[PATCH net-next v4 0/3] net: ethernet: mtk_eth_soc: improve device tree handling

[PATCH net-next v4 0/3] net: ethernet: mtk_eth_soc: improve device tree handling

[Daniel Golle]

This series further improves the mtk_eth_soc driver in preparation to
complete upstream support for the MediaTek MT7988 SoC family.

Frank Wunderlich's previous attempt to have the ethernet node included
in mt7988a.dtsi and cover support for MT7988 in the device tree bindings
was criticized for the way mtk_eth_soc references SRAM in device tree[1].

Having a 2nd 'reg' property, like introduced by commit ebb1e4f9cf38
("net: ethernet: mtk_eth_soc: add support for in-SoC SRAM") isn't
acceptable and a dedicated "mmio-sram" node should be used instead.

In order to make the code more clean and readable, the existing
hardcoded offsets for the scratch ring, RX and TX rings are dropped in
favor of using the generic allocator. In this way support for the
hard-coded offset and including the SRAM region as part of the
Ethernet's "reg" MMIO space is kept as it will still be required in
order to support existing legacy device trees of the MT7986 SoC family.

While at it also replace confusing error messages when using legacy
device trees without "interrupt-names" with a warning informing users
that they are using a legacy device tree.

[1]: https://patchwork.ozlabs.org/comment/3533543/

Daniel Golle (3):
  net: ethernet: mtk_eth_soc: improve support for named interrupts
  net: ethernet: mtk_eth_soc: fix kernel-doc comment
  net: ethernet: mtk_eth_soc: use generic allocator for SRAM

 drivers/net/ethernet/mediatek/Kconfig       |   1 +
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 155 +++++++++++---------
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |  11 +-
 3 files changed, 95 insertions(+), 72 deletions(-)

-- 
2.50.0

[PATCH net-next v4 1/3] net: ethernet: mtk_eth_soc: improve support for named interrupts

[Daniel Golle]

Use platform_get_irq_byname_optional() to avoid outputting error
messages when using legacy device trees which rely identifying
interrupts only by index. Instead, output a warning notifying the user
to update their device tree.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
v4: unchanged
v3: unchanged
v2: unchanged

 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index f8a907747db4..8f55069441f4 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -3341,17 +3341,22 @@ static int mtk_get_irqs(struct platform_device *pdev, struct mtk_eth *eth)
 	int i;
 
 	/* future SoCs beginning with MT7988 should use named IRQs in dts */
-	eth->irq[MTK_FE_IRQ_TX] = platform_get_irq_byname(pdev, "fe1");
-	eth->irq[MTK_FE_IRQ_RX] = platform_get_irq_byname(pdev, "fe2");
+	eth->irq[MTK_FE_IRQ_TX] = platform_get_irq_byname_optional(pdev, "fe1");
+	eth->irq[MTK_FE_IRQ_RX] = platform_get_irq_byname_optional(pdev, "fe2");
 	if (eth->irq[MTK_FE_IRQ_TX] >= 0 && eth->irq[MTK_FE_IRQ_RX] >= 0)
 		return 0;
 
-	/* only use legacy mode if platform_get_irq_byname returned -ENXIO */
+	/* only use legacy mode if platform_get_irq_byname_optional returned -ENXIO */
 	if (eth->irq[MTK_FE_IRQ_TX] != -ENXIO)
-		return eth->irq[MTK_FE_IRQ_TX];
+		return dev_err_probe(&pdev->dev, eth->irq[MTK_FE_IRQ_TX],
+				     "Error requesting FE TX IRQ\n");
 
 	if (eth->irq[MTK_FE_IRQ_RX] != -ENXIO)
-		return eth->irq[MTK_FE_IRQ_RX];
+		return dev_err_probe(&pdev->dev, eth->irq[MTK_FE_IRQ_RX],
+				     "Error requesting FE RX IRQ\n");
+
+	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_SHARED_INT))
+		dev_warn(&pdev->dev, "legacy DT: missing interrupt-names.");
 
 	/* legacy way:
 	 * On MTK_SHARED_INT SoCs (MT7621 + MT7628) the first IRQ is taken
-- 
2.50.0

[PATCH net-next v4 2/3] net: ethernet: mtk_eth_soc: fix kernel-doc comment

[Daniel Golle]

