ethernet: stm32h7: Move DMA buffers from sram3 to sram2

PR #30403 implemented nocache regions for ethernet DMA buffers in sram3 to
fix issue #29915. Unfortunately, some STM32H7 variants do not have any
sram3 so they still suffer from #29915.

All H7 variants have sram2 though, so use that for targets without sram3.

Signed-off-by: Björn Stenberg <[email protected]>

Author: zagor

drivers/ethernet/eth_stm32_hal.c

@@ -80,8 +80,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 	    DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
 #define __eth_stm32_desc __dtcm_noinit_section
 #define __eth_stm32_buf  __dtcm_noinit_section
-#elif defined(CONFIG_SOC_SERIES_STM32H7X) && \
-		DT_NODE_HAS_STATUS(DT_NODELABEL(sram3), okay)
+#elif defined(CONFIG_SOC_SERIES_STM32H7X)
 #define __eth_stm32_desc __attribute__((section(".eth_stm32_desc")))
 #define __eth_stm32_buf  __attribute__((section(".eth_stm32_buf")))
 #elif defined(CONFIG_NOCACHE_MEMORY)

soc/arm/st_stm32/stm32h7/mpu_regions.c

@@ -13,14 +13,22 @@ static const struct arm_mpu_region mpu_regions[] = {
 					 REGION_FLASH_ATTR(REGION_FLASH_SIZE)),
 	MPU_REGION_ENTRY("SRAM", CONFIG_SRAM_BASE_ADDRESS,
 					 REGION_RAM_ATTR(REGION_SRAM_SIZE)),
-#if DT_NODE_HAS_STATUS(DT_NODELABEL(sram3), okay) && \
-		DT_NODE_HAS_STATUS(DT_NODELABEL(mac), okay)
+#if DT_NODE_HAS_STATUS(DT_NODELABEL(mac), okay)
+#if DT_NODE_HAS_STATUS(DT_NODELABEL(sram3), okay)
 	MPU_REGION_ENTRY("SRAM3_ETH_BUF",
 					 DT_REG_ADDR(DT_NODELABEL(sram3)),
 					 REGION_RAM_NOCACHE_ATTR(REGION_16K)),
 	MPU_REGION_ENTRY("SRAM3_ETH_DESC",
 					 DT_REG_ADDR(DT_NODELABEL(sram3)),
 					 REGION_PPB_ATTR(REGION_256B)),
+#else
+	MPU_REGION_ENTRY("SRAM2_ETH_BUF",
+					 DT_REG_ADDR(DT_NODELABEL(sram2)),
+					 REGION_RAM_NOCACHE_ATTR(REGION_16K)),
+	MPU_REGION_ENTRY("SRAM2_ETH_DESC",
+					 DT_REG_ADDR(DT_NODELABEL(sram2)),
+					 REGION_PPB_ATTR(REGION_256B)),
+#endif
 #endif
 
 	/* DT-defined regions */

soc/arm/st_stm32/stm32h7/sections.ld

@@ -4,15 +4,24 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#if DT_NODE_HAS_STATUS(DT_NODELABEL(sram3), okay) && DT_NODE_HAS_STATUS(DT_NODELABEL(mac), okay)
+#if DT_NODE_HAS_STATUS(DT_NODELABEL(mac), okay)
 
 SECTION_DATA_PROLOGUE(eth_stm32,(NOLOAD),)
 {
+#if DT_NODE_HAS_STATUS(DT_NODELABEL(sram3), okay)
     . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram3)));
     *(.eth_stm32_desc)
     . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram3))) + 256;
     *(.eth_stm32_buf)
     . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram3))) + 16K;
 } GROUP_DATA_LINK_IN(LINKER_DT_NODE_REGION_NAME(DT_NODELABEL(sram3)), LINKER_DT_NODE_REGION_NAME(DT_NODELABEL(sram3)))
 
+#else
+    . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram2)));
+    *(.eth_stm32_desc)
+    . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram2))) + 256;
+    *(.eth_stm32_buf)
+    . = ABSOLUTE(DT_REG_ADDR(DT_NODELABEL(sram2))) + 16K;
+} GROUP_DATA_LINK_IN(LINKER_DT_NODE_REGION_NAME(DT_NODELABEL(sram2)), LINKER_DT_NODE_REGION_NAME(DT_NODELABEL(sram2)))
+#endif
 #endif