drivers/net/ethernet/micrel/ks8851_spi.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /* drivers/net/ethernet/micrel/ks8851.c
  *
  * Copyright 2009 Simtec Electronics
  *	http://www.simtec.co.uk/
  *	Ben Dooks <ben@simtec.co.uk>
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #define DEBUG

 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/cache.h>
 #include <linux/crc32.h>
 #include <linux/mii.h>
 #include <linux/regulator/consumer.h>

 #include <linux/spi/spi.h>
 #include <linux/gpio.h>
 #include <linux/of_gpio.h>
 #include <linux/of_net.h>

 #include "ks8851.h"

 static int msg_enable;

 /**
  * struct ks8851_net_spi - KS8851 SPI driver private data
  * @lock: Lock to ensure that the device is not accessed when busy.
  * @tx_work: Work queue for tx packets
  * @ks8851: KS8851 driver common private data
  * @spidev: The spi device we're bound to.
  * @spi_msg1: pre-setup SPI transfer with one message, @spi_xfer1.
  * @spi_msg2: pre-setup SPI transfer with two messages, @spi_xfer2.
  * @spi_xfer1: @spi_msg1 SPI transfer structure
  * @spi_xfer2: @spi_msg2 SPI transfer structure
  *
  * The @lock ensures that the chip is protected when certain operations are
  * in progress. When the read or write packet transfer is in progress, most
  * of the chip registers are not ccessible until the transfer is finished and
  * the DMA has been de-asserted.
  */
 struct ks8851_net_spi {
 	struct ks8851_net	ks8851;
 	struct mutex		lock;
 	struct work_struct	tx_work;
 	struct spi_device	*spidev;
 	struct spi_message	spi_msg1;
 	struct spi_message	spi_msg2;
 	struct spi_transfer	spi_xfer1;
 	struct spi_transfer	spi_xfer2[2];
 };

 #define to_ks8851_spi(ks) container_of((ks), struct ks8851_net_spi, ks8851)

 /* SPI frame opcodes */
 #define KS_SPIOP_RD	0x00
 #define KS_SPIOP_WR	0x40
 #define KS_SPIOP_RXFIFO	0x80
 #define KS_SPIOP_TXFIFO	0xC0

 /* shift for byte-enable data */
 #define BYTE_EN(_x)	((_x) << 2)

 /* turn register number and byte-enable mask into data for start of packet */
 #define MK_OP(_byteen, _reg)	\
 	(BYTE_EN(_byteen) | (_reg) << (8 + 2) | (_reg) >> 6)

 /**
  * ks8851_lock_spi - register access lock
  * @ks: The chip state
  * @flags: Spinlock flags
  *
  * Claim chip register access lock
  */
 static void ks8851_lock_spi(struct ks8851_net *ks, unsigned long *flags)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

 	mutex_lock(&kss->lock);
 }

 /**
  * ks8851_unlock_spi - register access unlock
  * @ks: The chip state
  * @flags: Spinlock flags
  *
  * Release chip register access lock
  */
 static void ks8851_unlock_spi(struct ks8851_net *ks, unsigned long *flags)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

 	mutex_unlock(&kss->lock);
 }

 /* SPI register read/write calls.
  *
  * All these calls issue SPI transactions to access the chip's registers. They
  * all require that the necessary lock is held to prevent accesses when the
  * chip is busy transferring packet data (RX/TX FIFO accesses).
  */

 /**
  * ks8851_wrreg16_spi - write 16bit register value to chip via SPI
  * @ks: The chip state
  * @reg: The register address
  * @val: The value to write
  *
  * Issue a write to put the value @val into the register specified in @reg.
  */
 static void ks8851_wrreg16_spi(struct ks8851_net *ks, unsigned int reg,
 			       unsigned int val)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
 	struct spi_transfer *xfer = &kss->spi_xfer1;
 	struct spi_message *msg = &kss->spi_msg1;
 	__le16 txb[2];
 	int ret;

 	txb[0] = cpu_to_le16(MK_OP(reg & 2 ? 0xC : 0x03, reg) | KS_SPIOP_WR);
 	txb[1] = cpu_to_le16(val);

 	xfer->tx_buf = txb;
 	xfer->rx_buf = NULL;
 	xfer->len = 4;

 	ret = spi_sync(kss->spidev, msg);
 	if (ret < 0)
 		netdev_err(ks->netdev, "spi_sync() failed\n");
 }

