More testing and fix Qav + refactor

lib_ethernet/api/ethernet.h

@@ -9,10 +9,13 @@
 #include "doxygen.h"    // Sphynx Documentation Workarounds
 
 
-#define ETHERNET_ALL_INTERFACES  (-1)
-#define ETHERNET_MAX_PACKET_SIZE (1518) /**< MAX packet size in bytes */
+#define ETHERNET_ALL_INTERFACES     (-1)
+#define ETHERNET_MAX_PACKET_SIZE    (1518) /**< MAX packet size in bytes including src, dst, ether/tags but NOT preamble or CRC*/
+
+#define MACADDR_NUM_BYTES           (6) /**< Number of octets in MAC address */
+
+#define MII_CREDIT_FRACTIONAL_BITS  (16) /** Fractional bits for Qav credit based shaper setting */
 
-#define MACADDR_NUM_BYTES 6
 
 /** Type representing the type of packet from the MAC */
 typedef enum eth_packet_type_t {
@@ -77,7 +80,7 @@ typedef interface ethernet_cfg_if {
    * \param ifnum       The index of the MAC interface to set
    * \param mac_address The six-octet MAC address to set
    */
-  void set_macaddr(size_t ifnum, uint8_t mac_address[MACADDR_NUM_BYTES]);
+  void set_macaddr(size_t ifnum, const uint8_t mac_address[MACADDR_NUM_BYTES]);
 
   /** Gets the source MAC address of the Ethernet MAC
    *

lib_ethernet/src/mii_ethernet_mac.xc

@@ -160,7 +160,7 @@ static void mii_ethernet_aux(client mii_if i_mii,
         memcpy(r_mac_address, mac_address, sizeof mac_address);
         break;
 
-      case i_cfg[int i].set_macaddr(size_t ifnum, uint8_t r_mac_address[MACADDR_NUM_BYTES]):
+      case i_cfg[int i].set_macaddr(size_t ifnum, const uint8_t r_mac_address[MACADDR_NUM_BYTES]):
         memcpy(mac_address, r_mac_address, sizeof r_mac_address);
         break;
 

lib_ethernet/src/mii_ethernet_rt_mac.xc

@@ -322,7 +322,7 @@ unsafe void mii_ethernet_server(mii_mempool_t rx_mem,
       memcpy(r_mac_address, mac_address, sizeof mac_address);
       break;
 
-    case i_cfg[int i].set_macaddr(size_t ifnum, uint8_t r_mac_address[MACADDR_NUM_BYTES]):
+    case i_cfg[int i].set_macaddr(size_t ifnum, const uint8_t r_mac_address[MACADDR_NUM_BYTES]):
       memcpy(mac_address, r_mac_address, sizeof r_mac_address);
       break;
 

lib_ethernet/src/mii_master.xc

@@ -13,6 +13,7 @@
 #include "mii_common_lld.h"
 #include "string.h"
 #include "check_ifg_wait.h"
+#include "shaper.h"
 
 #define QUOTEAUX(x) #x
 #define QUOTE(x) QUOTEAUX(x)
@@ -471,9 +472,9 @@ unsafe void mii_master_tx_pins(mii_mempool_t tx_mem_lp,
                                out buffered port:32 p_mii_txd,
                                volatile ethernet_port_state_t * unsafe p_port_state)
 {
-  int credit = 0; // No. of bits allowed to send
-  int credit_time;
-  // Need one timer to be able to read at any time for the shaper
+  qav_state_t qav_state = {0, 0, 0}; // Set times and credit to zero so it can tx first frame
+
+  // Need a timer to be able to read at any time for the shaper
   timer credit_tmr;
   // And a second timer to be enforcing the IFG gap
   hwtimer_t ifg_tmr;
@@ -485,7 +486,8 @@ unsafe void mii_master_tx_pins(mii_mempool_t tx_mem_lp,
     enable_shaper = 0;
 
   if (ETHERNET_SUPPORT_HP_QUEUES && enable_shaper) {
-    credit_tmr :> credit_time;
+    credit_tmr :> qav_state.current_time;
+    qav_state.prev_time = qav_state.current_time;
   }
 
   ifg_tmr :> ifg_time;
@@ -500,23 +502,10 @@ unsafe void mii_master_tx_pins(mii_mempool_t tx_mem_lp,
       buf = mii_get_next_buf(packets_hp);
 
