/*
   * Xilinx EmacLite Linux driver for the Xilinx Ethernet MAC Lite device.
   *
   * This is a new flat driver which is based on the original emac_lite
   * driver from John Williams <john.williams@xilinx.com>.
   *
   * 2007 - 2013 (c) Xilinx, Inc.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the
   * Free Software Foundation; either version 2 of the License, or (at your
   * option) any later version.
   */
  
  #include <linux/module.h>
  #include <linux/uaccess.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/skbuff.h>
  #include <linux/io.h>
  #include <linux/slab.h>
  #include <linux/of_address.h>
  #include <linux/of_device.h>
  #include <linux/of_platform.h>
  #include <linux/of_mdio.h>
  #include <linux/of_net.h>
  #include <linux/phy.h>
  #include <linux/interrupt.h>
  
  #define DRIVER_NAME "xilinx_emaclite"
  
  /* Register offsets for the EmacLite Core */
  #define XEL_TXBUFF_OFFSET	0x0		/* Transmit Buffer */
  #define XEL_MDIOADDR_OFFSET	0x07E4		/* MDIO Address Register */
  #define XEL_MDIOWR_OFFSET	0x07E8		/* MDIO Write Data Register */
  #define XEL_MDIORD_OFFSET	0x07EC		/* MDIO Read Data Register */
  #define XEL_MDIOCTRL_OFFSET	0x07F0		/* MDIO Control Register */
  #define XEL_GIER_OFFSET		0x07F8		/* GIE Register */
  #define XEL_TSR_OFFSET		0x07FC		/* Tx status */
  #define XEL_TPLR_OFFSET		0x07F4		/* Tx packet length */
  
  #define XEL_RXBUFF_OFFSET	0x1000		/* Receive Buffer */
  #define XEL_RPLR_OFFSET		0x100C		/* Rx packet length */
  #define XEL_RSR_OFFSET		0x17FC		/* Rx status */
  
  #define XEL_BUFFER_OFFSET	0x0800		/* Next Tx/Rx buffer's offset */
  
  /* MDIO Address Register Bit Masks */
  #define XEL_MDIOADDR_REGADR_MASK  0x0000001F	/* Register Address */
  #define XEL_MDIOADDR_PHYADR_MASK  0x000003E0	/* PHY Address */
  #define XEL_MDIOADDR_PHYADR_SHIFT 5
  #define XEL_MDIOADDR_OP_MASK	  0x00000400	/* RD/WR Operation */
  
  /* MDIO Write Data Register Bit Masks */
  #define XEL_MDIOWR_WRDATA_MASK	  0x0000FFFF	/* Data to be Written */
  
  /* MDIO Read Data Register Bit Masks */
  #define XEL_MDIORD_RDDATA_MASK	  0x0000FFFF	/* Data to be Read */
  
  /* MDIO Control Register Bit Masks */
  #define XEL_MDIOCTRL_MDIOSTS_MASK 0x00000001	/* MDIO Status Mask */
  #define XEL_MDIOCTRL_MDIOEN_MASK  0x00000008	/* MDIO Enable */
  
  /* Global Interrupt Enable Register (GIER) Bit Masks */
  #define XEL_GIER_GIE_MASK	0x80000000	/* Global Enable */
  
  /* Transmit Status Register (TSR) Bit Masks */
  #define XEL_TSR_XMIT_BUSY_MASK	 0x00000001	/* Tx complete */
  #define XEL_TSR_PROGRAM_MASK	 0x00000002	/* Program the MAC address */
  #define XEL_TSR_XMIT_IE_MASK	 0x00000008	/* Tx interrupt enable bit */
  #define XEL_TSR_XMIT_ACTIVE_MASK 0x80000000	/* Buffer is active, SW bit
  						 * only. This is not documented
  						 * in the HW spec */
  
  /* Define for programming the MAC address into the EmacLite */
  #define XEL_TSR_PROG_MAC_ADDR	(XEL_TSR_XMIT_BUSY_MASK | XEL_TSR_PROGRAM_MASK)
  
  /* Receive Status Register (RSR) */
  #define XEL_RSR_RECV_DONE_MASK	0x00000001	/* Rx complete */
  #define XEL_RSR_RECV_IE_MASK	0x00000008	/* Rx interrupt enable bit */
  
