On Wed, Jul 20, 2016 at 10:03:16AM +0200, LABBE Corentin wrote:
> This patch add support for sun8i-emac ethernet MAC hardware.
> It could be found in Allwinner H3/A83T/A64 SoCs.
> 
> It supports 10/100/1000 Mbit/s speed with half/full duplex.
> It can use an internal PHY (MII 10/100) or an external PHY
> via RGMII/RMII.
> 
> Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
> ---
>  drivers/net/ethernet/allwinner/Kconfig      |   13 +
>  drivers/net/ethernet/allwinner/Makefile     |    1 +
>  drivers/net/ethernet/allwinner/sun8i-emac.c | 2129 +++++++++++++++++++++++++++
>  3 files changed, 2143 insertions(+)
>  create mode 100644 drivers/net/ethernet/allwinner/sun8i-emac.c
> 
> diff --git a/drivers/net/ethernet/allwinner/Kconfig b/drivers/net/ethernet/allwinner/Kconfig
> index 47da7e7..060569c 100644
> --- a/drivers/net/ethernet/allwinner/Kconfig
> +++ b/drivers/net/ethernet/allwinner/Kconfig
> @@ -33,4 +33,17 @@ config SUN4I_EMAC
>            To compile this driver as a module, choose M here.  The module
>            will be called sun4i-emac.
>  
> +config SUN8I_EMAC
> +	tristate "Allwinner sun8i EMAC support"
> +	depends on ARCH_SUNXI || COMPILE_TEST
> +	depends on OF
> +	select MII
> +	select PHYLIB
> +        ---help---
> +	  This driver support the sun8i EMAC ethernet driver present on
> +	  H3/A83T/A64 Allwinner SoCs.
> +
> +          To compile this driver as a module, choose M here.  The module
> +          will be called sun8i-emac.
> +
>  endif # NET_VENDOR_ALLWINNER
> diff --git a/drivers/net/ethernet/allwinner/Makefile b/drivers/net/ethernet/allwinner/Makefile
> index 03129f7..8bd1693c 100644
> --- a/drivers/net/ethernet/allwinner/Makefile
> +++ b/drivers/net/ethernet/allwinner/Makefile
> @@ -3,3 +3,4 @@
>  #
>  
>  obj-$(CONFIG_SUN4I_EMAC) += sun4i-emac.o
> +obj-$(CONFIG_SUN8I_EMAC) += sun8i-emac.o
> diff --git a/drivers/net/ethernet/allwinner/sun8i-emac.c b/drivers/net/ethernet/allwinner/sun8i-emac.c
> new file mode 100644
> index 0000000..fc0c1dd
> --- /dev/null
> +++ b/drivers/net/ethernet/allwinner/sun8i-emac.c
> @@ -0,0 +1,2129 @@
> +/*
> + * sun8i-emac driver
> + *
> + * Copyright (C) 2015-2016 Corentin LABBE <clabbe.montjoie@gmail.com>
> + *
> + * This is the driver for Allwinner Ethernet MAC found in H3/A83T/A64 SoC
> + *
> + * TODO:
> + * - MAC filtering
> + * - Jumbo frame
> + * - features rx-all (NETIF_F_RXALL_BIT)
> + */
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/etherdevice.h>
> +#include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> +#include <linux/mii.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/of_device.h>
> +#include <linux/of_mdio.h>
> +#include <linux/of_net.h>
> +#include <linux/phy.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/pinctrl/pinctrl.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +#include <linux/scatterlist.h>
> +#include <linux/skbuff.h>
> +
> +#define SUN8I_EMAC_BASIC_CTL0	0x00
> +#define SUN8I_EMAC_BASIC_CTL1	0x04
> +#define SUN8I_EMAC_INT_STA	0x08
> +#define SUN8I_EMAC_INT_EN	0x0C
> +#define SUN8I_EMAC_TX_CTL0	0x10
> +#define SUN8I_EMAC_TX_CTL1	0x14
> +#define SUN8I_EMAC_TX_FLOW_CTL	0x1C
> +#define SUN8I_EMAC_RX_CTL0	0x24
> +#define SUN8I_EMAC_RX_CTL1	0x28
> +#define SUN8I_EMAC_RX_FRM_FLT	0x38
> +#define SUN8I_EMAC_MDIO_CMD	0x48
> +#define SUN8I_EMAC_MDIO_DATA	0x4C
> +#define SUN8I_EMAC_TX_DMA_STA	0xB0
> +#define SUN8I_EMAC_TX_CUR_DESC	0xB4
> +#define SUN8I_EMAC_TX_CUR_BUF	0xB8
> +#define SUN8I_EMAC_RX_DMA_STA	0xC0
> +
> +#define MDIO_CMD_MII_BUSY	BIT(0)
> +#define MDIO_CMD_MII_WRITE	BIT(1)
> +#define MDIO_CMD_MII_PHY_REG_ADDR_MASK	GENMASK(8, 4)
> +#define MDIO_CMD_MII_PHY_REG_ADDR_SHIFT	4
> +#define MDIO_CMD_MII_PHY_ADDR_MASK	GENMASK(16, 12)
> +#define MDIO_CMD_MII_PHY_ADDR_SHIFT	12
> +
> +#define SUN8I_EMAC_MACADDR_HI	0x50
> +#define SUN8I_EMAC_MACADDR_LO	0x54
> +
> +#define SUN8I_EMAC_RX_DESC_LIST 0x34
> +#define SUN8I_EMAC_TX_DESC_LIST 0x20
> +
> +#define SUN8I_EMAC_RX_DO_CRC BIT(27)
> +#define SUN8I_EMAC_RX_STRIP_FCS BIT(28)
> +
> +#define SUN8I_COULD_BE_USED_BY_DMA BIT(31)
> +
> +/* Used in RX_CTL1*/
> +#define RX_DMA_EN	BIT(30)
> +#define RX_DMA_START	BIT(31)
> +/* Used in TX_CTL1*/
> +#define TX_DMA_EN	BIT(30)
> +#define TX_DMA_START	BIT(31)
> +
> +/* Used in RX_CTL0 */
> +#define RX_RECEIVER_EN		BIT(31)
> +/* Used in TX_CTL0 */
> +#define TX_TRANSMITTER_EN	BIT(31)
> +
> +/* Basic CTL0 */
> +#define BCTL0_FD BIT(0)
> +#define BCTL0_SPEED_10		2
> +#define BCTL0_SPEED_100		3
> +#define BCTL0_SPEED_MASK	GENMASK(3, 2)
> +#define BCTL0_SPEED_SHIFT	2
> +
> +#define FLOW_RX 1
> +#define FLOW_TX 2
> +
> +#define RX_INT                  BIT(8)
> +#define TX_INT                  BIT(0)
> +
> +/* Bits used in frame RX status */
> +#define DSC_RX_FIRST		BIT(9)
> +#define DSC_RX_LAST		BIT(8)
> +
> +/* Bits used in frame TX ctl */
> +#define SUN8I_EMAC_MAGIC_TX_BIT	BIT(24)
> +#define SUN8I_EMAC_TX_DO_CRC	(BIT(27) | BIT(28))
> +#define DSC_TX_FIRST		BIT(29)
> +#define DSC_TX_LAST		BIT(30)
> +#define SUN8I_EMAC_WANT_INT	BIT(31)

Some defines are prefixed, some aren't, please be consistent (and I'd
prefer the former).

> +
> +enum emac_variant {
> +	NONE_EMAC,/* for be sure that variant is non-0 if set */
> +	A83T_EMAC,
> +	H3_EMAC,
> +	A64_EMAC,
> +};

Please don't use an enum, but attach a private structure with whatever
information you need there.

> +static const char const estats_str[][ETH_GSTRING_LEN] = {
> +	/* errors */
> +	"rx_payload_error",
> +	"rx_CRC_error",
> +	"rx_phy_error",
> +	"rx_length_error",
> +	"rx_col_error",
> +	"rx_header_error",
> +	"rx_overflow_error",
> +	"rx_saf_error",
> +	"rx_daf_error",
> +	"rx_buf_error",
> +	/* misc infos */
> +	"tx_stop_queue",
> +	"rx_dma_ua",
> +	"rx_dma_stop",
> +	"tx_dma_ua",
> +	"tx_dma_stop",
> +	"rx_hw_csum",
> +	"tx_hw_csum",
> +	/* interrupts */
> +	"rx_int",
> +	"tx_int",
> +	"rx_early_int",
> +	"tx_early_int",
> +	"tx_underflow_int",
> +	/* debug */
> +	"tx_used_desc",
> +	"napi_schedule",
> +	"napi_underflow",
> +};
> +
> +struct sun8i_emac_stats {
> +	u64 rx_payload_error;
> +	u64 rx_crc_error;
> +	u64 rx_phy_error;
> +	u64 rx_length_error;
> +	u64 rx_col_error;
> +	u64 rx_header_error;
> +	u64 rx_overflow_error;
> +	u64 rx_saf_fail;
> +	u64 rx_daf_fail;
> +	u64 rx_buf_error;
> +
> +	u64 tx_stop_queue;
> +	u64 rx_dma_ua;
> +	u64 rx_dma_stop;
> +	u64 tx_dma_ua;
> +	u64 tx_dma_stop;
> +	u64 rx_hw_csum;
> +	u64 tx_hw_csum;
> +
> +	u64 rx_int;
> +	u64 tx_int;
> +	u64 rx_early_int;
> +	u64 tx_early_int;
> +	u64 tx_underflow_int;
> +
> +	u64 tx_used_desc;
> +	u64 napi_schedule;
> +	u64 napi_underflow;
> +};
> +
> +/* The datasheet said that each descriptor can transfers up to 4096bytes
> + * But latter, a register documentation reduce that value to 2048
> + * Anyway using 2048 cause strange behaviours and even BSP driver use 2047
> + */
> +#define DESC_BUF_MAX 2044
> +#if (DESC_BUF_MAX < (ETH_FRAME_LEN + 4))
> +#error "DESC_BUF_MAX must be set at minimum to ETH_FRAME_LEN + 4"
> +#endif

Why would we need to change that?


> +/* MAGIC value for knowing if a descriptor is available or not */
> +#define DCLEAN (BIT(16) | BIT(14) | BIT(12) | BIT(10) | BIT(9))
> +
> +/* struct dma_desc - Structure of DMA descriptor used by the hardware
> + * @status: Status of the frame written by HW, so RO for the
> + *	driver (except for BIT(31) which is R/W)
> + * @ctl: Information on the frame written by the driver (INT, len,...)
> + * @buf_addr: physical address of the frame data
> + * @next: physical address of next dma_desc
> + */
> +struct dma_desc {
> +	u32 status;
> +	u32 ctl;
> +	u32 buf_addr;
> +	u32 next;
> +};

You should use the endian-aware variants here.