     if (enable_shaper) {
-      int prev_credit_time = credit_time;
-      credit_tmr :> credit_time;
-
-      int elapsed = credit_time - prev_credit_time;
-      credit += elapsed * p_port_state->qav_idle_slope; // add bit budget since last transmission to credit. ticks * bits/tick = bits
-
-      if (buf) {
-        if (credit < 0) {
-          buf = 0; // if out of credit drop this HP packet
-        }
-      }
-      else {
-        if (credit > 0)
-          credit = 0;
-      }
+      credit_tmr :> qav_state.current_time;
+      buf = shaper_do_idle_slope(buf, &qav_state, p_port_state);
     }
-
+    
     if (!buf) {
       buf = mii_get_next_buf(packets_lp);
       p_ts_queue = &ts_queue;
@@ -530,19 +519,15 @@ unsafe void mii_master_tx_pins(mii_mempool_t tx_mem_lp,
 
     unsigned time = mii_transmit_packet(tx_mem, buf, p_mii_txd, ifg_tmr, ifg_time, eof_time);
 
-    eof_time = ifg_time;
     // Setup the hardware timer to enforce the IFG
+    eof_time = ifg_time;
     ifg_time += MII_ETHERNET_IFS_AS_REF_CLOCK_COUNT;
     ifg_time += (buf->length & 0x3) * 8;
 
+    // Calculate the send slope (decrement credit) if enabled and was HP
     const int packet_is_high_priority = (p_ts_queue == null);
     if (enable_shaper && packet_is_high_priority) {
-      const int preamble_bytes = 8;
-      const int ifg_bytes = 96/8;
-      const int crc_bytes = 4;
-      int len = buf->length + preamble_bytes + ifg_bytes + crc_bytes;
-      // decrease credit by no. of bits transmitted
-      credit = credit - (len << (MII_CREDIT_FRACTIONAL_BITS+3)); // MII_CREDIT_FRACTIONAL_BITS+3 to convert from bytes to bits
+      shaper_do_send_slope(buf->length, &qav_state);
     }
 
     if (mii_get_and_dec_transmit_count(buf) == 0) {
@@ -559,6 +544,6 @@ unsafe void mii_master_tx_pins(mii_mempool_t tx_mem_lp,
         mii_free_current(packets_hp);
       }
     }
-  }
+  } // while(1)
 }
 

lib_ethernet/src/rgmii_buffering.xc

@@ -747,7 +747,7 @@ void rgmii_ethernet_mac_config(server ethernet_cfg_if i_cfg[n],
         memcpy(r_mac_address, mac_address, sizeof mac_address);
         break;
 
-      case i_cfg[int i].set_macaddr(size_t ifnum, uint8_t r_mac_address[MACADDR_NUM_BYTES]):
+      case i_cfg[int i].set_macaddr(size_t ifnum, const uint8_t r_mac_address[MACADDR_NUM_BYTES]):
         memcpy(mac_address, r_mac_address, sizeof r_mac_address);
         break;
 

lib_ethernet/src/rmii_master.xc

@@ -16,6 +16,7 @@
 #include "string.h"
 #include "check_ifg_wait.h"
 #include "rmii_rx_pins_exit.h"
+#include "shaper.h"
 
 
 #define QUOTEAUX(x) #x
@@ -992,21 +993,22 @@ unsafe void rmii_master_tx_pins(mii_mempool_t tx_mem_lp,
     // Flag for readability and faster comparison
     const unsigned use_4b = (tx_port_width == 4);
 
-    int credit = 0;
-    int credit_time;
     // Need one timer to be able to read at any time for the shaper
     timer credit_tmr;
     // And a second timer to be enforcing the IFG gap
     hwtimer_t ifg_tmr;
     unsigned ifg_time = 0;
     unsigned eof_time = 0;
+
+    qav_state_t qav_state = {0, 0, 0}; // Set times and credit to zero so it can tx first frame
     unsigned enable_shaper = p_port_state->qav_shaper_enabled;
 
     if (!ETHERNET_SUPPORT_TRAFFIC_SHAPER) {
         enable_shaper = 0;
     }
     if (ETHERNET_SUPPORT_HP_QUEUES && enable_shaper) {
-        credit_tmr :> credit_time;
+        credit_tmr :> qav_state.current_time;
+        qav_state.prev_time = qav_state.current_time;;
     }
 
     ifg_tmr :> ifg_time;
@@ -1021,21 +1023,8 @@ unsafe void rmii_master_tx_pins(mii_mempool_t tx_mem_lp,
         }
 
         if (enable_shaper) {
-            int prev_credit_time = credit_time;
-            credit_tmr :> credit_time;
-
-            int elapsed = credit_time - prev_credit_time;
-            credit += elapsed * p_port_state->qav_idle_slope;
-
-            if (buf) {
-                if (credit < 0) {
-                    buf = 0;
-                }
-            } else {
-                if (credit > 0) {
-                    credit = 0;
-                }
-            }
+            credit_tmr :> qav_state.current_time;
+            buf = shaper_do_idle_slope(buf, &qav_state, p_port_state);
         }
 
