|author||Jacob Keller <email@example.com>||2012-05-01 05:24:58 +0000|
|committer||Jeff Kirsher <firstname.lastname@example.org>||2012-05-09 22:48:51 -0700|
|parent||ixgbe: Fix bogus error message (diff)|
ixgbe: Hardware Timestamping + PTP Hardware Clock (PHC)
This patch enables hardware timestamping for use with PTP software by extracting a ns counter from an arbitrary fixed point cycles counter. The hardware generates SYSTIME registers using the DMA tick which changes based on the current link speed. These SYSTIME registers are converted to ns using the cyclecounter and timecounter structures provided by the kernel. Using the SO_TIMESTAMPING api, software can enable and access timestamps for PTP packets. The SO_TIMESTAMPING API has space for 3 different kinds of timestamps, SYS, RAW, and SOF. SYS hardware timestamps are hardware ns values that are then scaled to the software clock. RAW hardware timestamps are the direct raw value of the ns counter. SOF software timestamps are the software timestamp calculated as close as possible to the software transmit, but are not offloaded to the hardware. This patch only supports the RAW hardware timestamps due to inefficiency of the SYS design. This patch also enables the PHC subsystem features for atomically adjusting the cycle register, and adjusting the clock frequency in parts per billion. This frequency adjustment works by slightly adjusting the value added to the cycle registers each DMA tick. This causes the hardware registers to overflow rapidly (approximately once every 34 seconds, when at 10gig link). To solve this, the timecounter structure is used, along with a timer set for every 25 seconds. This allows for detecting register overflow and converting the cycle counter registers into ns values needed for providing useful timestamps to the network stack. Only the basic required clock functions are supported at this time, although the hardware supports some ancillary features and these could easily be enabled in the future. Note that use of this hardware timestamping requires modifying daemon software to use the SO_TIMESTAMPING API for timestamps, and the ptp_clock PHC framework for accessing the clock. The timestamps have no relation to the system time at all, so software must use the posix clock generated by the PHC framework instead. Signed-off-by: Jacob E Keller <email@example.com> Tested-by: Stephen Ko <firstname.lastname@example.org> Signed-off-by: Jeff Kirsher <email@example.com>
Diffstat (limited to 'drivers/net/ethernet/intel/Kconfig')
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/net/ethernet/intel/Kconfig b/drivers/net/ethernet/intel/Kconfig
index 546efe30c9b8..79b07ec6726f 100644
@@ -220,6 +220,17 @@ config IXGBE_DCB
If unsure, say N.
+ bool "PTP Clock Support"
+ default n
+ depends on IXGBE && PTP_1588_CLOCK
+ Say Y here if you want support for 1588 Timestamping with a
+ PHC device, using the PTP 1588 Clock support. This is
+ required to enable timestamping support for the device.
+ If unsure, say N.
tristate "Intel(R) 82599 Virtual Function Ethernet support"
depends on PCI_MSI