Fix and add some missing field descriptions to kernel-doc comment of
struct mtk_eth.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
v4: unchanged
v3: unchanged
v2: unchanged

 drivers/net/ethernet/mediatek/mtk_eth_soc.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 9261c0e13b59..1ad9075a9b69 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -1243,8 +1243,9 @@ struct mtk_soc_data {
 /* struct mtk_eth -	This is the main datasructure for holding the state
  *			of the driver
  * @dev:		The device pointer
- * @dev:		The device pointer used for dma mapping/alloc
+ * @dma_dev:		The device pointer used for dma mapping/alloc
  * @base:		The mapped register i/o base
+ * @sram_base:		The mapped SRAM base
  * @page_lock:		Make sure that register operations are atomic
  * @tx_irq__lock:	Make sure that IRQ register operations are atomic
  * @rx_irq__lock:	Make sure that IRQ register operations are atomic
-- 
2.50.0

[PATCH net-next v4 3/3] net: ethernet: mtk_eth_soc: use generic allocator for SRAM

[Daniel Golle]

Use a dedicated "mmio-sram" node and the generic allocator
instead of open-coding SRAM allocation for DMA rings.
Keep support for legacy device trees but notify the user via a
warning to update, and let the ethernet driver create the
gen_pool in this case.

Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
v4: always use gen_pool allocator completely replacing the
    previous approach of hardcoded SRAM offsets
    added missing Kconfig change
v3: fix resource leak on error in mtk_probe()
v2: fix return type of mtk_dma_ring_alloc() in case of error

 drivers/net/ethernet/mediatek/Kconfig       |   1 +
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 140 +++++++++++---------
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |  10 +-
 3 files changed, 84 insertions(+), 67 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/Kconfig b/drivers/net/ethernet/mediatek/Kconfig
index 7bfd3f230ff5..2ba361f8ce7d 100644
--- a/drivers/net/ethernet/mediatek/Kconfig
+++ b/drivers/net/ethernet/mediatek/Kconfig
@@ -17,6 +17,7 @@ config NET_MEDIATEK_SOC
 	select PINCTRL
 	select PHYLINK
 	select DIMLIB
+	select GENERIC_ALLOCATOR
 	select PAGE_POOL
 	select PAGE_POOL_STATS
 	select PCS_MTK_LYNXI
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 8f55069441f4..6e2aa01aedbd 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -27,6 +27,7 @@
 #include <net/dsa.h>
 #include <net/dst_metadata.h>
 #include <net/page_pool/helpers.h>
+#include <linux/genalloc.h>
 
 #include "mtk_eth_soc.h"
 #include "mtk_wed.h"
@@ -1267,6 +1268,34 @@ static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
 	return (void *)data;
 }
 
+static void *mtk_dma_ring_alloc(struct mtk_eth *eth, size_t size,
+				dma_addr_t *dma_handle, bool use_sram)
+{
+	void *dma_ring;
+
+	if (use_sram && eth->sram_pool) {
+		dma_ring = (void *)gen_pool_alloc(eth->sram_pool, size);
+		if (!dma_ring)
+			return dma_ring;
+		*dma_handle = gen_pool_virt_to_phys(eth->sram_pool,
+						    (unsigned long)dma_ring);
+	} else {
+		dma_ring = dma_alloc_coherent(eth->dma_dev, size, dma_handle,
+					      GFP_KERNEL);
+	}
+
+	return dma_ring;
+}
+
+static void mtk_dma_ring_free(struct mtk_eth *eth, size_t size, void *dma_ring,
+			      dma_addr_t dma_handle, bool in_sram)
+{
+	if (in_sram && eth->sram_pool)
+		gen_pool_free(eth->sram_pool, (unsigned long)dma_ring, size);
+	else
+		dma_free_coherent(eth->dma_dev, size, dma_ring, dma_handle);
+}
+
 /* the qdma core needs scratch memory to be setup */
 static int mtk_init_fq_dma(struct mtk_eth *eth)
 {
@@ -1276,13 +1305,8 @@ static int mtk_init_fq_dma(struct mtk_eth *eth)
 	dma_addr_t dma_addr;
 	int i, j, len;
 
-	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM))
-		eth->scratch_ring = eth->sram_base;
-	else
-		eth->scratch_ring = dma_alloc_coherent(eth->dma_dev,
-						       cnt * soc->tx.desc_size,
-						       &eth->phy_scratch_ring,
-						       GFP_KERNEL);
+	eth->scratch_ring = mtk_dma_ring_alloc(eth, cnt * soc->tx.desc_size,
+					       &eth->phy_scratch_ring, true);
 
 	if (unlikely(!eth->scratch_ring))
 		return -ENOMEM;
@@ -2620,14 +2644,7 @@ static int mtk_tx_alloc(struct mtk_eth *eth)
 	if (!ring->buf)
 		goto no_tx_mem;
 