  /* Transmit Packet Length Register (TPLR) */
  #define XEL_TPLR_LENGTH_MASK	0x0000FFFF	/* Tx packet length */
  
  /* Receive Packet Length Register (RPLR) */
  #define XEL_RPLR_LENGTH_MASK	0x0000FFFF	/* Rx packet length */
  
  #define XEL_HEADER_OFFSET	12		/* Offset to length field */
  #define XEL_HEADER_SHIFT	16		/* Shift value for length */
  
  /* General Ethernet Definitions */
  #define XEL_ARP_PACKET_SIZE		28	/* Max ARP packet size */
  #define XEL_HEADER_IP_LENGTH_OFFSET	16	/* IP Length Offset */
  
  
  
  #define TX_TIMEOUT		(60*HZ)		/* Tx timeout is 60 seconds. */
  #define ALIGNMENT		4
  
  /* BUFFER_ALIGN(adr) calculates the number of bytes to the next alignment. */
  #define BUFFER_ALIGN(adr) ((ALIGNMENT - ((u32) adr)) % ALIGNMENT)
  
  /**
   * struct net_local - Our private per device data
   * @ndev:		instance of the network device
   * @tx_ping_pong:	indicates whether Tx Pong buffer is configured in HW
   * @rx_ping_pong:	indicates whether Rx Pong buffer is configured in HW
   * @next_tx_buf_to_use:	next Tx buffer to write to
   * @next_rx_buf_to_use:	next Rx buffer to read from
   * @base_addr:		base address of the Emaclite device
   * @reset_lock:		lock used for synchronization
   * @deferred_skb:	holds an skb (for transmission at a later time) when the
   *			Tx buffer is not free
   * @phy_dev:		pointer to the PHY device
   * @phy_node:		pointer to the PHY device node
   * @mii_bus:		pointer to the MII bus
   * @mdio_irqs:		IRQs table for MDIO bus
   * @last_link:		last link status
   * @has_mdio:		indicates whether MDIO is included in the HW
   */
  struct net_local {
  
  	struct net_device *ndev;
  
  	bool tx_ping_pong;
  	bool rx_ping_pong;
  	u32 next_tx_buf_to_use;
  	u32 next_rx_buf_to_use;
  	void __iomem *base_addr;
  
  	spinlock_t reset_lock;
  	struct sk_buff *deferred_skb;
  
  	struct phy_device *phy_dev;
  	struct device_node *phy_node;
  
  	struct mii_bus *mii_bus;
  	int mdio_irqs[PHY_MAX_ADDR];
  
  	int last_link;
  	bool has_mdio;
  };
  
  
  /*************************/
  /* EmacLite driver calls */
  /*************************/
  
  /**
   * xemaclite_enable_interrupts - Enable the interrupts for the EmacLite device
   * @drvdata:	Pointer to the Emaclite device private data
   *
   * This function enables the Tx and Rx interrupts for the Emaclite device along
   * with the Global Interrupt Enable.
   */
  static void xemaclite_enable_interrupts(struct net_local *drvdata)
  {
  	u32 reg_data;
  
  	/* Enable the Tx interrupts for the first Buffer */
  	reg_data = __raw_readl(drvdata->base_addr + XEL_TSR_OFFSET);
  	__raw_writel(reg_data | XEL_TSR_XMIT_IE_MASK,
  		     drvdata->base_addr + XEL_TSR_OFFSET);
  
  	/* Enable the Rx interrupts for the first buffer */
  	__raw_writel(XEL_RSR_RECV_IE_MASK, drvdata->base_addr + XEL_RSR_OFFSET);
  
  	/* Enable the Global Interrupt Enable */
  	__raw_writel(XEL_GIER_GIE_MASK, drvdata->base_addr + XEL_GIER_OFFSET);
  }
  
  /**
   * xemaclite_disable_interrupts - Disable the interrupts for the EmacLite device
   * @drvdata:	Pointer to the Emaclite device private data
   *
   * This function disables the Tx and Rx interrupts for the Emaclite device,
   * along with the Global Interrupt Enable.
   */
  static void xemaclite_disable_interrupts(struct net_local *drvdata)
  {
  	u32 reg_data;
  
