stp: use the front panel number as the port ID

The port ID in the BPDUs was the chip port plus one, so on most boards
it did not match the port label, neither on the Spanning Tree page nor
on the neighbour. Send the front panel number instead, and 101 and up
for the LAGs, the same numbers the page already uses for the Port
column. A returned BPDU of our own is mapped back to the port by that
number.

Scenario 66 gives one port a front panel number that differs from its
chip port.

rtl837x_stp.c

@@ -413,13 +413,28 @@ static uint8_t stp_ent_active(uint8_t e) __reentrant
 }
 
 
+static uint8_t stp_pnum(uint8_t e) __reentrant
+{
+	if (e >= STP_LAG_BASE)
+		return e + 101 - STP_LAG_BASE;
+	return machine.log_to_phys_port[e];
+}
+
+
+static uint8_t stp_ent_by_pnum(uint8_t n) __reentrant
+{
+	for (stp_ss_i = 0; stp_ss_i < STP_ENTITIES; stp_ss_i++)
+		if (stp_ent_active(stp_ss_i) && stp_pnum(stp_ss_i) == n)
+			return stp_ss_i;
+	return 0xff;
+}
+
+
 uint8_t stp_ent_id(uint8_t e) __banked
 {
 	if (!stp_ent_active(e))
 		return 0;
-	if (e >= STP_LAG_BASE)
-		return e + 101 - STP_LAG_BASE;
-	return machine.log_to_phys_port[e];
+	return stp_pnum(e);
 }
 
 
@@ -624,9 +639,9 @@ static int8_t stp_cmp_designated(uint8_t port) __reentrant
 	stp_cmp = cmpBytes((__xdata uint8_t *)&stp_dbridge[port], (__xdata uint8_t *)&stp_self, 8);
 	if (stp_cmp)
 		return stp_cmp;
-	if (stp_dpid[port] == (((uint16_t)stp_pprio[port] << 8) | (port + 1)))
+	if (stp_dpid[port] == (((uint16_t)stp_pprio[port] << 8) | stp_pnum(port)))
 		return 0;
-	return stp_dpid[port] < (((uint16_t)stp_pprio[port] << 8) | (port + 1)) ? -1 : 1;
+	return stp_dpid[port] < (((uint16_t)stp_pprio[port] << 8) | stp_pnum(port)) ? -1 : 1;
 }
 
 
@@ -814,7 +829,7 @@ void stp_cnf_send(uint8_t port) __reentrant
 	STP_O->bridge.ext = 0x00;
 
 	STP_O->port_prio = stp_pprio[port];
-	STP_O->port_id = port + 1;
+	STP_O->port_id = stp_pnum(port);
 	/* Message age, incremented by one second per bridge we relay through.
 	 * The timer fields are in 1/256 s on the wire, and sdcc stores uint16
 	 * little-endian, so assigning the plain second count lands the value in
@@ -898,8 +913,8 @@ static int8_t stp_msg_vs_ours(uint8_t port) __reentrant
 		return stp_cmp;
 	if (STP_I->port_prio != stp_pprio[port])
 		return STP_I->port_prio < stp_pprio[port] ? -1 : 1;
-	if (STP_I->port_id != port + 1)
-		return STP_I->port_id < port + 1 ? -1 : 1;
+	if (STP_I->port_id != stp_pnum(port))
+		return STP_I->port_id < stp_pnum(port) ? -1 : 1;
 	return 0;
 }
 
@@ -1047,7 +1062,6 @@ void stp_in(void) __banked
 		stp_loop_peer = STP_I->port_id;		/* 1-based, as we send it */
 		if (!stp_loop_peer)
 			return;
-		stp_loop_peer--;
 		/* A Port ID is (priority, number) and priority is compared
 		 * first - stp_cnf_send() puts stp_pprio[] on the wire next to
 		 * the number, so "stp port N prio" has to be able to decide
@@ -1056,10 +1070,10 @@ void stp_in(void) __banked
 		if (STP_I->port_prio != stp_pprio[port]) {
 			if (STP_I->port_prio < stp_pprio[port])
 				return;			/* peer is better: it decides */
-		} else if (stp_loop_peer < port) {
+		} else if (stp_loop_peer < stp_pnum(port)) {
 			return;
 		}
-		stp_loop_hold_peer(stp_loop_peer);
+		stp_loop_hold_peer(stp_ent_by_pnum(stp_loop_peer));
 		return;
 	}