net: ethernet: mtk-star-emac: new driver

This adds the driver for the MediaTek STAR Ethernet MAC currently used
on the MT8* SoC family. For now we only support full-duplex.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/Kconfig

@@ -14,4 +14,11 @@ config NET_MEDIATEK_SOC
 	  This driver supports the gigabit ethernet MACs in the
 	  MediaTek SoC family.
 
+config NET_MEDIATEK_STAR_EMAC
+	tristate "MediaTek STAR Ethernet MAC support"
+	select PHYLIB
+	help
+	  This driver supports the ethernet MAC IP first used on
+	  MediaTek MT85** SoCs.
+
 endif #NET_VENDOR_MEDIATEK

drivers/net/ethernet/mediatek/Makefile

@@ -5,3 +5,4 @@
 
 obj-$(CONFIG_NET_MEDIATEK_SOC) += mtk_eth.o
 mtk_eth-y := mtk_eth_soc.o mtk_sgmii.o mtk_eth_path.o
+obj-$(CONFIG_NET_MEDIATEK_STAR_EMAC) += mtk_star_emac.o

drivers/net/ethernet/mediatek/mtk_star_emac.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020 MediaTek Corporation
+ * Copyright (c) 2020 BayLibre SAS
+ *
+ * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/compiler.h>
+#include <linux/dma-mapping.h>
+#include <linux/etherdevice.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mii.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/of_mdio.h>
+#include <linux/of_net.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+
+#define MTK_STAR_DRVNAME			"mtk_star_emac"
+
+#define MTK_STAR_WAIT_TIMEOUT			300
+#define MTK_STAR_MAX_FRAME_SIZE			1514
+#define MTK_STAR_SKB_ALIGNMENT			16
+#define MTK_STAR_NAPI_WEIGHT			64
+#define MTK_STAR_HASHTABLE_MC_LIMIT		256
+#define MTK_STAR_HASHTABLE_SIZE_MAX		512
+
+/* Normally we'd use NET_IP_ALIGN but on arm64 its value is 0 and it doesn't
+ * work for this controller.
+ */
+#define MTK_STAR_IP_ALIGN			2
+
+static const char *const mtk_star_clk_names[] = { "core", "reg", "trans" };
+#define MTK_STAR_NCLKS ARRAY_SIZE(mtk_star_clk_names)
+
+/* PHY Control Register 0 */
+#define MTK_STAR_REG_PHY_CTRL0			0x0000
+#define MTK_STAR_BIT_PHY_CTRL0_WTCMD		BIT(13)
+#define MTK_STAR_BIT_PHY_CTRL0_RDCMD		BIT(14)
+#define MTK_STAR_BIT_PHY_CTRL0_RWOK		BIT(15)
+#define MTK_STAR_MSK_PHY_CTRL0_PREG		GENMASK(12, 8)
+#define MTK_STAR_OFF_PHY_CTRL0_PREG		8
+#define MTK_STAR_MSK_PHY_CTRL0_RWDATA		GENMASK(31, 16)
+#define MTK_STAR_OFF_PHY_CTRL0_RWDATA		16
+
+/* PHY Control Register 1 */
+#define MTK_STAR_REG_PHY_CTRL1			0x0004
+#define MTK_STAR_BIT_PHY_CTRL1_LINK_ST		BIT(0)
+#define MTK_STAR_BIT_PHY_CTRL1_AN_EN		BIT(8)
+#define MTK_STAR_OFF_PHY_CTRL1_FORCE_SPD	9
+#define MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_10M	0x00
+#define MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_100M	0x01
+#define MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_1000M	0x02
+#define MTK_STAR_BIT_PHY_CTRL1_FORCE_DPX	BIT(11)
+#define MTK_STAR_BIT_PHY_CTRL1_FORCE_FC_RX	BIT(12)
+#define MTK_STAR_BIT_PHY_CTRL1_FORCE_FC_TX	BIT(13)
+
+/* MAC Configuration Register */
+#define MTK_STAR_REG_MAC_CFG			0x0008
+#define MTK_STAR_OFF_MAC_CFG_IPG		10
+#define MTK_STAR_VAL_MAC_CFG_IPG_96BIT		GENMASK(4, 0)
+#define MTK_STAR_BIT_MAC_CFG_MAXLEN_1522	BIT(16)
+#define MTK_STAR_BIT_MAC_CFG_AUTO_PAD		BIT(19)
+#define MTK_STAR_BIT_MAC_CFG_CRC_STRIP		BIT(20)
+#define MTK_STAR_BIT_MAC_CFG_VLAN_STRIP		BIT(22)
+#define MTK_STAR_BIT_MAC_CFG_NIC_PD		BIT(31)
+
+/* Flow-Control Configuration Register */
+#define MTK_STAR_REG_FC_CFG			0x000c
+#define MTK_STAR_BIT_FC_CFG_BP_EN		BIT(7)
+#define MTK_STAR_BIT_FC_CFG_UC_PAUSE_DIR	BIT(8)
+#define MTK_STAR_OFF_FC_CFG_SEND_PAUSE_TH	16
+#define MTK_STAR_MSK_FC_CFG_SEND_PAUSE_TH	GENMASK(27, 16)
+#define MTK_STAR_VAL_FC_CFG_SEND_PAUSE_TH_2K	0x800
+
+/* ARL Configuration Register */
+#define MTK_STAR_REG_ARL_CFG			0x0010
+#define MTK_STAR_BIT_ARL_CFG_HASH_ALG		BIT(0)
+#define MTK_STAR_BIT_ARL_CFG_MISC_MODE		BIT(4)
+
+/* MAC High and Low Bytes Registers */
+#define MTK_STAR_REG_MY_MAC_H			0x0014
+#define MTK_STAR_REG_MY_MAC_L			0x0018
+
+/* Hash Table Control Register */
+#define MTK_STAR_REG_HASH_CTRL			0x001c
+#define MTK_STAR_MSK_HASH_CTRL_HASH_BIT_ADDR	GENMASK(8, 0)
+#define MTK_STAR_BIT_HASH_CTRL_HASH_BIT_DATA	BIT(12)
+#define MTK_STAR_BIT_HASH_CTRL_ACC_CMD		BIT(13)
+#define MTK_STAR_BIT_HASH_CTRL_CMD_START	BIT(14)
+#define MTK_STAR_BIT_HASH_CTRL_BIST_OK		BIT(16)
+#define MTK_STAR_BIT_HASH_CTRL_BIST_DONE	BIT(17)
+#define MTK_STAR_BIT_HASH_CTRL_BIST_EN		BIT(31)
+
+/* TX DMA Control Register */
+#define MTK_STAR_REG_TX_DMA_CTRL		0x0034
+#define MTK_STAR_BIT_TX_DMA_CTRL_START		BIT(0)
+#define MTK_STAR_BIT_TX_DMA_CTRL_STOP		BIT(1)
+#define MTK_STAR_BIT_TX_DMA_CTRL_RESUME		BIT(2)
+
+/* RX DMA Control Register */
+#define MTK_STAR_REG_RX_DMA_CTRL		0x0038
+#define MTK_STAR_BIT_RX_DMA_CTRL_START		BIT(0)
+#define MTK_STAR_BIT_RX_DMA_CTRL_STOP		BIT(1)
+#define MTK_STAR_BIT_RX_DMA_CTRL_RESUME		BIT(2)
+
+/* DMA Address Registers */
+#define MTK_STAR_REG_TX_DPTR			0x003c
+#define MTK_STAR_REG_RX_DPTR			0x0040
+#define MTK_STAR_REG_TX_BASE_ADDR		0x0044
+#define MTK_STAR_REG_RX_BASE_ADDR		0x0048
+
+/* Interrupt Status Register */
+#define MTK_STAR_REG_INT_STS			0x0050
+#define MTK_STAR_REG_INT_STS_PORT_STS_CHG	BIT(2)
+#define MTK_STAR_REG_INT_STS_MIB_CNT_TH		BIT(3)
+#define MTK_STAR_BIT_INT_STS_FNRC		BIT(6)
+#define MTK_STAR_BIT_INT_STS_TNTC		BIT(8)
+
+/* Interrupt Mask Register */
+#define MTK_STAR_REG_INT_MASK			0x0054
+#define MTK_STAR_BIT_INT_MASK_FNRC		BIT(6)
+
+/* Misc. Config Register */
+#define MTK_STAR_REG_TEST1			0x005c
+#define MTK_STAR_BIT_TEST1_RST_HASH_MBIST	BIT(31)
+
+/* Extended Configuration Register */
+#define MTK_STAR_REG_EXT_CFG			0x0060
+#define MTK_STAR_OFF_EXT_CFG_SND_PAUSE_RLS	16