> +/* Describe how data from skb are DMA mapped (used in txinfo map member) */
> +#define MAP_SINGLE 1
> +#define MAP_PAGE 2
> +
> +/* Structure for storing information about data in TX ring buffer */
> +struct txinfo {
> +	struct sk_buff *skb;
> +	int map;
> +};
> +
> +struct sun8i_emac_priv {
> +	void __iomem *base;
> +	void __iomem *syscon;
> +	int irq;
> +	struct device *dev;
> +	struct net_device *ndev;
> +	struct mii_bus *mdio;
> +	struct napi_struct napi;
> +	spinlock_t tx_lock;/* control the access of transmit descriptors */
> +	int duplex;
> +	int speed;
> +	int link;
> +	int phy_interface;
> +	enum emac_variant variant;
> +	struct device_node *phy_node;
> +	struct clk *ahb_clk;
> +	struct clk *ephy_clk;
> +	bool use_internal_phy;
> +
> +	struct reset_control *rst;
> +	struct reset_control *rst_ephy;
> +
> +	struct dma_desc *dd_rx;
> +	dma_addr_t dd_rx_phy;
> +	struct dma_desc *dd_tx;
> +	dma_addr_t dd_tx_phy;
> +	struct sk_buff **rx_skb;
> +	struct txinfo *txl;
> +
> +	int nbdesc_tx;
> +	int nbdesc_rx;
> +	int tx_slot;
> +	int tx_dirty;
> +	int rx_dirty;
> +	struct sun8i_emac_stats estats;
> +	u32 msg_enable;
> +	int flow_ctrl;
> +	int pause;
> +};
> +
> +static irqreturn_t sun8i_emac_dma_interrupt(int irq, void *dev_id);
> +
> +static void rb_inc(int *p, const int max)
> +{
> +	(*p)++;
> +	(*p) %= max;

No locking?

> +}
> +
> +/* Return the number of contiguous free descriptors
> + * starting from tx_slot
> + */
> +static int rb_tx_numfreedesc(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	if (priv->tx_slot < priv->tx_dirty)
> +		return priv->tx_dirty - priv->tx_slot;
> +
> +	return (priv->nbdesc_tx - priv->tx_slot) + priv->tx_dirty;
> +}
> +
> +/* Allocate a skb in a DMA descriptor
> + *
> + * @i index of slot to fill
> +*/
> +static int sun8i_emac_rx_skb(struct net_device *ndev, int i)

You're missing the first parameters in your comment.

> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct dma_desc *ddesc;
> +	struct sk_buff *skb;
> +
> +	ddesc = priv->dd_rx + i;
> +
> +	ddesc->ctl = 0;
> +
> +	skb = netdev_alloc_skb_ip_align(ndev, DESC_BUF_MAX);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	/* should not happen */
> +	if (unlikely(priv->rx_skb[i]))
> +		dev_warn(priv->dev, "BUG: Leaking a skbuff\n");
> +
> +	priv->rx_skb[i] = skb;
> +
> +	ddesc->buf_addr = dma_map_single(priv->dev, skb->data,
> +					 DESC_BUF_MAX, DMA_FROM_DEVICE);
> +	if (dma_mapping_error(priv->dev, ddesc->buf_addr)) {
> +		dev_err(priv->dev, "ERROR: Cannot map RX buffer for DMA\n");
> +		dev_kfree_skb(skb);
> +		return -EFAULT;
> +	}
> +	ddesc->ctl |= DESC_BUF_MAX;
> +	wmb();/* SUN8I_COULD_BE_USED_BY_DMA must be the last value written */

Please don't put a comment on the line itself, but above.

> +	ddesc->status = SUN8I_COULD_BE_USED_BY_DMA;
> +
> +	return 0;
> +}
> +
> +static void sun8i_emac_stop_tx(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v;
> +
> +	netif_stop_queue(ndev);
> +
> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL0);
> +	v &= ~TX_TRANSMITTER_EN;/*Disable transmitter after current reception*/

Ditto. And put some spaces between /* and the text (and */)

> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL0);

A new line here.

> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL1);
> +	v &= ~TX_DMA_EN; /* Stop TX DMA */
> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL1);
> +}
> +
> +static void sun8i_emac_stop_rx(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v;
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL0);
> +	v &= ~RX_RECEIVER_EN; /* Disable receiver after current reception */
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL0);
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL1);
> +	v &= ~RX_DMA_EN; /* Stop RX DMA */
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL1);

Same comments.

> +}
> +
> +static void sun8i_emac_start_rx(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v;
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL0);
> +	v |= RX_RECEIVER_EN;/* Enable receiver */
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL0);
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL1);
> +	v |= RX_DMA_START;
> +	v |= RX_DMA_EN;
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL1);
> +}
> +
> +static void sun8i_emac_start_tx(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v;
> +
> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL0);
> +	v |= TX_TRANSMITTER_EN;
> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL0);
> +
> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL1);
> +	v |= TX_DMA_START;
> +	v |= TX_DMA_EN;
> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL1);
> +}
> +
> +/* Set MAC address for slot index
> + * @addr: the MAC address to set
> + * @index: The index of slot where to set address.
> + * The slot 0 is the main MACaddr
> + */

It looks like you have function comments in something that looks like
kerneldoc, but is not. And then you have comments that are not
following that at all. Please be consistent.

> +static void sun8i_emac_set_macaddr(struct sun8i_emac_priv *priv,
> +				   const u8 *addr, int index)
> +{
> +	u32 v;
> +
> +	dev_info(priv->dev, "device MAC address slot %d %02x:%02x:%02x:%02x:%02x:%02x\n",
> +		 index, addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);

The logging level is probably too high here, and you already have the
%pM format to print MAC addresses.

> +
> +	v = (addr[5] << 8) | addr[4];
> +	writel(v, priv->base + SUN8I_EMAC_MACADDR_HI + index * 8);

New line.

> +	v = (addr[3] << 24) | (addr[2] << 16) | (addr[1] << 8) | addr[0];
> +	writel(v, priv->base + SUN8I_EMAC_MACADDR_LO + index * 8);
> +}
> +
> +static void sun8i_emac_set_link_mode(struct sun8i_emac_priv *priv)
> +{
> +	u32 v;
> +
> +	v = readl(priv->base + SUN8I_EMAC_BASIC_CTL0);
> +
> +	if (priv->duplex)
> +		v |= BCTL0_FD;
> +	else
> +		v &= ~BCTL0_FD;
> +
> +	v &= ~BCTL0_SPEED_MASK;

New line.

> +	switch (priv->speed) {
> +	case 1000:
> +		break;
> +	case 100:
> +		v |= BCTL0_SPEED_100 << BCTL0_SPEED_SHIFT;
> +		break;
> +	case 10:
> +		v |= BCTL0_SPEED_10 << BCTL0_SPEED_SHIFT;
> +		break;
> +	}

No default?

> +	writel(v, priv->base + SUN8I_EMAC_BASIC_CTL0);
> +}
> +
> +static void sun8i_emac_flow_ctrl(struct sun8i_emac_priv *priv, int duplex,
> +				 int fc)
> +{
> +	u32 flow = 0;
> +
> +	netif_dbg(priv, link, priv->ndev, "%s %d %d\n", __func__,
> +		  duplex, fc);
> +
> +	flow = readl(priv->base + SUN8I_EMAC_RX_CTL0);
> +	if (fc & FLOW_RX)
> +		flow |= BIT(16);
> +	else
> +		flow &= ~BIT(16);
> +	writel(flow, priv->base + SUN8I_EMAC_RX_CTL0);
> +
> +	flow = readl(priv->base + SUN8I_EMAC_TX_FLOW_CTL);
> +	if (fc & FLOW_TX)
> +		flow |= BIT(0);
> +	else
> +		flow &= ~BIT(0);
> +	writel(flow, priv->base + SUN8I_EMAC_TX_FLOW_CTL);
> +}
> +
> +/* Grab a frame into a skb from descriptor number i */
> +static int sun8i_emac_rx_from_ddesc(struct net_device *ndev, int i)
> +{
> +	struct sk_buff *skb;
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct dma_desc *ddesc = priv->dd_rx + i;
> +	int frame_len;
> +	int rxcsum_done = 0;
> +
> +	if (ndev->features & NETIF_F_RXCSUM)
> +		rxcsum_done = 1;
> +
> +	/* bit0/bit7 work only on IPv4/IPv6 TCP traffic,
> +	 * (not on ARP for example) so we dont raise rx_errors/discard frame
> +	 */
> +	/* the checksum or length of received frame's payload is wrong*/
> +	if (ddesc->status & BIT(0)) {
> +		priv->estats.rx_payload_error++;
> +		rxcsum_done = 0;
> +	}

New line

> +	/* RX_CRC_ERR */
> +	if (ddesc->status & BIT(1)) {
> +		priv->ndev->stats.rx_errors++;
> +		priv->ndev->stats.rx_crc_errors++;
> +		priv->estats.rx_crc_error++;
> +		goto discard_frame;
> +	}

Ditto

> +	/* RX_PHY_ERR */
> +	if ((ddesc->status & BIT(3))) {
> +		priv->ndev->stats.rx_errors++;
> +		priv->estats.rx_phy_error++;
> +		goto discard_frame;
> +	}

Ditto

> +	/* RX_LENGTH_ERR */
> +	if ((ddesc->status & BIT(4))) {
> +		priv->ndev->stats.rx_errors++;
> +		priv->ndev->stats.rx_length_errors++;
> +		priv->estats.rx_length_error++;
> +		goto discard_frame;
> +	}

... You get the idea.

> +	/* RX_COL_ERR */
> +	if ((ddesc->status & BIT(6))) {
> +		priv->ndev->stats.rx_errors++;
> +		priv->estats.rx_col_error++;
> +		goto discard_frame;
> +	}
> +	/* RX_HEADER_ERR */
> +	if ((ddesc->status & BIT(7))) {
> +		priv->estats.rx_header_error++;
> +		rxcsum_done = 0;
> +	}
> +	/* RX_OVERFLOW_ERR */
> +	if ((ddesc->status & BIT(11))) {
> +		priv->ndev->stats.rx_over_errors++;
> +		priv->estats.rx_overflow_error++;
> +		goto discard_frame;
> +	}
> +	/* RX_NO_ENOUGTH_BUF_ERR */
> +	if ((ddesc->status & BIT(14))) {
> +		priv->ndev->stats.rx_errors++;
> +		priv->estats.rx_buf_error++;
> +		goto discard_frame;
> +	}
> +
> +	/* BIT(9) is for the first frame, not having it is bad since we do not
> +	 * handle Jumbo frame
> +	 */
> +	if ((ddesc->status & DSC_RX_FIRST) == 0) {
> +		dev_warn_ratelimited(priv->dev, "BUG: Non-first frame received. This should not happen\n");

Either you use a BUG macro, or you don't, but faking it doesn't really
seem appropriate (and please try to stay below the 80 chars limit).

> +		goto discard_frame;
> +	}
> +	frame_len = (ddesc->status >> 16) & 0x3FFF;
> +	if (!(ndev->features & NETIF_F_RXFCS))
> +		frame_len -= ETH_FCS_LEN;
> +
> +	skb = priv->rx_skb[i];
> +
> +	netif_dbg(priv, rx_status, priv->ndev,
> +		  "%s from %02d %pad len=%d status=%x st=%x\n",
> +		  __func__, i, &ddesc, frame_len, ddesc->status, ddesc->ctl);
> +
> +	skb_put(skb, frame_len);
> +
> +	dma_unmap_single(priv->dev, ddesc->buf_addr, DESC_BUF_MAX,
> +			 DMA_FROM_DEVICE);
> +	skb->protocol = eth_type_trans(skb, priv->ndev);
> +	if (rxcsum_done) {
> +		skb->ip_summed = CHECKSUM_UNNECESSARY;
> +		priv->estats.rx_hw_csum++;
> +	} else {
> +		skb->ip_summed = CHECKSUM_PARTIAL;
> +	}
> +
> +	priv->ndev->stats.rx_packets++;
> +	priv->ndev->stats.rx_bytes += frame_len;
> +	priv->rx_skb[i] = NULL;
> +
> +	/* this frame is not the last */
> +	if ((ddesc->status & DSC_RX_LAST) == 0) {
> +		dev_warn(priv->dev, "Multi frame not implemented currlen=%d\n",
> +			 frame_len);
> +	}
> +
> +	sun8i_emac_rx_skb(ndev, i);
> +	napi_gro_receive(&priv->napi, skb);
> +
> +	return 0;
> +	/* If the frame need to be dropped, we simply reuse the buffer */
> +discard_frame:
> +	ddesc->ctl = DESC_BUF_MAX;
> +	wmb();/* SUN8I_COULD_BE_USED_BY_DMA must be the last value written */
> +	ddesc->status = SUN8I_COULD_BE_USED_BY_DMA;
> +	return 0;
> +}
> +
> +/* iterate over dma_desc for finding completed xmit.
> + * Called from interrupt context, so no need to spinlock tx
> + *
> + * The problem is: how to know that a descriptor is sent and not just in
> + * preparation.
> + * Need to have status=0 and st set but this is the state of first frame just
> + * before setting the own-by-DMA bit.
> + * The solution is to used the artificial value DCLEAN.
> + */
> +static int sun8i_emac_complete_xmit(struct net_device *ndev, int budget)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct dma_desc *ddesc;
> +	int frame_len;
> +	int work = 0;
> +
> +	spin_lock(&priv->tx_lock);
> +	do {
> +		ddesc = priv->dd_tx + priv->tx_dirty;
> +
> +		if (ddesc->status & SUN8I_COULD_BE_USED_BY_DMA)
> +			goto xmit_end;
> +
> +		if (ddesc->status == DCLEAN)
> +			goto xmit_end;
> +
> +		if (ddesc->status == 0 && !ddesc->ctl) {
> +			dev_err(priv->dev, "BUG: reached the void %d %d\n",
> +				priv->tx_dirty, priv->tx_slot);
> +			goto xmit_end;
> +		}
> +
> +		/* TX_UNDERFLOW_ERR */
> +		if (ddesc->status & BIT(1))
> +			priv->ndev->stats.tx_errors++;
> +		/* TX_DEFER_ERR */
> +		if (ddesc->status & BIT(2))
> +			priv->ndev->stats.tx_errors++;
> +		/* BIT 6:3 numbers of collisions */
> +		if (ddesc->status & 0x78)
> +			priv->ndev->stats.collisions +=
> +				(ddesc->status & 0x78) >> 3;
> +		/* TX_COL_ERR_1 */
> +		if (ddesc->status & BIT(8))
> +			priv->ndev->stats.tx_errors++;
> +		/* TX_COL_ERR_0 */
> +		if (ddesc->status & BIT(9))
> +			priv->ndev->stats.tx_errors++;
> +		/* TX_CRS_ERR */
> +		if (ddesc->status & BIT(10))
> +			priv->ndev->stats.tx_carrier_errors++;
> +		/* TX_PAYLOAD_ERR */
> +		if (ddesc->status & BIT(12))
> +			priv->ndev->stats.tx_errors++;
> +		/* TX_LENGTH_ERR */
> +		if (ddesc->status & BIT(14))
> +			priv->ndev->stats.tx_errors++;
> +		/* TX_HEADER_ERR */
> +		if (ddesc->status & BIT(16))
> +			priv->ndev->stats.tx_errors++;
> +		frame_len = ddesc->ctl & 0x3FFF;
> +		if (priv->txl[priv->tx_dirty].map == MAP_SINGLE)
> +			dma_unmap_single(priv->dev, ddesc->buf_addr,
> +					 frame_len, DMA_TO_DEVICE);
> +		else
> +			dma_unmap_page(priv->dev, ddesc->buf_addr,
> +				       frame_len, DMA_TO_DEVICE);
> +		/* we can free skb only on last frame */
> +		if (priv->txl[priv->tx_dirty].skb && (ddesc->ctl & DSC_TX_LAST))
> +			dev_kfree_skb_irq(priv->txl[priv->tx_dirty].skb);
> +
> +		priv->txl[priv->tx_dirty].skb = NULL;
> +		priv->txl[priv->tx_dirty].map = 0;
> +		ddesc->ctl = 0;
> +		wmb(); /* setting to DCLEAN is the last value to be set */
> +		ddesc->status = DCLEAN;
> +		work++;
> +
> +		rb_inc(&priv->tx_dirty, priv->nbdesc_tx);
> +		ddesc = priv->dd_tx + priv->tx_dirty;
> +	} while (ddesc->ctl && !(ddesc->status & SUN8I_COULD_BE_USED_BY_DMA));
> +
> +	if (netif_queue_stopped(ndev) &&
> +	    rb_tx_numfreedesc(ndev) > MAX_SKB_FRAGS + 1)
> +		netif_wake_queue(ndev);
> +xmit_end:
> +	spin_unlock(&priv->tx_lock);
> +	return work;
> +}
> +
> +static int sun8i_emac_poll(struct napi_struct *napi, int budget)
> +{
> +	struct sun8i_emac_priv *priv =
> +		container_of(napi, struct sun8i_emac_priv, napi);
> +	struct net_device *ndev = priv->ndev;
> +	int worked;
> +	struct dma_desc *ddesc;
> +
> +	priv->estats.napi_schedule++;
> +	worked = sun8i_emac_complete_xmit(ndev, budget);
> +
> +	ddesc = priv->dd_rx + priv->rx_dirty;
> +	while (!(ddesc->status & SUN8I_COULD_BE_USED_BY_DMA) &&
> +	       worked < budget) {
> +		sun8i_emac_rx_from_ddesc(ndev, priv->rx_dirty);
> +		worked++;
> +		rb_inc(&priv->rx_dirty, priv->nbdesc_rx);
> +		ddesc = priv->dd_rx + priv->rx_dirty;
> +	};
> +	if (worked < budget) {
> +		priv->estats.napi_underflow++;
> +		napi_complete(&priv->napi);
> +		writel(RX_INT | TX_INT, priv->base + SUN8I_EMAC_INT_EN);
> +	}
> +	return worked;
> +}
> +
> +static int sun8i_mdio_read(struct mii_bus *bus, int phy_addr, int phy_reg)
> +{
> +	struct net_device *ndev = bus->priv;
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int err;
> +	u32 reg;
> +
> +	err = readl_poll_timeout(priv->base + SUN8I_EMAC_MDIO_CMD, reg,
> +				 !(reg & MDIO_CMD_MII_BUSY), 100, 10000);
> +	if (err) {
> +		dev_err(priv->dev, "%s timeout %x\n", __func__, reg);
> +		return err;
> +	}
> +
> +	reg &= ~MDIO_CMD_MII_WRITE;
> +	reg &= ~MDIO_CMD_MII_PHY_REG_ADDR_MASK;
> +	reg |= (phy_reg << MDIO_CMD_MII_PHY_REG_ADDR_SHIFT) &
> +		MDIO_CMD_MII_PHY_REG_ADDR_MASK;
> +
> +	reg &= ~MDIO_CMD_MII_PHY_ADDR_MASK;
> +
> +	reg |= (phy_addr << MDIO_CMD_MII_PHY_ADDR_SHIFT) &
> +		MDIO_CMD_MII_PHY_ADDR_MASK;
> +
> +	reg |= MDIO_CMD_MII_BUSY;
> +
> +	writel(reg, priv->base + SUN8I_EMAC_MDIO_CMD);
> +
> +	err = readl_poll_timeout(priv->base + SUN8I_EMAC_MDIO_CMD, reg,
> +				 !(reg & MDIO_CMD_MII_BUSY), 100, 10000);
> +
> +	if (err) {
> +		dev_err(priv->dev, "%s timeout %x\n", __func__, reg);
> +		return err;
> +	}
> +
> +	return readl(priv->base + SUN8I_EMAC_MDIO_DATA);
> +}
> +
> +static int sun8i_mdio_write(struct mii_bus *bus, int phy_addr, int phy_reg,
> +			    u16 data)
> +{
> +	struct net_device *ndev = bus->priv;
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 reg;
> +	int err;
> +
> +	err = readl_poll_timeout(priv->base + SUN8I_EMAC_MDIO_CMD, reg,
> +				 !(reg & MDIO_CMD_MII_BUSY), 100, 10000);
> +	if (err) {
> +		dev_err(priv->dev, "%s timeout %x\n", __func__, reg);
> +		return err;
> +	}

Why the poll_timeout variant?

