net: ethernet: mtk_eth_soc: support 36-bit DMA addressing on MT7988

Systems having 4 GiB of RAM and more require DMA addressing beyond the
current 32-bit limit. Starting from MT7988 the hardware now supports
36-bit DMA addressing, let's use that new capability in the driver to
avoid running into swiotlb on systems with 4 GiB of RAM or more.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://lore.kernel.org/r/95b919c98876c9e49761e44662e7c937479eecb8.1692721443.git.daniel@makrotopia.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -1328,6 +1328,10 @@ static void mtk_tx_set_dma_desc_v2(struct net_device *dev, void *txd,
 	data = TX_DMA_PLEN0(info->size);
 	if (info->last)
 		data |= TX_DMA_LS0;
+
+	if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
+		data |= TX_DMA_PREP_ADDR64(info->addr);
+
 	WRITE_ONCE(desc->txd3, data);
 
 	 /* set forward port */
@@ -1997,6 +2001,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 	bool xdp_flush = false;
 	int idx;
 	struct sk_buff *skb;
+	u64 addr64 = 0;
 	u8 *data, *new_data;
 	struct mtk_rx_dma_v2 *rxd, trxd;
 	int done = 0, bytes = 0;
@@ -2112,7 +2117,10 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 				goto release_desc;
 			}
 
-			dma_unmap_single(eth->dma_dev, trxd.rxd1,
+			if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
+				addr64 = RX_DMA_GET_ADDR64(trxd.rxd2);
+
+			dma_unmap_single(eth->dma_dev, ((u64)trxd.rxd1 | addr64),
 					 ring->buf_size, DMA_FROM_DEVICE);
 
 			skb = build_skb(data, ring->frag_size);
@@ -2178,6 +2186,9 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 		else
 			rxd->rxd2 = RX_DMA_PREP_PLEN0(ring->buf_size);
 
+		if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
+			rxd->rxd2 |= RX_DMA_PREP_ADDR64(dma_addr);
+
 		ring->calc_idx = idx;
 		done++;
 	}
@@ -2670,6 +2681,9 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 		else
 			rxd->rxd2 = RX_DMA_PREP_PLEN0(ring->buf_size);
 
+		if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
+			rxd->rxd2 |= RX_DMA_PREP_ADDR64(dma_addr);
+
 		rxd->rxd3 = 0;
 		rxd->rxd4 = 0;
 		if (mtk_is_netsys_v2_or_greater(eth)) {
@@ -2716,6 +2730,7 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 
 static void mtk_rx_clean(struct mtk_eth *eth, struct mtk_rx_ring *ring, bool in_sram)
 {
+	u64 addr64 = 0;
 	int i;
 
 	if (ring->data && ring->dma) {
@@ -2729,7 +2744,10 @@ static void mtk_rx_clean(struct mtk_eth *eth, struct mtk_rx_ring *ring, bool in_
 			if (!rxd->rxd1)
 				continue;
 
-			dma_unmap_single(eth->dma_dev, rxd->rxd1,
+			if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA))
+				addr64 = RX_DMA_GET_ADDR64(rxd->rxd2);
+
+			dma_unmap_single(eth->dma_dev, ((u64)rxd->rxd1 | addr64),
 					 ring->buf_size, DMA_FROM_DEVICE);
 			mtk_rx_put_buff(ring, ring->data[i], false);
 		}
@@ -4734,6 +4752,14 @@ static int mtk_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA)) {
+		err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(36));
+		if (err) {
+			dev_err(&pdev->dev, "Wrong DMA config\n");
+			return -EINVAL;
+		}
+	}
+
 	spin_lock_init(&eth->page_lock);
 	spin_lock_init(&eth->tx_irq_lock);
 	spin_lock_init(&eth->rx_irq_lock);

