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 d58669d6cb91aa30edc70d59a0a7e9d4e2298842..4a4f25975ca28b56c9aa1b083b1bd4825addb342 100644 (file)
--- 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 f0c39c874665fa3e6fd5cddd6ed94e74d5a7d6aa..5c1c5e6100e1936404a1c7e7326e0486ccf7de24 100644 (file)
--- 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;