docs: ptp.txt: convert to ReST and move to driver-api

The conversion is trivial: just adjust title markups.

In order to avoid conflicts, let's add an :orphan: tag
to it, to be removed when this file gets added to the
driver-api book.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/ptp/ptp.txt → Documentation/driver-api/ptp.rst

+:orphan:
 
-* PTP hardware clock infrastructure for Linux
+===========================================
+PTP hardware clock infrastructure for Linux
+===========================================
 
   This patch set introduces support for IEEE 1588 PTP clocks in
   Linux. Together with the SO_TIMESTAMPING socket options, this
@@ -22,7 +25,8 @@
     - Period output signals configurable from user space
     - Synchronization of the Linux system time via the PPS subsystem
 
-** PTP hardware clock kernel API
+PTP hardware clock kernel API
+=============================
 
    A PTP clock driver registers itself with the class driver. The
    class driver handles all of the dealings with user space. The
@@ -36,7 +40,8 @@
    development, it can be useful to have more than one clock in a
    single system, in order to allow performance comparisons.
 
-** PTP hardware clock user space API
+PTP hardware clock user space API
+=================================
 
    The class driver also creates a character device for each
    registered clock. User space can use an open file descriptor from
@@ -49,7 +54,8 @@
    ancillary clock features. User space can receive time stamped
    events via blocking read() and poll().
 
-** Writing clock drivers
+Writing clock drivers
+=====================
 
    Clock drivers include include/linux/ptp_clock_kernel.h and register
    themselves by presenting a 'struct ptp_clock_info' to the
@@ -66,14 +72,17 @@
    class driver, since the lock may also be needed by the clock
    driver's interrupt service routine.
 
-** Supported hardware
+Supported hardware
+==================
+
+   * Freescale eTSEC gianfar
 
-   + Freescale eTSEC gianfar
      - 2 Time stamp external triggers, programmable polarity (opt. interrupt)
      - 2 Alarm registers (optional interrupt)
      - 3 Periodic signals (optional interrupt)
 
-   + National DP83640
+   * National DP83640
+
      - 6 GPIOs programmable as inputs or outputs
      - 6 GPIOs with dedicated functions (LED/JTAG/clock) can also be
        used as general inputs or outputs
@@ -81,6 +90,7 @@
      - GPIO outputs can produce periodic signals
      - 1 interrupt pin
 
-   + Intel IXP465
+   * Intel IXP465
+
      - Auxiliary Slave/Master Mode Snapshot (optional interrupt)
      - Target Time (optional interrupt)

Documentation/networking/timestamping.txt

@@ -368,7 +368,7 @@ ts[1] used to hold hardware timestamps converted to system time.
 Instead, expose the hardware clock device on the NIC directly as
 a HW PTP clock source, to allow time conversion in userspace and
 optionally synchronize system time with a userspace PTP stack such
-as linuxptp. For the PTP clock API, see Documentation/ptp/ptp.txt.
+as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
 
 Note that if the SO_TIMESTAMP or SO_TIMESTAMPNS option is enabled
 together with SO_TIMESTAMPING using SOF_TIMESTAMPING_SOFTWARE, a false

MAINTAINERS

@@ -12765,7 +12765,7 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 W:	http://linuxptp.sourceforge.net/
 F:	Documentation/ABI/testing/sysfs-ptp
-F:	Documentation/ptp/*
+F:	Documentation/driver-api/ptp.rst
 F:	drivers/net/phy/dp83640*
 F:	drivers/ptp/*
 F:	include/linux/ptp_cl*