stp: full RSTP and a reworked Spanning Tree page

* stp: select the root port by cost and block redundant links
* stp: move the protocol to BANK4 and keep the command line in BANK2
* stp: implement the RSTP state machines of 802.1D-2004 clause 17
* stp: counters, more settings and a fuller Spanning Tree page
* stp: make a link aggregation group one port of the RSTP tree
* web: serve the Spanning Tree JSON from BANK4 as well

Kept in BANK1, the larger Spanning Tree page would leave under 1 kB
there for the rest of the web server and every page still to come, so
send_stp() and send_stp_counters() move to httpd/page_stp.c in BANK4
with the protocol, as banked calls, with their own copies of the few output
helpers and of the JSON header, so nothing in BANK4 calls into BANK1
directly or hands it a pointer into its code space. BANK4 takes the
free flash between BANK3 and the web files.

KP_9000_6XHML_X2: BANK1 44336, BANK2 36969, BANK3 11942, BANK4 20965
bytes of 49152.

rtl837x_stp.h

@@ -2,13 +2,21 @@
 #define _RTL837X_STP_H_
 
 #include <stdint.h>
-#include "rtl837x_common.h"
 void stp_in(void) __banked;
 void stp_setup(void) __banked;
 void stp_timers(void) __banked;
 void stp_off(void) __banked;
 void stp_parse(void) __banked __reentrant;
 void stp_defaults(void) __banked;
+void stp_status(void) __banked;
+void stp_port_admin(uint8_t port, uint8_t on) __banked;
+void stp_prio_apply(void) __banked;
+void stp_port_mcheck(uint8_t port) __banked;
+uint8_t stp_port_role(uint8_t port) __banked;
+uint8_t stp_port_state(uint8_t port) __banked;
+uint8_t stp_ent_id(uint8_t e) __banked;
+void stp_lag_map(void) __banked;
+void stp_counters_clear(void) __banked __reentrant;
 
 /* Tick rate of stp_timers(), also used by the web UI. */
 #define STP_HZ 50
@@ -43,22 +51,38 @@ extern __xdata uint8_t  stp_txhold;
 #define STP_PF_TRIPPED	0x80	/* runtime: disabled by BPDU guard           */
 
 extern __xdata uint8_t  stp_pflags[STP_ENTITIES];
-extern __xdata uint32_t stp_pcost[STP_ENTITIES];	/* path cost; 0 = auto (20000)      */
+extern __xdata uint32_t stp_pcost[STP_ENTITIES];
 extern __xdata uint8_t  stp_pprio[STP_ENTITIES];
 extern __xdata uint8_t  stp_pp2p[STP_ENTITIES];
-extern __xdata uint8_t  stp_ent_of[STP_PORTS];	/* the STP entity a port answers to: itself, or its lag */
-extern __xdata uint16_t stp_lag_mask[STP_LAG_COUNT];	/* member ports of each lag; 0 = not part of STP */
+extern __xdata uint8_t  stp_ent_of[STP_PORTS];
+extern __xdata uint16_t stp_lag_mask[STP_LAG_COUNT];
 
-/* Last-heard designated info per port (from received BPDUs); consult
- * stp_bpdu_age to decide whether it is still current. */
 extern __xdata struct bridge stp_dbridge[STP_ENTITIES];
 extern __xdata uint16_t stp_dpid[STP_ENTITIES];
 extern __xdata uint32_t stp_dcost[STP_ENTITIES];
-extern __xdata uint16_t stp_bpdu_age[STP_ENTITIES];	/* ticks since a BPDU was heard */
+extern __xdata uint16_t stp_bpdu_age[STP_ENTITIES];
+#define STP_CNT_RX	0	/* BPDUs taken in on an STP port          */
+#define STP_CNT_TX	1	/* BPDUs put on the wire                  */
+#define STP_CNT_TCRX	2	/* BPDUs received with the TC flag, TCNs  */
+#define STP_CNT_TCTX	3	/* BPDUs sent with the TC flag, TCNs      */
+#define STP_CNT_N	4
+extern __xdata uint32_t stp_cnt[STP_CNT_N][STP_ENTITIES];
+extern __xdata uint16_t stp_info_while[STP_ENTITIES];
 
 extern __xdata struct bridge root_bridge;
 extern __xdata uint32_t root_bridge_cost;
 extern __xdata uint8_t  stp_root_port;
+extern __xdata uint8_t  stp_root_maxage;
+extern __xdata uint8_t  stp_root_fwd;
+extern __xdata uint16_t stp_link_prev;
+extern __xdata uint16_t stp_alt;
+extern __xdata uint16_t stp_backup;
+extern __xdata uint16_t stp_legacy;
+extern __xdata uint16_t stp_rrwhile[STP_ENTITIES];
+extern __xdata uint16_t stp_rbwhile[STP_ENTITIES];
 extern __xdata uint16_t stp_tc_count;
+extern __xdata uint32_t stp_tc_secs;
+extern __xdata uint8_t  stp_pcost_short;
+extern __xdata uint8_t  stp_bpdu_filter;
 
 #endif