ptp: Added a brand new class driver for ptp clocks.

This patch adds an infrastructure for hardware clocks that implement
IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
registration method to particular hardware clock drivers. Each clock is
presented as a standard POSIX clock.

The ancillary clock features are exposed in two different ways, via
the sysfs and by a character device.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
new file mode 100644
index 000000000000..70d4bb1cbdab
--- /dev/null
+++ b/drivers/ptp/Kconfig
@@ -0,0 +1,30 @@
+#
+# PTP clock support configuration
+#
+
+menu "PTP clock support"
+
+comment "Enable Device Drivers -> PPS to see the PTP clock options."
+        depends on PPS=n
+
+config PTP_1588_CLOCK
+        tristate "PTP clock support"
+        depends on EXPERIMENTAL
+        depends on PPS
+        help
+          The IEEE 1588 standard defines a method to precisely
+          synchronize distributed clocks over Ethernet networks. The
+          standard defines a Precision Time Protocol (PTP), which can
+          be used to achieve synchronization within a few dozen
+          microseconds. In addition, with the help of special hardware
+          time stamping units, it can be possible to achieve
+          synchronization to within a few hundred nanoseconds.
+
+          This driver adds support for PTP clocks as character
+          devices. If you want to use a PTP clock, then you should
+          also enable at least one clock driver as well.
+
+          To compile this driver as a module, choose M here: the module
+          will be called ptp.
+
+endmenu