> +
> +	reg &= ~MDIO_CMD_MII_PHY_REG_ADDR_MASK;
> +	reg |= (phy_reg << MDIO_CMD_MII_PHY_REG_ADDR_SHIFT) &
> +		MDIO_CMD_MII_PHY_REG_ADDR_MASK;
> +
> +	reg &= ~MDIO_CMD_MII_PHY_ADDR_MASK;
> +	reg |= (phy_addr << MDIO_CMD_MII_PHY_ADDR_SHIFT) &
> +		MDIO_CMD_MII_PHY_ADDR_MASK;
> +
> +	reg |= MDIO_CMD_MII_WRITE;
> +	reg |= MDIO_CMD_MII_BUSY;
> +
> +	writel(reg, priv->base + SUN8I_EMAC_MDIO_CMD);
> +	writel(data, priv->base + SUN8I_EMAC_MDIO_DATA);
> +	dev_dbg(priv->dev, "%s %d %d %x %x\n", __func__, phy_addr, phy_reg,
> +		reg, data);

Ugh. No.

> +	err = readl_poll_timeout(priv->base + SUN8I_EMAC_MDIO_CMD, reg,
> +				 !(reg & MDIO_CMD_MII_BUSY), 100, 10000);
> +	if (err) {
> +		dev_err(priv->dev, "%s timeout %x\n", __func__, reg);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int sun8i_emac_mdio_register(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct mii_bus *bus;
> +	int ret;
> +
> +	bus = mdiobus_alloc();
> +	if (!bus) {
> +		netdev_err(ndev, "Failed to allocate a new mdio bus\n");
> +		return -ENOMEM;
> +	}
> +
> +	bus->name = dev_name(priv->dev);
> +	bus->read = &sun8i_mdio_read;
> +	bus->write = &sun8i_mdio_write;
> +	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%x", bus->name, priv->dev->id);
> +
> +	bus->parent = priv->dev;
> +	bus->priv = ndev;
> +
> +	ret = of_mdiobus_register(bus, priv->dev->of_node);
> +	if (ret) {
> +		netdev_err(ndev, "Could not register a MDIO bus: %d\n", ret);
> +		mdiobus_free(bus);
> +		return ret;
> +	}
> +
> +	priv->mdio = bus;
> +
> +	return 0;
> +}
> +
> +static void sun8i_emac_mdio_unregister(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	mdiobus_unregister(priv->mdio);
> +	mdiobus_free(priv->mdio);
> +}
> +
> +/* Run within phydev->lock */
> +static void sun8i_emac_adjust_link(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct phy_device *phydev = ndev->phydev;
> +	int new_state = 0;
> +
> +	netif_dbg(priv, link, priv->ndev,
> +		  "%s link=%x duplex=%x speed=%x\n", __func__,
> +		  phydev->link, phydev->duplex, phydev->speed);
> +	if (!phydev)
> +		return;
> +
> +	if (phydev->link) {
> +		if (phydev->duplex != priv->duplex) {
> +			new_state = 1;
> +			priv->duplex = phydev->duplex;
> +		}
> +		if (phydev->pause)
> +			sun8i_emac_flow_ctrl(priv, phydev->duplex,
> +					     priv->flow_ctrl);
> +
> +		if (phydev->speed != priv->speed) {
> +			new_state = 1;
> +			priv->speed = phydev->speed;
> +		}
> +
> +		if (priv->link == 0) {
> +			new_state = 1;
> +			priv->link = phydev->link;
> +		}
> +
> +		netif_dbg(priv, link, priv->ndev,
> +			  "%s new=%d link=%d pause=%d\n",
> +			  __func__, new_state, priv->link, phydev->pause);
> +		if (new_state)
> +			sun8i_emac_set_link_mode(priv);
> +	} else if (priv->link != phydev->link) {
> +		new_state = 1;
> +		priv->link = 0;
> +		priv->speed = 0;
> +		priv->duplex = -1;
> +	}
> +
> +	if (new_state)
> +		phy_print_status(phydev);
> +}
> +
> +/* H3 specific bits for EPHY */
> +#define H3_EPHY_ADDR_SHIFT	20
> +#define H3_EPHY_LED_POL		BIT(17) /* 1: active low, 0: active high */
> +#define H3_EPHY_SHUTDOWN	BIT(16) /* 1: shutdown, 0: power up */
> +#define H3_EPHY_SELECT		BIT(15) /* 1: internal PHY, 0: external PHY */
> +#define H3_EPHY_DEFAULT_VALUE	0x58000
> +#define H3_EPHY_DEFAULT_MASK	GENMASK(31, 15)
> +
> +/* H3/A64 specific bits */
> +#define SC_RMII_EN		BIT(13) /* 1: enable RMII (overrides EPIT) */
> +
> +/* Generic system control EMAC_CLK bits */
> +#define SC_ETXDC_MASK		GENMASK(2, 0)
> +#define SC_ETXDC_SHIFT		10
> +#define SC_ERXDC_MASK		GENMASK(4, 0)
> +#define SC_ERXDC_SHIFT		5
> +#define SC_EPIT			BIT(2) /* 1: RGMII, 0: MII */
> +#define SC_ETCS_MASK		GENMASK(1, 0)
> +#define SC_ETCS_MII		0x0
> +#define SC_ETCS_EXT_GMII	0x1
> +#define SC_ETCS_INT_GMII	0x2
> +
> +static int sun8i_emac_set_syscon_ephy(struct net_device *ndev, u32 *reg)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct device_node *node = priv->dev->of_node;
> +	int ret;
> +
> +	*reg &= ~H3_EPHY_DEFAULT_MASK;
> +	*reg |= H3_EPHY_DEFAULT_VALUE;
> +
> +	if (!priv->use_internal_phy) {
> +		/* switch to external PHY interface */
> +		*reg &= ~H3_EPHY_SELECT;
> +		return 0;
> +	}
> +
> +	if (priv->phy_interface != PHY_INTERFACE_MODE_MII) {
> +		netdev_warn(ndev,
> +			    "Internal PHY requested, forcing MII mode.\n");
> +		priv->phy_interface = PHY_INTERFACE_MODE_MII;
> +	}
> +
> +	*reg |= H3_EPHY_SELECT;
> +	*reg &= ~H3_EPHY_SHUTDOWN;
> +
> +	if (of_property_read_bool(node, "allwinner,leds-active-low"))
> +		*reg |= H3_EPHY_LED_POL;
> +
> +	ret = of_mdio_parse_addr(priv->dev, priv->phy_node);
> +	if (ret < 0) {
> +		netdev_err(ndev, "Could not parse MDIO addr\n");
> +		return ret;
> +	}
> +
> +	/* of_mdio_parse_addr returns a valid (0 ~ 31) PHY
> +	 * address. No need to mask it again.
> +	 */
> +	*reg |= ret << H3_EPHY_ADDR_SHIFT;
> +
> +	return 0;
> +}
> +
> +static int sun8i_emac_set_syscon(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct device_node *node = priv->dev->of_node;
> +	int ret;
> +	u32 reg, val;
> +
> +	reg = readl(priv->syscon);
> +
> +	if (priv->variant == H3_EMAC) {
> +		ret = sun8i_emac_set_syscon_ephy(ndev, &reg);

Passing the reg variable is quite unusual, why not simply do
everything at once?

> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (!of_property_read_u32(node, "allwinner,tx-delay", &val)) {
> +		if (val <= SC_ETXDC_MASK) {
> +			reg &= ~(SC_ETXDC_MASK << SC_ETXDC_SHIFT);
> +			reg |= (val << SC_ETXDC_SHIFT);
> +		} else {
> +			netdev_warn(ndev, "Invalid TX clock delay: %d\n", val);
> +		}
> +	}
> +
> +	if (!of_property_read_u32(node, "allwinner,rx-delay", &val)) {
> +		if (val <= SC_ERXDC_MASK) {
> +			reg &= ~(SC_ERXDC_MASK << SC_ERXDC_SHIFT);
> +			reg |= (val << SC_ERXDC_SHIFT);
> +		} else {
> +			netdev_warn(ndev, "Invalid RX clock delay: %d\n", val);
> +		}
> +	}
> +
> +	/* Clear interface mode bits */
> +	reg &= ~(SC_ETCS_MASK | SC_EPIT);
> +	if (priv->variant == H3_EMAC || priv->variant == A64_EMAC)
> +		reg &= ~SC_RMII_EN;
> +
> +	switch (priv->phy_interface) {
> +	case PHY_INTERFACE_MODE_MII:
> +		/* default */
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII:
> +		reg |= SC_EPIT | SC_ETCS_INT_GMII;
> +		break;
> +	case PHY_INTERFACE_MODE_RMII:
> +		if (priv->variant == H3_EMAC || priv->variant == A64_EMAC) {
> +			reg |= SC_RMII_EN | SC_ETCS_EXT_GMII;
> +			break;
> +		}
> +		/* RMII not supported on A83T */
> +	default:
> +		netdev_err(ndev, "Unsupported interface mode: %s",
> +			   phy_modes(priv->phy_interface));
> +		return -EINVAL;
> +	}
> +
> +	writel(reg, priv->syscon);
> +
> +	return 0;
> +}
> +
> +static void sun8i_emac_unset_syscon(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 reg = 0;
> +
> +	if (priv->variant == H3_EMAC)
> +		reg = H3_EPHY_DEFAULT_VALUE;

Why do you need that?

> +
> +	writel(reg, priv->syscon);
> +}
> +
> +/* Set Management Data Clock, must be call after device reset */
> +static void sun8i_emac_set_mdc(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	unsigned long rate;
> +	u32 reg;
> +
> +	rate = clk_get_rate(priv->ahb_clk);
> +	if (rate > 160000000)
> +		reg = 0x3 << 20; /* AHB / 128 */
> +	else if (rate > 80000000)
> +		reg = 0x2 << 20; /* AHB / 64 */
> +	else if (rate > 40000000)
> +		reg = 0x1 << 20; /* AHB / 32 */
> +	else
> +		reg = 0x0 << 20; /* AHB / 16 */
> +	netif_dbg(priv, link, ndev, "MDC auto : %x\n", reg);
> +	writel(reg, priv->base + SUN8I_EMAC_MDIO_CMD);

You could also expose that as a clock.

> +}
> +
> +/* "power" the device, by enabling clk/reset/regulators */
> +static int sun8i_emac_power(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(priv->ahb_clk);
> +	if (ret) {
> +		netdev_err(ndev, "Could not enable AHB clock\n");
> +		return ret;
> +	}
> +
> +	if (priv->rst) {
> +		ret = reset_control_deassert(priv->rst);
> +		if (ret) {
> +			netdev_err(ndev, "Could not deassert reset\n");
> +			goto err_reset;
> +		}
> +	}
> +
> +	if (priv->ephy_clk) {
> +		ret = clk_prepare_enable(priv->ephy_clk);
> +		if (ret) {
> +			netdev_err(ndev, "Could not enable EPHY clock\n");
> +			goto err_ephy_clk;
> +		}
> +	}
> +
> +	if (priv->rst_ephy) {
> +		ret = reset_control_deassert(priv->rst_ephy);
> +		if (ret) {
> +			netdev_err(ndev, "Could not deassert EPHY reset\n");
> +			goto err_ephy_reset;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_ephy_reset:
> +	if (priv->ephy_clk)
> +		clk_disable_unprepare(priv->ephy_clk);
> +err_ephy_clk:
> +	if (priv->rst)
> +		reset_control_assert(priv->rst);
> +err_reset:
> +	clk_disable_unprepare(priv->ahb_clk);
> +	return ret;
> +}
> +
> +/* "Unpower" the device, disabling clocks and regulators, asserting reset */
> +static void sun8i_emac_unpower(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	if (priv->rst_ephy)
> +		reset_control_assert(priv->rst_ephy);
> +
> +	if (priv->ephy_clk)
> +		clk_disable_unprepare(priv->ephy_clk);
> +
> +	if (priv->rst)
> +		reset_control_assert(priv->rst);
> +
> +	clk_disable_unprepare(priv->ahb_clk);
> +}
> +
> +static int sun8i_emac_init(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct device_node *node = priv->dev->of_node;
> +	const u8 *addr;
> +
> +	/* Try to get MAC address from DT, or assign a random one */
> +	addr = of_get_mac_address(node);
> +	if (addr)
> +		ether_addr_copy(ndev->dev_addr, addr);
> +	else
> +		eth_hw_addr_random(ndev);
> +
> +	priv->phy_interface = of_get_phy_mode(node);
> +	if (priv->phy_interface < 0) {
> +		netdev_err(ndev, "PHY interface mode node unspecified\n");
> +		return priv->phy_interface;
> +	}
> +
> +	return sun8i_emac_power(ndev);
> +}
> +
> +static void sun8i_emac_uninit(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	mdiobus_unregister(priv->mdio);
> +
> +	sun8i_emac_unpower(ndev);
> +}
> +
> +static int sun8i_emac_mdio_probe(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct phy_device *phydev = NULL;
> +
> +	phydev = of_phy_connect(ndev, priv->phy_node, &sun8i_emac_adjust_link,
> +				0, priv->phy_interface);
> +
> +	if (!phydev) {
> +		netdev_err(ndev, "Could not attach to PHY\n");
> +		return -ENODEV;
> +	}
> +
> +	phy_attached_info(phydev);
> +
> +	/* mask with MAC supported features */
> +	phydev->supported &= PHY_GBIT_FEATURES;
> +	phydev->advertising = phydev->supported;
> +
> +	priv->link = 0;
> +	priv->speed = 0;
> +	priv->duplex = -1;
> +
> +	return 0;
> +}
> +
> +/* Allocate both RX and TX ring buffer and init them
> + * This function also write the startbase of thoses ring in the device.
> + * All structures that help managing thoses rings are also handled
> + * by this functions (rx_skb/txl)
> + */
> +static int sun8i_emac_alloc_rings(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct dma_desc *ddesc;
> +	int err, i;
> +
> +	priv->rx_skb = kcalloc(priv->nbdesc_rx, sizeof(struct sk_buff *),
> +			      GFP_KERNEL);
> +	if (!priv->rx_skb) {
> +		err = -ENOMEM;
> +		goto rx_skb_error;
> +	}
> +	priv->txl = kcalloc(priv->nbdesc_tx, sizeof(struct txinfo), GFP_KERNEL);
> +	if (!priv->txl) {
> +		err = -ENOMEM;
> +		goto tx_error;
> +	}
> +
> +	/* allocate/init RX ring */
> +	priv->dd_rx = dma_zalloc_coherent(priv->dev,
> +			priv->nbdesc_rx * sizeof(struct dma_desc),
> +			&priv->dd_rx_phy, GFP_KERNEL);
> +	if (!priv->dd_rx) {
> +		dev_err(priv->dev, "ERROR: cannot allocate DMA RX buffer");
> +		err = -ENOMEM;
> +		goto dma_rx_error;
> +	}
> +	ddesc = priv->dd_rx;
> +	for (i = 0; i < priv->nbdesc_rx; i++) {
> +		sun8i_emac_rx_skb(ndev, i);
> +		ddesc->next = (u32)priv->dd_rx_phy + (i + 1)
> +			* sizeof(struct dma_desc);
> +		ddesc++;
> +	}
> +	/* last descriptor point back to first one */
> +	ddesc--;
> +	ddesc->next = (u32)priv->dd_rx_phy;
> +
> +	/* allocate/init TX ring */
> +	priv->dd_tx = dma_zalloc_coherent(priv->dev,
> +			priv->nbdesc_tx * sizeof(struct dma_desc),
> +			&priv->dd_tx_phy, GFP_KERNEL);
> +	if (!priv->dd_tx) {
> +		dev_err(priv->dev, "ERROR: cannot allocate DMA TX buffer");
> +		err = -ENOMEM;
> +		goto dma_tx_error;
> +	}
> +	ddesc = priv->dd_tx;
> +	for (i = 0; i < priv->nbdesc_tx; i++) {
> +		ddesc->status = DCLEAN;
> +		ddesc->ctl = 0;
> +		ddesc->next = (u32)(priv->dd_tx_phy + (i + 1)
> +			* sizeof(struct dma_desc));
> +		ddesc++;
> +	}
> +	/* last descriptor point back to first one */
> +	ddesc--;
> +	ddesc->next = (u32)priv->dd_tx_phy;
> +	i--;
> +
> +	priv->tx_slot = 0;
> +	priv->tx_dirty = 0;
> +	priv->rx_dirty = 0;
> +
> +	/* write start of RX ring descriptor */
> +	writel(priv->dd_rx_phy, priv->base + SUN8I_EMAC_RX_DESC_LIST);
> +	/* write start of TX ring descriptor */
> +	writel(priv->dd_tx_phy, priv->base + SUN8I_EMAC_TX_DESC_LIST);
> +
> +	return 0;
> +dma_tx_error:
> +	dma_free_coherent(priv->dev, priv->nbdesc_rx * sizeof(struct dma_desc),
> +			  priv->dd_rx, priv->dd_rx_phy);
> +dma_rx_error:
> +	kfree(priv->txl);
> +tx_error:
> +	kfree(priv->rx_skb);
> +rx_skb_error:
> +	return err;
> +}
> +
> +static int sun8i_emac_open(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int err;
> +	u32 v;
> +
> +	err = request_irq(priv->irq, sun8i_emac_dma_interrupt, 0,
> +			  dev_name(priv->dev), ndev);
> +	if (err) {
> +		dev_err(priv->dev, "Cannot request IRQ: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Set interface mode (and configure internal PHY on H3) */
> +	err = sun8i_emac_set_syscon(ndev);
> +	if (err)
> +		goto err_irq;
> +
> +	/* Do SOFT RST */
> +	v = readl(priv->base + SUN8I_EMAC_BASIC_CTL1);
> +	writel(v | 0x01, priv->base + SUN8I_EMAC_BASIC_CTL1);
> +
> +	err = readl_poll_timeout(priv->base + SUN8I_EMAC_BASIC_CTL1, v,
> +				 !(v & 0x01), 100, 10000);
> +	if (err) {
> +		dev_err(priv->dev, "EMAC reset timeout\n");
> +		err = -EFAULT;
> +		goto err_syscon;
> +	}
> +
> +	sun8i_emac_set_mdc(ndev);
> +
> +	err = sun8i_emac_mdio_register(ndev);
> +	if (err)
> +		goto err_syscon;
> +
> +	err = sun8i_emac_mdio_probe(ndev);
> +	if (err)
> +		goto err_syscon;
> +
> +	/* DMA */
> +	v = (8 << 24);/* burst len */
> +	writel(v, priv->base + SUN8I_EMAC_BASIC_CTL1);
> +
> +	writel(RX_INT | TX_INT, priv->base + SUN8I_EMAC_INT_EN);
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL0);
> +	/* CHECK_CRC */
> +	if (ndev->features & NETIF_F_RXCSUM)
> +		v |= SUN8I_EMAC_RX_DO_CRC;
> +	else
> +		v &= ~SUN8I_EMAC_RX_DO_CRC;
> +	/* STRIP_FCS */
> +	if (ndev->features & NETIF_F_RXFCS)
> +		v &= ~SUN8I_EMAC_RX_STRIP_FCS;
> +	else
> +		v |= SUN8I_EMAC_RX_STRIP_FCS;
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL0);
> +
> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL1);
> +	/* TX_MD Transmission starts after a full frame located in TX DMA FIFO*/
> +	v |= BIT(1);
> +	/* Undocumented bit (called TX_NEXT_FRM in BSP), the original comment is
> +	 * "Operating on second frame increase the performance
> +	 * especially when transmit store-and-forward is used."
> +	 */
> +	v |= BIT(2);

Why don't you call it the same then?

> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL1);
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL1);
> +	/* RX_MD RX DMA reads data from RX DMA FIFO to host memory after a
> +	 * complete frame has been written to RX DMA FIFO
> +	*/
> +	v |= BIT(1);
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL1);
> +
> +	sun8i_emac_set_macaddr(priv, ndev->dev_addr, 0);
> +
> +	err = sun8i_emac_alloc_rings(ndev);
> +	if (err) {
> +		netdev_err(ndev, "Fail to allocate rings\n");
> +		goto err_mdio;
> +	}
> +
> +	phy_start(ndev->phydev);
> +
> +	sun8i_emac_start_rx(ndev);
> +	sun8i_emac_start_tx(ndev);
> +
> +	netif_napi_add(ndev, &priv->napi, sun8i_emac_poll, 64);
> +	napi_enable(&priv->napi);
> +	netif_start_queue(ndev);
> +
> +	return 0;
> +err_mdio:
> +	phy_disconnect(ndev->phydev);
> +err_syscon:
> +	sun8i_emac_unset_syscon(ndev);
> +err_irq:
> +	free_irq(priv->irq, ndev);
> +	return err;
> +}
> +
> +/* Clean the TX ring of any accepted skb for xmit */
> +static void sun8i_emac_tx_clean(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int i;
> +	struct dma_desc *ddesc;
> +	int frame_len;
> +
> +	spin_lock(&priv->tx_lock);
> +
> +	for (i = 0; i < priv->nbdesc_tx; i++) {
> +		if (priv->txl[i].skb) {
> +			ddesc = priv->dd_tx + i;
> +			frame_len = ddesc->ctl & 0x3FFF;
> +			switch (priv->txl[i].map) {
> +			case MAP_SINGLE:
> +				dma_unmap_single(priv->dev, ddesc->buf_addr,
> +						 frame_len, DMA_TO_DEVICE);
> +				break;
> +			case MAP_PAGE:
> +				dma_unmap_page(priv->dev, ddesc->buf_addr,
> +					       frame_len, DMA_TO_DEVICE);
> +				break;
> +			default:
> +				dev_err(priv->dev, "Trying to free an empty slot\n");
> +				continue;
> +			}
> +			dev_kfree_skb_any(priv->txl[i].skb);
> +			priv->txl[i].skb = NULL;
> +			ddesc->ctl = 0;
> +			ddesc->status = DCLEAN;
> +		}
> +	}
> +	priv->tx_slot = 0;
> +	priv->tx_dirty = 0;
> +
> +	spin_unlock(&priv->tx_lock);
> +}
> +
> +/* Clean the RX ring */
> +static void sun8i_emac_rx_clean(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int i;
> +	struct dma_desc *ddesc;
> +
> +	/* clean RX ring */
> +	for (i = 0; i < priv->nbdesc_rx; i++)
> +		if (priv->rx_skb[i]) {
> +			ddesc = priv->dd_rx + i;
> +			dma_unmap_single(priv->dev, ddesc->buf_addr,
> +					 DESC_BUF_MAX, DMA_FROM_DEVICE);
> +			dev_kfree_skb_any(priv->rx_skb[i]);
> +			priv->rx_skb[i] = NULL;
> +		}
> +}
> +
> +static int sun8i_emac_stop(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	napi_disable(&priv->napi);
> +
> +	sun8i_emac_stop_tx(ndev);
> +	sun8i_emac_stop_rx(ndev);
> +
> +	phy_stop(ndev->phydev);
> +	phy_disconnect(ndev->phydev);
> +
> +	sun8i_emac_mdio_unregister(ndev);
> +
> +	sun8i_emac_unset_syscon(ndev);
> +
> +	free_irq(priv->irq, ndev);
> +
> +	sun8i_emac_rx_clean(ndev);
> +	sun8i_emac_tx_clean(ndev);
> +
> +	kfree(priv->rx_skb);
> +	kfree(priv->txl);
> +
> +	dma_free_coherent(priv->dev, priv->nbdesc_rx * sizeof(struct dma_desc),
> +			  priv->dd_rx, priv->dd_rx_phy);
> +	dma_free_coherent(priv->dev, priv->nbdesc_tx * sizeof(struct dma_desc),
> +			  priv->dd_tx, priv->dd_tx_phy);
> +
> +	return 0;
> +}
> +
> +static netdev_tx_t sun8i_emac_xmit(struct sk_buff *skb, struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct dma_desc *ddesc;
> +	struct dma_desc *first;
> +	int i = 0, rbd_first;
> +	unsigned int len, fraglen, tlen;
> +	u32 v;
> +	int n;
> +	int nf;
> +	const skb_frag_t *frag;
> +	int do_csum = 0;
> +
> +	if (skb_put_padto(skb, ETH_ZLEN))
> +		return NETDEV_TX_OK;
> +	len = skb_headlen(skb);
> +
> +	n = skb_shinfo(skb)->nr_frags;
> +
> +	if (skb->ip_summed == CHECKSUM_PARTIAL) {
> +		do_csum = 1;
> +		priv->estats.tx_hw_csum++;
> +	}
> +	netif_dbg(priv, tx_queued, ndev, "%s len=%u skblen=%u %x\n", __func__,
> +		  len, skb->len,
> +		  (skb->ip_summed == CHECKSUM_PARTIAL));
> +
> +	spin_lock(&priv->tx_lock);
> +
> +	/* check for contigous space
> +	 * We need at least 1(skb->data) + n(numfrags) + 1(one clean slot)
> +	 */
> +	if (rb_tx_numfreedesc(ndev) < n + 2) {
> +		dev_err_ratelimited(priv->dev, "BUG!: TX is full %d %d\n",
> +				    priv->tx_dirty, priv->tx_slot);
> +		netif_stop_queue(ndev);
> +		spin_unlock(&priv->tx_lock);
> +		return NETDEV_TX_BUSY;
> +	}
> +	i = priv->tx_slot;
> +
> +	ddesc = priv->dd_tx + i;
> +	first = priv->dd_tx + i;
> +	rbd_first = i;
> +
> +	priv->tx_slot = (i + 1 + n) % priv->nbdesc_tx;
> +
> +	ddesc->buf_addr = dma_map_single(priv->dev, skb->data, len,
> +					 DMA_TO_DEVICE);
> +	if (dma_mapping_error(priv->dev, ddesc->buf_addr)) {
> +		dev_err(priv->dev, "ERROR: Cannot map buffer for DMA\n");
> +		goto xmit_error;
> +	}
> +	priv->txl[i].map = MAP_SINGLE;
> +	priv->txl[i].skb = skb;
> +
> +	tlen = len;
> +	ddesc->ctl = len;
> +	/* Undocumented bit that make it works
> +	 * Without it, packets never be sent on H3 SoC
> +	 */
> +	ddesc->ctl |= SUN8I_EMAC_MAGIC_TX_BIT;
> +	if (do_csum)
> +		ddesc->ctl |= SUN8I_EMAC_TX_DO_CRC;
> +
> +	/* handle fragmented skb, one descriptor per fragment  */
> +	for (nf = 0; nf < n; nf++) {
> +		frag = &skb_shinfo(skb)->frags[nf];
> +		rb_inc(&i, priv->nbdesc_tx);
> +		priv->txl[i].skb = skb;
> +		ddesc = priv->dd_tx + i;
> +		fraglen = skb_frag_size(frag);
> +		ddesc->ctl = fraglen;
> +		tlen += fraglen,
> +		ddesc->ctl |= SUN8I_EMAC_MAGIC_TX_BIT;
> +		if (do_csum)
> +			ddesc->ctl |= SUN8I_EMAC_TX_DO_CRC;
> +
> +		ddesc->buf_addr = skb_frag_dma_map(priv->dev, frag, 0,
> +				fraglen, DMA_TO_DEVICE);
> +		if (dma_mapping_error(priv->dev, ddesc->buf_addr)) {
> +			dev_err(priv->dev, "Cannot map buffer for DMA\n");
> +			goto xmit_error;
> +		}
> +		priv->txl[i].map = MAP_PAGE;
> +		ddesc->status = SUN8I_COULD_BE_USED_BY_DMA;
> +	}
> +
> +	/* frame end */
> +	ddesc->ctl |= DSC_TX_LAST;
> +	/* We want an interrupt after transmission */
> +	ddesc->ctl |= SUN8I_EMAC_WANT_INT;
> +
> +	rb_inc(&i, priv->nbdesc_tx);
> +
> +	/* frame begin */
> +	first->ctl |= DSC_TX_FIRST;
> +	wmb();/* SUN8I_COULD_BE_USED_BY_DMA must be the last value written */
> +	first->status = SUN8I_COULD_BE_USED_BY_DMA;
> +	priv->tx_slot = i;
> +
> +	/* Trying to optimize this (recording DMA start/stop) seems
> +	 * to lead to errors. So we always start DMA.
> +	 */
> +	v = readl(priv->base + SUN8I_EMAC_TX_CTL1);
> +	v |= TX_DMA_START;
> +	v |= TX_DMA_EN;
> +	writel(v, priv->base + SUN8I_EMAC_TX_CTL1);
> +
> +	if (rb_tx_numfreedesc(ndev) < MAX_SKB_FRAGS + 1) {
> +		netif_stop_queue(ndev);
> +		priv->estats.tx_stop_queue++;
> +	}
> +	priv->estats.tx_used_desc = rb_tx_numfreedesc(ndev);
> +	priv->ndev->stats.tx_packets++;
> +	priv->ndev->stats.tx_bytes += tlen;
> +
> +	spin_unlock(&priv->tx_lock);
> +
> +	return NETDEV_TX_OK;
> +
> +xmit_error:
> +	/* destroy skb and return TX OK Documentation/DMA-API-HOWTO.txt */
> +	/* clean descritors from rbd_first to i */
> +	ddesc->ctl = 0;
> +	wmb(); /* setting to DCLEAN is the last value to be set */
> +	ddesc->status = DCLEAN;
> +	do {
> +		ddesc = priv->dd_tx + rbd_first;
> +		ddesc->ctl = 0;
> +		wmb(); /* setting to DCLEAN is the last value to be set */
> +		ddesc->status = DCLEAN;
> +		rb_inc(&rbd_first, priv->nbdesc_tx);
> +	} while (rbd_first != i);
> +	spin_unlock(&priv->tx_lock);
> +	dev_kfree_skb_any(skb);
> +	return NETDEV_TX_OK;
> +}
> +
> +static int sun8i_emac_change_mtu(struct net_device *ndev, int new_mtu)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int max_mtu;
> +
> +	dev_info(priv->dev, "%s set MTU to %d\n", __func__, new_mtu);
> +
> +	if (netif_running(ndev)) {
> +		dev_err(priv->dev, "%s: must be stopped to change its MTU\n",
> +			ndev->name);
> +		return -EBUSY;
> +	}
> +
> +	max_mtu = SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN);
> +
> +	if ((new_mtu < 68) || (new_mtu > max_mtu)) {
> +		dev_err(priv->dev, "%s: invalid MTU, max MTU is: %d\n",
> +			ndev->name, max_mtu);
> +		return -EINVAL;
> +	}
> +
> +	ndev->mtu = new_mtu;
> +	netdev_update_features(ndev);
> +	return 0;
> +}
> +
> +static netdev_features_t sun8i_emac_fix_features(struct net_device *ndev,
> +						 netdev_features_t features)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	netif_dbg(priv, drv, ndev, "%s %llx\n", __func__, features);
> +	return features;
> +}

Looks useless ...

