ptp: Request cycles for TX timestamp
The free running cycle counter of physical clocks called cycles shall be
used for hardware timestamps to enable synchronisation.
Introduce new flag SKBTX_HW_TSTAMP_USE_CYCLES, which signals driver to
provide a TX timestamp based on cycles if cycles are supported.
Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d58669d..4a4f259 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -615,6 +615,9 @@ enum {
/* device driver is going to provide hardware time stamp */
SKBTX_IN_PROGRESS = 1 << 2,
+ /* generate hardware time stamp based on cycles if supported */
+ SKBTX_HW_TSTAMP_USE_CYCLES = 1 << 3,
+
/* generate wifi status information (where possible) */
SKBTX_WIFI_STATUS = 1 << 4,
@@ -624,7 +627,9 @@ enum {
#define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
SKBTX_SCHED_TSTAMP)
-#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
+#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | \
+ SKBTX_HW_TSTAMP_USE_CYCLES | \
+ SKBTX_ANY_SW_TSTAMP)
/* Definitions for flags in struct skb_shared_info */
enum {
diff --git a/net/socket.c b/net/socket.c
index f0c39c8..5c1c5e6 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -683,9 +683,18 @@ void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags)
{
u8 flags = *tx_flags;
- if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
+ if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE) {
flags |= SKBTX_HW_TSTAMP;
+ /* PTP hardware clocks can provide a free running cycle counter
+ * as a time base for virtual clocks. Tell driver to use the
+ * free running cycle counter for timestamp if socket is bound
+ * to virtual clock.
+ */
+ if (tsflags & SOF_TIMESTAMPING_BIND_PHC)
+ flags |= SKBTX_HW_TSTAMP_USE_CYCLES;
+ }
+
if (tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
flags |= SKBTX_SW_TSTAMP;
