• Jacob Keller's avatar
    ice: enable transmit timestamps for E810 devices · ea9b847c
    Jacob Keller authored
    Add support for enabling Tx timestamp requests for outgoing packets on
    E810 devices.
    
    The ice hardware can support multiple outstanding Tx timestamp requests.
    When sending a descriptor to hardware, a Tx timestamp request is made by
    setting a request bit, and assigning an index that represents which Tx
    timestamp index to store the timestamp in.
    
    Hardware makes no effort to synchronize the index use, so it is up to
    software to ensure that Tx timestamp indexes are not re-used before the
    timestamp is reported back.
    
    To do this, introduce a Tx timestamp tracker which will keep track of
    currently in-use indexes.
    
    In the hot path, if a packet has a timestamp request, an index will be
    requested from the tracker. Unfortunately, this does require a lock as
    the indexes are shared across all queues on a PHY. There are not enough
    indexes to reliably assign only 1 to each queue.
    
    For the E810 devices, the timestamp indexes are not shared across PHYs,
    so each port can have its own tracking.
    
    Once hardware captures a timestamp, an interrupt is fired. In this
    interrupt, trigger a new work item that will figure out which timestamp
    was completed, and report the timestamp back to the stack.
    
    This function loops through the Tx timestamp indexes and checks whether
    there is now a valid timestamp. If so, it clears the PHY timestamp
    indication in the PHY memory, locks and removes the SKB and bit in the
    tracker, then reports the timestamp to the stack.
    
    It is possible in some cases that a timestamp request will be initiated
    but never completed. This might occur if the packet is dropped by
    software or hardware before it reaches the PHY.
    
    Add a task to the periodic work function that will check whether
    a timestamp request is more than a few seconds old. If so, the timestamp
    index is cleared in the PHY, and the SKB is released.
    
    Just as with Rx timestamps, the Tx timestamps are only 40 bits wide, and
    use the same overall logic for extending to 64 bits of nanoseconds.
    
    With this change, E810 devices should be able to perform basic PTP
    functionality.
    
    Future changes will extend the support to cover the E822-based devices.
    Signed-off-by: default avatarJacob Keller <jacob.e.keller@intel.com>
    Tested-by: default avatarTony Brelinski <tonyx.brelinski@intel.com>
    Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
    ea9b847c
ice_txrx.c 63.7 KB