fec_main.c

/*
 * Fast Ethernet Controller (FEC) driver for Motorola MPC8xx.
 * Copyright (c) 1997 Dan Malek (dmalek@jlc.net)
 *
 * Right now, I am very wasteful with the buffers.  I allocate memory
 * pages and then divide them into 2K frame buffers.  This way I know I
 * have buffers large enough to hold one frame within one buffer descriptor.
 * Once I get this working, I will use 64 or 128 byte CPM buffers, which
 * will be much more memory efficient and will easily handle lots of
 * small packets.
 *
 * Much better multiple PHY support by Magnus Damm.
 * Copyright (c) 2000 Ericsson Radio Systems AB.
 *
 * Support for FEC controller of ColdFire processors.
 * Copyright (c) 2001-2005 Greg Ungerer (gerg@snapgear.com)
 *
 * Bug fixes and cleanup by Philippe De Muyter (phdm@macqel.be)
 * Copyright (c) 2004-2006 Macq Electronique SA.
 *
 * Copyright (C) 2010-2011 Freescale Semiconductor, Inc.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <net/ip.h>
#include <net/tso.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/phy.h>
#include <linux/fec.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/of_mdio.h>
#include <linux/of_net.h>
#include <linux/regulator/consumer.h>
#include <linux/if_vlan.h>
#include <linux/pinctrl/consumer.h>

#include <asm/cacheflush.h>

#include "fec.h"

static void set_multicast_list(struct net_device *ndev);

#if defined(CONFIG_ARM)
#define FEC_ALIGNMENT	0xf
#else
#define FEC_ALIGNMENT	0x3
#endif

#define DRIVER_NAME	"fec"

#define FEC_ENET_GET_QUQUE(_x) ((_x == 0) ? 1 : ((_x == 1) ? 2 : 0))

/* Pause frame feild and FIFO threshold */
#define FEC_ENET_FCE	(1 << 5)
#define FEC_ENET_RSEM_V	0x84
#define FEC_ENET_RSFL_V	16
#define FEC_ENET_RAEM_V	0x8
#define FEC_ENET_RAFL_V	0x8
#define FEC_ENET_OPD_V	0xFFF0

/* Controller is ENET-MAC */
#define FEC_QUIRK_ENET_MAC		(1 << 0)
/* Controller needs driver to swap frame */
#define FEC_QUIRK_SWAP_FRAME		(1 << 1)
/* Controller uses gasket */
#define FEC_QUIRK_USE_GASKET		(1 << 2)
/* Controller has GBIT support */
#define FEC_QUIRK_HAS_GBIT		(1 << 3)
/* Controller has extend desc buffer */
#define FEC_QUIRK_HAS_BUFDESC_EX	(1 << 4)
/* Controller has hardware checksum support */
#define FEC_QUIRK_HAS_CSUM		(1 << 5)
/* Controller has hardware vlan support */
#define FEC_QUIRK_HAS_VLAN		(1 << 6)
/* ENET IP errata ERR006358
 *
 * If the ready bit in the transmit buffer descriptor (TxBD[R]) is previously
 * detected as not set during a prior frame transmission, then the
 * ENET_TDAR[TDAR] bit is cleared at a later time, even if additional TxBDs
 * were added to the ring and the ENET_TDAR[TDAR] bit is set. This results in
 * frames not being transmitted until there is a 0-to-1 transition on
 * ENET_TDAR[TDAR].
 */
#define FEC_QUIRK_ERR006358            (1 << 7)
/* ENET IP hw AVB
 *
 * i.MX6SX ENET IP add Audio Video Bridging (AVB) feature support.
 * - Two class indicators on receive with configurable priority
 * - Two class indicators and line speed timer on transmit allowing
 *   implementation class credit based shapers externally
 * - Additional DMA registers provisioned to allow managing up to 3
 *   independent rings
 */
#define FEC_QUIRK_HAS_AVB		(1 << 8)