-	if (MTK_HAS_CAPS(soc->caps, MTK_SRAM)) {
-		ring->dma = eth->sram_base + soc->tx.fq_dma_size * sz;
-		ring->phys = eth->phy_scratch_ring + soc->tx.fq_dma_size * (dma_addr_t)sz;
-	} else {
-		ring->dma = dma_alloc_coherent(eth->dma_dev, ring_size * sz,
-					       &ring->phys, GFP_KERNEL);
-	}
-
+	ring->dma = mtk_dma_ring_alloc(eth, ring_size * sz, &ring->phys, true);
 	if (!ring->dma)
 		goto no_tx_mem;
 
@@ -2726,10 +2743,10 @@ static void mtk_tx_clean(struct mtk_eth *eth)
 		kfree(ring->buf);
 		ring->buf = NULL;
 	}
-	if (!MTK_HAS_CAPS(soc->caps, MTK_SRAM) && ring->dma) {
-		dma_free_coherent(eth->dma_dev,
-				  ring->dma_size * soc->tx.desc_size,
-				  ring->dma, ring->phys);
+
+	if (ring->dma) {
+		mtk_dma_ring_free(eth, ring->dma_size * soc->tx.desc_size,
+				  ring->dma, ring->phys, true);
 		ring->dma = NULL;
 	}
 
@@ -2788,20 +2805,8 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 		ring->page_pool = pp;
 	}
 
-	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM) ||
-	    rx_flag != MTK_RX_FLAGS_NORMAL) {
-		ring->dma = dma_alloc_coherent(eth->dma_dev,
-				rx_dma_size * eth->soc->rx.desc_size,
-				&ring->phys, GFP_KERNEL);
-	} else {
-		struct mtk_tx_ring *tx_ring = &eth->tx_ring;
-
-		ring->dma = tx_ring->dma + tx_ring_size *
-			    eth->soc->tx.desc_size * (ring_no + 1);
-		ring->phys = tx_ring->phys + tx_ring_size *
-			     eth->soc->tx.desc_size * (ring_no + 1);
-	}
-
+	ring->dma = mtk_dma_ring_alloc(eth, rx_dma_size * eth->soc->rx.desc_size,
+				       &ring->phys, rx_flag == MTK_RX_FLAGS_NORMAL);
 	if (!ring->dma)
 		return -ENOMEM;
 
@@ -2916,10 +2921,9 @@ static void mtk_rx_clean(struct mtk_eth *eth, struct mtk_rx_ring *ring, bool in_
 		ring->data = NULL;
 	}
 
-	if (!in_sram && ring->dma) {
-		dma_free_coherent(eth->dma_dev,
-				  ring->dma_size * eth->soc->rx.desc_size,
-				  ring->dma, ring->phys);
+	if (ring->dma) {
+		mtk_dma_ring_free(eth, ring->dma_size * eth->soc->rx.desc_size,
+				  ring->dma, ring->phys, in_sram);
 		ring->dma = NULL;
 	}
 
@@ -3287,15 +3291,15 @@ static void mtk_dma_free(struct mtk_eth *eth)
 			netdev_tx_reset_subqueue(eth->netdev[i], j);
 	}
 
-	if (!MTK_HAS_CAPS(soc->caps, MTK_SRAM) && eth->scratch_ring) {
-		dma_free_coherent(eth->dma_dev,
-				  MTK_QDMA_RING_SIZE * soc->tx.desc_size,
-				  eth->scratch_ring, eth->phy_scratch_ring);
+	if (eth->scratch_ring) {
+		mtk_dma_ring_free(eth, soc->tx.fq_dma_size * soc->tx.desc_size,
+				  eth->scratch_ring, eth->phy_scratch_ring, true);
 		eth->scratch_ring = NULL;
 		eth->phy_scratch_ring = 0;
 	}
+
 	mtk_tx_clean(eth);
-	mtk_rx_clean(eth, &eth->rx_ring[0], MTK_HAS_CAPS(soc->caps, MTK_SRAM));
+	mtk_rx_clean(eth, &eth->rx_ring[0], true);
 	mtk_rx_clean(eth, &eth->rx_ring_qdma, false);
 
 	if (eth->hwlro) {
@@ -5007,9 +5011,28 @@ static int mtk_sgmii_init(struct mtk_eth *eth)
 	return 0;
 }
 