 /**
  * ks8851_rdreg - issue read register command and return the data
  * @ks: The device state
  * @op: The register address and byte enables in message format.
  * @rxb: The RX buffer to return the result into
  * @rxl: The length of data expected.
  *
  * This is the low level read call that issues the necessary spi message(s)
  * to read data from the register specified in @op.
  */
 static void ks8851_rdreg(struct ks8851_net *ks, unsigned int op,
 			 u8 *rxb, unsigned int rxl)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
 	struct spi_transfer *xfer;
 	struct spi_message *msg;
 	__le16 *txb = (__le16 *)ks->txd;
 	u8 *trx = ks->rxd;
 	int ret;

 	txb[0] = cpu_to_le16(op | KS_SPIOP_RD);

 	if (kss->spidev->master->flags & SPI_MASTER_HALF_DUPLEX) {
 		msg = &kss->spi_msg2;
 		xfer = kss->spi_xfer2;

 		xfer->tx_buf = txb;
 		xfer->rx_buf = NULL;
 		xfer->len = 2;

 		xfer++;
 		xfer->tx_buf = NULL;
 		xfer->rx_buf = trx;
 		xfer->len = rxl;
 	} else {
 		msg = &kss->spi_msg1;
 		xfer = &kss->spi_xfer1;

 		xfer->tx_buf = txb;
 		xfer->rx_buf = trx;
 		xfer->len = rxl + 2;
 	}

 	ret = spi_sync(kss->spidev, msg);
 	if (ret < 0)
 		netdev_err(ks->netdev, "read: spi_sync() failed\n");
 	else if (kss->spidev->master->flags & SPI_MASTER_HALF_DUPLEX)
 		memcpy(rxb, trx, rxl);
 	else
 		memcpy(rxb, trx + 2, rxl);
 }

 /**
  * ks8851_rdreg16_spi - read 16 bit register from device via SPI
  * @ks: The chip information
  * @reg: The register address
  *
  * Read a 16bit register from the chip, returning the result
  */
 static unsigned int ks8851_rdreg16_spi(struct ks8851_net *ks, unsigned int reg)
 {
 	__le16 rx = 0;

 	ks8851_rdreg(ks, MK_OP(reg & 2 ? 0xC : 0x3, reg), (u8 *)&rx, 2);
 	return le16_to_cpu(rx);
 }

 /**
  * ks8851_rdfifo_spi - read data from the receive fifo via SPI
  * @ks: The device state.
  * @buff: The buffer address
  * @len: The length of the data to read
  *
  * Issue an RXQ FIFO read command and read the @len amount of data from
  * the FIFO into the buffer specified by @buff.
  */
 static void ks8851_rdfifo_spi(struct ks8851_net *ks, u8 *buff, unsigned int len)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
 	struct spi_transfer *xfer = kss->spi_xfer2;
 	struct spi_message *msg = &kss->spi_msg2;
 	u8 txb[1];
 	int ret;

 	netif_dbg(ks, rx_status, ks->netdev,
 		  "%s: %d@%p\n", __func__, len, buff);

 	/* set the operation we're issuing */
 	txb[0] = KS_SPIOP_RXFIFO;

 	xfer->tx_buf = txb;
 	xfer->rx_buf = NULL;
 	xfer->len = 1;

 	xfer++;
 	xfer->rx_buf = buff;
 	xfer->tx_buf = NULL;
 	xfer->len = len;

 	ret = spi_sync(kss->spidev, msg);
 	if (ret < 0)
 		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
 }