static struct platform_device_id fec_devtype[] = {
	{
		/* keep it for coldfire */
		.name = DRIVER_NAME,
		.driver_data = 0,
	}, {
		.name = "imx25-fec",
		.driver_data = FEC_QUIRK_USE_GASKET,
	}, {
		.name = "imx27-fec",
		.driver_data = 0,
	}, {
		.name = "imx28-fec",
		.driver_data = FEC_QUIRK_ENET_MAC | FEC_QUIRK_SWAP_FRAME,
	}, {
		.name = "imx6q-fec",
		.driver_data = FEC_QUIRK_ENET_MAC | FEC_QUIRK_HAS_GBIT |
				FEC_QUIRK_HAS_BUFDESC_EX | FEC_QUIRK_HAS_CSUM |
				FEC_QUIRK_HAS_VLAN | FEC_QUIRK_ERR006358,
	}, {
		.name = "mvf600-fec",
		.driver_data = FEC_QUIRK_ENET_MAC,
	}, {
		.name = "imx6sx-fec",
		.driver_data = FEC_QUIRK_ENET_MAC | FEC_QUIRK_HAS_GBIT |
				FEC_QUIRK_HAS_BUFDESC_EX | FEC_QUIRK_HAS_CSUM |
				FEC_QUIRK_HAS_VLAN | FEC_QUIRK_ERR006358 |
				FEC_QUIRK_HAS_AVB,
	}, {
		/* sentinel */
	}
};
MODULE_DEVICE_TABLE(platform, fec_devtype);

enum imx_fec_type {
	IMX25_FEC = 1,	/* runs on i.mx25/50/53 */
	IMX27_FEC,	/* runs on i.mx27/35/51 */
	IMX28_FEC,
	IMX6Q_FEC,
	MVF600_FEC,
};

static const struct of_device_id fec_dt_ids[] = {
	{ .compatible = "fsl,imx25-fec", .data = &fec_devtype[IMX25_FEC], },
	{ .compatible = "fsl,imx27-fec", .data = &fec_devtype[IMX27_FEC], },
	{ .compatible = "fsl,imx28-fec", .data = &fec_devtype[IMX28_FEC], },
	{ .compatible = "fsl,imx6q-fec", .data = &fec_devtype[IMX6Q_FEC], },
	{ .compatible = "fsl,mvf600-fec", .data = &fec_devtype[MVF600_FEC], },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, fec_dt_ids);

static unsigned char macaddr[ETH_ALEN];
module_param_array(macaddr, byte, NULL, 0);
MODULE_PARM_DESC(macaddr, "FEC Ethernet MAC address");

#if defined(CONFIG_M5272)
/*
 * Some hardware gets it MAC address out of local flash memory.
 * if this is non-zero then assume it is the address to get MAC from.
 */
#if defined(CONFIG_NETtel)
#define	FEC_FLASHMAC	0xf0006006
#elif defined(CONFIG_GILBARCONAP) || defined(CONFIG_SCALES)
#define	FEC_FLASHMAC	0xf0006000
#elif defined(CONFIG_CANCam)
#define	FEC_FLASHMAC	0xf0020000
#elif defined (CONFIG_M5272C3)
#define	FEC_FLASHMAC	(0xffe04000 + 4)
#elif defined(CONFIG_MOD5272)
#define FEC_FLASHMAC	0xffc0406b
#else
#define	FEC_FLASHMAC	0
#endif
#endif /* CONFIG_M5272 */

/* Interrupt events/masks. */
#define FEC_ENET_HBERR	((uint)0x80000000)	/* Heartbeat error */
#define FEC_ENET_BABR	((uint)0x40000000)	/* Babbling receiver */
#define FEC_ENET_BABT	((uint)0x20000000)	/* Babbling transmitter */
#define FEC_ENET_GRA	((uint)0x10000000)	/* Graceful stop complete */
#define FEC_ENET_TXF	((uint)0x08000000)	/* Full frame transmitted */
#define FEC_ENET_TXB	((uint)0x04000000)	/* A buffer was transmitted */
#define FEC_ENET_RXF	((uint)0x02000000)	/* Full frame received */
#define FEC_ENET_RXB	((uint)0x01000000)	/* A buffer was received */
#define FEC_ENET_MII	((uint)0x00800000)	/* MII interrupt */
#define FEC_ENET_EBERR	((uint)0x00400000)	/* SDMA bus error */

#define FEC_DEFAULT_IMASK (FEC_ENET_TXF | FEC_ENET_RXF | FEC_ENET_MII)
#define FEC_RX_DISABLED_IMASK (FEC_DEFAULT_IMASK & (~FEC_ENET_RXF))

/* The FEC stores dest/src/type/vlan, data, and checksum for receive packets.
 */
#define PKT_MAXBUF_SIZE		1522
#define PKT_MINBUF_SIZE		64
#define PKT_MAXBLR_SIZE		1536

/* FEC receive acceleration */
#define FEC_RACC_IPDIS		(1 << 1)
#define FEC_RACC_PRODIS		(1 << 2)
#define FEC_RACC_OPTIONS	(FEC_RACC_IPDIS | FEC_RACC_PRODIS)

