[Linuxptp-devel] [RFC V3, 2/4] Add BMCA support for IEEE 802.1AS-2011
PTP IEEE 1588 stack for Linux
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[Linuxptp-devel] [RFC V3, 2/4] Add BMCA support for IEEE 802.1AS-2011
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From: Yangbo Lu <yan...@nx...> - 2020-03-23 10:02:40
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According to IEEE 802.1AS-2011, the BMCA used in gPTP is the same
as that used in IEEE 1588 with the following exceptions:
(1) Announce messages received on a slave port that were not sent
by the receiving time-aware system are used immediately,
i.e., there is no foreign-master qualification.
(2) A port that the BMCA determines should be a master port enters
the master state immediately, i.e., there is no pre-master state.
(3) The uncalibrated state is not needed and, therefore, not used.
(4) All time-aware systems are required to participate in best master
selection (even if it is not grandmaster capable).
This patch is to support (1) by using a specific FOREIGN_MASTER_THRESHOLD
case. (Treat FOREIGN_MASTER_THRESHOLD as 1.)
To support (2) and (3), reuse ptp_fsm and drop pre-master/uncalibrated
states. The (4) item is supported since IEEE 802.1AS reuses OC/BC.
Signed-off-by: Erik Hons <eri...@ni...>
Signed-off-by: Rodney Greenstreet <rod...@ni...>
Signed-off-by: Yangbo Lu <yan...@nx...>
---
Changes for v3:
- Added this patch.
---
fsm.c | 13 +++++++++++++
fsm.h | 10 ++++++++++
port.c | 57 +++++++++++++++++++++++++++++++++++++++------------------
3 files changed, 62 insertions(+), 18 deletions(-)
diff --git a/fsm.c b/fsm.c
index ce6efad..917dcae 100644
--- a/fsm.c
+++ b/fsm.c
@@ -335,3 +335,16 @@ enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event,
return next;
}
+
+enum port_state ieee8021as_fsm(enum port_state state, enum fsm_event event,
+ int mdiff)
+{
+ enum port_state next = ptp_fsm(state, event, mdiff);
+
+ if (next == PS_UNCALIBRATED)
+ return PS_SLAVE;
+ if (next == PS_PRE_MASTER)
+ return PS_MASTER;
+
+ return next;
+}
diff --git a/fsm.h b/fsm.h
index 857af05..7f22dc1 100644
--- a/fsm.h
+++ b/fsm.h
@@ -79,4 +79,14 @@ enum port_state ptp_fsm(enum port_state state, enum fsm_event event, int mdiff);
enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event,
int mdiff);
+/**
+ * Run the state machine for a ieee8021as port.
+ * @param state The current state of the port.
+ * @param event The event to be processed.
+ * @param mdiff Whether a new master has been selected.
+ * @return The new state for the port.
+ */
+enum port_state ieee8021as_fsm(enum port_state state, enum fsm_event event,
+ int mdiff);
+
#endif
diff --git a/port.c b/port.c
index 539fe3d..c625b01 100644
--- a/port.c
+++ b/port.c
@@ -278,12 +278,16 @@ void fc_clear(struct foreign_clock *fc)
static void fc_prune(struct foreign_clock *fc)
{
+ int threshold = FOREIGN_MASTER_THRESHOLD;
struct timespec now;
struct ptp_message *m;
clock_gettime(CLOCK_MONOTONIC, &now);
- while (fc->n_messages > FOREIGN_MASTER_THRESHOLD) {
+ if (port_is_ieee8021as(fc->port))
+ threshold = 1;
+
+ while (fc->n_messages > threshold) {
m = TAILQ_LAST(&fc->messages, messages);
TAILQ_REMOVE(&fc->messages, m, list);
fc->n_messages--;
@@ -339,6 +343,7 @@ void ts_add(tmv_t *ts, Integer64 correction)
*/
static int add_foreign_master(struct port *p, struct ptp_message *m)
{
+ int threshold = FOREIGN_MASTER_THRESHOLD;
struct foreign_clock *fc;
struct ptp_message *tmp;
int broke_threshold = 0, diff = 0;
@@ -362,15 +367,20 @@ static int add_foreign_master(struct port *p, struct ptp_message *m)
LIST_INSERT_HEAD(&p->foreign_masters, fc, list);
fc->port = p;
fc->dataset.sender = m->header.sourcePortIdentity;
- /* We do not count this first message, see 9.5.3(b) */
- return 0;
+ /* For 1588, we do not count this first message, see 9.5.3(b) */
+ if (!port_is_ieee8021as(fc->port))
+ return 0;
}
/*
* If this message breaks the threshold, that is an important change.