 /**
  * ks8851_wrfifo_spi - write packet to TX FIFO via SPI
  * @ks: The device state.
  * @txp: The sk_buff to transmit.
  * @irq: IRQ on completion of the packet.
  *
  * Send the @txp to the chip. This means creating the relevant packet header
  * specifying the length of the packet and the other information the chip
  * needs, such as IRQ on completion. Send the header and the packet data to
  * the device.
  */
 static void ks8851_wrfifo_spi(struct ks8851_net *ks, struct sk_buff *txp,
 			      bool irq)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
 	struct spi_transfer *xfer = kss->spi_xfer2;
 	struct spi_message *msg = &kss->spi_msg2;
 	unsigned int fid = 0;
 	int ret;

 	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
 		  __func__, txp, txp->len, txp->data, irq);

 	fid = ks->fid++;
 	fid &= TXFR_TXFID_MASK;

 	if (irq)
 		fid |= TXFR_TXIC;	/* irq on completion */

 	/* start header at txb[1] to align txw entries */
 	ks->txh.txb[1] = KS_SPIOP_TXFIFO;
 	ks->txh.txw[1] = cpu_to_le16(fid);
 	ks->txh.txw[2] = cpu_to_le16(txp->len);

 	xfer->tx_buf = &ks->txh.txb[1];
 	xfer->rx_buf = NULL;
 	xfer->len = 5;

 	xfer++;
 	xfer->tx_buf = txp->data;
 	xfer->rx_buf = NULL;
 	xfer->len = ALIGN(txp->len, 4);

 	ret = spi_sync(kss->spidev, msg);
 	if (ret < 0)
 		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
 }

 /**
  * ks8851_rx_skb_spi - receive skbuff
  * @ks: The device state
  * @skb: The skbuff
  */
 static void ks8851_rx_skb_spi(struct ks8851_net *ks, struct sk_buff *skb)
 {
 	netif_rx_ni(skb);
 }

 /**
  * ks8851_tx_work - process tx packet(s)
  * @work: The work strucutre what was scheduled.
  *
  * This is called when a number of packets have been scheduled for
  * transmission and need to be sent to the device.
  */
 static void ks8851_tx_work(struct work_struct *work)
 {
 	struct ks8851_net_spi *kss;
 	struct ks8851_net *ks;
 	unsigned long flags;
 	struct sk_buff *txb;
 	bool last;

 	kss = container_of(work, struct ks8851_net_spi, tx_work);
 	ks = &kss->ks8851;
 	last = skb_queue_empty(&ks->txq);

 	ks8851_lock_spi(ks, &flags);

 	while (!last) {
 		txb = skb_dequeue(&ks->txq);
 		last = skb_queue_empty(&ks->txq);

 		if (txb) {
 			ks8851_wrreg16_spi(ks, KS_RXQCR,
 					   ks->rc_rxqcr | RXQCR_SDA);
 			ks8851_wrfifo_spi(ks, txb, last);
 			ks8851_wrreg16_spi(ks, KS_RXQCR, ks->rc_rxqcr);
 			ks8851_wrreg16_spi(ks, KS_TXQCR, TXQCR_METFE);

 			ks8851_done_tx(ks, txb);
 		}
 	}

 	ks8851_unlock_spi(ks, &flags);
 }

 /**
  * ks8851_flush_tx_work_spi - flush outstanding TX work
  * @ks: The device state
  */
 static void ks8851_flush_tx_work_spi(struct ks8851_net *ks)
 {
 	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

 	flush_work(&kss->tx_work);
 }

 /**
  * calc_txlen - calculate size of message to send packet
  * @len: Length of data
  *
  * Returns the size of the TXFIFO message needed to send
  * this packet.
  */
 static unsigned int calc_txlen(unsigned int len)
 {
 	return ALIGN(len + 4, 4);
 }

