docs(linux): Add PTP support documentation for HSR and PRP offload

Document PTP synchronization support over HSR and PRP interfaces
using the linuxptp-hsr implementation (hsr_prp_v2_plus branch).

Add Prerequisites, Running PTP, and Verifying PTP Synchronization
subsections to both HSR_Offload.rst and PRP_Offload.rst covering:
- Cloning and building linuxptp-hsr
- Patching config files with interface names and p2p_dst_mac
- Running ptp4l with primary/secondary configs
- Verifying sync via master offset values

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>

Author: danish-ti

source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/HSR_Offload.rst

@@ -339,6 +339,11 @@ Example:
 
    # ip maddr del 01:80:c4:00:00:0e dev hsr0.5
 
+.. |PTP_PROTO_FULL| replace:: High-availability Seamless Redundancy (HSR)
+.. |PTP_CFG_PREFIX| replace:: hsr
+
+.. include:: _ptp_support.rst
+
 .. rubric:: Performance
 
 This section describes the throughput and CPU usage metrics in the offload case

source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/PRP_Offload.rst

@@ -309,6 +309,11 @@ Example:
 
    # ip maddr del 01:80:c4:00:00:0e dev prp0.5
 
+.. |PTP_PROTO_FULL| replace:: Parallel Redundancy Protocol (PRP)
+.. |PTP_CFG_PREFIX| replace:: prp
+
+.. include:: _ptp_support.rst
+
 .. rubric:: Performance
 
 This section describes the throughput and CPU usage metrics in the offload case

source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/_ptp_support.rst

@@ -0,0 +1,56 @@
+.. rubric:: *PTP Support*
+
+PTP (Precision Time Protocol) synchronization over |PTP_PROTO_FULL| is supported using the
+`linuxptp-hsr <https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/linuxptp-hsr.git>`_
+implementation on the ``hsr_prp_v2_plus`` branch.
+
+.. rubric:: Prerequisites
+
+The following will need to be done for each node.
+
+Clone linuxptp-hsr:
+
+.. code-block:: console
+
+   git clone https://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/linuxptp-hsr.git
+   cd linuxptp-hsr
+   git checkout hsr_prp_v2_plus
+
+Patch the config files with the actual interface names and the P2P destination MAC address:
+
+.. parsed-literal::
+
+   sed -i '/^delay_mechanism P2P/a p2p_dst_mac 01:1B:19:00:00:01' configs/|PTP_CFG_PREFIX|-master.cfg configs/|PTP_CFG_PREFIX|-slave.cfg
+   sed -i 's/^\[eth1\]/[<INTF_A>]/; s/^\[eth2\]/[<INTF_B>]/' configs/|PTP_CFG_PREFIX|-master.cfg configs/|PTP_CFG_PREFIX|-slave.cfg
+
+Build and install:
+
+.. code-block:: console
+
+   make && make install
+
+.. rubric:: Running PTP
+
+Set up the interface as described in the Introduction section. On the PTP primary node:
+
+.. parsed-literal::
+
+   ./ptp4l -f configs/|PTP_CFG_PREFIX|-master.cfg
+
+On each PTP secondary node:
+
+.. parsed-literal::
+
+   ./ptp4l -f configs/|PTP_CFG_PREFIX|-slave.cfg
+
+.. rubric:: Verifying PTP Synchronization
+
+Inspect the ``master offset`` values in the ptp4l log output to verify PTP synchronization.
+
+Sample ptp4l output showing a synchronized secondary node:
+
+.. code-block:: text
+
+   ptp4l[xx.xxx]: master offset   -123 s2 freq  +4321 path delay   543
+   ptp4l[xx.xxx]: master offset     45 s2 freq  +4290 path delay   541
+   ptp4l[xx.xxx]: master offset    -78 s2 freq  +4310 path delay   544