*/
fc_prune(fc);
- if (FOREIGN_MASTER_THRESHOLD - 1 == fc->n_messages) {
+
+ if (port_is_ieee8021as(fc->port))
+ threshold = 1;
+
+ if (threshold - 1 == fc->n_messages) {
broke_threshold = 1;
}
@@ -2396,6 +2406,7 @@ void port_close(struct port *p)
struct foreign_clock *port_compute_best(struct port *p)
{
int (*dscmp)(struct dataset *a, struct dataset *b);
+ int threshold = FOREIGN_MASTER_THRESHOLD;
struct foreign_clock *fc;
struct ptp_message *tmp;
@@ -2414,7 +2425,10 @@ struct foreign_clock *port_compute_best(struct port *p)
fc_prune(fc);
- if (fc->n_messages < FOREIGN_MASTER_THRESHOLD)
+ if (port_is_ieee8021as(fc->port))
+ threshold = 1;
+
+ if (fc->n_messages < threshold)
continue;
if (!p->best)
@@ -3053,19 +3067,6 @@ struct port *port_open(const char *phc_device,
p->master_only = config_get_int(cfg, interface_name(interface), "masterOnly");
p->bmca = config_get_int(cfg, interface_name(interface), "BMCA");
- if (p->bmca == BMCA_NOOP && transport != TRANS_UDS) {
- if (p->master_only) {
- p->state_machine = designated_master_fsm;
- } else if (clock_slave_only(clock)) {
- p->state_machine = designated_slave_fsm;
- } else {
- pr_err("Please enable at least one of masterOnly or slaveOnly when BMCA == noop.\n");
- goto err_port;
- }
- } else {
- p->state_machine = clock_slave_only(clock) ? ptp_slave_fsm : ptp_fsm;
- }
-
if (transport == TRANS_UDS) {
; /* UDS cannot have a PHC. */
} else if (!interface_tsinfo_valid(interface)) {
@@ -3116,6 +3117,26 @@ struct port *port_open(const char *phc_device,
p->delayMechanism = config_get_int(cfg, p->name, "delay_mechanism");
p->versionNumber = PTP_VERSION;
+ if (config_get_int(cfg, p->name, "asCapable") == AS_CAPABLE_TRUE) {
+ p->asCapable = ALWAYS_CAPABLE;
+ } else {
+ p->asCapable = NOT_CAPABLE;
+ }
+
+ if (p->bmca == BMCA_NOOP && transport != TRANS_UDS) {
+ if (p->master_only) {
+ p->state_machine = designated_master_fsm;
+ } else if (clock_slave_only(clock)) {
+ p->state_machine = designated_slave_fsm;
+ } else {
+ pr_err("Please enable at least one of masterOnly or slaveOnly when BMCA == noop.\n");
+ goto err_port;
+ }
+ } else {
+ p->state_machine = clock_slave_only(clock) ? ptp_slave_fsm :
+ port_is_ieee8021as(p) ? ieee8021as_fsm : ptp_fsm;
+ }
+
if (number && unicast_client_initialize(p)) {
goto err_transport;
}
--
2.7.4
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