> +
> +static int sun8i_emac_set_features(struct net_device *ndev,
> +				   netdev_features_t features)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v;
> +
> +	v = readl(priv->base + SUN8I_EMAC_BASIC_CTL0);
> +	if (features & NETIF_F_LOOPBACK && netif_running(ndev)) {
> +		netif_info(priv, hw, ndev, "Set loopback features");
> +		v |= BIT(1);
> +	} else {
> +		netif_info(priv, hw, ndev, "Unset loopback features");
> +		v &= ~BIT(1);
> +	}
> +	writel(v, priv->base + SUN8I_EMAC_BASIC_CTL0);
> +
> +	v = readl(priv->base + SUN8I_EMAC_RX_CTL0);
> +	if (features & NETIF_F_RXCSUM) {
> +		v |= SUN8I_EMAC_RX_DO_CRC;
> +		netif_info(priv, hw, ndev, "Doing RX CRC check by hardware");
> +	} else {
> +		v &= ~SUN8I_EMAC_RX_DO_CRC;
> +		netif_info(priv, hw, ndev, "No RX CRC check by hardware");
> +	}
> +	if (features & NETIF_F_RXFCS) {
> +		v &= ~SUN8I_EMAC_RX_STRIP_FCS;
> +		netif_info(priv, hw, ndev, "Keep FCS");
> +	} else {
> +		v |= SUN8I_EMAC_RX_STRIP_FCS;
> +		netif_info(priv, hw, ndev, "Strip FCS");
> +	}
> +	writel(v, priv->base + SUN8I_EMAC_RX_CTL0);
> +
> +	netif_dbg(priv, drv, ndev, "%s %llx %x\n", __func__, features, v);
> +
> +	return 0;
> +}
> +
> +static void sun8i_emac_set_rx_mode(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v = 0;
> +	int i = 0;
> +	struct netdev_hw_addr *ha;
> +
> +	/* Receive all multicast frames */
> +	v |= BIT(16);
> +	/* Receive all control frames */
> +	v |= BIT(13);
> +	if (ndev->flags & IFF_PROMISC)
> +		v |= BIT(1);
> +	if (netdev_uc_count(ndev) > 7) {
> +		v |= BIT(1);
> +	} else {
> +		netdev_for_each_uc_addr(ha, ndev) {
> +			i++;
> +			sun8i_emac_set_macaddr(priv, ha->addr, i);
> +		}
> +	}
> +	writel(v, priv->base + SUN8I_EMAC_RX_FRM_FLT);
> +}
> +
> +static void sun8i_emac_tx_timeout(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	netdev_err(ndev, "%s\n", __func__);
> +
> +	sun8i_emac_stop_tx(ndev);
> +
> +	sun8i_emac_tx_clean(ndev);
> +
> +	/* write start of tx ring descriptor */
> +	writel(priv->dd_tx_phy, priv->base + SUN8I_EMAC_TX_DESC_LIST);
> +
> +	sun8i_emac_start_tx(ndev);
> +
> +	netdev_reset_queue(ndev);
> +
> +	ndev->stats.tx_errors++;
> +	netif_wake_queue(ndev);
> +}
> +
> +static int sun8i_emac_ioctl(struct net_device *ndev, struct ifreq *rq, int cmd)
> +{
> +	struct phy_device *phydev = ndev->phydev;
> +
> +	if (!netif_running(ndev))
> +		return -EINVAL;
> +
> +	if (!phydev)
> +		return -ENODEV;
> +
> +	return phy_mii_ioctl(phydev, rq, cmd);
> +}
> +
> +static int sun8i_emac_check_if_running(struct net_device *ndev)
> +{
> +	if (!netif_running(ndev))
> +		return -EINVAL;
> +	return 0;
> +}
> +static int sun8i_emac_get_sset_count(struct net_device *ndev, int sset)
> +{
> +	switch (sset) {
> +	case ETH_SS_STATS:
> +		return ARRAY_SIZE(estats_str);
> +	}
> +	return -EOPNOTSUPP;
> +}
> +
> +static int sun8i_emac_ethtool_get_settings(struct net_device *ndev,
> +					   struct ethtool_cmd *cmd)
> +{
> +	struct phy_device *phy = ndev->phydev;
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	if (!phy) {
> +		netdev_err(ndev, "%s: %s: PHY is not registered\n",
> +			   __func__, ndev->name);
> +		return -ENODEV;
> +	}
> +
> +	if (!netif_running(ndev)) {
> +		dev_err(priv->dev, "interface disabled: we cannot track link speed / duplex setting\n");
> +		return -EBUSY;
> +	}
> +
> +	return phy_ethtool_gset(phy, cmd);
> +}
> +
> +static int sun8i_emac_ethtool_set_settings(struct net_device *ndev,
> +					   struct ethtool_cmd *cmd)
> +{
> +	struct phy_device *phy = ndev->phydev;
> +
> +	return phy_ethtool_sset(phy, cmd);
> +}
> +
> +static void sun8i_emac_ethtool_getdrvinfo(struct net_device *ndev,
> +					  struct ethtool_drvinfo *info)
> +{
> +	strlcpy(info->driver, "sun8i_emac", sizeof(info->driver));
> +	strcpy(info->version, "00");
> +	info->fw_version[0] = '\0';
> +}
> +
> +static void sun8i_emac_ethtool_stats(struct net_device *ndev,
> +				     struct ethtool_stats *dummy, u64 *data)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	memcpy(data, &priv->estats,
> +	       sun8i_emac_get_sset_count(ndev, ETH_SS_STATS) * sizeof(u64));
> +}
> +
> +static void sun8i_emac_ethtool_strings(struct net_device *dev, u32 stringset,
> +				       u8 *buffer)
> +{
> +	switch (stringset) {
> +	case ETH_SS_STATS:
> +		memcpy(buffer, &estats_str, sizeof(estats_str));
> +		break;
> +	}
> +}
> +
> +static u32 sun8i_emac_ethtool_getmsglevel(struct net_device *ndev)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	return priv->msg_enable;
> +}
> +
> +static void sun8i_emac_ethtool_setmsglevel(struct net_device *ndev, u32 level)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	priv->msg_enable = level;
> +}
> +
> +static void sun8i_emac_get_pauseparam(struct net_device *ndev,
> +				      struct ethtool_pauseparam *pause)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	pause->rx_pause = 0;
> +	pause->tx_pause = 0;
> +	pause->autoneg = ndev->phydev->autoneg;
> +
> +	if (priv->flow_ctrl & FLOW_RX)
> +		pause->rx_pause = 1;
> +	if (priv->flow_ctrl & FLOW_TX)
> +		pause->tx_pause = 1;
> +}
> +
> +static int sun8i_emac_set_pauseparam(struct net_device *ndev,
> +				     struct ethtool_pauseparam *pause)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	struct phy_device *phy = ndev->phydev;
> +	int new_pause = 0;
> +	int ret = 0;
> +
> +	if (pause->rx_pause)
> +		new_pause |= FLOW_RX;
> +	if (pause->tx_pause)
> +		new_pause |= FLOW_TX;
> +
> +	priv->flow_ctrl = new_pause;
> +	phy->autoneg = pause->autoneg;
> +
> +	if (phy->autoneg) {
> +		if (netif_running(ndev))
> +			ret = phy_start_aneg(phy);
> +	} else {
> +		sun8i_emac_flow_ctrl(priv, phy->duplex, priv->flow_ctrl);
> +	}
> +	return ret;
> +}
> +
> +static void sun8i_emac_ethtool_get_ringparam(struct net_device *ndev,
> +					     struct ethtool_ringparam *ring)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +
> +	ring->rx_pending = priv->nbdesc_rx;
> +	ring->tx_pending = priv->nbdesc_tx;
> +}
> +
> +static int sun8i_emac_ethtool_set_ringparam(struct net_device *ndev,
> +					    struct ethtool_ringparam *ring)
> +{
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	int err;
> +
> +	if (ring->rx_max_pending || ring->rx_mini_max_pending ||
> +	    ring->rx_jumbo_max_pending || ring->rx_mini_pending ||
> +	    ring->rx_jumbo_pending || ring->tx_max_pending)
> +		return -EINVAL;
> +
> +	if (ring->tx_pending < MAX_SKB_FRAGS + 1) {
> +		netdev_err(ndev, "The number of TX descriptors is too low");
> +		return -EINVAL;
> +	}
> +
> +	sun8i_emac_stop_tx(ndev);
> +	sun8i_emac_stop_rx(ndev);
> +
> +	sun8i_emac_rx_clean(ndev);
> +	sun8i_emac_tx_clean(ndev);
> +
> +	kfree(priv->rx_skb);
> +	kfree(priv->txl);
> +
> +	dma_free_coherent(priv->dev, priv->nbdesc_rx * sizeof(struct dma_desc),
> +			  priv->dd_rx, priv->dd_rx_phy);
> +	dma_free_coherent(priv->dev, priv->nbdesc_tx * sizeof(struct dma_desc),
> +			  priv->dd_tx, priv->dd_tx_phy);
> +
> +	priv->nbdesc_rx = ring->rx_pending;
> +	priv->nbdesc_tx = ring->tx_pending;
> +	err = sun8i_emac_alloc_rings(ndev);
> +	if (err) {
> +		/* Fatal error, we cannot re start */
> +		netdev_err(ndev, "Fail to allocate rings\n");
> +		return -EFAULT;
> +	}
> +
> +	sun8i_emac_start_rx(ndev);
> +	sun8i_emac_start_tx(ndev);
> +
> +	netif_start_queue(ndev);
> +
> +	netdev_info(ndev, "Ring Param settings: rx: %d, tx %d\n",
> +		    ring->rx_pending, ring->tx_pending);
> +	return 0;
> +}
> +
> +static const struct ethtool_ops sun8i_emac_ethtool_ops = {
> +	.begin = sun8i_emac_check_if_running,
> +	.get_settings = sun8i_emac_ethtool_get_settings,
> +	.set_settings = sun8i_emac_ethtool_set_settings,
> +	.get_link = ethtool_op_get_link,
> +	.get_pauseparam = sun8i_emac_get_pauseparam,
> +	.set_pauseparam = sun8i_emac_set_pauseparam,
> +	.get_ethtool_stats = sun8i_emac_ethtool_stats,
> +	.get_strings = sun8i_emac_ethtool_strings,
> +	.get_sset_count = sun8i_emac_get_sset_count,
> +	.get_drvinfo = sun8i_emac_ethtool_getdrvinfo,
> +	.get_msglevel = sun8i_emac_ethtool_getmsglevel,
> +	.set_msglevel = sun8i_emac_ethtool_setmsglevel,
> +	.get_ringparam = sun8i_emac_ethtool_get_ringparam,
> +	.set_ringparam = sun8i_emac_ethtool_set_ringparam,
> +};
> +
> +static const struct net_device_ops sun8i_emac_netdev_ops = {
> +	.ndo_init = sun8i_emac_init,
> +	.ndo_uninit = sun8i_emac_uninit,
> +	.ndo_open = sun8i_emac_open,
> +	.ndo_start_xmit = sun8i_emac_xmit,
> +	.ndo_stop = sun8i_emac_stop,
> +	.ndo_change_mtu = sun8i_emac_change_mtu,
> +	.ndo_fix_features = sun8i_emac_fix_features,
> +	.ndo_set_features = sun8i_emac_set_features,
> +	.ndo_set_rx_mode = sun8i_emac_set_rx_mode,
> +	.ndo_tx_timeout = sun8i_emac_tx_timeout,
> +	.ndo_do_ioctl = sun8i_emac_ioctl,
> +	.ndo_set_mac_address = eth_mac_addr,
> +};
> +
> +static irqreturn_t sun8i_emac_dma_interrupt(int irq, void *dev_id)
> +{
> +	struct net_device *ndev = dev_id;
> +	struct sun8i_emac_priv *priv = netdev_priv(ndev);
> +	u32 v, u;
> +
> +	v = readl(priv->base + SUN8I_EMAC_INT_STA);
> +
> +	/* When this bit is asserted, a frame transmission is completed. */
> +	if (v & BIT(0)) {
> +		priv->estats.tx_int++;
> +		writel(0, priv->base + SUN8I_EMAC_INT_EN);
> +		napi_schedule(&priv->napi);
> +	}
> +
> +	/* When this bit is asserted, the TX DMA FSM is stopped. */
> +	if (v & BIT(1))
> +		priv->estats.tx_dma_stop++;
> +
> +	/* When this asserted, the TX DMA can not acquire next TX descriptor
> +	 * and TX DMA FSM is suspended.
> +	*/
> +	if (v & BIT(2))
> +		priv->estats.tx_dma_ua++;
> +
> +	if (v & BIT(3))
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt TX TIMEOUT\n");

