1. 28 Jul, 2020 12 commits
  2. 27 Jul, 2020 28 commits
    • Gustavo A. R. Silva's avatar
      net/mlx4: Use fallthrough pseudo-keyword · 5e619d73
      Gustavo A. R. Silva authored
      Replace the existing /* fall through */ comments and its variants with
      the new pseudo-keyword macro fallthrough[1].
      
      [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5e619d73
    • David S. Miller's avatar
      Merge branch '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue · a02d26fe
      David S. Miller authored
      Tony Nguyen says:
      
      ====================
      1GbE Intel Wired LAN Driver Updates 2020-07-27
      
      This series contains updates to igc driver only.
      
      Sasha cleans up double definitions, unneeded and non applicable
      registers, and removes unused fields in structs. Ensures the Receive
      Descriptor Minimum Threshold Count is cleared and fixes a static checker
      error.
      
      v2: Remove fields from hw_stats in patches that removed their uses.
      Reworded patch descriptions for patches 1, 2, and 4.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a02d26fe
    • Colin Ian King's avatar
      qed: fix assignment of n_rq_elems to incorrect params field · 35406697
      Colin Ian King authored
      Currently n_rq_elems is being assigned to params.elem_size instead of the
      field params.num_elems.  Coverity is detecting this as a double assingment
      to params.elem_size and reporting this as an usused value on the first
      assignment.  Fix this.
      
      Addresses-Coverity: ("Unused value")
      Fixes: b6db3f71 ("qed: simplify chain allocation with init params struct")
      Signed-off-by: default avatarColin Ian King <colin.king@canonical.com>
      Acked-by: default avatarAlexander Lobakin <alobakin@marvell.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      35406697
    • David S. Miller's avatar
      Merge branch 'sfc-driver-for-EF100-family-NICs-part-1' · 86f968a0
      David S. Miller authored
      Edward Cree says:
      
      ====================
      sfc: driver for EF100 family NICs, part 1
      
      EF100 is a new NIC architecture under development at Xilinx, based
       partly on existing Solarflare technology.  As many of the hardware
       interfaces resemble EF10, support is implemented within the 'sfc'
       driver, which previous patch series "commonised" for this purpose.
      
      In order to maintain bisectability while splitting into patches of a
       reasonable size, I had to do a certain amount of back-and-forth with
       stubs for things that the common code may try to call, mainly because
       we can't do them until we've set up MCDI, but we can't set up MCDI
       without probing the event queues, at which point a lot of the common
       machinery becomes reachable from event handlers.
      Consequently, this first series doesn't get as far as actually sending
       and receiving packets.  I have a second series ready to follow it
       which implements the datapath (and a few other things like ethtool).
      
      Changes from v4:
       * Fix build on CONFIG_RETPOLINE=n by using plain prototypes instead
         of INDIRECT_CALLABLE_DECLARE.
      
      Changes from v3:
       * combine both drivers (sfc_ef100 and sfc) into a single module, to
         make non-modular builds work.  Patch #4 now adds a few indirections
         to support this; the ones in the RX and TX path use indirect-call-
         wrappers to minimise the performance impact.
      
      Changes from v2:
       * remove MODULE_VERSION.
       * call efx_destroy_reset_workqueue() from ef100_exit_module().
       * correct uint32_ts to u32s.  While I was at it, I fixed a bunch of
         other style issues in the function-control-window code.
      All in patch #4.
      
      Changes from v1:
       * kernel test robot spotted a link error when sfc_ef100 was built
         without mdio.  It turns out the thing we were trying to link to
         was a bogus thing to do on anything but Falcon, so new patch #1
         removes it from this driver.
       * fix undeclared symbols in patch #4 by shuffling around prototypes
         and #includes and adding 'static' where appropriate.
       * fix uninitialised variable 'rc2' in patch #7.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      86f968a0
    • Edward Cree's avatar
      1c748843
    • Edward Cree's avatar
      29ec1b27
    • Edward Cree's avatar
      99a23c11
    • Edward Cree's avatar
      sfc_ef100: actually perform resets · 4e5675bb
      Edward Cree authored
      In ef100_reset(), make the MCDI call to do the reset.
      Also, do a reset at start-of-day during probe, to put the function in
       a clean state.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4e5675bb
    • Edward Cree's avatar
      sfc_ef100: extend ef100_check_caps to cover datapath_caps3 · d802b0ae
      Edward Cree authored
      MC_CMD_GET_CAPABILITIES now has a third word of flags; extend the
       efx_has_cap() machinery to cover it.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d802b0ae
    • Edward Cree's avatar
    • Edward Cree's avatar
      sfc_ef100: process events for MCDI completions · 5e4ef673
      Edward Cree authored
      Currently RX and TX-completion events are unhandled, as neither the RX
       nor the TX path has been implemented yet.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5e4ef673
    • Edward Cree's avatar
      sfc_ef100: implement ndo_open/close and EVQ probing · 965b549f
      Edward Cree authored
      Channels are probed, but actual event handling is still stubbed out.
      
