret;
+	u16 reg;
+
+	/*
+	 * The write counter contains a pseudo-random number which is
+	 * regenerated every time we set the RTC so it should be a
+	 * useful per-system source of entropy.
+	 */
+	ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
+	if (ret >= 0) {
+		reg = ret;
+		add_device_randomness(&reg, sizeof(reg));
+	} else {
+		dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n",
+			 ret);
+	}
+}
+
 /*
  * Read current time and date in RTC
  */
@@ -431,6 +451,8 @@ static int wm831x_rtc_probe(struct platform_device *pdev)
 			alm_irq, ret);
 	}
 
+	wm831x_rtc_add_randomness(wm831x);
+
 	return 0;
 
 err: