path: root/target/linux/bcm4908/patches-5.4/170-0002-net-broadcom-bcm4908_enet-add-BCM4908-controller-dri.patch

From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Fri, 5 Feb 2021 21:59:51 +0100
Subject: [PATCH 2/2] net: broadcom: bcm4908_enet: add BCM4908 controller
 driver
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

BCM4908 SoCs family has integrated Ethernel controller that includes
UniMAC but uses different DMA engine (than other controllers) and
requires different programming.

Ethernet controller in BCM4908 is always connected to the internal SF2
switch's port and uses fixed link.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 MAINTAINERS                                  |   9 +
 drivers/net/ethernet/broadcom/Kconfig        |   8 +
 drivers/net/ethernet/broadcom/Makefile       |   1 +
 drivers/net/ethernet/broadcom/bcm4908_enet.c | 671 +++++++++++++++++++
 drivers/net/ethernet/broadcom/bcm4908_enet.h |  96 +++
 5 files changed, 785 insertions(+)
 create mode 100644 drivers/net/ethernet/broadcom/bcm4908_enet.c
 create mode 100644 drivers/net/ethernet/broadcom/bcm4908_enet.h

--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3207,6 +3207,15 @@ F:	Documentation/devicetree/bindings/mip
 F:	arch/mips/bcm47xx/*
 F:	arch/mips/include/asm/mach-bcm47xx/*
 
+BROADCOM BCM4908 ETHERNET DRIVER
+M:	Rafał Miłecki <rafal@milecki.pl>
+M:	bcm-kernel-feedback-list@broadcom.com
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/net/brcm,bcm4908-enet.yaml
+F:	drivers/net/ethernet/broadcom/bcm4908_enet.*
+F:	drivers/net/ethernet/broadcom/unimac.h
+
 BROADCOM BCM5301X ARM ARCHITECTURE
 M:	Hauke Mehrtens <hauke@hauke-m.de>
 M:	Rafał Miłecki <zajec5@gmail.com>
--- a/drivers/net/ethernet/broadcom/Kconfig
+++ b/drivers/net/ethernet/broadcom/Kconfig
@@ -51,6 +51,14 @@ config B44_PCI
 	depends on B44_PCI_AUTOSELECT && B44_PCICORE_AUTOSELECT
 	default y
 
+config BCM4908_ENET
+	tristate "Broadcom BCM4908 internal mac support"
+	depends on ARCH_BCM4908 || COMPILE_TEST
+	default ARCH_BCM4908
+	help
+	  This driver supports Ethernet controller integrated into Broadcom
+	  BCM4908 family SoCs.
+
 config BCM63XX_ENET
 	tristate "Broadcom 63xx internal mac support"
 	depends on BCM63XX
--- a/drivers/net/ethernet/broadcom/Makefile
+++ b/drivers/net/ethernet/broadcom/Makefile
@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_B44) += b44.o
+obj-$(CONFIG_BCM4908_ENET) += bcm4908_enet.o
 obj-$(CONFIG_BCM63XX_ENET) += bcm63xx_enet.o
 obj-$(CONFIG_BCMGENET) += genet/
 obj-$(CONFIG_BNX2) += bnx2.o
--- /dev/null
+++ b/drivers/net/ethernet/broadcom/bcm4908_enet.c
@@ -0,0 +1,671 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <linux/delay.h>
+#include <linux/etherdevice.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "bcm4908_enet.h"
+#include "unimac.h"
+
+#define ENET_DMA_CH_RX_CFG			ENET_DMA_CH0_CFG
+#define ENET_DMA_CH_TX_CFG			ENET_DMA_CH1_CFG
+#define ENET_DMA_CH_RX_STATE_RAM		ENET_DMA_CH0_STATE_RAM
+#define ENET_DMA_CH_TX_STATE_RAM		ENET_DMA_CH1_STATE_RAM
+
+#define ENET_TX_BDS_NUM				200
+#define ENET_RX_BDS_NUM				200
+#define ENET_RX_BDS_NUM_MAX			8192
+
+#define ENET_DMA_INT_DEFAULTS			(ENET_DMA_CH_CFG_INT_DONE | \
+						 ENET_DMA_CH_CFG_INT_NO_DESC | \
+						 ENET_DMA_CH_CFG_INT_BUFF_DONE)
+#define ENET_DMA_MAX_BURST_LEN			8 /* in 64 bit words */
+
+#define ENET_MTU_MIN				60
+#define ENET_MTU_MAX				1500 /* Is it possible to support 2044? */
+#define ENET_MTU_MAX_EXTRA_SIZE			32 /* L2 */
+
+struct bcm4908_enet_dma_ring_bd {
+	__le32 ctl;
+	__le32 addr;
+} __packed;
+
+struct bcm4908_enet_dma_ring_slot {
+	struct sk_buff *skb;
+	unsigned int len;
+	dma_addr_t dma_addr;
+};
+
+struct bcm4908_enet_dma_ring {
+	int is_tx;
+	int read_idx;
+	int write_idx;
+	int length;
+	u16 cfg_block;
+	u16 st_ram_block;
+
+	union {
+		void *cpu_addr;
+		struct bcm4908_enet_dma_ring_bd *buf_desc;
+	};
+	dma_addr_t dma_addr;
+
+	struct bcm4908_enet_dma_ring_slot *slots;
+};
+
+struct bcm4908_enet {
+	struct device *dev;
+	struct net_device *netdev;
+	struct napi_struct napi;
+	void __iomem *base;
+
+	struct bcm4908_enet_dma_ring tx_ring;
+	struct bcm4908_enet_dma_ring rx_ring;
+};
+
+/***
+ * R/W ops
+ */
+
+static u32 enet_read(struct bcm4908_enet *enet, u16 offset)
+{
+	return readl(enet->base + offset);
+}
+
+static void enet_write(struct bcm4908_enet *enet, u16 offset, u32 value)
+{
+	writel(value, enet->base + offset);
+}
+
+static void enet_maskset(struct bcm4908_enet *enet, u16 offset, u32 mask, u32 set)
+{
+	u32 val;
+
+	WARN_ON(set & ~mask);
+
+	val = enet_read(enet, offset);
+	val = (val & ~mask) | (set & mask);
+	enet_write(enet, offset, val);
+}
+
+static void enet_set(struct bcm4908_enet *enet, u16 offset, u32 set)
+{
+	enet_maskset(enet, offset, set, set);
+}
+
+static u32 enet_umac_read(struct bcm4908_enet *enet, u16 offset)
+{
+	return enet_read(enet, ENET_UNIMAC + offset);
+}
+
+static void enet_umac_write(struct bcm4908_enet *enet, u16 offset, u32 value)
+{
+	enet_write(enet, ENET_UNIMAC + offset, value);
+}
+
+static void enet_umac_set(struct bcm4908_enet *enet, u16 offset, u32 set)
+{
+	enet_set(enet, ENET_UNIMAC + offset, set);
+}
+
+/***
+ * Helpers
+ */
+
+static void bcm4908_enet_intrs_on(struct bcm4908_enet *enet)
+{
+	enet_write(enet, ENET_DMA_CH_RX_CFG + ENET_DMA_CH_CFG_INT_MASK, ENET_DMA_INT_DEFAULTS);
+}
+
+static void bcm4908_enet_intrs_off(struct bcm4908_enet *enet)
+{
+	enet_write(enet, ENET_DMA_CH_RX_CFG + ENET_DMA_CH_CFG_INT_MASK, 0);
+}
+
+static void bcm4908_enet_intrs_ack(struct bcm4908_enet *enet)
+{
+	enet_write(enet, ENET_DMA_CH_RX_CFG + ENET_DMA_CH_CFG_INT_STAT, ENET_DMA_INT_DEFAULTS);
+}
+
+/***
+ * DMA
+ */
+
+static int bcm4908_dma_alloc_buf_descs(struct bcm4908_enet *enet,
+				       struct bcm4908_enet_dma_ring *ring)
+{
+	int size = ring->length * sizeof(struct bcm4908_enet_dma_ring_bd);
+	struct device *dev = enet->dev;
+
+	ring->cpu_addr = dma_alloc_coherent(dev, size, &ring->dma_addr, GFP_KERNEL);
+	if (!ring->cpu_addr)
+		return -ENOMEM;
+
+	if (((uintptr_t)ring->cpu_addr) & (0x40 - 1)) {
+		dev_err(dev, "Invalid DMA ring alignment\n");
+		goto err_free_buf_descs;
+	}
+
+	ring->slots = kzalloc(ring->length * sizeof(*ring->slots), GFP_KERNEL);
+	if (!ring->slots)
+		goto err_free_buf_descs;
+
+	ring->read_idx = 0;
+	ring->write_idx = 0;
+
+	return 0;
+
+err_free_buf_descs:
+	dma_free_coherent(dev, size, ring->cpu_addr, ring->dma_addr);
+	return -ENOMEM;
+}
+