/*
 * The 5270/5271/5280/5282/532x RX control register also contains maximum frame
 * size bits. Other FEC hardware does not, so we need to take that into
 * account when setting it.
 */
#if defined(CONFIG_M523x) || defined(CONFIG_M527x) || defined(CONFIG_M528x) || \
    defined(CONFIG_M520x) || defined(CONFIG_M532x) || defined(CONFIG_ARM)
#define	OPT_FRAME_SIZE	(PKT_MAXBUF_SIZE << 16)
#else
#define	OPT_FRAME_SIZE	0
#endif

/* FEC MII MMFR bits definition */
#define FEC_MMFR_ST		(1 << 30)
#define FEC_MMFR_OP_READ	(2 << 28)
#define FEC_MMFR_OP_WRITE	(1 << 28)
#define FEC_MMFR_PA(v)		((v & 0x1f) << 23)
#define FEC_MMFR_RA(v)		((v & 0x1f) << 18)
#define FEC_MMFR_TA		(2 << 16)
#define FEC_MMFR_DATA(v)	(v & 0xffff)

#define FEC_MII_TIMEOUT		30000 /* us */

/* Transmitter timeout */
#define TX_TIMEOUT (2 * HZ)

#define FEC_PAUSE_FLAG_AUTONEG	0x1
#define FEC_PAUSE_FLAG_ENABLE	0x2

#define TSO_HEADER_SIZE		128
/* Max number of allowed TCP segments for software TSO */
#define FEC_MAX_TSO_SEGS	100
#define FEC_MAX_SKB_DESCS	(FEC_MAX_TSO_SEGS * 2 + MAX_SKB_FRAGS)

#define IS_TSO_HEADER(txq, addr) \
	((addr >= txq->tso_hdrs_dma) && \
	(addr < txq->tso_hdrs_dma + txq->tx_ring_size * TSO_HEADER_SIZE))

static int mii_cnt;

static inline
struct bufdesc *fec_enet_get_nextdesc(struct bufdesc *bdp,
				      struct fec_enet_private *fep,
				      int queue_id)
{
	struct bufdesc *new_bd = bdp + 1;
	struct bufdesc_ex *ex_new_bd = (struct bufdesc_ex *)bdp + 1;
	struct fec_enet_priv_tx_q *txq = fep->tx_queue[queue_id];
	struct fec_enet_priv_rx_q *rxq = fep->rx_queue[queue_id];
	struct bufdesc_ex *ex_base;
	struct bufdesc *base;
	int ring_size;

	if (bdp >= txq->tx_bd_base) {
		base = txq->tx_bd_base;
		ring_size = txq->tx_ring_size;
		ex_base = (struct bufdesc_ex *)txq->tx_bd_base;
	} else {
		base = rxq->rx_bd_base;
		ring_size = rxq->rx_ring_size;
		ex_base = (struct bufdesc_ex *)rxq->rx_bd_base;
	}

	if (fep->bufdesc_ex)
		return (struct bufdesc *)((ex_new_bd >= (ex_base + ring_size)) ?
			ex_base : ex_new_bd);
	else
		return (new_bd >= (base + ring_size)) ?
			base : new_bd;
}

static inline
struct bufdesc *fec_enet_get_prevdesc(struct bufdesc *bdp,
				      struct fec_enet_private *fep,
				      int queue_id)
{
	struct bufdesc *new_bd = bdp - 1;
	struct bufdesc_ex *ex_new_bd = (struct bufdesc_ex *)bdp - 1;
	struct fec_enet_priv_tx_q *txq = fep->tx_queue[queue_id];
	struct fec_enet_priv_rx_q *rxq = fep->rx_queue[queue_id];
	struct bufdesc_ex *ex_base;
	struct bufdesc *base;
	int ring_size;

	if (bdp >= txq->tx_bd_base) {
		base = txq->tx_bd_base;
		ring_size = txq->tx_ring_size;
		ex_base = (struct bufdesc_ex *)txq->tx_bd_base;
	} else {
		base = rxq->rx_bd_base;
		ring_size = rxq->rx_ring_size;
		ex_base = (struct bufdesc_ex *)rxq->rx_bd_base;
	}

	if (fep->bufdesc_ex)
		return (struct bufdesc *)((ex_new_bd < ex_base) ?
			(ex_new_bd + ring_size) : ex_new_bd);
	else
		return (new_bd < base) ? (new_bd + ring_size) : new_bd;
}