         if (!buf) {
@@ -1071,11 +1060,7 @@ unsafe void rmii_master_tx_pins(mii_mempool_t tx_mem_lp,
 
         const int packet_is_high_priority = (p_ts_queue == null);
         if (enable_shaper && packet_is_high_priority) {
-            const int preamble_bytes = 8;
-            const int ifg_bytes = 96/8;
-            const int crc_bytes = 4;
-            int len = buf->length + preamble_bytes + ifg_bytes + crc_bytes;
-            credit = credit - (len << (MII_CREDIT_FRACTIONAL_BITS+3));
+            shaper_do_send_slope(buf->length, &qav_state);
         }
 
         if (mii_get_and_dec_transmit_count(buf) == 0) {

lib_ethernet/src/server_state.h

@@ -6,8 +6,6 @@
 #include "xccompat.h"
 #include "ethernet.h"
 
-#define MII_CREDIT_FRACTIONAL_BITS 16
-
 // Server is shared for rmii/mii so pass in enum
 typedef enum phy_100mb_t {
     ETH_MAC_IF_MII = 0,
@@ -21,6 +19,7 @@ typedef struct ethernet_port_state_t
   ethernet_speed_t link_speed;
   int qav_shaper_enabled;
   int qav_idle_slope;
+  int64_t qav_credit_limit;
   int ingress_ts_latency[NUM_ETHERNET_SPEEDS];
   int egress_ts_latency[NUM_ETHERNET_SPEEDS];
 } ethernet_port_state_t;

lib_ethernet/src/server_state.xc

@@ -8,5 +8,6 @@ void init_server_port_state(ethernet_port_state_t &state, int enable_qav_shaper)
   memset(&state, 0, sizeof(ethernet_port_state_t));
   state.link_state = ETHERNET_LINK_DOWN;
   state.qav_shaper_enabled = enable_qav_shaper;
-  state.qav_idle_slope = (11<<MII_CREDIT_FRACTIONAL_BITS);
+  state.qav_credit_limit = 0; // No credit limit
+  state.qav_idle_slope = (11<<MII_CREDIT_FRACTIONAL_BITS); // 11 bits per tick (more than max egress even in gbit)
 }

