powerpc/crypto: add 842 hardware compression driver

This patch adds the driver for interacting with the 842
compression accelerator on IBM Power7+ systems.

The device is a child of the Platform Facilities Option (PFO)
and shows up as a child of the IBM VIO bus.

The compression/decompression API takes the same arguments
as existing compression methods like lzo and deflate.  The 842
hardware operates on 4K hardware pages and the driver breaks up
input on 4K boundaries to submit it to the hardware accelerator.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/nx/Kconfig

@@ -15,3 +15,12 @@ config CRYPTO_DEV_NX_ENCRYPT
 	  Support for Power7+ in-Nest encryption acceleration. This
 	  module supports acceleration for AES and SHA2 algorithms. If you
 	  choose 'M' here, this module will be called nx_crypto.
+
+config CRYPTO_DEV_NX_COMPRESS
+	tristate "Compression acceleration support"
+	depends on PPC64 && IBMVIO
+	default y
+	help
+	  Support for Power7+ in-Nest compression acceleration. This
+	  module supports acceleration for AES and SHA2 algorithms. If you
+	  choose 'M' here, this module will be called nx_compress.

drivers/crypto/nx/Makefile

@@ -9,3 +9,6 @@ nx-crypto-objs := nx.o \
 		  nx-aes-xcbc.o \
 		  nx-sha256.o \
 		  nx-sha512.o
+
+obj-$(CONFIG_CRYPTO_DEV_NX_COMPRESS) += nx-compress.o
+nx-compress-objs := nx-842.o