static int fec_enet_get_bd_index(struct bufdesc *base, struct bufdesc *bdp,
				struct fec_enet_private *fep)
{
	return ((const char *)bdp - (const char *)base) / fep->bufdesc_size;
}

static int fec_enet_get_free_txdesc_num(struct fec_enet_private *fep,
					struct fec_enet_priv_tx_q *txq)
{
	int entries;

	entries = ((const char *)txq->dirty_tx -
			(const char *)txq->cur_tx) / fep->bufdesc_size - 1;

	return entries > 0 ? entries : entries + txq->tx_ring_size;
}

static void *swap_buffer(void *bufaddr, int len)
{
	int i;
	unsigned int *buf = bufaddr;

	for (i = 0; i < DIV_ROUND_UP(len, 4); i++, buf++)
		*buf = cpu_to_be32(*buf);

	return bufaddr;
}

static void fec_dump(struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	struct bufdesc *bdp;
	struct fec_enet_priv_tx_q *txq;
	int index = 0;

	netdev_info(ndev, "TX ring dump\n");
	pr_info("Nr     SC     addr       len  SKB\n");

	txq = fep->tx_queue[0];
	bdp = txq->tx_bd_base;

	do {
		pr_info("%3u %c%c 0x%04x 0x%08lx %4u %p\n",
			index,
			bdp == txq->cur_tx ? 'S' : ' ',
			bdp == txq->dirty_tx ? 'H' : ' ',
			bdp->cbd_sc, bdp->cbd_bufaddr, bdp->cbd_datlen,
			txq->tx_skbuff[index]);
		bdp = fec_enet_get_nextdesc(bdp, fep, 0);
		index++;
	} while (bdp != txq->tx_bd_base);
}

static inline bool is_ipv4_pkt(struct sk_buff *skb)
{
	return skb->protocol == htons(ETH_P_IP) && ip_hdr(skb)->version == 4;
}

static int
fec_enet_clear_csum(struct sk_buff *skb, struct net_device *ndev)
{
	/* Only run for packets requiring a checksum. */
	if (skb->ip_summed != CHECKSUM_PARTIAL)
		return 0;

	if (unlikely(skb_cow_head(skb, 0)))
		return -1;

	if (is_ipv4_pkt(skb))
		ip_hdr(skb)->check = 0;
	*(__sum16 *)(skb->head + skb->csum_start + skb->csum_offset) = 0;

	return 0;
}

static int
fec_enet_txq_submit_frag_skb(struct fec_enet_priv_tx_q *txq,
			     struct sk_buff *skb,
			     struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	const struct platform_device_id *id_entry =
				platform_get_device_id(fep->pdev);
	struct bufdesc *bdp = txq->cur_tx;
	struct bufdesc_ex *ebdp;
	int nr_frags = skb_shinfo(skb)->nr_frags;
	unsigned short queue = skb_get_queue_mapping(skb);
	int frag, frag_len;
	unsigned short status;
	unsigned int estatus = 0;
	skb_frag_t *this_frag;
	unsigned int index;
	void *bufaddr;
	dma_addr_t addr;
	int i;

	for (frag = 0; frag < nr_frags; frag++) {
		this_frag = &skb_shinfo(skb)->frags[frag];
		bdp = fec_enet_get_nextdesc(bdp, fep, queue);
		ebdp = (struct bufdesc_ex *)bdp;

		status = bdp->cbd_sc;
		status &= ~BD_ENET_TX_STATS;
		status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);
		frag_len = skb_shinfo(skb)->frags[frag].size;

		/* Handle the last BD specially */
		if (frag == nr_frags - 1) {
			status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST);
			if (fep->bufdesc_ex) {
				estatus |= BD_ENET_TX_INT;
				if (unlikely(skb_shinfo(skb)->tx_flags &
					SKBTX_HW_TSTAMP && fep->hwts_tx_en))
					estatus |= BD_ENET_TX_TS;
			}
		}

		if (fep->bufdesc_ex) {
			if (skb->ip_summed == CHECKSUM_PARTIAL)
				estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;
			ebdp->cbd_bdu = 0;
			ebdp->cbd_esc = estatus;
		}

		bufaddr = page_address(this_frag->page.p) + this_frag->page_offset;

		index = fec_enet_get_bd_index(txq->tx_bd_base, bdp, fep);
		if (((unsigned long) bufaddr) & FEC_ALIGNMENT ||
			id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
			memcpy(txq->tx_bounce[index], bufaddr, frag_len);
			bufaddr = txq->tx_bounce[index];