      Stub implementation of check_caps is needed because ptp.c will call into
       it from efx_ptp_use_mac_tx_timestamps() to decide if it wants TXQs.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      965b549f
    • Edward Cree's avatar
      sfc_ef100: implement MCDI transport · 2200e6d9
      Edward Cree authored
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2200e6d9
    • Edward Cree's avatar
      sfc_ef100: don't call efx_reset_down()/up() on EF100 · 35a36af8
      Edward Cree authored
      We handle everything ourselves in ef100_reset(), rather than relying on
       the generic down/up routines.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      35a36af8
    • Edward Cree's avatar
      sfc_ef100: PHY probe stub · aa86a75f
      Edward Cree authored
      We can't actually do the MCDI to probe it fully until we have working
       MCDI, which comes later, but we need efx->phy_data to be allocated so
       that when we get MCDI events the link-state change handler doesn't
       NULL-dereference.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      aa86a75f
    • Edward Cree's avatar
      sfc_ef100: reset-handling stub · c027f2a7
      Edward Cree authored
      We don't actually do the efx_mcdi_reset() because we don't have MCDI yet.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      c027f2a7
    • Edward Cree's avatar
      sfc: skeleton EF100 PF driver · 51b35a45
      Edward Cree authored
      No TX or RX path, no MCDI, not even an ifup/down handler.
      Besides stubs, the bulk of the patch deals with reading the Xilinx
       extended PCIe capability, which tells us where to find our BAR.
      
      Though in the same module, EF100 has its own struct pci_driver,
       which is named sfc_ef100.
      
      A small number of additional nic_type methods are added; those in the
       TX (tx_enqueue) and RX (rx_packet) paths are called through indirect
       call wrappers to minimise the performance impact.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      51b35a45
    • Edward Cree's avatar
      sfc_ef100: register accesses on EF100 · 61060c5d
      Edward Cree authored
      EF100 adds a few new valid addresses for efx_writed_page(), as well as
       a Function Control Window in the BAR whose location is variable.
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      61060c5d
    • Edward Cree's avatar
      adf72ee3
    • Edward Cree's avatar
      sfc: remove efx_ethtool_nway_reset() · 0ccf267e
      Edward Cree authored
      An MDIO-based n-way restart does not make sense for any of the NICs
       supported by this driver, nor for the coming EF100.
      Unlike on Falcon (which was already split off into a separate driver),
       the PHY on all of Siena, EF10 and EF100 is managed by MC firmware.
      While Siena can talk to the PHY over MDIO, doing so for anything other
       than debugging purposes (mdio_mii_ioctl) is likely to confuse the
       firmware.
      (According to the SFC firmware team, this support was originally added
       to the Siena driver early in the development of that product, before
       it was decided to have firmware manage the PHY.)
      Signed-off-by: default avatarEdward Cree <ecree@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      0ccf267e
    • David S. Miller's avatar
      Merge branch 'Add-PRP-driver' · 65ccbbda
      David S. Miller authored
      Murali Karicheri says:
      
      ====================
      Add PRP driver
      
      This series is dependent on the following patches sent out to
      netdev list. All (1-3) are already merged to net/master as of
      sending this, but not on the net-next master branch. So need
      to apply them to net-next before applying this series. v3 of
      the iproute2 patches can be merged to work with this series
      as there are no updates since then.
      
      [1] https://marc.info/?l=linux-netdev&m=159526378131542&w=2
      [2] https://marc.info/?l=linux-netdev&m=159499772225350&w=2
      [3] https://marc.info/?l=linux-netdev&m=159499772425352&w=2
      
      This series adds support for Parallel Redundancy Protocol (PRP)
      in the Linux HSR driver as defined in IEC-62439-3. PRP Uses a
      Redundancy Control Trailer (RCT) the format of which is
      similar to HSR Tag. This is used for implementing redundancy.
      RCT consists of 6 bytes similar to HSR tag and contain following
      fields:-
      
      - 16-bit sequence number (SeqNr);
      - 4-bit LAN identifier (LanId);
      - 12 bit frame size (LSDUsize);
      - 16-bit suffix (PRPsuffix).
      