Why do you enable that interrupt if you can't handle it?

And printing in the interrupt handler is a very bad idea.

> +	if (v & BIT(4)) {
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt TX underflow\n");
> +		priv->estats.tx_underflow_int++;
> +	}
> +
> +	/* When this bit asserted , the frame is transmitted to FIFO totally. */
> +	if (v & BIT(5)) {
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt TX_EARLY_INT\n");
> +		priv->estats.tx_early_int++;
> +	}
> +
> +	/* When this bit is asserted, a frame reception is completed  */
> +	if (v & BIT(8)) {
> +		priv->estats.rx_int++;
> +		writel(0, priv->base + SUN8I_EMAC_INT_EN);
> +		napi_schedule(&priv->napi);
> +	}
> +
> +	/* When this asserted, the RX DMA can not acquire next TX descriptor
> +	 * and RX DMA FSM is suspended.
> +	*/
> +	if (v & BIT(9)) {
> +		u = readl(priv->base + SUN8I_EMAC_RX_CTL1);
> +		netif_info(priv, intr, ndev, "Re-run RX DMA %x\n", u);

Seriously?

> +		writel(u | RX_DMA_START, priv->base + SUN8I_EMAC_RX_CTL1);
> +		priv->estats.rx_dma_ua++;
> +	}
> +
> +	if (v & BIT(10)) {
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt RX_DMA_STOPPED_INT\n");
> +		priv->estats.rx_dma_stop++;
> +	}
> +	if (v & BIT(11))
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt RX_TIMEOUT\n");
> +	if (v & BIT(12))
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt RX OVERFLOW\n");
> +	if (v & BIT(13)) {
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt RX EARLY\n");
> +		priv->estats.rx_early_int++;
> +	}
> +	if (v & BIT(16))
> +		netif_dbg(priv, intr, ndev, "Unhandled interrupt RGMII\n");
> +
> +	/* the datasheet state those register as read-only
> +	 * but nothing work(freeze) without writing to it
> +	 */
> +	writel(v & 0x3FFF, priv->base + SUN8I_EMAC_INT_STA);

Why don't you just write what you read?

> +
> +	return IRQ_HANDLED;

The lack of spinlocks in there is quite worrying.

> +}
> +
> +static int sun8i_emac_probe(struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	struct sun8i_emac_priv *priv;
> +	struct net_device *ndev;
> +	struct resource *res;
> +	int ret;
> +
> +	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> +	if (ret) {
> +		dev_err(&pdev->dev, "No suitable DMA available\n");
> +		return ret;
> +	}

Isn't that the default?

> +	ndev = alloc_etherdev(sizeof(*priv));
> +	if (!ndev)
> +		return -ENOMEM;
> +
> +	SET_NETDEV_DEV(ndev, &pdev->dev);
> +	priv = netdev_priv(ndev);
> +	platform_set_drvdata(pdev, ndev);
> +
> +	priv->variant = (enum emac_variant)of_device_get_match_data(&pdev->dev);
> +	if (!priv->variant) {
> +		dev_err(&pdev->dev, "Missing sun8i-emac variant\n");
> +		return -EINVAL;
> +	}
> +
> +	priv->phy_node = of_parse_phandle(node, "phy", 0);
> +	if (!priv->phy_node) {
> +		netdev_err(ndev, "No associated PHY\n");
> +		return -ENODEV;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	priv->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(priv->base)) {
> +		ret = PTR_ERR(priv->base);
> +		dev_err(&pdev->dev, "Cannot request MMIO: %d\n", ret);
> +		return ret;
> +	}
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "syscon");
> +	priv->syscon = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(priv->syscon)) {
> +		ret = PTR_ERR(priv->syscon);
> +		dev_err(&pdev->dev,
> +			"Cannot map system control registers: %d\n", ret);
> +		return ret;
> +	}
> +
> +	priv->ahb_clk = devm_clk_get(&pdev->dev, "ahb");
> +	if (IS_ERR(priv->ahb_clk)) {
> +		ret = PTR_ERR(priv->ahb_clk);
> +		dev_err(&pdev->dev, "Cannot get AHB clock err=%d\n", ret);
> +		goto probe_err;
> +	}
> +
> +	priv->rst = devm_reset_control_get_optional(&pdev->dev, "ahb");
> +	if (IS_ERR(priv->rst)) {
> +		ret = PTR_ERR(priv->rst);
> +		if (ret == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +		dev_info(&pdev->dev, "No MAC reset control found %d\n", ret);
> +		priv->rst = NULL;
> +	}
> +
> +	if (priv->variant == H3_EMAC)
> +		priv->use_internal_phy = of_property_read_bool(node,
> +				"allwinner,use-internal-phy");
> +
> +	if (priv->use_internal_phy) {
> +		priv->ephy_clk = devm_clk_get(&pdev->dev, "ephy");
> +		if (IS_ERR(priv->ephy_clk)) {
> +			ret = PTR_ERR(priv->ephy_clk);
> +			dev_err(&pdev->dev, "Cannot get EPHY clock err=%d\n",
> +				ret);
> +			goto probe_err;
> +		}
> +
> +		priv->rst_ephy = devm_reset_control_get_optional(&pdev->dev,
> +								 "ephy");
> +		if (IS_ERR(priv->rst_ephy)) {
> +			ret = PTR_ERR(priv->rst_ephy);
> +			if (ret == -EPROBE_DEFER)
> +				goto probe_err;
> +			dev_info(&pdev->dev,
> +				 "No EPHY reset control found %d\n", ret);
> +			priv->rst_ephy = NULL;
> +		}
> +	}
> +
> +	priv->irq = platform_get_irq(pdev, 0);
> +	if (priv->irq < 0) {
> +		ret = priv->irq;
> +		dev_err(&pdev->dev, "Cannot claim IRQ: %d\n", ret);
> +		goto probe_err;
> +	}
> +
> +	spin_lock_init(&priv->tx_lock);
> +
> +	ndev->netdev_ops = &sun8i_emac_netdev_ops;
> +	ndev->ethtool_ops = &sun8i_emac_ethtool_ops;
> +
> +	priv->ndev = ndev;
> +	priv->dev = &pdev->dev;
> +
> +	ndev->hw_features = NETIF_F_SG | NETIF_F_HIGHDMA;
> +	ndev->hw_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
> +		NETIF_F_RXCSUM;
> +	ndev->features |= ndev->hw_features;
> +	ndev->hw_features |= NETIF_F_RXFCS;
> +	ndev->hw_features |= NETIF_F_RXALL;
> +	ndev->hw_features |= NETIF_F_LOOPBACK;
> +	ndev->priv_flags |= IFF_UNICAST_FLT;
> +
> +	ndev->watchdog_timeo = msecs_to_jiffies(5000);
> +	netif_carrier_off(ndev);
> +
> +	/* Benched on OPIPC with 100M, setting more than 256 does not give any
> +	 * perf boost
> +	 */
> +	priv->nbdesc_rx = 128;
> +	priv->nbdesc_tx = 256;
> +
> +	ret = register_netdev(ndev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "ERROR: Register %s failed\n", ndev->name);
> +		goto probe_err;
> +	}
> +
> +	return 0;
> +
> +probe_err:
> +	free_netdev(ndev);
> +	return ret;
> +}
> +
> +static int sun8i_emac_remove(struct platform_device *pdev)
> +{
> +	struct net_device *ndev = platform_get_drvdata(pdev);
> +
> +	unregister_netdev(ndev);
> +	platform_set_drvdata(pdev, NULL);
> +	free_netdev(ndev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id sun8i_emac_of_match_table[] = {
> +	{ .compatible = "allwinner,sun8i-a83t-emac",
> +	  .data = (void *)A83T_EMAC },
> +	{ .compatible = "allwinner,sun8i-h3-emac",
> +	  .data = (void *)H3_EMAC },
> +	{ .compatible = "allwinner,sun50i-a64-emac",
> +	  .data = (void *)A64_EMAC },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, sun8i_emac_of_match_table);
> +
> +static struct platform_driver sun8i_emac_driver = {
> +	.probe          = sun8i_emac_probe,
> +	.remove         = sun8i_emac_remove,
> +	.driver         = {
> +		.name           = "sun8i-emac",
> +		.of_match_table	= sun8i_emac_of_match_table,
> +	},
> +};
> +
> +module_platform_driver(sun8i_emac_driver);
> +
> +MODULE_DESCRIPTION("sun8i Ethernet driver");
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("LABBE Corentin <clabbe.montjoie@gmail.com");

Having runtime_pm working would be great.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com