  	/* Disable the Global Interrupt Enable */
  	__raw_writel(XEL_GIER_GIE_MASK, drvdata->base_addr + XEL_GIER_OFFSET);
  
  	/* Disable the Tx interrupts for the first buffer */
  	reg_data = __raw_readl(drvdata->base_addr + XEL_TSR_OFFSET);
  	__raw_writel(reg_data & (~XEL_TSR_XMIT_IE_MASK),
  		     drvdata->base_addr + XEL_TSR_OFFSET);
  
  	/* Disable the Rx interrupts for the first buffer */
  	reg_data = __raw_readl(drvdata->base_addr + XEL_RSR_OFFSET);
  	__raw_writel(reg_data & (~XEL_RSR_RECV_IE_MASK),
  		     drvdata->base_addr + XEL_RSR_OFFSET);
  }
  
  /**
   * xemaclite_aligned_write - Write from 16-bit aligned to 32-bit aligned address
   * @src_ptr:	Void pointer to the 16-bit aligned source address
   * @dest_ptr:	Pointer to the 32-bit aligned destination address
   * @length:	Number bytes to write from source to destination
   *
   * This function writes data from a 16-bit aligned buffer to a 32-bit aligned
   * address in the EmacLite device.
   */
  static void xemaclite_aligned_write(void *src_ptr, u32 *dest_ptr,
  				    unsigned length)
  {
  	u32 align_buffer;
  	u32 *to_u32_ptr;
  	u16 *from_u16_ptr, *to_u16_ptr;
  
  	to_u32_ptr = dest_ptr;
  	from_u16_ptr = src_ptr;
  	align_buffer = 0;
  
  	for (; length > 3; length -= 4) {
  		to_u16_ptr = (u16 *)&align_buffer;
  		*to_u16_ptr++ = *from_u16_ptr++;
  		*to_u16_ptr++ = *from_u16_ptr++;
  
  		/* This barrier resolves occasional issues seen around
  		 * cases where the data is not properly flushed out
  		 * from the processor store buffers to the destination
  		 * memory locations.
  		 */
  		wmb();
  
  		/* Output a word */
  		*to_u32_ptr++ = align_buffer;
  	}
  	if (length) {
  		u8 *from_u8_ptr, *to_u8_ptr;
  
  		/* Set up to output the remaining data */
  		align_buffer = 0;
  		to_u8_ptr = (u8 *) &align_buffer;
  		from_u8_ptr = (u8 *) from_u16_ptr;
  
  		/* Output the remaining data */
  		for (; length > 0; length--)
  			*to_u8_ptr++ = *from_u8_ptr++;
  
  		/* This barrier resolves occasional issues seen around
  		 * cases where the data is not properly flushed out
  		 * from the processor store buffers to the destination
  		 * memory locations.
  		 */
  		wmb();
  		*to_u32_ptr = align_buffer;
  	}
  }
  
  /**
   * xemaclite_aligned_read - Read from 32-bit aligned to 16-bit aligned buffer
   * @src_ptr:	Pointer to the 32-bit aligned source address
   * @dest_ptr:	Pointer to the 16-bit aligned destination address
   * @length:	Number bytes to read from source to destination
   *
   * This function reads data from a 32-bit aligned address in the EmacLite device
   * to a 16-bit aligned buffer.
   */
  static void xemaclite_aligned_read(u32 *src_ptr, u8 *dest_ptr,
  				   unsigned length)
  {
  	u16 *to_u16_ptr, *from_u16_ptr;
  	u32 *from_u32_ptr;
  	u32 align_buffer;
  
  	from_u32_ptr = src_ptr;
  	to_u16_ptr = (u16 *) dest_ptr;
  
  	for (; length > 3; length -= 4) {
  		/* Copy each word into the temporary buffer */
  		align_buffer = *from_u32_ptr++;
  		from_u16_ptr = (u16 *)&align_buffer;
  
  		/* Read data from source */
  		*to_u16_ptr++ = *from_u16_ptr++;
  		*to_u16_ptr++ = *from_u16_ptr++;
  	}
  
  	if (length) {
  		u8 *to_u8_ptr, *from_u8_ptr;
  
  		/* Set up to read the remaining data */
  		to_u8_ptr = (u8 *) to_u16_ptr;
  		align_buffer = *from_u32_ptr++;
  		from_u8_ptr = (u8 *) &align_buffer;
  