 /**
  * ks8851_start_xmit_spi - transmit packet using SPI
  * @skb: The buffer to transmit
  * @dev: The device used to transmit the packet.
  *
  * Called by the network layer to transmit the @skb. Queue the packet for
  * the device and schedule the necessary work to transmit the packet when
  * it is free.
  *
  * We do this to firstly avoid sleeping with the network device locked,
  * and secondly so we can round up more than one packet to transmit which
  * means we can try and avoid generating too many transmit done interrupts.
  */
 static netdev_tx_t ks8851_start_xmit_spi(struct sk_buff *skb,
 					 struct net_device *dev)
 {
 	unsigned int needed = calc_txlen(skb->len);
 	struct ks8851_net *ks = netdev_priv(dev);
 	netdev_tx_t ret = NETDEV_TX_OK;
 	struct ks8851_net_spi *kss;

 	kss = to_ks8851_spi(ks);

 	netif_dbg(ks, tx_queued, ks->netdev,
 		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);

 	spin_lock(&ks->statelock);

 	if (needed > ks->tx_space) {
 		netif_stop_queue(dev);
 		ret = NETDEV_TX_BUSY;
 	} else {
 		ks->tx_space -= needed;
 		skb_queue_tail(&ks->txq, skb);
 	}

 	spin_unlock(&ks->statelock);
 	schedule_work(&kss->tx_work);

 	return ret;
 }

 static int ks8851_probe_spi(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
 	struct ks8851_net_spi *kss;
 	struct net_device *netdev;
 	struct ks8851_net *ks;

 	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_spi));
 	if (!netdev)
 		return -ENOMEM;

 	spi->bits_per_word = 8;

 	ks = netdev_priv(netdev);

 	ks->lock = ks8851_lock_spi;
 	ks->unlock = ks8851_unlock_spi;
 	ks->rdreg16 = ks8851_rdreg16_spi;
 	ks->wrreg16 = ks8851_wrreg16_spi;
 	ks->rdfifo = ks8851_rdfifo_spi;
 	ks->wrfifo = ks8851_wrfifo_spi;
 	ks->start_xmit = ks8851_start_xmit_spi;
 	ks->rx_skb = ks8851_rx_skb_spi;
 	ks->flush_tx_work = ks8851_flush_tx_work_spi;

 #define STD_IRQ (IRQ_LCI |	/* Link Change */	\
 		 IRQ_TXI |	/* TX done */		\
 		 IRQ_RXI |	/* RX done */		\
 		 IRQ_SPIBEI |	/* SPI bus error */	\
 		 IRQ_TXPSI |	/* TX process stop */	\
 		 IRQ_RXPSI)	/* RX process stop */
 	ks->rc_ier = STD_IRQ;

 	kss = to_ks8851_spi(ks);

 	kss->spidev = spi;
 	mutex_init(&kss->lock);
 	INIT_WORK(&kss->tx_work, ks8851_tx_work);

 	/* initialise pre-made spi transfer messages */
 	spi_message_init(&kss->spi_msg1);
 	spi_message_add_tail(&kss->spi_xfer1, &kss->spi_msg1);

 	spi_message_init(&kss->spi_msg2);
 	spi_message_add_tail(&kss->spi_xfer2[0], &kss->spi_msg2);
 	spi_message_add_tail(&kss->spi_xfer2[1], &kss->spi_msg2);

 	netdev->irq = spi->irq;

 	return ks8851_probe_common(netdev, dev, msg_enable);
 }

 static int ks8851_remove_spi(struct spi_device *spi)
 {
 	return ks8851_remove_common(&spi->dev);
 }

 static const struct of_device_id ks8851_match_table[] = {
 	{ .compatible = "micrel,ks8851" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ks8851_match_table);

 static struct spi_driver ks8851_driver = {
 	.driver = {
 		.name = "ks8851",
 		.of_match_table = ks8851_match_table,
 		.pm = &ks8851_pm_ops,
 	},
 	.probe = ks8851_probe_spi,
 	.remove = ks8851_remove_spi,
 };
 module_spi_driver(ks8851_driver);

