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authorMiroslav Lichvar <mlichvar@redhat.com>2018-11-09 11:14:44 +0100
committerDavid S. Miller <davem@davemloft.net>2018-11-09 19:43:51 -0800
commit361800876f80da3915c46e388fc682532228b2c3 (patch)
tree70275bdce7fd76b3142ee743433828670488bade /drivers/ptp
parent83d0bdc7390b890905634186baaa294475cd6a06 (diff)
downloadlinux-361800876f80da3915c46e388fc682532228b2c3.tar.bz2
ptp: add PTP_SYS_OFFSET_EXTENDED ioctl
The PTP_SYS_OFFSET ioctl, which can be used to measure the offset between a PHC and the system clock, includes the total time that the driver needs to read the PHC timestamp. This typically involves reading of multiple PCI registers (sometimes in multiple iterations) and the register that contains the lowest bits of the timestamp is not read in the middle between the two readings of the system clock. This asymmetry causes the measured offset to have a significant error. Introduce a new ioctl, driver function, and helper functions, which allow the reading of the lowest register to be isolated from the other readings in order to reduce the asymmetry. The ioctl returns three timestamps for each measurement: - system time right before reading the lowest bits of the PHC timestamp - PHC time - system time immediately after reading the lowest bits of the PHC timestamp Cc: Richard Cochran <richardcochran@gmail.com> Cc: Jacob Keller <jacob.e.keller@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/ptp')
-rw-r--r--drivers/ptp/ptp_chardev.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 3c681bed5703..aad0d36cf5c0 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -122,10 +122,12 @@ int ptp_open(struct posix_clock *pc, fmode_t fmode)
long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
{
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+ struct ptp_sys_offset_extended *extoff = NULL;
struct ptp_sys_offset_precise precise_offset;
struct system_device_crosststamp xtstamp;
struct ptp_clock_info *ops = ptp->info;
struct ptp_sys_offset *sysoff = NULL;
+ struct ptp_system_timestamp sts;
struct ptp_clock_request req;
struct ptp_clock_caps caps;
struct ptp_clock_time *pct;
@@ -211,6 +213,36 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -EFAULT;
break;
+ case PTP_SYS_OFFSET_EXTENDED:
+ if (!ptp->info->gettimex64) {
+ err = -EOPNOTSUPP;
+ break;
+ }
+ extoff = memdup_user((void __user *)arg, sizeof(*extoff));
+ if (IS_ERR(extoff)) {
+ err = PTR_ERR(extoff);
+ extoff = NULL;
+ break;
+ }
+ if (extoff->n_samples > PTP_MAX_SAMPLES) {
+ err = -EINVAL;
+ break;
+ }
+ for (i = 0; i < extoff->n_samples; i++) {
+ err = ptp->info->gettimex64(ptp->info, &ts, &sts);
+ if (err)
+ goto out;
+ extoff->ts[i][0].sec = sts.pre_ts.tv_sec;
+ extoff->ts[i][0].nsec = sts.pre_ts.tv_nsec;
+ extoff->ts[i][1].sec = ts.tv_sec;
+ extoff->ts[i][1].nsec = ts.tv_nsec;
+ extoff->ts[i][2].sec = sts.post_ts.tv_sec;
+ extoff->ts[i][2].nsec = sts.post_ts.tv_nsec;
+ }
+ if (copy_to_user((void __user *)arg, extoff, sizeof(*extoff)))
+ err = -EFAULT;
+ break;
+
case PTP_SYS_OFFSET:
sysoff = memdup_user((void __user *)arg, sizeof(*sysoff));
if (IS_ERR(sysoff)) {
@@ -284,6 +316,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
}
out:
+ kfree(extoff);
kfree(sysoff);
return err;
}