+#define MTK_STAR_MSK_EXT_CFG_SND_PAUSE_RLS	GENMASK(26, 16)
+#define MTK_STAR_VAL_EXT_CFG_SND_PAUSE_RLS_1K	0x400
+
+/* EthSys Configuration Register */
+#define MTK_STAR_REG_SYS_CONF			0x0094
+#define MTK_STAR_BIT_MII_PAD_OUT_ENABLE		BIT(0)
+#define MTK_STAR_BIT_EXT_MDC_MODE		BIT(1)
+#define MTK_STAR_BIT_SWC_MII_MODE		BIT(2)
+
+/* MAC Clock Configuration Register */
+#define MTK_STAR_REG_MAC_CLK_CONF		0x00ac
+#define MTK_STAR_MSK_MAC_CLK_CONF		GENMASK(7, 0)
+#define MTK_STAR_BIT_CLK_DIV_10			0x0a
+
+/* Counter registers. */
+#define MTK_STAR_REG_C_RXOKPKT			0x0100
+#define MTK_STAR_REG_C_RXOKBYTE			0x0104
+#define MTK_STAR_REG_C_RXRUNT			0x0108
+#define MTK_STAR_REG_C_RXLONG			0x010c
+#define MTK_STAR_REG_C_RXDROP			0x0110
+#define MTK_STAR_REG_C_RXCRC			0x0114
+#define MTK_STAR_REG_C_RXARLDROP		0x0118
+#define MTK_STAR_REG_C_RXVLANDROP		0x011c
+#define MTK_STAR_REG_C_RXCSERR			0x0120
+#define MTK_STAR_REG_C_RXPAUSE			0x0124
+#define MTK_STAR_REG_C_TXOKPKT			0x0128
+#define MTK_STAR_REG_C_TXOKBYTE			0x012c
+#define MTK_STAR_REG_C_TXPAUSECOL		0x0130
+#define MTK_STAR_REG_C_TXRTY			0x0134
+#define MTK_STAR_REG_C_TXSKIP			0x0138
+#define MTK_STAR_REG_C_TX_ARP			0x013c
+#define MTK_STAR_REG_C_RX_RERR			0x01d8
+#define MTK_STAR_REG_C_RX_UNI			0x01dc
+#define MTK_STAR_REG_C_RX_MULTI			0x01e0
+#define MTK_STAR_REG_C_RX_BROAD			0x01e4
+#define MTK_STAR_REG_C_RX_ALIGNERR		0x01e8
+#define MTK_STAR_REG_C_TX_UNI			0x01ec
+#define MTK_STAR_REG_C_TX_MULTI			0x01f0
+#define MTK_STAR_REG_C_TX_BROAD			0x01f4
+#define MTK_STAR_REG_C_TX_TIMEOUT		0x01f8
+#define MTK_STAR_REG_C_TX_LATECOL		0x01fc
+#define MTK_STAR_REG_C_RX_LENGTHERR		0x0214
+#define MTK_STAR_REG_C_RX_TWIST			0x0218
+
+/* Ethernet CFG Control */
+#define MTK_PERICFG_REG_NIC_CFG_CON		0x03c4
+#define MTK_PERICFG_MSK_NIC_CFG_CON_CFG_MII	GENMASK(3, 0)
+#define MTK_PERICFG_BIT_NIC_CFG_CON_RMII	BIT(0)
+
+/* Represents the actual structure of descriptors used by the MAC. We can
+ * reuse the same structure for both TX and RX - the layout is the same, only
+ * the flags differ slightly.
+ */
+struct mtk_star_ring_desc {
+	/* Contains both the status flags as well as packet length. */
+	u32 status;
+	u32 data_ptr;
+	u32 vtag;
+	u32 reserved;
+};
+
+#define MTK_STAR_DESC_MSK_LEN			GENMASK(15, 0)
+#define MTK_STAR_DESC_BIT_RX_CRCE		BIT(24)
+#define MTK_STAR_DESC_BIT_RX_OSIZE		BIT(25)
+#define MTK_STAR_DESC_BIT_INT			BIT(27)
+#define MTK_STAR_DESC_BIT_LS			BIT(28)
+#define MTK_STAR_DESC_BIT_FS			BIT(29)
+#define MTK_STAR_DESC_BIT_EOR			BIT(30)
+#define MTK_STAR_DESC_BIT_COWN			BIT(31)
+
+/* Helper structure for storing data read from/written to descriptors in order
+ * to limit reads from/writes to DMA memory.
+ */
+struct mtk_star_ring_desc_data {
+	unsigned int len;
+	unsigned int flags;
+	dma_addr_t dma_addr;
+	struct sk_buff *skb;
+};
+
+#define MTK_STAR_RING_NUM_DESCS			128
+#define MTK_STAR_NUM_TX_DESCS			MTK_STAR_RING_NUM_DESCS
+#define MTK_STAR_NUM_RX_DESCS			MTK_STAR_RING_NUM_DESCS
+#define MTK_STAR_NUM_DESCS_TOTAL		(MTK_STAR_RING_NUM_DESCS * 2)
+#define MTK_STAR_DMA_SIZE \
+		(MTK_STAR_NUM_DESCS_TOTAL * sizeof(struct mtk_star_ring_desc))
+
+struct mtk_star_ring {
+	struct mtk_star_ring_desc *descs;
+	struct sk_buff *skbs[MTK_STAR_RING_NUM_DESCS];
+	dma_addr_t dma_addrs[MTK_STAR_RING_NUM_DESCS];
+	unsigned int head;
+	unsigned int tail;
+};
+
+struct mtk_star_priv {
+	struct net_device *ndev;
+
+	struct regmap *regs;
+	struct regmap *pericfg;
+
+	struct clk_bulk_data clks[MTK_STAR_NCLKS];
+
+	void *ring_base;
+	struct mtk_star_ring_desc *descs_base;
+	dma_addr_t dma_addr;
+	struct mtk_star_ring tx_ring;
+	struct mtk_star_ring rx_ring;
+
+	struct mii_bus *mii;
+	struct napi_struct napi;
+
+	struct device_node *phy_node;
+	phy_interface_t phy_intf;
+	struct phy_device *phydev;
+	unsigned int link;
+	int speed;
+	int duplex;
+	int pause;
+
+	/* Protects against concurrent descriptor access. */
+	spinlock_t lock;
+
+	struct rtnl_link_stats64 stats;
+	struct work_struct stats_work;
+};
+
+static struct device *mtk_star_get_dev(struct mtk_star_priv *priv)
+{
+	return priv->ndev->dev.parent;
+}
+
+static const struct regmap_config mtk_star_regmap_config = {
+	.reg_bits		= 32,
+	.val_bits		= 32,
+	.reg_stride		= 4,
+	.disable_locking	= true,
+};
+
+static void mtk_star_ring_init(struct mtk_star_ring *ring,
+			       struct mtk_star_ring_desc *descs)
+{
+	memset(ring, 0, sizeof(*ring));
+	ring->descs = descs;
+	ring->head = 0;
+	ring->tail = 0;
+}
+
+static int mtk_star_ring_pop_tail(struct mtk_star_ring *ring,
+				  struct mtk_star_ring_desc_data *desc_data)
+{
+	struct mtk_star_ring_desc *desc = &ring->descs[ring->tail];
+	unsigned int status;
+
+	status = READ_ONCE(desc->status);
+	dma_rmb(); /* Make sure we read the status bits before checking it. */
+
+	if (!(status & MTK_STAR_DESC_BIT_COWN))
+		return -1;
+
+	desc_data->len = status & MTK_STAR_DESC_MSK_LEN;
+	desc_data->flags = status & ~MTK_STAR_DESC_MSK_LEN;
+	desc_data->dma_addr = ring->dma_addrs[ring->tail];
+	desc_data->skb = ring->skbs[ring->tail];
+
+	ring->dma_addrs[ring->tail] = 0;
+	ring->skbs[ring->tail] = NULL;
+
+	status &= MTK_STAR_DESC_BIT_COWN | MTK_STAR_DESC_BIT_EOR;
+
+	WRITE_ONCE(desc->data_ptr, 0);
+	WRITE_ONCE(desc->status, status);
+
+	ring->tail = (ring->tail + 1) % MTK_STAR_RING_NUM_DESCS;
+
+	return 0;
+}
+
+static void mtk_star_ring_push_head(struct mtk_star_ring *ring,
+				    struct mtk_star_ring_desc_data *desc_data,
+				    unsigned int flags)
+{
+	struct mtk_star_ring_desc *desc = &ring->descs[ring->head];
+	unsigned int status;
+
+	status = READ_ONCE(desc->status);
+
+	ring->skbs[ring->head] = desc_data->skb;
+	ring->dma_addrs[ring->head] = desc_data->dma_addr;
+
+	status |= desc_data->len;
+	if (flags)
+		status |= flags;
+
+	WRITE_ONCE(desc->data_ptr, desc_data->dma_addr);
+	WRITE_ONCE(desc->status, status);
+	status &= ~MTK_STAR_DESC_BIT_COWN;
+	/* Flush previous modifications before ownership change. */
+	dma_wmb();
+	WRITE_ONCE(desc->status, status);
+
+	ring->head = (ring->head + 1) % MTK_STAR_RING_NUM_DESCS;
+}
+
+static void
+mtk_star_ring_push_head_rx(struct mtk_star_ring *ring,
+			   struct mtk_star_ring_desc_data *desc_data)
+{
+	mtk_star_ring_push_head(ring, desc_data, 0);
+}
+
+static void
+mtk_star_ring_push_head_tx(struct mtk_star_ring *ring,
+			   struct mtk_star_ring_desc_data *desc_data)
+{
+	static const unsigned int flags = MTK_STAR_DESC_BIT_FS |
+					  MTK_STAR_DESC_BIT_LS |
+					  MTK_STAR_DESC_BIT_INT;
+
+	mtk_star_ring_push_head(ring, desc_data, flags);
+}
+
+static unsigned int mtk_star_ring_num_used_descs(struct mtk_star_ring *ring)
+{
+	return abs(ring->head - ring->tail);
+}
+
+static bool mtk_star_ring_full(struct mtk_star_ring *ring)
+{
+	return mtk_star_ring_num_used_descs(ring) == MTK_STAR_RING_NUM_DESCS;
+}
+
+static bool mtk_star_ring_descs_available(struct mtk_star_ring *ring)
+{
+	return mtk_star_ring_num_used_descs(ring) > 0;
+}
+
+static dma_addr_t mtk_star_dma_map_rx(struct mtk_star_priv *priv,
+				      struct sk_buff *skb)
+{
+	struct device *dev = mtk_star_get_dev(priv);
+
+	/* Data pointer for the RX DMA descriptor must be aligned to 4N + 2. */
+	return dma_map_single(dev, skb_tail_pointer(skb) - 2,
+			      skb_tailroom(skb), DMA_FROM_DEVICE);
+}
+
+static void mtk_star_dma_unmap_rx(struct mtk_star_priv *priv,
+				  struct mtk_star_ring_desc_data *desc_data)
+{
+	struct device *dev = mtk_star_get_dev(priv);
+
+	dma_unmap_single(dev, desc_data->dma_addr,
+			 skb_tailroom(desc_data->skb), DMA_FROM_DEVICE);
+}
+
+static dma_addr_t mtk_star_dma_map_tx(struct mtk_star_priv *priv,
+				      struct sk_buff *skb)
+{
+	struct device *dev = mtk_star_get_dev(priv);
+
+	return dma_map_single(dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE);
+}
+
+static void mtk_star_dma_unmap_tx(struct mtk_star_priv *priv,
+				  struct mtk_star_ring_desc_data *desc_data)
+{
+	struct device *dev = mtk_star_get_dev(priv);
+
+	return dma_unmap_single(dev, desc_data->dma_addr,
+				skb_headlen(desc_data->skb), DMA_TO_DEVICE);
+}
+
+static void mtk_star_nic_disable_pd(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_MAC_CFG,
+			   MTK_STAR_BIT_MAC_CFG_NIC_PD, 0);
+}
+
+/* Unmask the three interrupts we care about, mask all others. */
+static void mtk_star_intr_enable(struct mtk_star_priv *priv)
+{
+	unsigned int val = MTK_STAR_BIT_INT_STS_TNTC |
+			   MTK_STAR_BIT_INT_STS_FNRC |
+			   MTK_STAR_REG_INT_STS_MIB_CNT_TH;
+
+	regmap_write(priv->regs, MTK_STAR_REG_INT_MASK, ~val);
+}
+
+static void mtk_star_intr_disable(struct mtk_star_priv *priv)
+{
+	regmap_write(priv->regs, MTK_STAR_REG_INT_MASK, ~0);
+}
+
+static void mtk_star_intr_enable_tx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_BIT_INT_STS_TNTC, 0);
+}
+
+static void mtk_star_intr_enable_rx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_BIT_INT_STS_FNRC, 0);
+}
+
+static void mtk_star_intr_enable_stats(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_REG_INT_STS_MIB_CNT_TH, 0);
+}
+
+static void mtk_star_intr_disable_tx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_BIT_INT_STS_TNTC,
+			   MTK_STAR_BIT_INT_STS_TNTC);
+}
+
+static void mtk_star_intr_disable_rx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_BIT_INT_STS_FNRC,
+			   MTK_STAR_BIT_INT_STS_FNRC);
+}
+
+static void mtk_star_intr_disable_stats(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_INT_MASK,
+			   MTK_STAR_REG_INT_STS_MIB_CNT_TH,
+			   MTK_STAR_REG_INT_STS_MIB_CNT_TH);
+}
+
+static unsigned int mtk_star_intr_read(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	regmap_read(priv->regs, MTK_STAR_REG_INT_STS, &val);
+
+	return val;
+}
+
+static unsigned int mtk_star_intr_ack_all(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	val = mtk_star_intr_read(priv);
+	regmap_write(priv->regs, MTK_STAR_REG_INT_STS, val);
+
+	return val;
+}
+
+static void mtk_star_dma_init(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring_desc *desc;
+	unsigned int val;
+	int i;
+
+	priv->descs_base = (struct mtk_star_ring_desc *)priv->ring_base;
+
+	for (i = 0; i < MTK_STAR_NUM_DESCS_TOTAL; i++) {
+		desc = &priv->descs_base[i];
+
+		memset(desc, 0, sizeof(*desc));
+		desc->status = MTK_STAR_DESC_BIT_COWN;
+		if ((i == MTK_STAR_NUM_TX_DESCS - 1) ||
+		    (i == MTK_STAR_NUM_DESCS_TOTAL - 1))
+			desc->status |= MTK_STAR_DESC_BIT_EOR;
+	}
+
+	mtk_star_ring_init(&priv->tx_ring, priv->descs_base);
+	mtk_star_ring_init(&priv->rx_ring,
+			   priv->descs_base + MTK_STAR_NUM_TX_DESCS);
+
+	/* Set DMA pointers. */
+	val = (unsigned int)priv->dma_addr;
+	regmap_write(priv->regs, MTK_STAR_REG_TX_BASE_ADDR, val);
+	regmap_write(priv->regs, MTK_STAR_REG_TX_DPTR, val);
+
+	val += sizeof(struct mtk_star_ring_desc) * MTK_STAR_NUM_TX_DESCS;
+	regmap_write(priv->regs, MTK_STAR_REG_RX_BASE_ADDR, val);
+	regmap_write(priv->regs, MTK_STAR_REG_RX_DPTR, val);
+}
+
+static void mtk_star_dma_start(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_TX_DMA_CTRL,
+			   MTK_STAR_BIT_TX_DMA_CTRL_START,
+			   MTK_STAR_BIT_TX_DMA_CTRL_START);
+	regmap_update_bits(priv->regs, MTK_STAR_REG_RX_DMA_CTRL,
+			   MTK_STAR_BIT_RX_DMA_CTRL_START,
+			   MTK_STAR_BIT_RX_DMA_CTRL_START);
+}
+
+static void mtk_star_dma_stop(struct mtk_star_priv *priv)
+{
+	regmap_write(priv->regs, MTK_STAR_REG_TX_DMA_CTRL,
+		     MTK_STAR_BIT_TX_DMA_CTRL_STOP);
+	regmap_write(priv->regs, MTK_STAR_REG_RX_DMA_CTRL,
+		     MTK_STAR_BIT_RX_DMA_CTRL_STOP);
+}
+
+static void mtk_star_dma_disable(struct mtk_star_priv *priv)
+{
+	int i;
+
+	mtk_star_dma_stop(priv);
+
+	/* Take back all descriptors. */
+	for (i = 0; i < MTK_STAR_NUM_DESCS_TOTAL; i++)
+		priv->descs_base[i].status |= MTK_STAR_DESC_BIT_COWN;
+}
+
+static void mtk_star_dma_resume_rx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_RX_DMA_CTRL,
+			   MTK_STAR_BIT_RX_DMA_CTRL_RESUME,
+			   MTK_STAR_BIT_RX_DMA_CTRL_RESUME);
+}
+
+static void mtk_star_dma_resume_tx(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->regs, MTK_STAR_REG_TX_DMA_CTRL,
+			   MTK_STAR_BIT_TX_DMA_CTRL_RESUME,
+			   MTK_STAR_BIT_TX_DMA_CTRL_RESUME);
+}
+
+static void mtk_star_set_mac_addr(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	u8 *mac_addr = ndev->dev_addr;
+	unsigned int high, low;
+
+	high = mac_addr[0] << 8 | mac_addr[1] << 0;
+	low = mac_addr[2] << 24 | mac_addr[3] << 16 |
+	      mac_addr[4] << 8 | mac_addr[5];
+
+	regmap_write(priv->regs, MTK_STAR_REG_MY_MAC_H, high);
+	regmap_write(priv->regs, MTK_STAR_REG_MY_MAC_L, low);
+}
+
+static void mtk_star_reset_counters(struct mtk_star_priv *priv)
+{
+	static const unsigned int counter_regs[] = {
+		MTK_STAR_REG_C_RXOKPKT,
+		MTK_STAR_REG_C_RXOKBYTE,
+		MTK_STAR_REG_C_RXRUNT,
+		MTK_STAR_REG_C_RXLONG,
+		MTK_STAR_REG_C_RXDROP,
+		MTK_STAR_REG_C_RXCRC,
+		MTK_STAR_REG_C_RXARLDROP,
+		MTK_STAR_REG_C_RXVLANDROP,
+		MTK_STAR_REG_C_RXCSERR,
+		MTK_STAR_REG_C_RXPAUSE,
+		MTK_STAR_REG_C_TXOKPKT,
+		MTK_STAR_REG_C_TXOKBYTE,
+		MTK_STAR_REG_C_TXPAUSECOL,
+		MTK_STAR_REG_C_TXRTY,
+		MTK_STAR_REG_C_TXSKIP,
+		MTK_STAR_REG_C_TX_ARP,
+		MTK_STAR_REG_C_RX_RERR,
+		MTK_STAR_REG_C_RX_UNI,
+		MTK_STAR_REG_C_RX_MULTI,
+		MTK_STAR_REG_C_RX_BROAD,
+		MTK_STAR_REG_C_RX_ALIGNERR,
+		MTK_STAR_REG_C_TX_UNI,
+		MTK_STAR_REG_C_TX_MULTI,
+		MTK_STAR_REG_C_TX_BROAD,
+		MTK_STAR_REG_C_TX_TIMEOUT,
+		MTK_STAR_REG_C_TX_LATECOL,
+		MTK_STAR_REG_C_RX_LENGTHERR,
+		MTK_STAR_REG_C_RX_TWIST,
+	};
+
+	unsigned int i, val;
+
+	for (i = 0; i < ARRAY_SIZE(counter_regs); i++)
+		regmap_read(priv->regs, counter_regs[i], &val);
+}
+
+static void mtk_star_update_stat(struct mtk_star_priv *priv,
+				 unsigned int reg, u64 *stat)
+{
+	unsigned int val;
+
+	regmap_read(priv->regs, reg, &val);
+	*stat += val;
+}
+
+/* Try to get as many stats as possible from the internal registers instead
+ * of tracking them ourselves.
+ */
+static void mtk_star_update_stats(struct mtk_star_priv *priv)
+{
+	struct rtnl_link_stats64 *stats = &priv->stats;
+
+	/* OK packets and bytes. */
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXOKPKT, &stats->rx_packets);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_TXOKPKT, &stats->tx_packets);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXOKBYTE, &stats->rx_bytes);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_TXOKBYTE, &stats->tx_bytes);
+
+	/* RX & TX multicast. */
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RX_MULTI, &stats->multicast);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_TX_MULTI, &stats->multicast);
+
+	/* Collisions. */
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_TXPAUSECOL,
+			     &stats->collisions);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_TX_LATECOL,
+			     &stats->collisions);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXRUNT, &stats->collisions);
+
+	/* RX Errors. */
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RX_LENGTHERR,
+			     &stats->rx_length_errors);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXLONG,
+			     &stats->rx_over_errors);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXCRC, &stats->rx_crc_errors);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RX_ALIGNERR,
+			     &stats->rx_frame_errors);
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RXDROP,
+			     &stats->rx_fifo_errors);
+	/* Sum of the general RX error counter + all of the above. */
+	mtk_star_update_stat(priv, MTK_STAR_REG_C_RX_RERR, &stats->rx_errors);
+	stats->rx_errors += stats->rx_length_errors;
+	stats->rx_errors += stats->rx_over_errors;
+	stats->rx_errors += stats->rx_crc_errors;
+	stats->rx_errors += stats->rx_frame_errors;
+	stats->rx_errors += stats->rx_fifo_errors;
+}
+
+/* This runs in process context and parallel TX and RX paths executing in
+ * napi context may result in losing some stats data but this should happen
+ * seldom enough to be acceptable.
+ */
+static void mtk_star_update_stats_work(struct work_struct *work)
+{
+	struct mtk_star_priv *priv = container_of(work, struct mtk_star_priv,
+						 stats_work);
+
+	mtk_star_update_stats(priv);
+	mtk_star_reset_counters(priv);
+	mtk_star_intr_enable_stats(priv);
+}
+
+static struct sk_buff *mtk_star_alloc_skb(struct net_device *ndev)
+{
+	uintptr_t tail, offset;
+	struct sk_buff *skb;
+
+	skb = dev_alloc_skb(MTK_STAR_MAX_FRAME_SIZE);
+	if (!skb)
+		return NULL;
+
+	/* Align to 16 bytes. */
+	tail = (uintptr_t)skb_tail_pointer(skb);
+	if (tail & (MTK_STAR_SKB_ALIGNMENT - 1)) {
+		offset = tail & (MTK_STAR_SKB_ALIGNMENT - 1);
+		skb_reserve(skb, MTK_STAR_SKB_ALIGNMENT - offset);
+	}
+
+	/* Ensure 16-byte alignment of the skb pointer: eth_type_trans() will
+	 * extract the Ethernet header (14 bytes) so we need two more bytes.
+	 */
+	skb_reserve(skb, MTK_STAR_IP_ALIGN);
+
+	return skb;
+}
+
+static int mtk_star_prepare_rx_skbs(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	struct mtk_star_ring *ring = &priv->rx_ring;
+	struct device *dev = mtk_star_get_dev(priv);
+	struct mtk_star_ring_desc *desc;
+	struct sk_buff *skb;
+	dma_addr_t dma_addr;
+	int i;
+
+	for (i = 0; i < MTK_STAR_NUM_RX_DESCS; i++) {
+		skb = mtk_star_alloc_skb(ndev);
+		if (!skb)
+			return -ENOMEM;
+
+		dma_addr = mtk_star_dma_map_rx(priv, skb);
+		if (dma_mapping_error(dev, dma_addr)) {
+			dev_kfree_skb(skb);
+			return -ENOMEM;
+		}
+
+		desc = &ring->descs[i];
+		desc->data_ptr = dma_addr;
+		desc->status |= skb_tailroom(skb) & MTK_STAR_DESC_MSK_LEN;
+		desc->status &= ~MTK_STAR_DESC_BIT_COWN;
+		ring->skbs[i] = skb;
+		ring->dma_addrs[i] = dma_addr;
+	}
+
+	return 0;
+}
+
+static void
+mtk_star_ring_free_skbs(struct mtk_star_priv *priv, struct mtk_star_ring *ring,
+			void (*unmap_func)(struct mtk_star_priv *,
+					   struct mtk_star_ring_desc_data *))
+{
+	struct mtk_star_ring_desc_data desc_data;
+	struct mtk_star_ring_desc *desc;
+	int i;
+
+	for (i = 0; i < MTK_STAR_RING_NUM_DESCS; i++) {
+		if (!ring->dma_addrs[i])
+			continue;
+
+		desc = &ring->descs[i];
+
+		desc_data.dma_addr = ring->dma_addrs[i];
+		desc_data.skb = ring->skbs[i];
+
+		unmap_func(priv, &desc_data);
+		dev_kfree_skb(desc_data.skb);
+	}
+}
+
+static void mtk_star_free_rx_skbs(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring *ring = &priv->rx_ring;
+
+	mtk_star_ring_free_skbs(priv, ring, mtk_star_dma_unmap_rx);
+}
+
+static void mtk_star_free_tx_skbs(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring *ring = &priv->tx_ring;
+
+	mtk_star_ring_free_skbs(priv, ring, mtk_star_dma_unmap_tx);
+}
+
+/* All processing for TX and RX happens in the napi poll callback. */
+static irqreturn_t mtk_star_handle_irq(int irq, void *data)
+{
+	struct mtk_star_priv *priv;
+	struct net_device *ndev;
+	bool need_napi = false;
+	unsigned int status;
+
+	ndev = data;
+	priv = netdev_priv(ndev);
+
+	if (netif_running(ndev)) {
+		status = mtk_star_intr_read(priv);
+
+		if (status & MTK_STAR_BIT_INT_STS_TNTC) {
+			mtk_star_intr_disable_tx(priv);
+			need_napi = true;
+		}
+
+		if (status & MTK_STAR_BIT_INT_STS_FNRC) {
+			mtk_star_intr_disable_rx(priv);
+			need_napi = true;
+		}
+
+		if (need_napi)
+			napi_schedule(&priv->napi);
+
+		/* One of the counters reached 0x8000000 - update stats and
+		 * reset all counters.
+		 */
+		if (unlikely(status & MTK_STAR_REG_INT_STS_MIB_CNT_TH)) {
+			mtk_star_intr_disable_stats(priv);
+			schedule_work(&priv->stats_work);
+		}
+
+		mtk_star_intr_ack_all(priv);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* Wait for the completion of any previous command - CMD_START bit must be
+ * cleared by hardware.
+ */
+static int mtk_star_hash_wait_cmd_start(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	return regmap_read_poll_timeout_atomic(priv->regs,
+				MTK_STAR_REG_HASH_CTRL, val,
+				!(val & MTK_STAR_BIT_HASH_CTRL_CMD_START),
+				10, MTK_STAR_WAIT_TIMEOUT);
+}
+
+static int mtk_star_hash_wait_ok(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+	int ret;
+
+	/* Wait for BIST_DONE bit. */
+	ret = regmap_read_poll_timeout_atomic(priv->regs,
+					MTK_STAR_REG_HASH_CTRL, val,
+					val & MTK_STAR_BIT_HASH_CTRL_BIST_DONE,
+					10, MTK_STAR_WAIT_TIMEOUT);
+	if (ret)
+		return ret;
+
+	/* Check the BIST_OK bit. */
+	regmap_read(priv->regs, MTK_STAR_REG_HASH_CTRL, &val);
+	if (!(val & MTK_STAR_BIT_HASH_CTRL_BIST_OK))
+		return -EIO;
+
+	return 0;
+}
+
+static int mtk_star_set_hashbit(struct mtk_star_priv *priv,
+				unsigned int hash_addr)
+{
+	unsigned int val;
+	int ret;
+
+	ret = mtk_star_hash_wait_cmd_start(priv);
+	if (ret)
+		return ret;
+
+	val = hash_addr & MTK_STAR_MSK_HASH_CTRL_HASH_BIT_ADDR;
+	val |= MTK_STAR_BIT_HASH_CTRL_ACC_CMD;
+	val |= MTK_STAR_BIT_HASH_CTRL_CMD_START;
+	val |= MTK_STAR_BIT_HASH_CTRL_BIST_EN;
+	val |= MTK_STAR_BIT_HASH_CTRL_HASH_BIT_DATA;
+	regmap_write(priv->regs, MTK_STAR_REG_HASH_CTRL, val);
+
+	return mtk_star_hash_wait_ok(priv);
+}
+
+static int mtk_star_reset_hash_table(struct mtk_star_priv *priv)
+{
+	int ret;
+
+	ret = mtk_star_hash_wait_cmd_start(priv);
+	if (ret)
+		return ret;
+
+	regmap_update_bits(priv->regs, MTK_STAR_REG_HASH_CTRL,
+			   MTK_STAR_BIT_HASH_CTRL_BIST_EN,
+			   MTK_STAR_BIT_HASH_CTRL_BIST_EN);
+	regmap_update_bits(priv->regs, MTK_STAR_REG_TEST1,
+			   MTK_STAR_BIT_TEST1_RST_HASH_MBIST,
+			   MTK_STAR_BIT_TEST1_RST_HASH_MBIST);
+
+	return mtk_star_hash_wait_ok(priv);
+}
+
+static void mtk_star_phy_config(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	if (priv->speed == SPEED_1000)
+		val = MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_1000M;
+	else if (priv->speed == SPEED_100)
+		val = MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_100M;
+	else
+		val = MTK_STAR_VAL_PHY_CTRL1_FORCE_SPD_10M;
+	val <<= MTK_STAR_OFF_PHY_CTRL1_FORCE_SPD;
+
+	val |= MTK_STAR_BIT_PHY_CTRL1_AN_EN;
+	val |= MTK_STAR_BIT_PHY_CTRL1_FORCE_FC_RX;
+	val |= MTK_STAR_BIT_PHY_CTRL1_FORCE_FC_TX;
+	/* Only full-duplex supported for now. */
+	val |= MTK_STAR_BIT_PHY_CTRL1_FORCE_DPX;
+
+	regmap_write(priv->regs, MTK_STAR_REG_PHY_CTRL1, val);
+
+	if (priv->pause) {
+		val = MTK_STAR_VAL_FC_CFG_SEND_PAUSE_TH_2K;
+		val <<= MTK_STAR_OFF_FC_CFG_SEND_PAUSE_TH;
+		val |= MTK_STAR_BIT_FC_CFG_UC_PAUSE_DIR;
+	} else {
+		val = 0;
+	}
+
+	regmap_update_bits(priv->regs, MTK_STAR_REG_FC_CFG,
+			   MTK_STAR_MSK_FC_CFG_SEND_PAUSE_TH |
+			   MTK_STAR_BIT_FC_CFG_UC_PAUSE_DIR, val);
+
+	if (priv->pause) {
+		val = MTK_STAR_VAL_EXT_CFG_SND_PAUSE_RLS_1K;
+		val <<= MTK_STAR_OFF_EXT_CFG_SND_PAUSE_RLS;
+	} else {
+		val = 0;
+	}
+
+	regmap_update_bits(priv->regs, MTK_STAR_REG_EXT_CFG,
+			   MTK_STAR_MSK_EXT_CFG_SND_PAUSE_RLS, val);
+}
+
+static void mtk_star_adjust_link(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	struct phy_device *phydev = priv->phydev;
+	bool new_state = false;
+
+	if (phydev->link) {
+		if (!priv->link) {
+			priv->link = phydev->link;
+			new_state = true;
+		}
+
+		if (priv->speed != phydev->speed) {
+			priv->speed = phydev->speed;
+			new_state = true;
+		}
+
+		if (priv->pause != phydev->pause) {
+			priv->pause = phydev->pause;
+			new_state = true;
+		}
+	} else {
+		if (priv->link) {
+			priv->link = phydev->link;
+			new_state = true;
+		}
+	}
+
+	if (new_state) {
+		if (phydev->link)
+			mtk_star_phy_config(priv);
+
+		phy_print_status(ndev->phydev);
+	}
+}
+
+static void mtk_star_init_config(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	val = (MTK_STAR_BIT_MII_PAD_OUT_ENABLE |
+	       MTK_STAR_BIT_EXT_MDC_MODE |
+	       MTK_STAR_BIT_SWC_MII_MODE);
+
+	regmap_write(priv->regs, MTK_STAR_REG_SYS_CONF, val);
+	regmap_update_bits(priv->regs, MTK_STAR_REG_MAC_CLK_CONF,
+			   MTK_STAR_MSK_MAC_CLK_CONF,
+			   MTK_STAR_BIT_CLK_DIV_10);
+}
+
+static void mtk_star_set_mode_rmii(struct mtk_star_priv *priv)
+{
+	regmap_update_bits(priv->pericfg, MTK_PERICFG_REG_NIC_CFG_CON,
+			   MTK_PERICFG_MSK_NIC_CFG_CON_CFG_MII,
+			   MTK_PERICFG_BIT_NIC_CFG_CON_RMII);
+}
+
+static int mtk_star_enable(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	unsigned int val;
+	int ret;
+
+	mtk_star_nic_disable_pd(priv);
+	mtk_star_intr_disable(priv);
+	mtk_star_dma_stop(priv);
+
+	mtk_star_set_mac_addr(ndev);
+
+	/* Configure the MAC */
+	val = MTK_STAR_VAL_MAC_CFG_IPG_96BIT;
+	val <<= MTK_STAR_OFF_MAC_CFG_IPG;
+	val |= MTK_STAR_BIT_MAC_CFG_MAXLEN_1522;
+	val |= MTK_STAR_BIT_MAC_CFG_AUTO_PAD;
+	val |= MTK_STAR_BIT_MAC_CFG_CRC_STRIP;
+	regmap_write(priv->regs, MTK_STAR_REG_MAC_CFG, val);
+
+	/* Enable Hash Table BIST and reset it */
+	ret = mtk_star_reset_hash_table(priv);
+	if (ret)
+		return ret;
+
+	/* Setup the hashing algorithm */
+	regmap_update_bits(priv->regs, MTK_STAR_REG_ARL_CFG,
+			   MTK_STAR_BIT_ARL_CFG_HASH_ALG |
+			   MTK_STAR_BIT_ARL_CFG_MISC_MODE, 0);
+
+	/* Don't strip VLAN tags */
+	regmap_update_bits(priv->regs, MTK_STAR_REG_MAC_CFG,
+			   MTK_STAR_BIT_MAC_CFG_VLAN_STRIP, 0);
+
+	/* Setup DMA */
+	mtk_star_dma_init(priv);
+
+	ret = mtk_star_prepare_rx_skbs(ndev);
+	if (ret)
+		goto err_out;
+
+	/* Request the interrupt */
+	ret = request_irq(ndev->irq, mtk_star_handle_irq,
+			  IRQF_TRIGGER_FALLING, ndev->name, ndev);
+	if (ret)
+		goto err_free_skbs;
+
+	napi_enable(&priv->napi);
+
+	mtk_star_intr_ack_all(priv);
+	mtk_star_intr_enable(priv);
+
+	/* Connect to and start PHY */
+	priv->phydev = of_phy_connect(ndev, priv->phy_node,
+				      mtk_star_adjust_link, 0, priv->phy_intf);
+	if (!priv->phydev) {
+		netdev_err(ndev, "failed to connect to PHY\n");
+		goto err_free_irq;
+	}
+
+	mtk_star_dma_start(priv);
+	phy_start(priv->phydev);
+	netif_start_queue(ndev);
+
+	return 0;
+
+err_free_irq:
+	free_irq(ndev->irq, ndev);
+err_free_skbs:
+	mtk_star_free_rx_skbs(priv);
+err_out:
+	return ret;
+}
+
+static void mtk_star_disable(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+
+	netif_stop_queue(ndev);
+	napi_disable(&priv->napi);
+	mtk_star_intr_disable(priv);
+	mtk_star_dma_disable(priv);
+	mtk_star_intr_ack_all(priv);
+	phy_stop(priv->phydev);
+	phy_disconnect(priv->phydev);
+	free_irq(ndev->irq, ndev);
+	mtk_star_free_rx_skbs(priv);
+	mtk_star_free_tx_skbs(priv);
+}
+
+static int mtk_star_netdev_open(struct net_device *ndev)
+{
+	return mtk_star_enable(ndev);
+}
+
+static int mtk_star_netdev_stop(struct net_device *ndev)
+{
+	mtk_star_disable(ndev);
+
+	return 0;
+}
+
+static int mtk_star_netdev_ioctl(struct net_device *ndev,
+				 struct ifreq *req, int cmd)
+{
+	if (!netif_running(ndev))
+		return -EINVAL;
+
+	return phy_mii_ioctl(ndev->phydev, req, cmd);
+}
+
+static int mtk_star_netdev_start_xmit(struct sk_buff *skb,
+				      struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	struct mtk_star_ring *ring = &priv->tx_ring;
+	struct device *dev = mtk_star_get_dev(priv);
+	struct mtk_star_ring_desc_data desc_data;
+
+	desc_data.dma_addr = mtk_star_dma_map_tx(priv, skb);
+	if (dma_mapping_error(dev, desc_data.dma_addr))
+		goto err_drop_packet;
+
+	desc_data.skb = skb;
+	desc_data.len = skb->len;
+
+	spin_lock_bh(&priv->lock);
+
+	mtk_star_ring_push_head_tx(ring, &desc_data);
+
+	netdev_sent_queue(ndev, skb->len);
+
+	if (mtk_star_ring_full(ring))
+		netif_stop_queue(ndev);
+
+	spin_unlock_bh(&priv->lock);
+
+	mtk_star_dma_resume_tx(priv);
+
+	return NETDEV_TX_OK;
+
+err_drop_packet:
+	dev_kfree_skb(skb);
+	ndev->stats.tx_dropped++;
+	return NETDEV_TX_BUSY;
+}
+
+/* Returns the number of bytes sent or a negative number on the first
+ * descriptor owned by DMA.
+ */
+static int mtk_star_tx_complete_one(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring *ring = &priv->tx_ring;
+	struct mtk_star_ring_desc_data desc_data;
+	int ret;
+
+	ret = mtk_star_ring_pop_tail(ring, &desc_data);
+	if (ret)
+		return ret;
+
+	mtk_star_dma_unmap_tx(priv, &desc_data);
+	ret = desc_data.skb->len;
+	dev_kfree_skb_irq(desc_data.skb);
+
+	return ret;
+}
+
+static void mtk_star_tx_complete_all(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring *ring = &priv->tx_ring;
+	struct net_device *ndev = priv->ndev;
+	int ret, pkts_compl, bytes_compl;
+	bool wake = false;
+
+	spin_lock(&priv->lock);
+
+	for (pkts_compl = 0, bytes_compl = 0;;
+	     pkts_compl++, bytes_compl += ret, wake = true) {
+		if (!mtk_star_ring_descs_available(ring))
+			break;
+
+		ret = mtk_star_tx_complete_one(priv);
+		if (ret < 0)
+			break;
+	}
+
+	netdev_completed_queue(ndev, pkts_compl, bytes_compl);
+
+	if (wake && netif_queue_stopped(ndev))
+		netif_wake_queue(ndev);
+
+	mtk_star_intr_enable_tx(priv);
+
+	spin_unlock(&priv->lock);
+}
+
+static void mtk_star_netdev_get_stats64(struct net_device *ndev,
+					struct rtnl_link_stats64 *stats)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+
+	mtk_star_update_stats(priv);
+
+	memcpy(stats, &priv->stats, sizeof(*stats));
+}
+
+static void mtk_star_set_rx_mode(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	struct netdev_hw_addr *hw_addr;
+	unsigned int hash_addr, i;
+	int ret;
+
+	if (ndev->flags & IFF_PROMISC) {
+		regmap_update_bits(priv->regs, MTK_STAR_REG_ARL_CFG,
+				   MTK_STAR_BIT_ARL_CFG_MISC_MODE,
+				   MTK_STAR_BIT_ARL_CFG_MISC_MODE);
+	} else if (netdev_mc_count(ndev) > MTK_STAR_HASHTABLE_MC_LIMIT ||
+		   ndev->flags & IFF_ALLMULTI) {
+		for (i = 0; i < MTK_STAR_HASHTABLE_SIZE_MAX; i++) {
+			ret = mtk_star_set_hashbit(priv, i);
+			if (ret)
+				goto hash_fail;
+		}
+	} else {
+		/* Clear previous settings. */
+		ret = mtk_star_reset_hash_table(priv);
+		if (ret)
+			goto hash_fail;
+
+		netdev_for_each_mc_addr(hw_addr, ndev) {
+			hash_addr = (hw_addr->addr[0] & 0x01) << 8;
+			hash_addr += hw_addr->addr[5];
+			ret = mtk_star_set_hashbit(priv, hash_addr);
+			if (ret)
+				goto hash_fail;
+		}
+	}
+
+	return;
+
+hash_fail:
+	if (ret == -ETIMEDOUT)
+		netdev_err(ndev, "setting hash bit timed out\n");
+	else
+		/* Should be -EIO */
+		netdev_err(ndev, "unable to set hash bit");
+}
+
+static const struct net_device_ops mtk_star_netdev_ops = {
+	.ndo_open		= mtk_star_netdev_open,
+	.ndo_stop		= mtk_star_netdev_stop,
+	.ndo_start_xmit		= mtk_star_netdev_start_xmit,
+	.ndo_get_stats64	= mtk_star_netdev_get_stats64,
+	.ndo_set_rx_mode	= mtk_star_set_rx_mode,
+	.ndo_do_ioctl		= mtk_star_netdev_ioctl,
+	.ndo_set_mac_address	= eth_mac_addr,
+	.ndo_validate_addr	= eth_validate_addr,
+};
+
+static void mtk_star_get_drvinfo(struct net_device *dev,
+				 struct ethtool_drvinfo *info)
+{
+	strlcpy(info->driver, MTK_STAR_DRVNAME, sizeof(info->driver));
+}
+
+/* TODO Add ethtool stats. */
+static const struct ethtool_ops mtk_star_ethtool_ops = {
+	.get_drvinfo		= mtk_star_get_drvinfo,
+	.get_link		= ethtool_op_get_link,
+	.get_link_ksettings	= phy_ethtool_get_link_ksettings,
+	.set_link_ksettings	= phy_ethtool_set_link_ksettings,
+};
+
+static int mtk_star_receive_packet(struct mtk_star_priv *priv)
+{
+	struct mtk_star_ring *ring = &priv->rx_ring;
+	struct device *dev = mtk_star_get_dev(priv);
+	struct mtk_star_ring_desc_data desc_data;
+	struct net_device *ndev = priv->ndev;
+	struct sk_buff *curr_skb, *new_skb;
+	dma_addr_t new_dma_addr;
+	int ret;
+
+	spin_lock(&priv->lock);
+	ret = mtk_star_ring_pop_tail(ring, &desc_data);
+	spin_unlock(&priv->lock);
+	if (ret)
+		return -1;
+
+	curr_skb = desc_data.skb;
+
+	if ((desc_data.flags & MTK_STAR_DESC_BIT_RX_CRCE) ||
+	    (desc_data.flags & MTK_STAR_DESC_BIT_RX_OSIZE)) {
+		/* Error packet -> drop and reuse skb. */
+		new_skb = curr_skb;
+		goto push_new_skb;
+	}
+
+	/* Prepare new skb before receiving the current one. Reuse the current
+	 * skb if we fail at any point.
+	 */
+	new_skb = mtk_star_alloc_skb(ndev);
+	if (!new_skb) {
+		ndev->stats.rx_dropped++;
+		new_skb = curr_skb;
+		goto push_new_skb;
+	}
+
+	new_dma_addr = mtk_star_dma_map_rx(priv, new_skb);
+	if (dma_mapping_error(dev, new_dma_addr)) {
+		ndev->stats.rx_dropped++;
+		dev_kfree_skb(new_skb);
+		new_skb = curr_skb;
+		netdev_err(ndev, "DMA mapping error of RX descriptor\n");
+		goto push_new_skb;
+	}
+
+	/* We can't fail anymore at this point: it's safe to unmap the skb. */
+	mtk_star_dma_unmap_rx(priv, &desc_data);
+
+	skb_put(desc_data.skb, desc_data.len);
+	desc_data.skb->ip_summed = CHECKSUM_NONE;
+	desc_data.skb->protocol = eth_type_trans(desc_data.skb, ndev);
+	desc_data.skb->dev = ndev;
+	netif_receive_skb(desc_data.skb);
+
+push_new_skb:
+	desc_data.dma_addr = new_dma_addr;
+	desc_data.len = skb_tailroom(new_skb);
+	desc_data.skb = new_skb;
+
+	spin_lock(&priv->lock);
+	mtk_star_ring_push_head_rx(ring, &desc_data);
+	spin_unlock(&priv->lock);
+
+	return 0;
+}
+
+static int mtk_star_process_rx(struct mtk_star_priv *priv, int budget)
+{
+	int received, ret;
+
+	for (received = 0, ret = 0; received < budget && ret == 0; received++)
+		ret = mtk_star_receive_packet(priv);
+
+	mtk_star_dma_resume_rx(priv);
+
+	return received;
+}
+
+static int mtk_star_poll(struct napi_struct *napi, int budget)
+{
+	struct mtk_star_priv *priv;
+	int received = 0;
+
+	priv = container_of(napi, struct mtk_star_priv, napi);
+
+	/* Clean-up all TX descriptors. */
+	mtk_star_tx_complete_all(priv);
+	/* Receive up to $budget packets. */
+	received = mtk_star_process_rx(priv, budget);
+
+	if (received < budget) {
+		napi_complete_done(napi, received);
+		mtk_star_intr_enable_rx(priv);
+	}
+
+	return received;
+}
+
+static void mtk_star_mdio_rwok_clear(struct mtk_star_priv *priv)
+{
+	regmap_write(priv->regs, MTK_STAR_REG_PHY_CTRL0,
+		     MTK_STAR_BIT_PHY_CTRL0_RWOK);
+}
+
+static int mtk_star_mdio_rwok_wait(struct mtk_star_priv *priv)
+{
+	unsigned int val;
+
+	return regmap_read_poll_timeout(priv->regs, MTK_STAR_REG_PHY_CTRL0,
+					val, val & MTK_STAR_BIT_PHY_CTRL0_RWOK,
+					10, MTK_STAR_WAIT_TIMEOUT);
+}
+
+static int mtk_star_mdio_read(struct mii_bus *mii, int phy_id, int regnum)
+{
+	struct mtk_star_priv *priv = mii->priv;
+	unsigned int val, data;
+	int ret;
+
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
+	mtk_star_mdio_rwok_clear(priv);
+
+	val = (regnum << MTK_STAR_OFF_PHY_CTRL0_PREG);
+	val &= MTK_STAR_MSK_PHY_CTRL0_PREG;
+	val |= MTK_STAR_BIT_PHY_CTRL0_RDCMD;
+
+	regmap_write(priv->regs, MTK_STAR_REG_PHY_CTRL0, val);
+
+	ret = mtk_star_mdio_rwok_wait(priv);