 MODULE_DESCRIPTION("KS8851 Network driver");
 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
 MODULE_LICENSE("GPL");

 module_param_named(message, msg_enable, int, 0);
 MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
 MODULE_ALIAS("spi:ks8851");
	// SPDX-License-Identifier: GPL-2.0-only
	/* drivers/net/ethernet/micrel/ks8851.c
	*
	* Copyright 2009 Simtec Electronics
	* http://www.simtec.co.uk/
	* Ben Dooks <ben@simtec.co.uk>
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#define DEBUG

	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/netdevice.h>
	#include <linux/etherdevice.h>
	#include <linux/ethtool.h>
	#include <linux/cache.h>
	#include <linux/crc32.h>
	#include <linux/mii.h>
	#include <linux/regulator/consumer.h>

	#include <linux/spi/spi.h>
	#include <linux/gpio.h>
	#include <linux/of_gpio.h>
	#include <linux/of_net.h>

	#include "ks8851.h"

	static int msg_enable;

	/**
	* struct ks8851_net_spi - KS8851 SPI driver private data
	* @lock: Lock to ensure that the device is not accessed when busy.
	* @tx_work: Work queue for tx packets
	* @ks8851: KS8851 driver common private data
	* @spidev: The spi device we're bound to.
	* @spi_msg1: pre-setup SPI transfer with one message, @spi_xfer1.
	* @spi_msg2: pre-setup SPI transfer with two messages, @spi_xfer2.
	* @spi_xfer1: @spi_msg1 SPI transfer structure
	* @spi_xfer2: @spi_msg2 SPI transfer structure
	*
	* The @lock ensures that the chip is protected when certain operations are
	* in progress. When the read or write packet transfer is in progress, most
	* of the chip registers are not ccessible until the transfer is finished and
	* the DMA has been de-asserted.
	*/
	struct ks8851_net_spi {
	struct ks8851_net ks8851;
	struct mutex lock;
	struct work_struct tx_work;
	struct spi_device *spidev;
	struct spi_message spi_msg1;
	struct spi_message spi_msg2;
	struct spi_transfer spi_xfer1;
	struct spi_transfer spi_xfer2[2];
	};

	#define to_ks8851_spi(ks) container_of((ks), struct ks8851_net_spi, ks8851)

	/* SPI frame opcodes */
	#define KS_SPIOP_RD 0x00
	#define KS_SPIOP_WR 0x40
	#define KS_SPIOP_RXFIFO 0x80
	#define KS_SPIOP_TXFIFO 0xC0

	/* shift for byte-enable data */
	#define BYTE_EN(_x) ((_x) << 2)

	/* turn register number and byte-enable mask into data for start of packet */
	#define MK_OP(_byteen, _reg) \
	(BYTE_EN(_byteen) \| (_reg) << (8 + 2) \| (_reg) >> 6)

	/**
	* ks8851_lock_spi - register access lock
	* @ks: The chip state
	* @flags: Spinlock flags
	*
	* Claim chip register access lock
	*/
	static void ks8851_lock_spi(struct ks8851_net ks, unsigned long flags)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

	mutex_lock(&kss->lock);
	}

	/**
	* ks8851_unlock_spi - register access unlock
	* @ks: The chip state
	* @flags: Spinlock flags
	*
	* Release chip register access lock
	*/
	static void ks8851_unlock_spi(struct ks8851_net ks, unsigned long flags)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

	mutex_unlock(&kss->lock);
	}

	/* SPI register read/write calls.
	*
	* All these calls issue SPI transactions to access the chip's registers. They
	* all require that the necessary lock is held to prevent accesses when the
	* chip is busy transferring packet data (RX/TX FIFO accesses).
	*/

	/**
	* ks8851_wrreg16_spi - write 16bit register value to chip via SPI
	* @ks: The chip state
	* @reg: The register address
	* @val: The value to write
	*
	* Issue a write to put the value @val into the register specified in @reg.
	*/
	static void ks8851_wrreg16_spi(struct ks8851_net *ks, unsigned int reg,
	unsigned int val)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
	struct spi_transfer *xfer = &kss->spi_xfer1;
	struct spi_message *msg = &kss->spi_msg1;
	__le16 txb[2];
	int ret;

	txb[0] = cpu_to_le16(MK_OP(reg & 2 ? 0xC : 0x03, reg) \| KS_SPIOP_WR);
	txb[1] = cpu_to_le16(val);

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 4;

	ret = spi_sync(kss->spidev, msg);
	if (ret < 0)
	netdev_err(ks->netdev, "spi_sync() failed\n");
	}

	/**
	* ks8851_rdreg - issue read register command and return the data
	* @ks: The device state
	* @op: The register address and byte enables in message format.
	* @rxb: The RX buffer to return the result into
	* @rxl: The length of data expected.
	*
	* This is the low level read call that issues the necessary spi message(s)
	* to read data from the register specified in @op.
	*/
	static void ks8851_rdreg(struct ks8851_net *ks, unsigned int op,
	u8 *rxb, unsigned int rxl)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
	struct spi_transfer *xfer;
	struct spi_message *msg;
	__le16 txb = (__le16 )ks->txd;
	u8 *trx = ks->rxd;
	int ret;

	txb[0] = cpu_to_le16(op \| KS_SPIOP_RD);

	if (kss->spidev->master->flags & SPI_MASTER_HALF_DUPLEX) {
	msg = &kss->spi_msg2;
	xfer = kss->spi_xfer2;

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 2;

	xfer++;
	xfer->tx_buf = NULL;
	xfer->rx_buf = trx;
	xfer->len = rxl;
	} else {
	msg = &kss->spi_msg1;
	xfer = &kss->spi_xfer1;

	xfer->tx_buf = txb;
	xfer->rx_buf = trx;
	xfer->len = rxl + 2;
	}

	ret = spi_sync(kss->spidev, msg);
	if (ret < 0)
	netdev_err(ks->netdev, "read: spi_sync() failed\n");
	else if (kss->spidev->master->flags & SPI_MASTER_HALF_DUPLEX)
	memcpy(rxb, trx, rxl);
	else
	memcpy(rxb, trx + 2, rxl);
	}

	/**
	* ks8851_rdreg16_spi - read 16 bit register from device via SPI
	* @ks: The chip information
	* @reg: The register address
	*
	* Read a 16bit register from the chip, returning the result
	*/
	static unsigned int ks8851_rdreg16_spi(struct ks8851_net *ks, unsigned int reg)
	{
	__le16 rx = 0;

	ks8851_rdreg(ks, MK_OP(reg & 2 ? 0xC : 0x3, reg), (u8 *)&rx, 2);
	return le16_to_cpu(rx);
	}

	/**
	* ks8851_rdfifo_spi - read data from the receive fifo via SPI
	* @ks: The device state.
	* @buff: The buffer address
	* @len: The length of the data to read
	*
	* Issue an RXQ FIFO read command and read the @len amount of data from
	* the FIFO into the buffer specified by @buff.
	*/
	static void ks8851_rdfifo_spi(struct ks8851_net ks, u8 buff, unsigned int len)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
	struct spi_transfer *xfer = kss->spi_xfer2;
	struct spi_message *msg = &kss->spi_msg2;
	u8 txb[1];
	int ret;

	netif_dbg(ks, rx_status, ks->netdev,
	"%s: %d@%p\n", __func__, len, buff);

	/* set the operation we're issuing */
	txb[0] = KS_SPIOP_RXFIFO;

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 1;

	xfer++;
	xfer->rx_buf = buff;
	xfer->tx_buf = NULL;
	xfer->len = len;

	ret = spi_sync(kss->spidev, msg);
	if (ret < 0)
	netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
	}