      The PRPsuffix identifies PRP frames and distinguishes PRP frames
      from other protocols that also append a trailer to their useful
      data. The LSDUsize field allows the receiver to distinguish PRP
      frames from random, nonredundant frames as an additional check.
      LSDUsize is the size of the Ethernet payload inclusive of the
      RCT. Sequence number along with LanId is used for duplicate
      detection and discard.
      
      PRP node is also known as Dual Attached Node (DAN-P) since it
      is typically attached to two different LAN for redundancy.
      DAN-P duplicates each of L2 frames and send it over the two
      Ethernet links. Each outgoing frame is appended with RCT.
      Unlike HSR, these are added to the end of L2 frame and will be
      treated as pad by bridges and therefore would be work with
      traditional bridges or switches, where as HSR wouldn't as Tag
      is prefixed to the Ethenet frame. At the remote end, these are
      received and the duplicate frame is discarded before the stripped
      frame is send up the networking stack. Like HSR, PRP also sends
      periodic Supervision frames to the network. These frames are
      received and MAC address from the SV frames are populated in a
      database called Node Table. The above functions are grouped into
      a block called Link Redundancy Entity (LRE) in the IEC spec.
      
      As there are many similarities between HSR and PRP protocols,
      this patch re-uses the code from HSR driver to implement PRP
      driver. As per feedback from the RFC series, the implementation
      uses the existing HSR Netlink socket interface to create the
      PRP interface by adding a new proto parameter to the ip link
      command to identify the PRP protocol. iproute2 is enhanced to
      implement this new parameter. The hsr_netlink.c is enhanced
      to handle the new proto parameter. As suggested during the RFC
      review, the driver introduced a proto_ops structure to hold
      protocol specfic functions to handle HSR and PRP specific
      function pointers and use them in the code based on the
      protocol to handle protocol specific part differently in the
      driver.
      
      Please review this and provide me feedback so that I can work to
      incorporate them and spin the next version if needed.
      
      The patch was tested using two TI AM57x IDK boards for PRP which
      are connected back to back over two CPSW Ethernet ports.
      
      PRP Test setup
      ---------------
      
      --------eth0             eth0 --------
      |AM572x|----------------------|AM572x|
      |      |----------------------|      |
      --------eth1             eth1 --------
      
      To build, enable CONFIG_HSR=y or m
      make omap2plus_defconfig
      make zImage; make modules; make dtbs
      Copy the zImage and dtb files to the file system on SD card
      and power on the AM572x boards.
      This can be tested on any platforms with 2 Ethernet interfaces.
      So will appreciate if you can give it a try and provide your
      Tested-by.
      
      Command to create PRP interface
      -------------------------------
      ifconfig eth0 0.0.0.0 down
      ifconfig eth1 0.0.0.0 down
      ifconfig eth0 hw ether 70:FF:76:1C:0E:8C
      ifconfig eth1 hw ether 70:FF:76:1C:0E:8C
      ifconfig eth0 up
      ifconfig eth1 up
      ip link add name prp0 type hsr slave1 eth0 slave2 eth1 supervision 45 proto 1
      ifconfig prp0 192.168.2.10
      
      ifconfig eth0 0.0.0.0 down
      ifconfig eth1 0.0.0.0 down
      ifconfig eth0 hw ether 70:FF:76:1C:0E:8D
      ifconfig eth1 hw ether 70:FF:76:1C:0E:8D
      ifconfig eth0 up
      ifconfig eth1 up
      ip link add name prp0 type hsr slave1 eth0 slave2 eth1 supervision 45 proto 1
      ifconfig prp0 192.168.2.20
      
      command to show node table
      ----------------------------
      Ping the peer board after the prp0 interface is up.
      
      The remote node (DAN-P) will be shown in the node table as below.
      
      root@am57xx-evm:~# cat /sys/kernel/debug/hsr/prp0/node_table
      Node Table entries for (PRP) device
      MAC-Address-A,    MAC-Address-B,    time_in[A], time_in[B], Address-B port, SAN-A, SAN-B, DAN-P
      70:ff:76:1c:0e:8c 00:00:00:00:00:00   ffffe83f,   ffffe83f,              0,     0,     0,     1
      
      Try to capture the raw PRP frames at the eth0 interface as
      tcpdump -i eth0 -xxx
      
      Sample Supervision frames and ARP frames shown below.
      