+static int mtk_setup_legacy_sram(struct mtk_eth *eth, struct resource *res)
+{
+	if (res->start + MTK_ETH_SRAM_OFFSET + MTK_ETH_NETSYS_V2_SRAM_SIZE - 1 >
+	    res->end)
+		return -EINVAL;
+
+	eth->sram_pool = devm_gen_pool_create(eth->dev,
+					      const_ilog2(MTK_ETH_SRAM_GRANULARITY),
+					      NUMA_NO_NODE, dev_name(eth->dev));
+
+	if (IS_ERR(eth->sram_pool))
+		return PTR_ERR(eth->sram_pool);
+
+	return gen_pool_add_virt(eth->sram_pool,
+				 (unsigned long)eth->base + MTK_ETH_SRAM_OFFSET,
+				 res->start + MTK_ETH_SRAM_OFFSET,
+				 MTK_ETH_NETSYS_V2_SRAM_SIZE, NUMA_NO_NODE);
+}
+
 static int mtk_probe(struct platform_device *pdev)
 {
-	struct resource *res = NULL, *res_sram;
+	struct resource *res = NULL;
 	struct device_node *mac_np;
 	struct mtk_eth *eth;
 	int err, i;
@@ -5029,20 +5052,6 @@ static int mtk_probe(struct platform_device *pdev)
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628))
 		eth->ip_align = NET_IP_ALIGN;
 
-	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
-		/* SRAM is actual memory and supports transparent access just like DRAM.
-		 * Hence we don't require __iomem being set and don't need to use accessor
-		 * functions to read from or write to SRAM.
-		 */
-		if (mtk_is_netsys_v3_or_greater(eth)) {
-			eth->sram_base = (void __force *)devm_platform_ioremap_resource(pdev, 1);
-			if (IS_ERR(eth->sram_base))
-				return PTR_ERR(eth->sram_base);
-		} else {
-			eth->sram_base = (void __force *)eth->base + MTK_ETH_SRAM_OFFSET;
-		}
-	}
-
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA)) {
 		err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(36));
 		if (!err)
@@ -5117,16 +5126,21 @@ static int mtk_probe(struct platform_device *pdev)
 			err = -EINVAL;
 			goto err_destroy_sgmii;
 		}
+
 		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
-			if (mtk_is_netsys_v3_or_greater(eth)) {
-				res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-				if (!res_sram) {
+			eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
+			if (!eth->sram_pool) {
+				if (!mtk_is_netsys_v3_or_greater(eth)) {
+					err = mtk_setup_legacy_sram(eth, res);
+					if (err)
+						goto err_destroy_sgmii;
+					dev_warn(&pdev->dev,
+						 "legacy DT: using hard-coded SRAM offset.\n");
+				} else {
+					dev_err(&pdev->dev, "Could not get SRAM pool\n");
 					err = -EINVAL;
 					goto err_destroy_sgmii;
 				}
-				eth->phy_scratch_ring = res_sram->start;
-			} else {
-				eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
 			}
 		}
 	}
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 1ad9075a9b69..0168e2fbc619 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -141,8 +141,10 @@
 #define MTK_GDMA_MAC_ADRH(x)	({ typeof(x) _x = (x); (_x == MTK_GMAC3_ID) ?	\
 				   0x54C : 0x50C + (_x * 0x1000); })
 
-/* Internal SRAM offset */
-#define MTK_ETH_SRAM_OFFSET	0x40000
+/* legacy DT support for internal SRAM */
+#define MTK_ETH_SRAM_OFFSET		0x40000
+#define MTK_ETH_SRAM_GRANULARITY	32
+#define MTK_ETH_NETSYS_V2_SRAM_SIZE	0x40000
 
 /* FE global misc reg*/
 #define MTK_FE_GLO_MISC         0x124
@@ -1245,7 +1247,7 @@ struct mtk_soc_data {
  * @dev:		The device pointer
  * @dma_dev:		The device pointer used for dma mapping/alloc
  * @base:		The mapped register i/o base
- * @sram_base:		The mapped SRAM base
+ * @sram_pool:		Pointer to SRAM pool used for DMA descriptor rings
  * @page_lock:		Make sure that register operations are atomic
  * @tx_irq__lock:	Make sure that IRQ register operations are atomic
  * @rx_irq__lock:	Make sure that IRQ register operations are atomic
@@ -1291,7 +1293,7 @@ struct mtk_eth {
 	struct device			*dev;
 	struct device			*dma_dev;
 	void __iomem			*base;
-	void				*sram_base;
+	struct gen_pool			*sram_pool;
 	spinlock_t			page_lock;
 	spinlock_t			tx_irq_lock;
 	spinlock_t			rx_irq_lock;
-- 
2.50.0

Re: [PATCH net-next v4 3/3] net: ethernet: mtk_eth_soc: use generic allocator for SRAM

[Andrew Lunn]

On Wed, Jul 02, 2025 at 03:38:15AM +0100, Daniel Golle wrote:
> Use a dedicated "mmio-sram" node and the generic allocator
> instead of open-coding SRAM allocation for DMA rings.
> Keep support for legacy device trees but notify the user via a
> warning to update, and let the ethernet driver create the
> gen_pool in this case.
> 
> Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
> Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew