Subject: [PATCH] net: ethernet: mtk_eth_soc: add support for coherent DMA
From: Felix Fietkau <[email-masked]>
Date: Sat, 5 Feb 2022 17:59:07 +0100

It improves performance by eliminating the need for a cache flush on rx and tx
In preparation for supporting WED (Wireless Ethernet Dispatch), also add a
function for disabling coherent DMA at runtime.

Signed-off-by: Felix Fietkau <[email-masked]>
---

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -9,6 +9,7 @@
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
+#include <linux/of_address.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 #include <linux/clk.h>
@@ -833,7 +834,7 @@ static int mtk_init_fq_dma(struct mtk_et
 	dma_addr_t dma_addr;
 	int i;
 
-	eth->scratch_ring = dma_alloc_coherent(eth->dev,
+	eth->scratch_ring = dma_alloc_coherent(eth->dma_dev,
 					       cnt * sizeof(struct mtk_tx_dma),
 					       &eth->phy_scratch_ring,
 					       GFP_ATOMIC);
@@ -845,10 +846,10 @@ static int mtk_init_fq_dma(struct mtk_et
 	if (unlikely(!eth->scratch_head))
 		return -ENOMEM;
 
-	dma_addr = dma_map_single(eth->dev,
+	dma_addr = dma_map_single(eth->dma_dev,
 				  eth->scratch_head, cnt * MTK_QDMA_PAGE_SIZE,
 				  DMA_FROM_DEVICE);
-	if (unlikely(dma_mapping_error(eth->dev, dma_addr)))
+	if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr)))
 		return -ENOMEM;
 
 	phy_ring_tail = eth->phy_scratch_ring +
@@ -902,26 +903,26 @@ static void mtk_tx_unmap(struct mtk_eth
 {
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA)) {
 		if (tx_buf->flags & MTK_TX_FLAGS_SINGLE0) {
-			dma_unmap_single(eth->dev,
+			dma_unmap_single(eth->dma_dev,
 					 dma_unmap_addr(tx_buf, dma_addr0),
 					 dma_unmap_len(tx_buf, dma_len0),
 					 DMA_TO_DEVICE);
 		} else if (tx_buf->flags & MTK_TX_FLAGS_PAGE0) {
-			dma_unmap_page(eth->dev,
+			dma_unmap_page(eth->dma_dev,
 				       dma_unmap_addr(tx_buf, dma_addr0),
 				       dma_unmap_len(tx_buf, dma_len0),
 				       DMA_TO_DEVICE);
 		}
 	} else {
 		if (dma_unmap_len(tx_buf, dma_len0)) {
-			dma_unmap_page(eth->dev,
+			dma_unmap_page(eth->dma_dev,
 				       dma_unmap_addr(tx_buf, dma_addr0),
 				       dma_unmap_len(tx_buf, dma_len0),
 				       DMA_TO_DEVICE);
 		}
 
 		if (dma_unmap_len(tx_buf, dma_len1)) {
-			dma_unmap_page(eth->dev,
+			dma_unmap_page(eth->dma_dev,
 				       dma_unmap_addr(tx_buf, dma_addr1),
 				       dma_unmap_len(tx_buf, dma_len1),
 				       DMA_TO_DEVICE);
@@ -999,9 +1000,9 @@ static int mtk_tx_map(struct sk_buff *sk
 	if (skb_vlan_tag_present(skb))
 		txd4 |= TX_DMA_INS_VLAN | skb_vlan_tag_get(skb);
 
-	mapped_addr = dma_map_single(eth->dev, skb->data,
+	mapped_addr = dma_map_single(eth->dma_dev, skb->data,
 				     skb_headlen(skb), DMA_TO_DEVICE);
-	if (unlikely(dma_mapping_error(eth->dev, mapped_addr)))
+	if (unlikely(dma_mapping_error(eth->dma_dev, mapped_addr)))
 		return -ENOMEM;
 
 	WRITE_ONCE(itxd->txd1, mapped_addr);
@@ -1040,10 +1041,10 @@ static int mtk_tx_map(struct sk_buff *sk

 			frag_map_size = min(frag_size, MTK_TX_DMA_BUF_LEN);
-			mapped_addr = skb_frag_dma_map(eth->dev, frag, offset,
+			mapped_addr = skb_frag_dma_map(eth->dma_dev, frag, offset,
 						       frag_map_size,
 						       DMA_TO_DEVICE);
-			if (unlikely(dma_mapping_error(eth->dev, mapped_addr)))
+			if (unlikely(dma_mapping_error(eth->dma_dev, mapped_addr)))
 				goto err_dma;
 
 			if (i == nr_frags - 1 &&
@@ -1324,18 +1325,18 @@ static int mtk_poll_rx(struct napi_struc
 			netdev->stats.rx_dropped++;
 			goto release_desc;
 		}
-		dma_addr = dma_map_single(eth->dev,
+		dma_addr = dma_map_single(eth->dma_dev,
 					  new_data + NET_SKB_PAD +
 					  eth->ip_align,
 					  ring->buf_size,
 					  DMA_FROM_DEVICE);
-		if (unlikely(dma_mapping_error(eth->dev, dma_addr))) {
+		if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr))) {
 			skb_free_frag(new_data);
 			netdev->stats.rx_dropped++;
 			goto release_desc;
 		}
 
-		dma_unmap_single(eth->dev, trxd.rxd1,
+		dma_unmap_single(eth->dma_dev, trxd.rxd1,
 				 ring->buf_size, DMA_FROM_DEVICE);
 
 		/* receive data */
@@ -1608,7 +1609,7 @@ static int mtk_tx_alloc(struct mtk_eth *
 	if (!ring->buf)
 		goto no_tx_mem;
 
-	ring->dma = dma_alloc_coherent(eth->dev, MTK_DMA_SIZE * sz,
+	ring->dma = dma_alloc_coherent(eth->dma_dev, MTK_DMA_SIZE * sz,
 				       &ring->phys, GFP_ATOMIC);
 	if (!ring->dma)
 		goto no_tx_mem;
@@ -1626,7 +1627,7 @@ static int mtk_tx_alloc(struct mtk_eth *
 	 * descriptors in ring->dma_pdma.
 	 */
 	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA)) {
-		ring->dma_pdma = dma_alloc_coherent(eth->dev, MTK_DMA_SIZE * sz,
+		ring->dma_pdma = dma_alloc_coherent(eth->dma_dev, MTK_DMA_SIZE * sz,
 						    &ring->phys_pdma,
 						    GFP_ATOMIC);
 		if (!ring->dma_pdma)
@@ -1685,7 +1686,7 @@ static void mtk_tx_clean(struct mtk_eth
 	}
 
 	if (ring->dma) {
-		dma_free_coherent(eth->dev,
+		dma_free_coherent(eth->dma_dev,
 				  MTK_DMA_SIZE * sizeof(*ring->dma),
 				  ring->dma,
 				  ring->phys);
@@ -1693,7 +1694,7 @@ static void mtk_tx_clean(struct mtk_eth
 	}
 
 	if (ring->dma_pdma) {
-		dma_free_coherent(eth->dev,
+		dma_free_coherent(eth->dma_dev,
 				  MTK_DMA_SIZE * sizeof(*ring->dma_pdma),
 				  ring->dma_pdma,
 				  ring->phys_pdma);
@@ -1741,18 +1742,18 @@ static int mtk_rx_alloc(struct mtk_eth *
 			return -ENOMEM;
 	}
 
-	ring->dma = dma_alloc_coherent(eth->dev,
+	ring->dma = dma_alloc_coherent(eth->dma_dev,
 				       rx_dma_size * sizeof(*ring->dma),
 				       &ring->phys, GFP_ATOMIC);
 	if (!ring->dma)
 		return -ENOMEM;
 
 	for (i = 0; i < rx_dma_size; i++) {
-		dma_addr_t dma_addr = dma_map_single(eth->dev,
+		dma_addr_t dma_addr = dma_map_single(eth->dma_dev,
 				ring->data[i] + NET_SKB_PAD + eth->ip_align,
 				ring->buf_size,
 				DMA_FROM_DEVICE);
-		if (unlikely(dma_mapping_error(eth->dev, dma_addr)))
+		if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr)))
 			return -ENOMEM;
 		ring->dma[i].rxd1 = (unsigned int)dma_addr;
 
@@ -1788,7 +1789,7 @@ static void mtk_rx_clean(struct mtk_eth
 				continue;
 			if (!ring->dma[i].rxd1)
 				continue;
-			dma_unmap_single(eth->dev,
+			dma_unmap_single(eth->dma_dev,
 					 ring->dma[i].rxd1,
 					 ring->buf_size,
 					 DMA_FROM_DEVICE);
@@ -1799,7 +1800,7 @@ static void mtk_rx_clean(struct mtk_eth
 	}
 
 	if (ring->dma) {
-		dma_free_coherent(eth->dev,
+		dma_free_coherent(eth->dma_dev,
 				  ring->dma_size * sizeof(*ring->dma),
 				  ring->dma,
 				  ring->phys);
@@ -2158,7 +2159,7 @@ static void mtk_dma_free(struct mtk_eth
 		if (eth->netdev[i])
 			netdev_reset_queue(eth->netdev[i]);
 	if (eth->scratch_ring) {
-		dma_free_coherent(eth->dev,
+		dma_free_coherent(eth->dma_dev,
 				  MTK_DMA_SIZE * sizeof(struct mtk_tx_dma),
 				  eth->scratch_ring,
 				  eth->phy_scratch_ring);
@@ -2509,6 +2510,8 @@ static void mtk_dim_tx(struct work_struc
 
