[BACKPORT] stm32h7: allow Ethernet MAC without PHY

- In some cases, an operational Ethernet MAC may have no PHY, for example
when the system has a direct RMII MAC-to-MAC link.
- New config option STM32H7_NO_PHY
- With this option, PHY-specific code in the ethernet driver is not built
- This option is inherently incompatible with autonegotiation and speed and
duplex settings must be compiled in

arch/arm/src/stm32h7/Kconfig

@@ -5249,6 +5249,10 @@ config STM32H7_ETHMAC_REGDEBUG
 		Enable very low-level register access debug.  Depends on
 		CONFIG_DEBUG_FEATURES.
 
+config STM32H7_NO_PHY
+	bool "MAC has no PHY"
+	default n
+
 endmenu # Ethernet MAC configuration
 
 menu "QEncoder Driver"

arch/arm/src/stm32h7/stm32_ethernet.c

@@ -754,7 +754,7 @@ static void stm32_rxdescinit(struct stm32_ethmac_s *priv,
                              union stm32_desc_u *rxtable, uint8_t *rxbuffer);
 
 /* PHY Initialization */
-
+#ifndef CONFIG_STM32H7_NO_PHY
 #if defined(CONFIG_NETDEV_PHY_IOCTL) && defined(CONFIG_ARCH_PHY_INTERRUPT)
 static int  stm32_phyintenable(struct stm32_ethmac_s *priv);
 #endif
@@ -769,6 +769,7 @@ static int  stm32_phyinit(struct stm32_ethmac_s *priv);
 #ifdef CONFIG_STM32H7_ETHMAC_REGDEBUG
 static void  stm32_phyregdump(void);
 #endif
+#endif
 
 /* MAC/DMA Initialization */
 
@@ -2996,6 +2997,7 @@ static void stm32_rxdescinit(struct stm32_ethmac_s *priv,
 #ifdef CONFIG_NETDEV_PHY_IOCTL
 static int stm32_ioctl(struct net_driver_s *dev, int cmd, unsigned long arg)
 {
+#ifndef CONFIG_STM32H7_NO_PHY
 #ifdef CONFIG_ARCH_PHY_INTERRUPT
   struct stm32_ethmac_s *priv = (struct stm32_ethmac_s *)dev->d_private;
 #endif
@@ -3053,9 +3055,13 @@ static int stm32_ioctl(struct net_driver_s *dev, int cmd, unsigned long arg)
     }
 
   return ret;
+#else
+  return -EIO;
+#endif
 }
 #endif /* CONFIG_NETDEV_PHY_IOCTL */
 
+#ifndef CONFIG_STM32H7_NO_PHY
 /****************************************************************************
  * Function: stm32_phyintenable
  *
@@ -3576,6 +3582,8 @@ static int stm32_phyinit(struct stm32_ethmac_s *priv)
   return OK;
 }
 
+#endif
+
 /****************************************************************************
  * Name: stm32_selectmii
  *
@@ -4222,13 +4230,27 @@ static int stm32_ethconfig(struct stm32_ethmac_s *priv)
 
   /* Initialize the PHY */
 
+#ifdef CONFIG_STM32H7_NO_PHY
+  ninfo("MAC without PHY\n");
+#ifdef CONFIG_STM32H7_ETHFD
+  priv->fduplex = 1;
+#else
+  priv->fduplex = 0;
+#endif
+#ifdef CONFIG_STM32H7_ETH100MBPS
+  priv->mbps100 = 1;
+#else
+  priv->mbps100 = 0;
+#endif
+#else
   ninfo("Initialize the PHY\n");
   ret = stm32_phyinit(priv);
   if (ret < 0)
     {
       return ret;
     }
 
+#endif
   /* Initialize the MAC and DMA */
 
   ninfo("Initialize the MAC and DMA\n");