drivers/net/ethernet/mediatek/mtk_eth_soc.h

@@ -331,6 +331,14 @@
 #define TX_DMA_PLEN1(x)		((x) & eth->soc->txrx.dma_max_len)
 #define TX_DMA_SWC		BIT(14)
 #define TX_DMA_PQID		GENMASK(3, 0)
+#define TX_DMA_ADDR64_MASK	GENMASK(3, 0)
+#if IS_ENABLED(CONFIG_64BIT)
+# define TX_DMA_GET_ADDR64(x)	(((u64)FIELD_GET(TX_DMA_ADDR64_MASK, (x))) << 32)
+# define TX_DMA_PREP_ADDR64(x)	FIELD_PREP(TX_DMA_ADDR64_MASK, ((x) >> 32))
+#else
+# define TX_DMA_GET_ADDR64(x)	(0)
+# define TX_DMA_PREP_ADDR64(x)	(0)
+#endif
 
 /* PDMA on MT7628 */
 #define TX_DMA_DONE		BIT(31)
@@ -343,6 +351,14 @@
 #define RX_DMA_PREP_PLEN0(x)	(((x) & eth->soc->txrx.dma_max_len) << eth->soc->txrx.dma_len_offset)
 #define RX_DMA_GET_PLEN0(x)	(((x) >> eth->soc->txrx.dma_len_offset) & eth->soc->txrx.dma_max_len)
 #define RX_DMA_VTAG		BIT(15)
+#define RX_DMA_ADDR64_MASK	GENMASK(3, 0)
+#if IS_ENABLED(CONFIG_64BIT)
+# define RX_DMA_GET_ADDR64(x)	(((u64)FIELD_GET(RX_DMA_ADDR64_MASK, (x))) << 32)
+# define RX_DMA_PREP_ADDR64(x)	FIELD_PREP(RX_DMA_ADDR64_MASK, ((x) >> 32))
+#else
+# define RX_DMA_GET_ADDR64(x)	(0)
+# define RX_DMA_PREP_ADDR64(x)	(0)
+#endif
 
 /* QDMA descriptor rxd3 */
 #define RX_DMA_VID(x)		((x) & VLAN_VID_MASK)
@@ -942,6 +958,7 @@ enum mkt_eth_capabilities {
 	MTK_RSTCTRL_PPE2_BIT,
 	MTK_U3_COPHY_V2_BIT,
 	MTK_SRAM_BIT,
+	MTK_36BIT_DMA_BIT,
 
 	/* MUX BITS*/
 	MTK_ETH_MUX_GDM1_TO_GMAC1_ESW_BIT,
@@ -978,6 +995,7 @@ enum mkt_eth_capabilities {
 #define MTK_RSTCTRL_PPE2	BIT_ULL(MTK_RSTCTRL_PPE2_BIT)
 #define MTK_U3_COPHY_V2		BIT_ULL(MTK_U3_COPHY_V2_BIT)
 #define MTK_SRAM		BIT_ULL(MTK_SRAM_BIT)
+#define MTK_36BIT_DMA	BIT_ULL(MTK_36BIT_DMA_BIT)
 
 #define MTK_ETH_MUX_GDM1_TO_GMAC1_ESW		\
 	BIT_ULL(MTK_ETH_MUX_GDM1_TO_GMAC1_ESW_BIT)
@@ -1059,8 +1077,8 @@ enum mkt_eth_capabilities {
 		      MTK_MUX_GMAC12_TO_GEPHY_SGMII | MTK_QDMA | \
 		      MTK_RSTCTRL_PPE1 | MTK_SRAM)
 
-#define MT7988_CAPS  (MTK_GDM1_ESW | MTK_QDMA | MTK_RSTCTRL_PPE1 | \
-		      MTK_RSTCTRL_PPE2 | MTK_SRAM)
+#define MT7988_CAPS  (MTK_36BIT_DMA | MTK_GDM1_ESW | MTK_QDMA | \
+		      MTK_RSTCTRL_PPE1 | MTK_RSTCTRL_PPE2 | MTK_SRAM)
 
 struct mtk_tx_dma_desc_info {
 	dma_addr_t	addr;