+static void bcm4908_enet_dma_free(struct bcm4908_enet *enet)
+{
+	struct bcm4908_enet_dma_ring *tx_ring = &enet->tx_ring;
+	struct bcm4908_enet_dma_ring *rx_ring = &enet->rx_ring;
+	struct device *dev = enet->dev;
+	int size;
+
+	size = rx_ring->length * sizeof(struct bcm4908_enet_dma_ring_bd);
+	if (rx_ring->cpu_addr)
+		dma_free_coherent(dev, size, rx_ring->cpu_addr, rx_ring->dma_addr);
+	kfree(rx_ring->slots);
+
+	size = tx_ring->length * sizeof(struct bcm4908_enet_dma_ring_bd);
+	if (tx_ring->cpu_addr)
+		dma_free_coherent(dev, size, tx_ring->cpu_addr, tx_ring->dma_addr);
+	kfree(tx_ring->slots);
+}
+
+static int bcm4908_enet_dma_alloc(struct bcm4908_enet *enet)
+{
+	struct bcm4908_enet_dma_ring *tx_ring = &enet->tx_ring;
+	struct bcm4908_enet_dma_ring *rx_ring = &enet->rx_ring;
+	struct device *dev = enet->dev;
+	int err;
+
+	tx_ring->length = ENET_TX_BDS_NUM;
+	tx_ring->is_tx = 1;
+	tx_ring->cfg_block = ENET_DMA_CH_TX_CFG;
+	tx_ring->st_ram_block = ENET_DMA_CH_TX_STATE_RAM;
+	err = bcm4908_dma_alloc_buf_descs(enet, tx_ring);
+	if (err) {
+		dev_err(dev, "Failed to alloc TX buf descriptors: %d\n", err);
+		return err;
+	}
+
+	rx_ring->length = ENET_RX_BDS_NUM;
+	rx_ring->is_tx = 0;
+	rx_ring->cfg_block = ENET_DMA_CH_RX_CFG;
+	rx_ring->st_ram_block = ENET_DMA_CH_RX_STATE_RAM;
+	err = bcm4908_dma_alloc_buf_descs(enet, rx_ring);
+	if (err) {
+		dev_err(dev, "Failed to alloc RX buf descriptors: %d\n", err);
+		bcm4908_enet_dma_free(enet);
+		return err;
+	}
+
+	return 0;
+}
+
+static void bcm4908_enet_dma_reset(struct bcm4908_enet *enet)
+{
+	struct bcm4908_enet_dma_ring *rings[] = { &enet->rx_ring, &enet->tx_ring };
+	int i;
+
+	/* Disable the DMA controller and channel */
+	for (i = 0; i < ARRAY_SIZE(rings); i++)
+		enet_write(enet, rings[i]->cfg_block + ENET_DMA_CH_CFG, 0);
+	enet_maskset(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_MASTER_EN, 0);
+
+	/* Reset channels state */
+	for (i = 0; i < ARRAY_SIZE(rings); i++) {
+		struct bcm4908_enet_dma_ring *ring = rings[i];
+
+		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_BASE_DESC_PTR, 0);
+		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_STATE_DATA, 0);
+		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_DESC_LEN_STATUS, 0);
+		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_DESC_BASE_BUFPTR, 0);
+	}
+}
+
+static int bcm4908_enet_dma_alloc_rx_buf(struct bcm4908_enet *enet, unsigned int idx)
+{
+	struct bcm4908_enet_dma_ring_bd *buf_desc = &enet->rx_ring.buf_desc[idx];
+	struct bcm4908_enet_dma_ring_slot *slot = &enet->rx_ring.slots[idx];
+	struct device *dev = enet->dev;
+	u32 tmp;
+	int err;
+
+	slot->len = ENET_MTU_MAX + ENET_MTU_MAX_EXTRA_SIZE;
+
+	slot->skb = netdev_alloc_skb(enet->netdev, slot->len);
+	if (!slot->skb)
+		return -ENOMEM;
+
+	slot->dma_addr = dma_map_single(dev, slot->skb->data, slot->len, DMA_FROM_DEVICE);
+	err = dma_mapping_error(dev, slot->dma_addr);
+	if (err) {
+		dev_err(dev, "Failed to map DMA buffer: %d\n", err);
+		kfree_skb(slot->skb);
+		slot->skb = NULL;
+		return err;
+	}
+
+	tmp = slot->len << DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT;
+	tmp |= DMA_CTL_STATUS_OWN;
+	if (idx == enet->rx_ring.length - 1)
+		tmp |= DMA_CTL_STATUS_WRAP;
+	buf_desc->ctl = cpu_to_le32(tmp);
+	buf_desc->addr = cpu_to_le32(slot->dma_addr);
+
+	return 0;
+}
+
+static void bcm4908_enet_dma_ring_init(struct bcm4908_enet *enet,
+				       struct bcm4908_enet_dma_ring *ring)
+{
+	int reset_channel = 0; /* We support only 1 main channel (with TX and RX) */
+	int reset_subch = ring->is_tx ? 1 : 0;
+
+	/* Reset the DMA channel */
+	enet_write(enet, ENET_DMA_CTRL_CHANNEL_RESET, BIT(reset_channel * 2 + reset_subch));
+	enet_write(enet, ENET_DMA_CTRL_CHANNEL_RESET, 0);
+
+	enet_write(enet, ring->cfg_block + ENET_DMA_CH_CFG, 0);
+	enet_write(enet, ring->cfg_block + ENET_DMA_CH_CFG_MAX_BURST, ENET_DMA_MAX_BURST_LEN);
+	enet_write(enet, ring->cfg_block + ENET_DMA_CH_CFG_INT_MASK, 0);
+
+	enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_BASE_DESC_PTR,
+		   (uint32_t)ring->dma_addr);
+}
+
+static void bcm4908_enet_dma_uninit(struct bcm4908_enet *enet)
+{
+	struct bcm4908_enet_dma_ring *rx_ring = &enet->rx_ring;
+	struct bcm4908_enet_dma_ring_slot *slot;
+	struct device *dev = enet->dev;
+	int i;
+
+	for (i = rx_ring->length - 1; i >= 0; i--) {
+		slot = &rx_ring->slots[i];
+		if (!slot->skb)
+			continue;
+		dma_unmap_single(dev, slot->dma_addr, slot->len, DMA_FROM_DEVICE);
+		kfree_skb(slot->skb);
+		slot->skb = NULL;
+	}
+}
+
+static int bcm4908_enet_dma_init(struct bcm4908_enet *enet)
+{
+	struct bcm4908_enet_dma_ring *rx_ring = &enet->rx_ring;
+	struct device *dev = enet->dev;
+	int err;
+	int i;
+
+	for (i = 0; i < rx_ring->length; i++) {
+		err = bcm4908_enet_dma_alloc_rx_buf(enet, i);
+		if (err) {
+			dev_err(dev, "Failed to alloc RX buffer: %d\n", err);
+			bcm4908_enet_dma_uninit(enet);
+			return err;
+		}
+	}
+
+	bcm4908_enet_dma_ring_init(enet, &enet->tx_ring);
+	bcm4908_enet_dma_ring_init(enet, &enet->rx_ring);
+
+	return 0;
+}
+
+static void bcm4908_enet_dma_tx_ring_enable(struct bcm4908_enet *enet,
+					    struct bcm4908_enet_dma_ring *ring)
+{
+	enet_write(enet, ring->cfg_block + ENET_DMA_CH_CFG, ENET_DMA_CH_CFG_ENABLE);
+}
+
+static void bcm4908_enet_dma_tx_ring_disable(struct bcm4908_enet *enet,
+					     struct bcm4908_enet_dma_ring *ring)
+{
+	enet_write(enet, ring->cfg_block + ENET_DMA_CH_CFG, 0);
+}
+
+static void bcm4908_enet_dma_rx_ring_enable(struct bcm4908_enet *enet,
+					    struct bcm4908_enet_dma_ring *ring)
+{
+	enet_set(enet, ring->cfg_block + ENET_DMA_CH_CFG, ENET_DMA_CH_CFG_ENABLE);
+}
+
+static void bcm4908_enet_dma_rx_ring_disable(struct bcm4908_enet *enet,
+					     struct bcm4908_enet_dma_ring *ring)
+{
+	unsigned long deadline;
+	u32 tmp;
+
+	enet_maskset(enet, ring->cfg_block + ENET_DMA_CH_CFG, ENET_DMA_CH_CFG_ENABLE, 0);
+
+	deadline = jiffies + usecs_to_jiffies(2000);
+	do {
+		tmp = enet_read(enet, ring->cfg_block + ENET_DMA_CH_CFG);
+		if (!(tmp & ENET_DMA_CH_CFG_ENABLE))
+			return;
+		enet_maskset(enet, ring->cfg_block + ENET_DMA_CH_CFG, ENET_DMA_CH_CFG_ENABLE, 0);
+		usleep_range(10, 30);
+	} while (!time_after_eq(jiffies, deadline));
+
+	dev_warn(enet->dev, "Timeout waiting for DMA TX stop\n");
+}
+
+/***
+ * Ethernet driver
+ */
+
+static void bcm4908_enet_gmac_init(struct bcm4908_enet *enet)
+{
+	u32 cmd;
+
+	cmd = enet_umac_read(enet, UMAC_CMD);
+	enet_umac_write(enet, UMAC_CMD, cmd | CMD_SW_RESET);
+	enet_umac_write(enet, UMAC_CMD, cmd & ~CMD_SW_RESET);
+
+	enet_set(enet, ENET_FLUSH, ENET_FLUSH_RXFIFO_FLUSH | ENET_FLUSH_TXFIFO_FLUSH);
+	enet_maskset(enet, ENET_FLUSH, ENET_FLUSH_RXFIFO_FLUSH | ENET_FLUSH_TXFIFO_FLUSH, 0);
+
+	enet_set(enet, ENET_MIB_CTRL, ENET_MIB_CTRL_CLR_MIB);
+	enet_maskset(enet, ENET_MIB_CTRL, ENET_MIB_CTRL_CLR_MIB, 0);
+
+	cmd = enet_umac_read(enet, UMAC_CMD);
+	cmd &= ~(CMD_SPEED_MASK << CMD_SPEED_SHIFT);
+	cmd &= ~CMD_TX_EN;
+	cmd &= ~CMD_RX_EN;
+	cmd |= CMD_SPEED_1000 << CMD_SPEED_SHIFT;
+	enet_umac_write(enet, UMAC_CMD, cmd);
+
+	enet_maskset(enet, ENET_GMAC_STATUS,
+		     ENET_GMAC_STATUS_ETH_SPEED_MASK |
+		     ENET_GMAC_STATUS_HD |
+		     ENET_GMAC_STATUS_AUTO_CFG_EN |
+		     ENET_GMAC_STATUS_LINK_UP,
+		     ENET_GMAC_STATUS_ETH_SPEED_1000 |
+		     ENET_GMAC_STATUS_AUTO_CFG_EN |
+		     ENET_GMAC_STATUS_LINK_UP);
+}
+
+static irqreturn_t bcm4908_enet_irq_handler(int irq, void *dev_id)
+{
+	struct bcm4908_enet *enet = dev_id;
+
+	bcm4908_enet_intrs_off(enet);
+	bcm4908_enet_intrs_ack(enet);
+
+	napi_schedule(&enet->napi);
+
+	return IRQ_HANDLED;
+}
+
+static int bcm4908_enet_open(struct net_device *netdev)
+{
+	struct bcm4908_enet *enet = netdev_priv(netdev);
+	struct device *dev = enet->dev;
+	int err;
+
+	err = request_irq(netdev->irq, bcm4908_enet_irq_handler, 0, "enet", enet);
+	if (err) {
+		dev_err(dev, "Failed to request IRQ %d: %d\n", netdev->irq, err);
+		return err;
+	}
+
+	bcm4908_enet_gmac_init(enet);
+	bcm4908_enet_dma_reset(enet);
+	bcm4908_enet_dma_init(enet);
+
+	enet_umac_set(enet, UMAC_CMD, CMD_TX_EN | CMD_RX_EN);
+
+	enet_set(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_MASTER_EN);
+	enet_maskset(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_FLOWC_CH1_EN, 0);
+	bcm4908_enet_dma_rx_ring_enable(enet, &enet->rx_ring);
+
+	napi_enable(&enet->napi);
+	netif_carrier_on(netdev);
+	netif_start_queue(netdev);
+
+	bcm4908_enet_intrs_ack(enet);
+	bcm4908_enet_intrs_on(enet);
+
+	return 0;
+}
+
+static int bcm4908_enet_stop(struct net_device *netdev)
+{
+	struct bcm4908_enet *enet = netdev_priv(netdev);
+
+	netif_stop_queue(netdev);
+	netif_carrier_off(netdev);
+	napi_disable(&enet->napi);
+
+	bcm4908_enet_dma_rx_ring_disable(enet, &enet->rx_ring);
+	bcm4908_enet_dma_tx_ring_disable(enet, &enet->tx_ring);
+
+	bcm4908_enet_dma_uninit(enet);
+
+	free_irq(enet->netdev->irq, enet);
+
+	return 0;
+}
+
+static int bcm4908_enet_start_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	struct bcm4908_enet *enet = netdev_priv(netdev);
+	struct bcm4908_enet_dma_ring *ring = &enet->tx_ring;
+	struct bcm4908_enet_dma_ring_slot *slot;
+	struct device *dev = enet->dev;
+	struct bcm4908_enet_dma_ring_bd *buf_desc;
+	int free_buf_descs;
+	u32 tmp;
+
+	/* Free transmitted skbs */
+	while (ring->read_idx != ring->write_idx) {
+		buf_desc = &ring->buf_desc[ring->read_idx];
+		if (le32_to_cpu(buf_desc->ctl) & DMA_CTL_STATUS_OWN)
+			break;
+		slot = &ring->slots[ring->read_idx];
+
+		dma_unmap_single(dev, slot->dma_addr, slot->len, DMA_TO_DEVICE);
+		dev_kfree_skb(slot->skb);
+		if (++ring->read_idx == ring->length)
+			ring->read_idx = 0;
+	}
+
+	/* Don't use the last empty buf descriptor */
+	if (ring->read_idx <= ring->write_idx)
+		free_buf_descs = ring->read_idx - ring->write_idx + ring->length;
+	else
+		free_buf_descs = ring->read_idx - ring->write_idx;
+	if (free_buf_descs < 2)
+		return NETDEV_TX_BUSY;
+
+	/* Hardware removes OWN bit after sending data */
+	buf_desc = &ring->buf_desc[ring->write_idx];
+	if (unlikely(le32_to_cpu(buf_desc->ctl) & DMA_CTL_STATUS_OWN)) {
+		netif_stop_queue(netdev);
+		return NETDEV_TX_BUSY;
+	}
+
+	slot = &ring->slots[ring->write_idx];
+	slot->skb = skb;
+	slot->len = skb->len;
+	slot->dma_addr = dma_map_single(dev, skb->data, skb->len, DMA_TO_DEVICE);
+	if (unlikely(dma_mapping_error(dev, slot->dma_addr)))
+		return NETDEV_TX_BUSY;
+
+	tmp = skb->len << DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT;
+	tmp |= DMA_CTL_STATUS_OWN;
+	tmp |= DMA_CTL_STATUS_SOP;
+	tmp |= DMA_CTL_STATUS_EOP;
+	tmp |= DMA_CTL_STATUS_APPEND_CRC;
+	if (ring->write_idx + 1 == ring->length - 1)
+		tmp |= DMA_CTL_STATUS_WRAP;
+
+	buf_desc->addr = cpu_to_le32((uint32_t)slot->dma_addr);
+	buf_desc->ctl = cpu_to_le32(tmp);
+
+	bcm4908_enet_dma_tx_ring_enable(enet, &enet->tx_ring);
+
+	if (++ring->write_idx == ring->length - 1)
+		ring->write_idx = 0;
+	enet->netdev->stats.tx_bytes += skb->len;
+	enet->netdev->stats.tx_packets++;
+
+	return NETDEV_TX_OK;
+}
+
+static int bcm4908_enet_poll(struct napi_struct *napi, int weight)
+{
+	struct bcm4908_enet *enet = container_of(napi, struct bcm4908_enet, napi);
+	struct device *dev = enet->dev;
+	int handled = 0;
+
+	while (handled < weight) {
+		struct bcm4908_enet_dma_ring_bd *buf_desc;
+		struct bcm4908_enet_dma_ring_slot slot;
+		u32 ctl;
+		int len;
+		int err;
+
+		buf_desc = &enet->rx_ring.buf_desc[enet->rx_ring.read_idx];
+		ctl = le32_to_cpu(buf_desc->ctl);
+		if (ctl & DMA_CTL_STATUS_OWN)
+			break;
+
+		slot = enet->rx_ring.slots[enet->rx_ring.read_idx];
+
+		/* Provide new buffer before unpinning the old one */
+		err = bcm4908_enet_dma_alloc_rx_buf(enet, enet->rx_ring.read_idx);
+		if (err)
+			break;
+
+		if (++enet->rx_ring.read_idx == enet->rx_ring.length)
+			enet->rx_ring.read_idx = 0;
+
+		len = (ctl & DMA_CTL_LEN_DESC_BUFLENGTH) >> DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT;
+
+		if (len < ENET_MTU_MIN ||
+		    (ctl & (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) != (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) {
+			kfree(slot.skb);
+			enet->netdev->stats.rx_dropped++;
+			break;
+		}
+
+		dma_unmap_single(dev, slot.dma_addr, slot.len, DMA_FROM_DEVICE);
+
+		skb_put(slot.skb, len - ETH_FCS_LEN);
+		slot.skb->protocol = eth_type_trans(slot.skb, enet->netdev);
+		netif_receive_skb(slot.skb);
+
+		enet->netdev->stats.rx_packets++;
+		enet->netdev->stats.rx_bytes += len;
+	}
+
+	if (handled < weight) {
+		napi_complete_done(napi, handled);
+		bcm4908_enet_intrs_on(enet);
+	}
+
+	return handled;
+}
+
+static const struct net_device_ops bcm4908_enet_netdev_ops = {
+	.ndo_open = bcm4908_enet_open,
+	.ndo_stop = bcm4908_enet_stop,
+	.ndo_start_xmit = bcm4908_enet_start_xmit,
+	.ndo_set_mac_address = eth_mac_addr,
+};
+
+static int bcm4908_enet_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct net_device *netdev;
+	struct bcm4908_enet *enet;
+	int err;
+
+	netdev = devm_alloc_etherdev(dev, sizeof(*enet));
+	if (!netdev)
+		return -ENOMEM;
+
+	enet = netdev_priv(netdev);
+	enet->dev = dev;
+	enet->netdev = netdev;
+
+	enet->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(enet->base)) {
+		dev_err(dev, "Failed to map registers: %ld\n", PTR_ERR(enet->base));
+		return PTR_ERR(enet->base);
+	}
+
+	netdev->irq = platform_get_irq(pdev, 0);
+	if (netdev->irq < 0)
+		return netdev->irq;
+
+	dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
+
+	err = bcm4908_enet_dma_alloc(enet);
+	if (err)
+		return err;
+
+	SET_NETDEV_DEV(netdev, &pdev->dev);
+	eth_hw_addr_random(netdev);
+	netdev->netdev_ops = &bcm4908_enet_netdev_ops;
+	netdev->min_mtu = ETH_ZLEN;
+	netdev->mtu = ENET_MTU_MAX;
+	netdev->max_mtu = ENET_MTU_MAX;
+	netif_napi_add(netdev, &enet->napi, bcm4908_enet_poll, 64);
+
+	err = register_netdev(netdev);
+	if (err) {
+		bcm4908_enet_dma_free(enet);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, enet);
+
+	return 0;
+}
+
+static int bcm4908_enet_remove(struct platform_device *pdev)
+{
+	struct bcm4908_enet *enet = platform_get_drvdata(pdev);
+
+	unregister_netdev(enet->netdev);
+	netif_napi_del(&enet->napi);
+	bcm4908_enet_dma_free(enet);
+
+	return 0;
+}
+
+static const struct of_device_id bcm4908_enet_of_match[] = {
+	{ .compatible = "brcm,bcm4908-enet"},
+	{},
+};
+
+static struct platform_driver bcm4908_enet_driver = {
+	.driver = {
+		.name = "bcm4908_enet",
+		.of_match_table = bcm4908_enet_of_match,
+	},
+	.probe	= bcm4908_enet_probe,
+	.remove = bcm4908_enet_remove,
+};
+module_platform_driver(bcm4908_enet_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DEVICE_TABLE(of, bcm4908_enet_of_match);
--- /dev/null
+++ b/drivers/net/ethernet/broadcom/bcm4908_enet.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __BCM4908_ENET_H
+#define __BCM4908_ENET_H
+
+#define ENET_CONTROL					0x000
+#define ENET_MIB_CTRL					0x004
+#define  ENET_MIB_CTRL_CLR_MIB				0x00000001
+#define ENET_RX_ERR_MASK				0x008
+#define ENET_MIB_MAX_PKT_SIZE				0x00C
+#define  ENET_MIB_MAX_PKT_SIZE_VAL			0x00003fff
+#define ENET_DIAG_OUT					0x01c
+#define ENET_ENABLE_DROP_PKT				0x020
+#define ENET_IRQ_ENABLE					0x024
+#define  ENET_IRQ_ENABLE_OVFL				0x00000001
+#define ENET_GMAC_STATUS				0x028
+#define  ENET_GMAC_STATUS_ETH_SPEED_MASK		0x00000003
+#define  ENET_GMAC_STATUS_ETH_SPEED_10			0x00000000
+#define  ENET_GMAC_STATUS_ETH_SPEED_100			0x00000001
+#define  ENET_GMAC_STATUS_ETH_SPEED_1000		0x00000002
+#define  ENET_GMAC_STATUS_HD				0x00000004
+#define  ENET_GMAC_STATUS_AUTO_CFG_EN			0x00000008
+#define  ENET_GMAC_STATUS_LINK_UP			0x00000010
+#define ENET_IRQ_STATUS					0x02c
+#define  ENET_IRQ_STATUS_OVFL				0x00000001
+#define ENET_OVERFLOW_COUNTER				0x030
+#define ENET_FLUSH					0x034
+#define  ENET_FLUSH_RXFIFO_FLUSH			0x00000001
+#define  ENET_FLUSH_TXFIFO_FLUSH			0x00000002
+#define ENET_RSV_SELECT					0x038
+#define ENET_BP_FORCE					0x03c
+#define  ENET_BP_FORCE_FORCE				0x00000001
+#define ENET_DMA_RX_OK_TO_SEND_COUNT			0x040
+#define  ENET_DMA_RX_OK_TO_SEND_COUNT_VAL		0x0000000f
+#define ENET_TX_CRC_CTRL				0x044
+#define ENET_MIB					0x200
+#define ENET_UNIMAC					0x400
+#define ENET_DMA					0x800
+#define ENET_DMA_CONTROLLER_CFG				0x800
