d94ba80ebb
This patch adds an infrastructure for hardware clocks that implement IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a registration method to particular hardware clock drivers. Each clock is presented as a standard POSIX clock. The ancillary clock features are exposed in two different ways, via the sysfs and by a character device. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: John Stultz <john.stultz@linaro.org>
3.3 KiB
What: /sys/class/ptp/ Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This directory contains files and directories providing a standardized interface to the ancillary features of PTP hardware clocks.
What: /sys/class/ptp/ptpN/ Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This directory contains the attributes of the Nth PTP hardware clock registered into the PTP class driver subsystem.
What: /sys/class/ptp/ptpN/clock_name Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file contains the name of the PTP hardware clock as a human readable string.
What: /sys/class/ptp/ptpN/max_adjustment Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file contains the PTP hardware clock's maximum frequency adjustment value (a positive integer) in parts per billion.
What: /sys/class/ptp/ptpN/n_alarms Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file contains the number of periodic or one shot alarms offer by the PTP hardware clock.
What: /sys/class/ptp/ptpN/n_external_timestamps Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file contains the number of external timestamp channels offered by the PTP hardware clock.
What: /sys/class/ptp/ptpN/n_periodic_outputs Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file contains the number of programmable periodic output channels offered by the PTP hardware clock.
What: /sys/class/ptp/ptpN/pps_avaiable Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file indicates whether the PTP hardware clock supports a Pulse Per Second to the host CPU. Reading "1" means that the PPS is supported, while "0" means not supported.
What: /sys/class/ptp/ptpN/extts_enable Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This write-only file enables or disables external timestamps. To enable external timestamps, write the channel index followed by a "1" into the file. To disable external timestamps, write the channel index followed by a "0" into the file.
What: /sys/class/ptp/ptpN/fifo Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This file provides timestamps on external events, in the form of three integers: channel index, seconds, and nanoseconds.
What: /sys/class/ptp/ptpN/period Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This write-only file enables or disables periodic outputs. To enable a periodic output, write five integers into the file: channel index, start time seconds, start time nanoseconds, period seconds, and period nanoseconds. To disable a periodic output, set all the seconds and nanoseconds values to zero.
What: /sys/class/ptp/ptpN/pps_enable Date: September 2010 Contact: Richard Cochran richardcochran@gmail.com Description: This write-only file enables or disables delivery of PPS events to the Linux PPS subsystem. To enable PPS events, write a "1" into the file. To disable events, write a "0" into the file.