      ==================================================================================
      Successive Supervision frames captured with tcpdump (with RCT at the end):
      
      03:43:29.500999 70:ff:76:1c:0e:8d (oui Unknown) > 01:15:4e:00:01:2d (oui Unknown), ethertype Unknown (0x88f
              0x0000:  0115 4e00 012d 70ff 761c 0e8d 88fb 0001
              0x0010:  7e0a 1406 70ff 761c 0e8d 0000 0000 0000
              0x0020:  0000 0000 0000 0000 0000 0000 0000 0000
              0x0030:  0000 0000 0000 0000 0000 0000 fc2b a034
              0x0040:  88fb
      
      03:43:31.581025 70:ff:76:1c:0e:8d (oui Unknown) > 01:15:4e:00:01:2d (oui Unknown), ethertype Unknown (0x88f
              0x0000:  0115 4e00 012d 70ff 761c 0e8d 88fb 0001
              0x0010:  7e0b 1406 70ff 761c 0e8d 0000 0000 0000
              0x0020:  0000 0000 0000 0000 0000 0000 0000 0000
              0x0030:  0000 0000 0000 0000 0000 0000 fc2c a034
              0x0040:  88fb
      
      ICMP Echo request frame with RCT
      03:43:33.805354 IP 192.168.2.20 > 192.168.2.10: ICMP echo request, id 63748, seq 1, length 64
              0x0000:  70ff 761c 0e8c 70ff 761c 0e8d 0800 4500
              0x0010:  0054 26a4 4000 4001 8e96 c0a8 0214 c0a8
              0x0020:  020a 0800 c28e f904 0001 202e 1c3d 0000
              0x0030:  0000 0000 0000 0000 0000 0000 0000 0000
              0x0040:  0000 0000 0000 0000 0000 0000 0000 0000
              0x0050:  0000 0000 0000 0000 0000 0000 0000 0000
              0x0060:  0000 fc31 a05a 88fb
      ==================================================================================
      The iperf3 traffic test logs can be accessed at the links below.
      DUT-1: https://pastebin.ubuntu.com/p/8SkQzWJMn8/
      DUT-2: https://pastebin.ubuntu.com/p/j2BZvvs7p4/
      
      Other tests done.
       - Connect a SAN (eth0 and eth1 without prp interface) and
         do ping test from eth0 (192.168.2.40) to prp0 (192.168.2.10)
         verify the SAN node shows at the correct link A and B as shown
         in the node table dump
       - Regress HSR interface using 3 nodes connected in a ring topology.
         create hsr link version 0. Do iperf3 test between all nodes
         create hsr link version 1. Do iperf3 test between all nodes.
      
               --------eth0             eth1 --------eth0      eth1-------|
               |AM572x|----------------------|AM572x|--------------|AM572x|
               |      |                      |      |        ------|      |
               --------eth1---|               -------        | eth0 -------
                              |-------------------------------
      
         command used for HSR interface
      
         HSR V0
      
         ifconfig eth0 0.0.0.0 down
         ifconfig eth1 0.0.0.0 down
         ifconfig eth0 hw ether 70:FF:76:1C:0E:8C
         ifconfig eth1 hw ether 70:FF:76:1C:0E:8C
         ifconfig eth0 up
         ifconfig eth1 up
         ip link add name hsr0 type hsr slave1 eth0 slave2 eth1 supervision 45 version 0
         ifconfig hsr0 192.168.2.10
      
         HSR V1
      
         ifconfig eth0 0.0.0.0 down
         ifconfig eth1 0.0.0.0 down
         ifconfig eth0 hw ether 70:FF:76:1C:0E:8C
         ifconfig eth1 hw ether 70:FF:76:1C:0E:8C
         ifconfig eth0 up
         ifconfig eth1 up
         ip link add name hsr0 type hsr slave1 eth0 slave2 eth1 supervision 45 version 1
         ifconfig hsr0 192.168.2.10
      
         Logs at
         DUT-1 : https://pastebin.ubuntu.com/p/6PSJbZwQ6y/
         DUT-2 : https://pastebin.ubuntu.com/p/T8TqJsPRHc/
         DUT-3 : https://pastebin.ubuntu.com/p/VNzpv6HzKj/
       - Build tests :-
         Build with CONFIG_HSR=m
         allmodconfig build
         build with CONFIG_HSR=y and rebuild with sparse checker
         make C=1 zImage; make modules
      
      Version history:
        v5 : Fixed comments about Kconfig changes on Patch 1/7 against v4
             Rebased to netnext/master branch.
      
        v4 : fixed following vs v3
             reverse xmas tree for local variables
             check for return type in call to skb_put_padto()
      
        v3 : Separated bug fixes from this series and send them for immediate merge
             But for that this is same as v2.
      
        v2 : updated comments on RFC. Following are the main changes:-
             - Removed the hsr_prp prefix
             - Added PRP information in header files to indicate
               the support for PRP explicitely
             - Re-use netlink socket interface with an added
               parameter proto for identifying PRP.
             - Use function pointers using a proto_ops struct
               to do things differently for PRP vs HSR.
      
