caif: Add CAIF HSI Link layer driver

This patch introduces the CAIF HSI Protocol Driver for the
CAIF Link Layer.

This driver implements a platform driver to accommodate for a
platform specific HSI devices. A general platform driver is not
possible as there are no HSI side Kernel API defined.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/caif/Kconfig

@@ -38,3 +38,12 @@ config CAIF_SHM
 	default n
 	---help---
 	The CAIF shared memory protocol driver for the STE UX5500 platform.
+
+config CAIF_HSI
+       tristate "CAIF HSI transport driver"
+       depends on CAIF
+       default n
+       ---help---
+       The caif low level driver for CAIF over HSI.
+       Be aware that if you enable this then you also need to
+       enable a low-level HSI driver.

drivers/net/caif/Makefile

@@ -10,3 +10,6 @@ obj-$(CONFIG_CAIF_SPI_SLAVE) += cfspi_slave.o
 # Shared memory
 caif_shm-objs := caif_shmcore.o caif_shm_u5500.o
 obj-$(CONFIG_CAIF_SHM) += caif_shm.o
+
+# HSI interface
+obj-$(CONFIG_CAIF_HSI) += caif_hsi.o