hwrng: ppc4xx - add support for ppc4xx TRNG

Various PowerPC 4xx SoCs contain a TRNG embedded in the Security function.
This adds a device driver for that TRNG.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index a60043b..1d2ebc7 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -210,3 +210,15 @@
 	  module will be called picoxcell-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_PPC4XX
+	tristate "PowerPC 4xx generic true random number generator support"
+	depends on HW_RANDOM && PPC && 4xx
+	---help---
+	 This driver provides the kernel-side support for the TRNG hardware
+	 found in the security function of some PowerPC 4xx SoCs.
+
+	 To compile this driver as a module, choose M here: the
+	 module will be called ppc4xx-rng.
+
+	 If unsure, say N.