			if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
				swap_buffer(bufaddr, frag_len);
		}

		addr = dma_map_single(&fep->pdev->dev, bufaddr, frag_len,
				      DMA_TO_DEVICE);
		if (dma_mapping_error(&fep->pdev->dev, addr)) {
			dev_kfree_skb_any(skb);
			if (net_ratelimit())
				netdev_err(ndev, "Tx DMA memory map failed\n");
			goto dma_mapping_error;
		}

		bdp->cbd_bufaddr = addr;
		bdp->cbd_datlen = frag_len;
		bdp->cbd_sc = status;
	}

	txq->cur_tx = bdp;

	return 0;

dma_mapping_error:
	bdp = txq->cur_tx;
	for (i = 0; i < frag; i++) {
		bdp = fec_enet_get_nextdesc(bdp, fep, queue);
		dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
				bdp->cbd_datlen, DMA_TO_DEVICE);
	}
	return NETDEV_TX_OK;
}

static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq,
				   struct sk_buff *skb, struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	const struct platform_device_id *id_entry =
				platform_get_device_id(fep->pdev);
	int nr_frags = skb_shinfo(skb)->nr_frags;
	struct bufdesc *bdp, *last_bdp;
	void *bufaddr;
	dma_addr_t addr;
	unsigned short status;
	unsigned short buflen;
	unsigned short queue;
	unsigned int estatus = 0;
	unsigned int index;
	int entries_free;
	int ret;

	entries_free = fec_enet_get_free_txdesc_num(fep, txq);
	if (entries_free < MAX_SKB_FRAGS + 1) {
		dev_kfree_skb_any(skb);
		if (net_ratelimit())
			netdev_err(ndev, "NOT enough BD for SG!\n");
		return NETDEV_TX_OK;
	}

	/* Protocol checksum off-load for TCP and UDP. */
	if (fec_enet_clear_csum(skb, ndev)) {
		dev_kfree_skb_any(skb);
		return NETDEV_TX_OK;
	}

	/* Fill in a Tx ring entry */
	bdp = txq->cur_tx;
	status = bdp->cbd_sc;
	status &= ~BD_ENET_TX_STATS;

	/* Set buffer length and buffer pointer */
	bufaddr = skb->data;
	buflen = skb_headlen(skb);

	queue = skb_get_queue_mapping(skb);
	index = fec_enet_get_bd_index(txq->tx_bd_base, bdp, fep);
	if (((unsigned long) bufaddr) & FEC_ALIGNMENT ||
		id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
		memcpy(txq->tx_bounce[index], skb->data, buflen);
		bufaddr = txq->tx_bounce[index];

		if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
			swap_buffer(bufaddr, buflen);
	}

	/* Push the data cache so the CPM does not get stale memory data. */
	addr = dma_map_single(&fep->pdev->dev, bufaddr, buflen, DMA_TO_DEVICE);
	if (dma_mapping_error(&fep->pdev->dev, addr)) {
		dev_kfree_skb_any(skb);
		if (net_ratelimit())
			netdev_err(ndev, "Tx DMA memory map failed\n");
		return NETDEV_TX_OK;
	}

	if (nr_frags) {
		ret = fec_enet_txq_submit_frag_skb(txq, skb, ndev);
		if (ret)
			return ret;
	} else {
		status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST);
		if (fep->bufdesc_ex) {
			estatus = BD_ENET_TX_INT;
			if (unlikely(skb_shinfo(skb)->tx_flags &
				SKBTX_HW_TSTAMP && fep->hwts_tx_en))
				estatus |= BD_ENET_TX_TS;
		}
	}

	if (fep->bufdesc_ex) {

		struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;

		if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
			fep->hwts_tx_en))
			skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;

		if (skb->ip_summed == CHECKSUM_PARTIAL)
			estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;

		ebdp->cbd_bdu = 0;
		ebdp->cbd_esc = estatus;
	}

	last_bdp = txq->cur_tx;
	index = fec_enet_get_bd_index(txq->tx_bd_base, last_bdp, fep);
	/* Save skb pointer */
	txq->tx_skbuff[index] = skb;

	bdp->cbd_datlen = buflen;
	bdp->cbd_bufaddr = addr;

	/* Send it on its way.  Tell FEC it's ready, interrupt when done,
	 * it's the last BD of the frame, and to put the CRC on the end.
	 */
	status |= (BD_ENET_TX_READY | BD_ENET_TX_TC);
	bdp->cbd_sc = status;