+	if (ret)
+		return ret;
+
+	regmap_read(priv->regs, MTK_STAR_REG_PHY_CTRL0, &data);
+
+	data &= MTK_STAR_MSK_PHY_CTRL0_RWDATA;
+	data >>= MTK_STAR_OFF_PHY_CTRL0_RWDATA;
+
+	return data;
+}
+
+static int mtk_star_mdio_write(struct mii_bus *mii, int phy_id,
+			       int regnum, u16 data)
+{
+	struct mtk_star_priv *priv = mii->priv;
+	unsigned int val;
+
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
+	mtk_star_mdio_rwok_clear(priv);
+
+	val = data;
+	val <<= MTK_STAR_OFF_PHY_CTRL0_RWDATA;
+	val &= MTK_STAR_MSK_PHY_CTRL0_RWDATA;
+	regnum <<= MTK_STAR_OFF_PHY_CTRL0_PREG;
+	regnum &= MTK_STAR_MSK_PHY_CTRL0_PREG;
+	val |= regnum;
+	val |= MTK_STAR_BIT_PHY_CTRL0_WTCMD;
+
+	regmap_write(priv->regs, MTK_STAR_REG_PHY_CTRL0, val);
+
+	return mtk_star_mdio_rwok_wait(priv);
+}
+
+static int mtk_star_mdio_init(struct net_device *ndev)
+{
+	struct mtk_star_priv *priv = netdev_priv(ndev);
+	struct device *dev = mtk_star_get_dev(priv);
+	struct device_node *of_node, *mdio_node;
+	int ret;
+
+	of_node = dev->of_node;
+
+	mdio_node = of_get_child_by_name(of_node, "mdio");
+	if (!mdio_node)
+		return -ENODEV;
+
+	if (!of_device_is_available(mdio_node)) {
+		ret = -ENODEV;
+		goto out_put_node;
+	}
+
+	priv->mii = devm_mdiobus_alloc(dev);
+	if (!priv->mii) {
+		ret = -ENOMEM;
+		goto out_put_node;
+	}
+
+	snprintf(priv->mii->id, MII_BUS_ID_SIZE, "%s", dev_name(dev));
+	priv->mii->name = "mtk-mac-mdio";
+	priv->mii->parent = dev;
+	priv->mii->read = mtk_star_mdio_read;
+	priv->mii->write = mtk_star_mdio_write;
+	priv->mii->priv = priv;
+
+	ret = of_mdiobus_register(priv->mii, mdio_node);
+
+out_put_node:
+	of_node_put(mdio_node);
+	return ret;
+}
+
+static int mtk_star_suspend(struct device *dev)
+{
+	struct mtk_star_priv *priv;
+	struct net_device *ndev;
+
+	ndev = dev_get_drvdata(dev);
+	priv = netdev_priv(ndev);
+
+	if (netif_running(ndev))
+		mtk_star_disable(ndev);
+
+	clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
+
+	return 0;
+}
+
+static int mtk_star_resume(struct device *dev)
+{
+	struct mtk_star_priv *priv;
+	struct net_device *ndev;
+	int ret;
+
+	ndev = dev_get_drvdata(dev);
+	priv = netdev_priv(ndev);
+
+	ret = clk_bulk_prepare_enable(MTK_STAR_NCLKS, priv->clks);
+	if (ret)
+		return ret;
+
+	if (netif_running(ndev)) {
+		ret = mtk_star_enable(ndev);
+		if (ret)
+			clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
+	}
+
+	return ret;
+}
+
+static void mtk_star_clk_disable_unprepare(void *data)
+{
+	struct mtk_star_priv *priv = data;
+
+	clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
+}
+
+static void mtk_star_mdiobus_unregister(void *data)
+{
+	struct mtk_star_priv *priv = data;
+
+	mdiobus_unregister(priv->mii);
+}
+
+static void mtk_star_unregister_netdev(void *data)
+{
+	struct net_device *ndev = data;
+
+	unregister_netdev(ndev);
+}
+
+static int mtk_star_probe(struct platform_device *pdev)
+{
+	struct device_node *of_node;
+	struct mtk_star_priv *priv;
+	struct net_device *ndev;
+	struct device *dev;
+	void __iomem *base;
+	int ret, i;
+
+	dev = &pdev->dev;
+	of_node = dev->of_node;
+
+	ndev = devm_alloc_etherdev(dev, sizeof(*priv));
+	if (!ndev)
+		return -ENOMEM;
+
+	priv = netdev_priv(ndev);
+	priv->ndev = ndev;
+	SET_NETDEV_DEV(ndev, dev);
+	platform_set_drvdata(pdev, ndev);
+
+	ndev->min_mtu = ETH_ZLEN;
+	ndev->max_mtu = MTK_STAR_MAX_FRAME_SIZE;
+
+	spin_lock_init(&priv->lock);
+	INIT_WORK(&priv->stats_work, mtk_star_update_stats_work);
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/* We won't be checking the return values of regmap read & write
+	 * functions. They can only fail for mmio if there's a clock attached
+	 * to regmap which is not the case here.
+	 */
+	priv->regs = devm_regmap_init_mmio(dev, base,
+					   &mtk_star_regmap_config);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->pericfg = syscon_regmap_lookup_by_phandle(of_node,
+							"mediatek,pericfg");
+	if (IS_ERR(priv->pericfg)) {
+		dev_err(dev, "Failed to lookup the PERICFG syscon\n");
+		return PTR_ERR(priv->pericfg);
+	}
+
+	ndev->irq = platform_get_irq(pdev, 0);
+	if (ndev->irq < 0)
+		return ndev->irq;
+
+	for (i = 0; i < MTK_STAR_NCLKS; i++)
+		priv->clks[i].id = mtk_star_clk_names[i];
+	ret = devm_clk_bulk_get(dev, MTK_STAR_NCLKS, priv->clks);
+	if (ret)
+		return ret;
+
+	ret = clk_bulk_prepare_enable(MTK_STAR_NCLKS, priv->clks);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev,
+				       mtk_star_clk_disable_unprepare, priv);
+	if (ret)
+		return ret;
+
+	ret = of_get_phy_mode(of_node, &priv->phy_intf);
+	if (ret) {
+		return ret;
+	} else if (priv->phy_intf != PHY_INTERFACE_MODE_RMII) {
+		dev_err(dev, "unsupported phy mode: %s\n",
+			phy_modes(priv->phy_intf));
+		return -EINVAL;
+	}
+
+	priv->phy_node = of_parse_phandle(of_node, "phy-handle", 0);
+	if (!priv->phy_node) {
+		dev_err(dev, "failed to retrieve the phy handle from device tree\n");
+		return -ENODEV;
+	}
+
+	mtk_star_set_mode_rmii(priv);
+
+	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
+	if (ret) {
+		dev_err(dev, "unsupported DMA mask\n");
+		return ret;
+	}
+
+	priv->ring_base = dmam_alloc_coherent(dev, MTK_STAR_DMA_SIZE,
+					      &priv->dma_addr,
+					      GFP_KERNEL | GFP_DMA);
+	if (!priv->ring_base)
+		return -ENOMEM;
+
+	mtk_star_nic_disable_pd(priv);
+	mtk_star_init_config(priv);
+
+	ret = mtk_star_mdio_init(ndev);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, mtk_star_mdiobus_unregister, priv);
+	if (ret)
+		return ret;
+
+	ret = eth_platform_get_mac_address(dev, ndev->dev_addr);
+	if (ret || !is_valid_ether_addr(ndev->dev_addr))
+		eth_hw_addr_random(ndev);
+
+	ndev->netdev_ops = &mtk_star_netdev_ops;
+	ndev->ethtool_ops = &mtk_star_ethtool_ops;
+
+	netif_napi_add(ndev, &priv->napi, mtk_star_poll, MTK_STAR_NAPI_WEIGHT);
+
+	ret = register_netdev(ndev);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, mtk_star_unregister_netdev, ndev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct of_device_id mtk_star_of_match[] = {
+	{ .compatible = "mediatek,mt8516-eth", },
+	{ .compatible = "mediatek,mt8518-eth", },
+	{ .compatible = "mediatek,mt8175-eth", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mtk_star_of_match);
+
+static SIMPLE_DEV_PM_OPS(mtk_star_pm_ops,
+			 mtk_star_suspend, mtk_star_resume);
+
+static struct platform_driver mtk_star_driver = {
+	.driver = {
+		.name = MTK_STAR_DRVNAME,
+		.pm = &mtk_star_pm_ops,
+		.of_match_table = of_match_ptr(mtk_star_of_match),
+	},
+	.probe = mtk_star_probe,
+};
+module_platform_driver(mtk_star_driver);
+
+MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
+MODULE_DESCRIPTION("Mediatek STAR Ethernet MAC Driver");
+MODULE_LICENSE("GPL");