lib_ethernet/src/shaper.h

@@ -0,0 +1,129 @@
+// Copyright 2025 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+#ifndef __shaper_h__
+#define __shaper_h__
+
+#include <stdio.h>
+#include "ethernet.h"
+#include "server_state.h"
+#include "mii_buffering.h"
+#include "xassert.h"
+#include <print.h>
+
+#ifndef ETHERNET_SUPPORT_TRAFFIC_SHAPER_CREDIT_LIMIT
+#define ETHERNET_SUPPORT_TRAFFIC_SHAPER_CREDIT_LIMIT 1
+#endif
+
+static const unsigned preamble_bytes = 8;
+static const unsigned crc_bytes = 4;
+static const unsigned ifg_bytes = 96 / 8;
+
+/** Type which stores the Qav credit based shaper state */
+typedef struct qav_state_t{
+  int prev_time;    /**< Previous time in hw_timer ticks (10ns, 32b). */
+  int current_time; /**< Current time in hw_timer ticks (10ns, 32b). */
+  int credit;       /**< Credit in MII_CREDIT_FRACTIONAL_BITS fractional format. */
+} qav_state_t;
+
+/** Sets the Qav idle slope in units of bits per second.
+ *
+ *   \param port_state  Pointer to the port state to be modified
+ *   \param limit_bps   The idle slope setting in bits per second
+ *
+ */
+void set_qav_idle_slope(ethernet_port_state_t * port_state, unsigned limit_bps);
+
+
+/** Sets the Qav credit limit in units of frame size byte
+ *
+ *   \param port_state    Pointer to the port state to be modified
+ *   \param limit_bytes   The credit limit in units of payload size in bytes to set as a credit limit,
+ *                        not including preamble, CRC and IFG. Set to 0 for no limit (default)
+ *
+ */
+void set_qav_credit_limit(ethernet_port_state_t * port_state, int payload_limit_bytes);
+
+
+/** Performs the idle slope calculation for MII and RMII MACs.
+ * 
+ * Adds credits based on time since last HP packet and bit rate. If credit after calculation is above zero then
+ * the HP packet is allowed to be transmitted. If credit is negative then the return buffer
+ * is null so that it waits until credit is sufficient. 
+ * 
+ * The credit is optionally limited to hiCredit which is initialised by set_qav_credit_limit()
+ * 
+ *   \param hp_buf        Pointer to packet to be transmitted
+ *   \param qav_state     Pointer to Qav state struct
+ *   \param port_state    Pointer to MAC port state
+ * 
+ *   \returns             The hp_buf passed to it which is either maintained if credit is sufficient
+ *                        or NULL if credit is not sufficient.
+ */
+static inline mii_packet_t * unsafe shaper_do_idle_slope(mii_packet_t * unsafe hp_buf,
+                                                         qav_state_t * unsafe qav_state,
+                                                         ethernet_port_state_t * unsafe port_state){
+  unsafe{
+    uint32_t elapsed_ticks = qav_state->current_time - qav_state->prev_time;
+
+#if ETHERNET_SUPPORT_TRAFFIC_SHAPER_CREDIT_LIMIT
+    int64_t credit64 = (int64_t)elapsed_ticks * (int64_t)port_state->qav_idle_slope + (int64_t)qav_state->credit;
+
+    // cast qav_credit_limit as saves a cycle
+    if((unsigned)port_state->qav_credit_limit){
+      // Apply limit
+      if(credit64 > port_state->qav_credit_limit)
+      {
+        // printf("limited credit: %lld limit: %lld\n", credit64, port_state->qav_credit_limit);
+        credit64 = port_state->qav_credit_limit;
+      }
+    } else {
+      // Clip to max_int to avoid overflow
+      const int64_t max_int = 0x7fffffff;
+      if(credit64 > max_int){
+        // printf("clip credit: %lld limit: %lld\n", credit64, port_state->qav_credit_limit);
+        credit64 = max_int;
+      }
+    }
+    qav_state->credit = (int)credit64;
+#else
+    // This is the old code from <4.0.0
+    qav_state->credit += elapsed_ticks * (int)port_state->qav_idle_slope; // add bit budget since last transmission to credit. ticks * bits/tick = bits
+#endif
+
+    // If valid hp buffer
+    if (hp_buf) {
+      if (qav_state->credit < 0) {
+        hp_buf = 0; // if out of credit drop this HP packet
+      }
+    }
+    else
+    // Buffer invalid, no HP packet so reset credit as per Annex L of Qav
+    {
+      if (qav_state->credit > 0){
+        qav_state->credit = 0; // HP ready to send next time
+      }
+    }
+
+    // Ensure we keep track of state (time since last packet) for next time
+    qav_state->prev_time = qav_state->current_time;
+
+    return hp_buf;
+  }
+}
+
+
+static inline void shaper_do_send_slope(int len_bytes, qav_state_t * unsafe qav_state){
+  unsafe{
+    // Calculate number of additional byte slots on wire over the payload
+    const int overhead_bytes = preamble_bytes + crc_bytes + ifg_bytes;
+
+    // decrease credit by no. of bits transmitted, scaled by MII_CREDIT_FRACTIONAL_BITS
+    // Note we don't need to check for overflow here as we will only be here if credit
+    // was previously positive (worst case 1) and len_bytes <= ETHERNET_MAX_PACKET_SIZE so
+    // will only decrement by roughly -(1<<29)
+    qav_state->credit = qav_state->credit - ((len_bytes + overhead_bytes) << (MII_CREDIT_FRACTIONAL_BITS + 3)); // MII_CREDIT_FRACTIONAL_BITS+3 to convert from bytes to bits
+  }
+}
+
+
+#endif // __shaper_h__

lib_ethernet/src/shaper.xc

@@ -0,0 +1,29 @@
+// Copyright 2025 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+#include "ethernet.h"
+#include "shaper.h"
+
+void set_qav_idle_slope(ethernet_port_state_t * port_state, unsigned limit_bps)
+{
+  // Scale for 16.16 representation 
+  uint64_t slope = ((uint64_t)limit_bps) << MII_CREDIT_FRACTIONAL_BITS;
+
+  // Calculate bits per tick per bit in 16.16
+  slope = slope / XS1_TIMER_HZ;
+
+  port_state->qav_idle_slope = (unsigned)slope;
+}
+
+
+void set_qav_credit_limit(ethernet_port_state_t * port_state, int payload_limit_bytes)
+{
+  int64_t max_interferring_frame_bits = (preamble_bytes + payload_limit_bytes + crc_bytes + ifg_bytes) * 8;
+  if(payload_limit_bytes > 0){
+    port_state->qav_credit_limit = max_interferring_frame_bits;
+  }
+  else
+  {
+    // No limit
+    port_state->qav_credit_limit = 0;
+  }
+}