	/* If this was the last BD in the ring, start at the beginning again. */
	bdp = fec_enet_get_nextdesc(last_bdp, fep, queue);

	skb_tx_timestamp(skb);

	txq->cur_tx = bdp;

	/* Trigger transmission start */
	writel(0, fep->hwp + FEC_X_DES_ACTIVE(queue));

	return 0;
}

static int
fec_enet_txq_put_data_tso(struct fec_enet_priv_tx_q *txq, struct sk_buff *skb,
			  struct net_device *ndev,
			  struct bufdesc *bdp, int index, char *data,
			  int size, bool last_tcp, bool is_last)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	const struct platform_device_id *id_entry =
				platform_get_device_id(fep->pdev);
	struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
	unsigned short status;
	unsigned int estatus = 0;
	dma_addr_t addr;

	status = bdp->cbd_sc;
	status &= ~BD_ENET_TX_STATS;

	status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);

	if (((unsigned long) data) & FEC_ALIGNMENT ||
		id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
		memcpy(txq->tx_bounce[index], data, size);
		data = txq->tx_bounce[index];

		if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
			swap_buffer(data, size);
	}

	addr = dma_map_single(&fep->pdev->dev, data, size, DMA_TO_DEVICE);
	if (dma_mapping_error(&fep->pdev->dev, addr)) {
		dev_kfree_skb_any(skb);
		if (net_ratelimit())
			netdev_err(ndev, "Tx DMA memory map failed\n");
		return NETDEV_TX_BUSY;
	}

	bdp->cbd_datlen = size;
	bdp->cbd_bufaddr = addr;

	if (fep->bufdesc_ex) {
		if (skb->ip_summed == CHECKSUM_PARTIAL)
			estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;
		ebdp->cbd_bdu = 0;
		ebdp->cbd_esc = estatus;
	}

	/* Handle the last BD specially */
	if (last_tcp)
		status |= (BD_ENET_TX_LAST | BD_ENET_TX_TC);
	if (is_last) {
		status |= BD_ENET_TX_INTR;
		if (fep->bufdesc_ex)
			ebdp->cbd_esc |= BD_ENET_TX_INT;
	}

	bdp->cbd_sc = status;

	return 0;
}

static int
fec_enet_txq_put_hdr_tso(struct fec_enet_priv_tx_q *txq,
			 struct sk_buff *skb, struct net_device *ndev,
			 struct bufdesc *bdp, int index)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	const struct platform_device_id *id_entry =
				platform_get_device_id(fep->pdev);
	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
	struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
	void *bufaddr;
	unsigned long dmabuf;
	unsigned short status;
	unsigned int estatus = 0;

	status = bdp->cbd_sc;
	status &= ~BD_ENET_TX_STATS;
	status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);

	bufaddr = txq->tso_hdrs + index * TSO_HEADER_SIZE;
	dmabuf = txq->tso_hdrs_dma + index * TSO_HEADER_SIZE;
	if (((unsigned long) bufaddr) & FEC_ALIGNMENT ||
		id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
		memcpy(txq->tx_bounce[index], skb->data, hdr_len);
		bufaddr = txq->tx_bounce[index];

		if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
			swap_buffer(bufaddr, hdr_len);

		dmabuf = dma_map_single(&fep->pdev->dev, bufaddr,
					hdr_len, DMA_TO_DEVICE);
		if (dma_mapping_error(&fep->pdev->dev, dmabuf)) {
			dev_kfree_skb_any(skb);
			if (net_ratelimit())
				netdev_err(ndev, "Tx DMA memory map failed\n");
			return NETDEV_TX_BUSY;
		}
	}

	bdp->cbd_bufaddr = dmabuf;
	bdp->cbd_datlen = hdr_len;

	if (fep->bufdesc_ex) {
		if (skb->ip_summed == CHECKSUM_PARTIAL)
			estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;
		ebdp->cbd_bdu = 0;
		ebdp->cbd_esc = estatus;
	}

	bdp->cbd_sc = status;

	return 0;
}

static int fec_enet_txq_submit_tso(struct fec_enet_priv_tx_q *txq,
				   struct sk_buff *skb,
				   struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
	int total_len, data_left;
	struct bufdesc *bdp = txq->cur_tx;
	unsigned short queue = skb_get_queue_mapping(skb);
	struct tso_t tso;
	unsigned int index = 0;
	int ret;

	if (tso_count_descs(skb) >= fec_enet_get_free_txdesc_num(fep, txq)) {
		dev_kfree_skb_any(skb);
		if (net_ratelimit())
			netdev_err(ndev, "NOT enough BD for TSO!\n");
		return NETDEV_TX_OK;
	}