+#define  ENET_DMA_CTRL_CFG_MASTER_EN			0x00000001
+#define  ENET_DMA_CTRL_CFG_FLOWC_CH1_EN			0x00000002
+#define  ENET_DMA_CTRL_CFG_FLOWC_CH3_EN			0x00000004
+#define ENET_DMA_FLOWCTL_CH1_THRESH_LO			0x804
+#define ENET_DMA_FLOWCTL_CH1_THRESH_HI			0x808
+#define ENET_DMA_FLOWCTL_CH1_ALLOC			0x80c
+#define  ENET_DMA_FLOWCTL_CH1_ALLOC_FORCE		0x80000000
+#define ENET_DMA_FLOWCTL_CH3_THRESH_LO			0x810
+#define ENET_DMA_FLOWCTL_CH3_THRESH_HI			0x814
+#define ENET_DMA_FLOWCTL_CH3_ALLOC			0x818
+#define ENET_DMA_FLOWCTL_CH5_THRESH_LO			0x81C
+#define ENET_DMA_FLOWCTL_CH5_THRESH_HI			0x820
+#define ENET_DMA_FLOWCTL_CH5_ALLOC			0x824
+#define ENET_DMA_FLOWCTL_CH7_THRESH_LO			0x828
+#define ENET_DMA_FLOWCTL_CH7_THRESH_HI			0x82C
+#define ENET_DMA_FLOWCTL_CH7_ALLOC			0x830
+#define ENET_DMA_CTRL_CHANNEL_RESET			0x834
+#define ENET_DMA_CTRL_CHANNEL_DEBUG			0x838
+#define ENET_DMA_CTRL_GLOBAL_INTERRUPT_STATUS		0x840
+#define ENET_DMA_CTRL_GLOBAL_INTERRUPT_MASK		0x844
+#define ENET_DMA_CH0_CFG				0xa00		/* RX */
+#define ENET_DMA_CH1_CFG				0xa10		/* TX */
+#define ENET_DMA_CH0_STATE_RAM				0xc00		/* RX */
+#define ENET_DMA_CH1_STATE_RAM				0xc10		/* TX */
+
+#define ENET_DMA_CH_CFG					0x00		/* assorted configuration */
+#define  ENET_DMA_CH_CFG_ENABLE				0x00000001	/* set to enable channel */
+#define  ENET_DMA_CH_CFG_PKT_HALT			0x00000002	/* idle after an EOP flag is detected */
+#define  ENET_DMA_CH_CFG_BURST_HALT			0x00000004	/* idle after finish current memory burst */
+#define ENET_DMA_CH_CFG_INT_STAT			0x04		/* interrupts control and status */
+#define ENET_DMA_CH_CFG_INT_MASK			0x08		/* interrupts mask */
+#define  ENET_DMA_CH_CFG_INT_BUFF_DONE			0x00000001	/* buffer done */
+#define  ENET_DMA_CH_CFG_INT_DONE			0x00000002	/* packet xfer complete */
+#define  ENET_DMA_CH_CFG_INT_NO_DESC			0x00000004	/* no valid descriptors */
+#define  ENET_DMA_CH_CFG_INT_RX_ERROR			0x00000008	/* rxdma detect client protocol error */
+#define ENET_DMA_CH_CFG_MAX_BURST			0x0c		/* max burst length permitted */
+#define  ENET_DMA_CH_CFG_MAX_BURST_DESCSIZE_SEL		0x00040000	/* DMA Descriptor Size Selection */
+#define ENET_DMA_CH_CFG_SIZE				0x10
+
+#define ENET_DMA_CH_STATE_RAM_BASE_DESC_PTR		0x00		/* descriptor ring start address */
+#define ENET_DMA_CH_STATE_RAM_STATE_DATA		0x04		/* state/bytes done/ring offset */
+#define ENET_DMA_CH_STATE_RAM_DESC_LEN_STATUS		0x08		/* buffer descriptor status and len */
+#define ENET_DMA_CH_STATE_RAM_DESC_BASE_BUFPTR		0x0c		/* buffer descrpitor current processing */
+#define ENET_DMA_CH_STATE_RAM_SIZE			0x10
+
+#define DMA_CTL_STATUS_APPEND_CRC			0x00000100
+#define DMA_CTL_STATUS_APPEND_BRCM_TAG			0x00000200
+#define DMA_CTL_STATUS_PRIO				0x00000C00  /* Prio for Tx */
+#define DMA_CTL_STATUS_WRAP				0x00001000  /* */
+#define DMA_CTL_STATUS_SOP				0x00002000  /* first buffer in packet */
+#define DMA_CTL_STATUS_EOP				0x00004000  /* last buffer in packet */
+#define DMA_CTL_STATUS_OWN				0x00008000  /* cleared by DMA, set by SW */
+#define DMA_CTL_LEN_DESC_BUFLENGTH			0x0fff0000
+#define DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT		16
+#define DMA_CTL_LEN_DESC_MULTICAST			0x40000000
+#define DMA_CTL_LEN_DESC_USEFPM				0x80000000
+
+#endif