boards: st: stm32h7s78_dk: add Ethernet support

Add Ethernet configuration for mac and mdio nodes.
Define the SRAM region for Ethernet descriptor and buffer
using memory-region = <...> in the mac node for this board
and for nucleo_h7s3l8, since they both use the same
mpu_regions.c and sections.ld files.

Update mpu_regions.c and sections.ld to use the region defined
in board's .dtsi file via phandle. Add a check to mpu_regions.c
to make sure the memory-region node doesn't refer to the
zephyr,sram region.

Disable mac node in .overlay files for tests/drivers/memc/ram
since ethernet drivers that get enabled by it consume sram1
node and thus fail the test.

Update the yaml files to include Ethernet tag and
update documentation to explain Ethernet usage.

Signed-off-by: Benjamin Klaric <benjamin.klaric01@gmail.com>

Author: bklaric1

boards/st/nucleo_h7s3l8/nucleo_h7s3l8.dts

@@ -181,6 +181,7 @@
 	pinctrl-names = "default";
 	phy-connection-type = "rmii";
 	phy-handle = <&eth_phy>;
+	memory-region = <&sram1>;
 	status = "okay";
 };
 

boards/st/stm32h7s78_dk/doc/index.rst

@@ -181,6 +181,7 @@ Default Zephyr Peripheral Mapping:
 - XSPI1 NCS/DQS0/DQS1/CLK/IO: PO0/PO2/PO3/PO4/PP0..15
 - I2C1 SCL/SDA: PB6/PB9
 - FDCAN1 RX/TX : PB8/PB9
+- ETH: PA2/PA7/PB0/PB1/PC1/PC4/PC5/PD7/PG11
 
 System Clock
 ------------
@@ -208,6 +209,12 @@ STM32H7S78-DK Discovery board has 2 FDCAN bus interfaces.
 FDCAN1 is configured but not enabled by default. To enable it, make sure
 that ``i2c1`` is disabled, since they share the PB9 pin.
 
+Ethernet
+--------
+
+In order to use Ethernet on STM32H7S78-DK, you need to set the ``JP6`` jumper
+to PC1 position on the back side of the board.
+
 Programming and Debugging
 *************************
 

boards/st/stm32h7s78_dk/stm32h7s78_dk-common.dtsi

@@ -11,6 +11,11 @@
 #include "zephyr/dt-bindings/display/panel.h"
 #include <zephyr/dt-bindings/input/input-event-codes.h>
 
+/*
+ * WARNING:
+ * JP6 must be in PC1 position when using Ethernet.
+ */
+
 / {
 	chosen {
 		zephyr,console = &uart4;
@@ -228,6 +233,32 @@
 	status = "disabled";
 };
 
+&mac {
+	pinctrl-0 = <&eth_rmii_ref_clk_pd7
+		     &eth_rmii_crs_dv_pa7
+		     &eth_rmii_rxd0_pc4
+		     &eth_rmii_rxd1_pc5
+		     &eth_rmii_tx_en_pg11
+		     &eth_rmii_txd0_pb0
+		     &eth_rmii_txd1_pb1>;
+	pinctrl-names = "default";
+	phy-connection-type = "rmii";
+	phy-handle = <&eth_phy>;
+	memory-region = <&sram1>;
+	status = "okay";
+};
+
+&mdio {
+	pinctrl-0 = <&eth_mdio_pa2 &eth_mdc_pc1>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	eth_phy: ethernet-phy@0 {
+		compatible = "ethernet-phy";
+		reg = <0x00>;
+	};
+};
+
 &xspi1 {
 	pinctrl-0 = <&xspim_p1_ncs1_po0 &xspim_p1_dqs0_po2
 		     &xspim_p1_dqs1_po3 &xspim_p1_clk_po4

boards/st/stm32h7s78_dk/stm32h7s78_dk.yaml

@@ -16,4 +16,5 @@ supported:
   - octospi
   - usbd
   - memc
+  - netif:eth
 vendor: st

boards/st/stm32h7s78_dk/stm32h7s78_dk_stm32h7s7xx_ext_flash_app.yaml

@@ -17,4 +17,5 @@ supported:
   - octospi
   - usbd
   - memc
+  - netif:eth
 vendor: st

dts/bindings/ethernet/st,stm32h7-ethernet.yaml

@@ -12,3 +12,9 @@ description: |
 compatible: "st,stm32h7-ethernet"
 
 include: st,stm32-ethernet-common.yaml
+
+properties:
+  memory-region:
+    type: phandle
+    description: |
+      Reference to SRAM node used for Ethernet DMA buffer and descriptor.

soc/st/stm32/stm32h7rsx/mpu_regions.c

@@ -31,7 +31,13 @@ static const struct arm_mpu_region mpu_regions[] = {
 	MPU_REGION_ENTRY("ID", 0x08FFF800, REGION_FLASH_ATTR(REGION_2K)),
 
 #if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(mac))
-#define sram_eth_node DT_NODELABEL(sram2)
+#define sram_eth_node DT_PHANDLE(DT_NODELABEL(mac), memory_region)
+
+#if DT_NODE_HAS_COMPAT(sram_eth_node, zephyr_sram)
+#error "Invalid Ethernet memory-region: cannot use zephyr,sram. \
+Use a SRAM region like sram1 or sram2 for Ethernet."
+#endif
+
 #if DT_NODE_HAS_STATUS_OKAY(sram_eth_node)
 	/* Region 5 - Ethernet DMA buffer RAM */
 	MPU_REGION_ENTRY("SRAM_ETH_BUF", DT_REG_ADDR(sram_eth_node),

soc/st/stm32/stm32h7rsx/sections.ld

@@ -5,7 +5,8 @@
  */
 
 #if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(mac))
-#define sram_eth_node	DT_NODELABEL(sram2)
+#define sram_eth_node DT_PHANDLE(DT_NODELABEL(mac), memory_region)
+
 #if DT_NODE_HAS_STATUS_OKAY(sram_eth_node)
 SECTION_DATA_PROLOGUE(eth_stm32,(NOLOAD),)
 {

tests/drivers/memc/ram/boards/stm32h7s78_dk.overlay

@@ -8,3 +8,11 @@
 	zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
 	status = "okay";
 };
+
+&mac {
+	/*
+	 * mac is disabled for this test since the ethernet driver that gets
+	 * enabled by this node consumes the sram1 node thus failing this test
+	 */
+	status = "disabled";
+};

tests/drivers/memc/ram/boards/stm32h7s78_dk_stm32h7s7xx_ext_flash_app.overlay

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2025 Benjamin Klaric <benjamin.klaric01@gmail.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&sram2 {
+	zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
+	status = "okay";
+};
+
+&mac {
+	/*
+	 * mac is disabled for this test since the ethernet driver that gets
+	 * enabled by this node consumes the sram1 node thus failing this test
+	 */
+	status = "disabled";
+};