	/**
	* ks8851_wrfifo_spi - write packet to TX FIFO via SPI
	* @ks: The device state.
	* @txp: The sk_buff to transmit.
	* @irq: IRQ on completion of the packet.
	*
	* Send the @txp to the chip. This means creating the relevant packet header
	* specifying the length of the packet and the other information the chip
	* needs, such as IRQ on completion. Send the header and the packet data to
	* the device.
	*/
	static void ks8851_wrfifo_spi(struct ks8851_net ks, struct sk_buff txp,
	bool irq)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);
	struct spi_transfer *xfer = kss->spi_xfer2;
	struct spi_message *msg = &kss->spi_msg2;
	unsigned int fid = 0;
	int ret;

	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
	__func__, txp, txp->len, txp->data, irq);

	fid = ks->fid++;
	fid &= TXFR_TXFID_MASK;

	if (irq)
	fid \|= TXFR_TXIC; /* irq on completion */

	/* start header at txb[1] to align txw entries */
	ks->txh.txb[1] = KS_SPIOP_TXFIFO;
	ks->txh.txw[1] = cpu_to_le16(fid);
	ks->txh.txw[2] = cpu_to_le16(txp->len);

	xfer->tx_buf = &ks->txh.txb[1];
	xfer->rx_buf = NULL;
	xfer->len = 5;

	xfer++;
	xfer->tx_buf = txp->data;
	xfer->rx_buf = NULL;
	xfer->len = ALIGN(txp->len, 4);

	ret = spi_sync(kss->spidev, msg);
	if (ret < 0)
	netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
	}

	/**
	* ks8851_rx_skb_spi - receive skbuff
	* @ks: The device state
	* @skb: The skbuff
	*/
	static void ks8851_rx_skb_spi(struct ks8851_net ks, struct sk_buff skb)
	{
	netif_rx_ni(skb);
	}

	/**
	* ks8851_tx_work - process tx packet(s)
	* @work: The work strucutre what was scheduled.
	*
	* This is called when a number of packets have been scheduled for
	* transmission and need to be sent to the device.
	*/
	static void ks8851_tx_work(struct work_struct *work)
	{
	struct ks8851_net_spi *kss;
	struct ks8851_net *ks;
	unsigned long flags;
	struct sk_buff *txb;
	bool last;

	kss = container_of(work, struct ks8851_net_spi, tx_work);
	ks = &kss->ks8851;
	last = skb_queue_empty(&ks->txq);

	ks8851_lock_spi(ks, &flags);

	while (!last) {
	txb = skb_dequeue(&ks->txq);
	last = skb_queue_empty(&ks->txq);

	if (txb) {
	ks8851_wrreg16_spi(ks, KS_RXQCR,
	ks->rc_rxqcr \| RXQCR_SDA);
	ks8851_wrfifo_spi(ks, txb, last);
	ks8851_wrreg16_spi(ks, KS_RXQCR, ks->rc_rxqcr);
	ks8851_wrreg16_spi(ks, KS_TXQCR, TXQCR_METFE);

	ks8851_done_tx(ks, txb);
	}
	}

	ks8851_unlock_spi(ks, &flags);
	}

	/**
	* ks8851_flush_tx_work_spi - flush outstanding TX work
	* @ks: The device state
	*/
	static void ks8851_flush_tx_work_spi(struct ks8851_net *ks)
	{
	struct ks8851_net_spi *kss = to_ks8851_spi(ks);

	flush_work(&kss->tx_work);
	}

	/**
	* calc_txlen - calculate size of message to send packet
	* @len: Length of data
	*
	* Returns the size of the TXFIFO message needed to send
	* this packet.
	*/
	static unsigned int calc_txlen(unsigned int len)
	{
	return ALIGN(len + 4, 4);
	}