         RFC: initial version posted and discussed at
             https://www.spinics.net/lists/netdev/msg656229.html
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      65ccbbda
    • Murali Karicheri's avatar
      net: prp: enhance debugfs to display PRP info · 795ec4f5
      Murali Karicheri authored
      Print PRP specific information from node table as part of debugfs
      node table display. Also display the node as DAN-H or DAN-P depending
      on the info from node table.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      795ec4f5
    • Murali Karicheri's avatar
      net: prp: add packet handling support · 451d8123
      Murali Karicheri authored
      DAN-P (Dual Attached Nodes PRP) nodes are expected to receive
      traditional IP packets as well as PRP (Parallel Redundancy
      Protocol) tagged (trailer) packets. PRP trailer is 6 bytes
      of PRP protocol unit called RCT, Redundancy Control Trailer
      (RCT) similar to HSR tag. PRP network can have traditional
      devices such as bridges/switches or PC attached to it and
      should be able to communicate. Regular Ethernet devices treat
      the RCT as pads.  This patch adds logic to format L2 frames
      from network stack to add a trailer (RCT) and send it as
      duplicates over the slave interfaces when the protocol is
      PRP as per IEC 62439-3. At the ingress, it strips the trailer,
      do duplicate detection and rejection and forward a stripped
      frame up the network stack. PRP device should accept frames
      from Singly Attached Nodes (SAN) and thus the driver mark
      the link where the frame came from in the node table.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      451d8123
    • Murali Karicheri's avatar
      net: hsr: define and use proto_ops ptrs to handle hsr specific frames · fa4dc895
      Murali Karicheri authored
      As a preparatory patch to introduce PRP, refactor the code specific to
      handling HSR frames into separate functions and call them through
      proto_ops function pointers.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      fa4dc895
    • Murali Karicheri's avatar
      net: prp: add supervision frame generation utility function · c643ff03
      Murali Karicheri authored
      Add support for generation of PRP supervision frames. For PRP,
      supervision frame format is similar to HSR version 0, but have
      a PRP Redundancy Control Trailer (RCT) added and uses a different
      message type, PRP_TLV_LIFE_CHECK_DD. Also update
      is_supervision_frame() to include the new message type used for
      PRP supervision frame.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      c643ff03
    • Murali Karicheri's avatar
      net: hsr: introduce protocol specific function pointers · 28e458e0
      Murali Karicheri authored
      As a preparatory patch to introduce support for PRP protocol, add a
      protocol ops ptr in the private hsr structure to hold function
      pointers as some of the functions at protocol level packet
      handling is different for HSR vs PRP. It is expected that PRP will
      add its of set of functions for protocol handling. Modify existing
      hsr_announce() function to call proto_ops->send_sv_frame() to send
      supervision frame for HSR. This is expected to be different for PRP.
      So introduce a ops function ptr, send_sv_frame() for the same and
      initialize it to send_hsr_supervsion_frame(). Modify hsr_announce()
      to call proto_ops->send_sv_frame().
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      28e458e0
    • Murali Karicheri's avatar
      net: hsr: introduce common code for skb initialization · 121c33b0
      Murali Karicheri authored
      As a preparatory patch to introduce PRP protocol support in the
      driver, refactor the skb init code to a separate function.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      121c33b0
    • Murali Karicheri's avatar
      hsr: enhance netlink socket interface to support PRP · 8f4c0e01
      Murali Karicheri authored
      Parallel Redundancy Protocol (PRP) is another redundancy protocol
      introduced by IEC 63439 standard. It is similar to HSR in many
      aspects:-
      
       - Use a pair of Ethernet interfaces to created the PRP device
       - Use a 6 byte redundancy protocol part (RCT, Redundancy Check
         Trailer) similar to HSR Tag.
       - Has Link Redundancy Entity (LRE) that works with RCT to implement
         redundancy.
      
      Key difference is that the protocol unit is a trailer instead of a
      prefix as in HSR. That makes it inter-operable with tradition network
      components such as bridges/switches which treat it as pad bytes,
      whereas HSR nodes requires some kind of translators (Called redbox) to
      talk to regular network devices. This features allows regular linux box
      to be converted to a DAN-P box. DAN-P stands for Dual Attached Node - PRP
      similar to DAN-H (Dual Attached Node - HSR).
      
      Add a comment at the header/source code to explicitly state that the
      driver files also handles PRP protocol as well.
      Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8f4c0e01