ptp: Added a clock driver for the IXP46x.

This patch adds a driver for the hardware time stamping unit found on the
IXP465. The basic clock operations and an external trigger are implemented.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 12eb844..fcfafd0 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -40,4 +40,17 @@
 	  To compile this driver as a module, choose M here: the module
 	  will be called gianfar_ptp.
 
+config PTP_1588_CLOCK_IXP46X
+	tristate "Intel IXP46x as PTP clock"
+	depends on PTP_1588_CLOCK
+	depends on IXP4XX_ETH
+	help
+	  This driver adds support for using the IXP46X as a PTP
+	  clock. This clock is only useful if your PTP programs are
+	  getting hardware time stamps on the PTP Ethernet packets
+	  using the SO_TIMESTAMPING API.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ptp_ixp46x.
+
 endmenu