nfp: add support for TLV device stats

Device stats are currently hard coded in the PCI BAR0 layout.
Add a ability to read them from the TLV area instead.
Names for the stats are maintained by the driver, and their
meaning documented. This allows us to more easily add and
remove device stats.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 116 insertions, 0 deletions

diff --git a/Documentation/networking/device_drivers/netronome/nfp.rst b/Documentation/networking/device_drivers/netronome/nfp.rst
index 6c08ac8b5147..ada611fb427c 100644
--- a/Documentation/networking/device_drivers/netronome/nfp.rst
+++ b/Documentation/networking/device_drivers/netronome/nfp.rst
@@ -131,3 +131,119 @@ abi_drv_reset
 abi_drv_load_ifc
     Defines a list of PF devices allowed to load FW on the device.
     This variable is not currently user configurable.
+
+Statistics
+==========
+
+Following device statistics are available through the ``ethtool -S`` interface:
+
+.. flat-table:: NFP device statistics
+   :header-rows: 1
+   :widths: 3 1 11
+
+   * - Name
+     - ID
+     - Meaning
+
+   * - dev_rx_discards
+     - 1
+     - Packet can be discarded on the RX path for one of the following reasons:
+
+        * The NIC is not in promisc mode, and the destination MAC address
+          doesn't match the interfaces' MAC address.
+        * The received packet is larger than the max buffer size on the host.
+          I.e. it exceeds the Layer 3 MRU.
+        * There is no freelist descriptor available on the host for the packet.
+          It is likely that the NIC couldn't cache one in time.
+        * A BPF program discarded the packet.
+        * The datapath drop action was executed.
+        * The MAC discarded the packet due to lack of ingress buffer space
+          on the NIC.
+
+   * - dev_rx_errors
+     - 2
+     - A packet can be counted (and dropped) as RX error for the following
+       reasons:
+
+       * A problem with the VEB lookup (only when SR-IOV is used).
+       * A physical layer problem that causes Ethernet errors, like FCS or
+         alignment errors. The cause is usually faulty cables or SFPs.
+
+   * - dev_rx_bytes
+     - 3
+     - Total number of bytes received.
+
+   * - dev_rx_uc_bytes
+     - 4
+     - Unicast bytes received.
+
+   * - dev_rx_mc_bytes
+     - 5
+     - Multicast bytes received.
+
+   * - dev_rx_bc_bytes
+     - 6
+     - Broadcast bytes received.
+
+   * - dev_rx_pkts
+     - 7
+     - Total number of packets received.
+
+   * - dev_rx_mc_pkts
+     - 8
+     - Multicast packets received.
+
+   * - dev_rx_bc_pkts
+     - 9
+     - Broadcast packets received.
+
+   * - dev_tx_discards
+     - 10
+     - A packet can be discarded in the TX direction if the MAC is
+       being flow controlled and the NIC runs out of TX queue space.
+
+   * - dev_tx_errors
+     - 11
+     - A packet can be counted as TX error (and dropped) for one for the
+       following reasons:
+
+       * The packet is an LSO segment, but the Layer 3 or Layer 4 offset
+         could not be determined. Therefore LSO could not continue.
+       * An invalid packet descriptor was received over PCIe.
+       * The packet Layer 3 length exceeds the device MTU.
+       * An error on the MAC/physical layer. Usually due to faulty cables or
+         SFPs.
+       * A CTM buffer could not be allocated.
+       * The packet offset was incorrect and could not be fixed by the NIC.
+
+   * - dev_tx_bytes
+     - 12
+     - Total number of bytes transmitted.
+
+   * - dev_tx_uc_bytes
+     - 13
+     - Unicast bytes transmitted.
+
+   * - dev_tx_mc_bytes
+     - 14
+     - Multicast bytes transmitted.
+
+   * - dev_tx_bc_bytes
+     - 15
+     - Broadcast bytes transmitted.
+
+   * - dev_tx_pkts
+     - 16
+     - Total number of packets transmitted.
+
+   * - dev_tx_mc_pkts
+     - 17
+     - Multicast packets transmitted.
+
+   * - dev_tx_bc_pkts
+     - 18
+     - Broadcast packets transmitted.
+
+Note that statistics unknown to the driver will be displayed as
+``dev_unknown_stat$ID``, where ``$ID`` refers to the second column
+above.