 static int mtk_hw_init(struct mtk_eth *eth)
 {
+	u32 dma_mask = ETHSYS_DMA_AG_MAP_PDMA | ETHSYS_DMA_AG_MAP_QDMA |
+		       ETHSYS_DMA_AG_MAP_PPE;
 	int i, val, ret;
 
 	if (test_and_set_bit(MTK_HW_INIT, &eth->state))
@@ -2521,6 +2524,10 @@ static int mtk_hw_init(struct mtk_eth *e
 	if (ret)
 		goto err_disable_pm;
 
+	if (eth->ethsys)
+		regmap_update_bits(eth->ethsys, ETHSYS_DMA_AG_MAP, dma_mask,
+				   of_dma_is_coherent(eth->dma_dev->of_node) * dma_mask);
+
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628)) {
 		ret = device_reset(eth->dev);
 		if (ret) {
@@ -3070,6 +3077,35 @@ free_netdev:
 	return err;
 }
 
+void mtk_eth_set_dma_device(struct mtk_eth *eth, struct device *dma_dev)
+{
+	struct net_device *dev, *tmp;
+	LIST_HEAD(dev_list);
+	int i;
+
+	rtnl_lock();
+
+	for (i = 0; i < MTK_MAC_COUNT; i++) {
+		dev = eth->netdev[i];
+
+		if (!dev || !(dev->flags & IFF_UP))
+			continue;
+
+		list_add_tail(&dev->close_list, &dev_list);
+	}
+
+	dev_close_many(&dev_list, false);
+
+	eth->dma_dev = dma_dev;
+
+	list_for_each_entry_safe(dev, tmp, &dev_list, close_list) {
+		list_del_init(&dev->close_list);
+		dev_open(dev, NULL);
+	}
+
+	rtnl_unlock();
+}
+
 static int mtk_probe(struct platform_device *pdev)
 {
 	struct device_node *mac_np;
@@ -3083,6 +3119,7 @@ static int mtk_probe(struct platform_dev
 	eth->soc = of_device_get_match_data(&pdev->dev);
 
 	eth->dev = &pdev->dev;
+	eth->dma_dev = &pdev->dev;
 	eth->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(eth->base))
 		return PTR_ERR(eth->base);
@@ -3131,6 +3168,16 @@ static int mtk_probe(struct platform_dev
 		}
 	}
 
+	if (of_dma_is_coherent(pdev->dev.of_node)) {
+		struct regmap *cci;
+
+		cci = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+						      "mediatek,cci-control");
+		/* enable CPU/bus coherency */
+		if (!IS_ERR(cci))
+			regmap_write(cci, 0, 3);
+	}
+
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SGMII)) {
 		eth->sgmii = devm_kzalloc(eth->dev, sizeof(*eth->sgmii),
 					  GFP_KERNEL);
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -457,6 +457,12 @@
 #define RSTCTRL_FE		BIT(6)
 #define RSTCTRL_PPE		BIT(31)
 
+/* ethernet dma channel agent map */
+#define ETHSYS_DMA_AG_MAP	0x408
+#define ETHSYS_DMA_AG_MAP_PDMA	BIT(0)
+#define ETHSYS_DMA_AG_MAP_QDMA	BIT(1)
+#define ETHSYS_DMA_AG_MAP_PPE	BIT(2)
+
 /* SGMII subsystem config registers */
 /* Register to auto-negotiation restart */
 #define SGMSYS_PCS_CONTROL_1	0x0
@@ -874,6 +880,7 @@ struct mtk_sgmii {
 /* 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
  * @base:		The mapped register i/o base
  * @page_lock:		Make sure that register operations are atomic
  * @tx_irq__lock:	Make sure that IRQ register operations are atomic
@@ -917,6 +924,7 @@ struct mtk_sgmii {
 
 struct mtk_eth {
 	struct device			*dev;
+	struct device			*dma_dev;
 	void __iomem			*base;
 	spinlock_t			page_lock;
 	spinlock_t			tx_irq_lock;
@@ -1015,6 +1023,7 @@ int mtk_gmac_rgmii_path_setup(struct mtk
 int mtk_eth_offload_init(struct mtk_eth *eth);
 int mtk_eth_setup_tc(struct net_device *dev, enum tc_setup_type type,
 		     void *type_data);
+void mtk_eth_set_dma_device(struct mtk_eth *eth, struct device *dma_dev);

 #endif /* MTK_ETH_H */