	/**
	* ks8851_start_xmit_spi - transmit packet using SPI
	* @skb: The buffer to transmit
	* @dev: The device used to transmit the packet.
	*
	* Called by the network layer to transmit the @skb. Queue the packet for
	* the device and schedule the necessary work to transmit the packet when
	* it is free.
	*
	* We do this to firstly avoid sleeping with the network device locked,
	* and secondly so we can round up more than one packet to transmit which
	* means we can try and avoid generating too many transmit done interrupts.
	*/
	static netdev_tx_t ks8851_start_xmit_spi(struct sk_buff *skb,
	struct net_device *dev)
	{
	unsigned int needed = calc_txlen(skb->len);
	struct ks8851_net *ks = netdev_priv(dev);
	netdev_tx_t ret = NETDEV_TX_OK;
	struct ks8851_net_spi *kss;

	kss = to_ks8851_spi(ks);

	netif_dbg(ks, tx_queued, ks->netdev,
	"%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);

	spin_lock(&ks->statelock);

	if (needed > ks->tx_space) {
	netif_stop_queue(dev);
	ret = NETDEV_TX_BUSY;
	} else {
	ks->tx_space -= needed;
	skb_queue_tail(&ks->txq, skb);
	}

	spin_unlock(&ks->statelock);
	schedule_work(&kss->tx_work);

	return ret;
	}

	static int ks8851_probe_spi(struct spi_device *spi)
	{
	struct device *dev = &spi->dev;
	struct ks8851_net_spi *kss;
	struct net_device *netdev;
	struct ks8851_net *ks;

	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_spi));
	if (!netdev)
	return -ENOMEM;

	spi->bits_per_word = 8;

	ks = netdev_priv(netdev);

	ks->lock = ks8851_lock_spi;
	ks->unlock = ks8851_unlock_spi;
	ks->rdreg16 = ks8851_rdreg16_spi;
	ks->wrreg16 = ks8851_wrreg16_spi;
	ks->rdfifo = ks8851_rdfifo_spi;
	ks->wrfifo = ks8851_wrfifo_spi;
	ks->start_xmit = ks8851_start_xmit_spi;
	ks->rx_skb = ks8851_rx_skb_spi;
	ks->flush_tx_work = ks8851_flush_tx_work_spi;

	#define STD_IRQ (IRQ_LCI \| /* Link Change */ \
	IRQ_TXI \| /* TX done */ \
	IRQ_RXI \| /* RX done */ \
	IRQ_SPIBEI \| /* SPI bus error */ \
	IRQ_TXPSI \| /* TX process stop */ \
	IRQ_RXPSI) /* RX process stop */
	ks->rc_ier = STD_IRQ;

	kss = to_ks8851_spi(ks);

	kss->spidev = spi;
	mutex_init(&kss->lock);
	INIT_WORK(&kss->tx_work, ks8851_tx_work);

	/* initialise pre-made spi transfer messages */
	spi_message_init(&kss->spi_msg1);
	spi_message_add_tail(&kss->spi_xfer1, &kss->spi_msg1);

	spi_message_init(&kss->spi_msg2);
	spi_message_add_tail(&kss->spi_xfer2[0], &kss->spi_msg2);
	spi_message_add_tail(&kss->spi_xfer2[1], &kss->spi_msg2);

	netdev->irq = spi->irq;

	return ks8851_probe_common(netdev, dev, msg_enable);
	}

	static int ks8851_remove_spi(struct spi_device *spi)
	{
	return ks8851_remove_common(&spi->dev);
	}

	static const struct of_device_id ks8851_match_table[] = {
	{ .compatible = "micrel,ks8851" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, ks8851_match_table);

	static struct spi_driver ks8851_driver = {
	.driver = {
	.name = "ks8851",
	.of_match_table = ks8851_match_table,
	.pm = &ks8851_pm_ops,
	},
	.probe = ks8851_probe_spi,
	.remove = ks8851_remove_spi,
	};
	module_spi_driver(ks8851_driver);

	MODULE_DESCRIPTION("KS8851 Network driver");
	MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
	MODULE_LICENSE("GPL");

	module_param_named(message, msg_enable, int, 0);
	MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
	MODULE_ALIAS("spi:ks8851");