	/* Protocol checksum off-load for TCP and UDP. */
	if (fec_enet_clear_csum(skb, ndev)) {
		dev_kfree_skb_any(skb);
		return NETDEV_TX_OK;
	}

	/* Initialize the TSO handler, and prepare the first payload */
	tso_start(skb, &tso);

	total_len = skb->len - hdr_len;
	while (total_len > 0) {
		char *hdr;

		index = fec_enet_get_bd_index(txq->tx_bd_base, bdp, fep);
		data_left = min_t(int, skb_shinfo(skb)->gso_size, total_len);
		total_len -= data_left;

		/* prepare packet headers: MAC + IP + TCP */
		hdr = txq->tso_hdrs + index * TSO_HEADER_SIZE;
		tso_build_hdr(skb, hdr, &tso, data_left, total_len == 0);
		ret = fec_enet_txq_put_hdr_tso(txq, skb, ndev, bdp, index);
		if (ret)
			goto err_release;

		while (data_left > 0) {
			int size;

			size = min_t(int, tso.size, data_left);
			bdp = fec_enet_get_nextdesc(bdp, fep, queue);
			index = fec_enet_get_bd_index(txq->tx_bd_base,
						      bdp, fep);
			ret = fec_enet_txq_put_data_tso(txq, skb, ndev,
							bdp, index,
							tso.data, size,
							size == data_left,
							total_len == 0);
			if (ret)
				goto err_release;

			data_left -= size;
			tso_build_data(skb, &tso, size);
		}

		bdp = fec_enet_get_nextdesc(bdp, fep, queue);
	}

	/* Save skb pointer */
	txq->tx_skbuff[index] = skb;

	skb_tx_timestamp(skb);
	txq->cur_tx = bdp;

	/* Trigger transmission start */
	writel(0, fep->hwp + FEC_X_DES_ACTIVE(queue));

	return 0;

err_release:
	/* TODO: Release all used data descriptors for TSO */
	return ret;
}

static netdev_tx_t
fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	int entries_free;
	unsigned short queue;
	struct fec_enet_priv_tx_q *txq;
	struct netdev_queue *nq;
	int ret;

	queue = skb_get_queue_mapping(skb);
	txq = fep->tx_queue[queue];
	nq = netdev_get_tx_queue(ndev, queue);

	if (skb_is_gso(skb))
		ret = fec_enet_txq_submit_tso(txq, skb, ndev);
	else
		ret = fec_enet_txq_submit_skb(txq, skb, ndev);
	if (ret)
		return ret;

	entries_free = fec_enet_get_free_txdesc_num(fep, txq);
	if (entries_free <= txq->tx_stop_threshold)
		netif_tx_stop_queue(nq);

	return NETDEV_TX_OK;
}

/* Init RX & TX buffer descriptors
 */
static void fec_enet_bd_init(struct net_device *dev)
{
	struct fec_enet_private *fep = netdev_priv(dev);
	struct fec_enet_priv_tx_q *txq;
	struct fec_enet_priv_rx_q *rxq;
	struct bufdesc *bdp;
	unsigned int i;
	unsigned int q;

	for (q = 0; q < fep->num_rx_queues; q++) {
		/* Initialize the receive buffer descriptors. */
		rxq = fep->rx_queue[q];
		bdp = rxq->rx_bd_base;

		for (i = 0; i < rxq->rx_ring_size; i++) {

			/* Initialize the BD for every fragment in the page. */
			if (bdp->cbd_bufaddr)
				bdp->cbd_sc = BD_ENET_RX_EMPTY;
			else
				bdp->cbd_sc = 0;
			bdp = fec_enet_get_nextdesc(bdp, fep, q);
		}

		/* Set the last buffer to wrap */
		bdp = fec_enet_get_prevdesc(bdp, fep, q);
		bdp->cbd_sc |= BD_SC_WRAP;

		rxq->cur_rx = rxq->rx_bd_base;
	}

	for (q = 0; q < fep->num_tx_queues; q++) {
		/* ...and the same for transmit */
		txq = fep->tx_queue[q];
		bdp = txq->tx_bd_base;
		txq->cur_tx = bdp;

		for (i = 0; i < txq->tx_ring_size; i++) {
			/* Initialize the BD for every fragment in the page. */
			bdp->cbd_sc = 0;
			if (txq->tx_skbuff[i]) {
				dev_kfree_skb_any(txq->tx_skbuff[i]);
				txq->tx_skbuff[i] = NULL;
			}
			bdp->cbd_bufaddr = 0;
			bdp = fec_enet_get_nextdesc(bdp, fep, q);
		}

		/* Set the last buffer to wrap */
		bdp = fec_enet_get_prevdesc(bdp, fep, q);
		bdp->cbd_sc |= BD_SC_WRAP;
		txq->dirty_tx = bdp;
	}
}

static void fec_enet_enable_ring(struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	struct fec_enet_priv_tx_q *txq;
	struct fec_enet_priv_rx_q *rxq;
	int i;

	for (i = 0; i < fep->num_rx_queues; i++) {
		rxq = fep->rx_queue[i];
		writel(rxq->bd_dma, fep->hwp + FEC_R_DES_START(i));

		/* enable DMA1/2 */
		if (i)
			writel(RCMR_MATCHEN | RCMR_CMP(i),
			       fep->hwp + FEC_RCMR(i));
	}

	for (i = 0; i < fep->num_tx_queues; i++) {
		txq = fep->tx_queue[i];
		writel(txq->bd_dma, fep->hwp + FEC_X_DES_START(i));

		/* enable DMA1/2 */
		if (i)
			writel(DMA_CLASS_EN | IDLE_SLOPE(i),
			       fep->hwp + FEC_DMA_CFG(i));
	}
}

static void fec_enet_reset_skb(struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	struct fec_enet_priv_tx_q *txq;
	int i, j;

	for (i = 0; i < fep->num_tx_queues; i++) {
		txq = fep->tx_queue[i];

		for (j = 0; j < txq->tx_ring_size; j++) {
			if (txq->tx_skbuff[j]) {
				dev_kfree_skb_any(txq->tx_skbuff[j]);
				txq->tx_skbuff[j] = NULL;
			}
		}
	}
}

/*
 * This function is called to start or restart the FEC during a link
 * change, transmit timeout, or to reconfigure the FEC.  The network
 * packet processing for this device must be stopped before this call.
 */
static void
fec_restart(struct net_device *ndev)
{
	struct fec_enet_private *fep = netdev_priv(ndev);
	const struct platform_device_id *id_entry =
				platform_get_device_id(fep->pdev);
	int i;
	u32 val;
	u32 temp_mac[2];
	u32 rcntl = OPT_FRAME_SIZE | 0x04;
	u32 ecntl = 0x2; /* ETHEREN */

	/* Whack a reset.  We should wait for this. */
	writel(1, fep->hwp + FEC_ECNTRL);
	udelay(10);

	/*
	 * enet-mac reset will reset mac address registers too,
	 * so need to reconfigure it.
	 */
	if (id_entry->driver_data & FEC_QUIRK_ENET_MAC) {
		memcpy(&temp_mac, ndev->dev_addr, ETH_ALEN);
		writel(cpu_to_be32(temp_mac[0]), fep->hwp + FEC_ADDR_LOW);
		writel(cpu_to_be32(temp_mac[1]), fep->hwp + FEC_ADDR_HIGH);
	}

	/* Clear any outstanding interrupt. */
	writel(0xffc00000, fep->hwp + FEC_IEVENT);

	/* Set maximum receive buffer size. */
	writel(PKT_MAXBLR_SIZE, fep->hwp + FEC_R_BUFF_SIZE);

	fec_enet_bd_init(ndev);

	fec_enet_enable_ring(ndev);

	/* Reset tx SKB buffers. */
	fec_enet_reset_skb(ndev);

	/* Enable MII mode */
	if (fep->full_duplex == DUPLEX_FULL) {
		/* FD enable */
		writel(0x04, fep->hwp + FEC_X_CNTRL);
	} else {
		/* No Rcv on Xmit */
		rcntl |= 0x02;
		writel(0x0, fep->hwp + FEC_X_CNTRL);
	}

	/* Set MII speed */
	writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);

#if !defined(CONFIG_M5272)
	/* set RX checksum */
	val = readl(fep->hwp + FEC_RACC);
	if (fep->csum_flags & FLAG_RX_CSUM_ENABLED)
		val |= FEC_RACC_OPTIONS;
	else
		val &= ~FEC_RACC_OPTIONS;
	writel(val, fep->hwp + FEC_RACC);
#endif

	/*
	 * The phy interface and speed need to get configured
	 * differently on enet-mac.