  		/* Read the remaining data */
  		for (; length > 0; length--)
  			*to_u8_ptr = *from_u8_ptr;
  	}
  }
  
  /**
   * xemaclite_send_data - Send an Ethernet frame
   * @drvdata:	Pointer to the Emaclite device private data
   * @data:	Pointer to the data to be sent
   * @byte_count:	Total frame size, including header
   *
   * This function checks if the Tx buffer of the Emaclite device is free to send
   * data. If so, it fills the Tx buffer with data for transmission. Otherwise, it
   * returns an error.
   *
   * Return:	0 upon success or -1 if the buffer(s) are full.
   *
   * Note:	The maximum Tx packet size can not be more than Ethernet header
   *		(14 Bytes) + Maximum MTU (1500 bytes). This is excluding FCS.
   */
  static int xemaclite_send_data(struct net_local *drvdata, u8 *data,
  			       unsigned int byte_count)
  {
  	u32 reg_data;
  	void __iomem *addr;
  
  	/* Determine the expected Tx buffer address */
  	addr = drvdata->base_addr + drvdata->next_tx_buf_to_use;
  
  	/* If the length is too large, truncate it */
  	if (byte_count > ETH_FRAME_LEN)
  		byte_count = ETH_FRAME_LEN;
  
  	/* Check if the expected buffer is available */
  	reg_data = __raw_readl(addr + XEL_TSR_OFFSET);
  	if ((reg_data & (XEL_TSR_XMIT_BUSY_MASK |
  	     XEL_TSR_XMIT_ACTIVE_MASK)) == 0) {
  
  		/* Switch to next buffer if configured */
  		if (drvdata->tx_ping_pong != 0)
  			drvdata->next_tx_buf_to_use ^= XEL_BUFFER_OFFSET;
  	} else if (drvdata->tx_ping_pong != 0) {
  		/* If the expected buffer is full, try the other buffer,
  		 * if it is configured in HW */
  
  		addr = (void __iomem __force *)((u32 __force)addr ^
  						 XEL_BUFFER_OFFSET);
  		reg_data = __raw_readl(addr + XEL_TSR_OFFSET);
  
  		if ((reg_data & (XEL_TSR_XMIT_BUSY_MASK |
  		     XEL_TSR_XMIT_ACTIVE_MASK)) != 0)
  			return -1; /* Buffers were full, return failure */
  	} else
  		return -1; /* Buffer was full, return failure */
  
  	/* Write the frame to the buffer */
  	xemaclite_aligned_write(data, (u32 __force *) addr, byte_count);
  
  	__raw_writel((byte_count & XEL_TPLR_LENGTH_MASK),
  		     addr + XEL_TPLR_OFFSET);
  
  	/* Update the Tx Status Register to indicate that there is a
  	 * frame to send. Set the XEL_TSR_XMIT_ACTIVE_MASK flag which
  	 * is used by the interrupt handler to check whether a frame
  	 * has been transmitted */
  	reg_data = __raw_readl(addr + XEL_TSR_OFFSET);
  	reg_data |= (XEL_TSR_XMIT_BUSY_MASK | XEL_TSR_XMIT_ACTIVE_MASK);
  	__raw_writel(reg_data, addr + XEL_TSR_OFFSET);
  
  	return 0;
  }
  
  /**
   * xemaclite_recv_data - Receive a frame
   * @drvdata:	Pointer to the Emaclite device private data
   * @data:	Address where the data is to be received
   *
   * This function is intended to be called from the interrupt context or
   * with a wrapper which waits for the receive frame to be available.
   *
   * Return:	Total number of bytes received
   */
  static u16 xemaclite_recv_data(struct net_local *drvdata, u8 *data)
  {
  	void __iomem *addr;
  	u16 length, proto_type;
  	u32 reg_data;
  
  	/* Determine the expected buffer address */
  	addr = (drvdata->base_addr + drvdata->next_rx_buf_to_use);
  
  	/* Verify which buffer has valid data */
  	reg_data = __raw_readl(addr + XEL_RSR_OFFSET);
  
  	if ((reg_data & XEL_RSR_RECV_DONE_MASK) == XEL_RSR_RECV_DONE_MASK) {
  		if (drvdata->rx_ping_pong != 0)
  			drvdata->next_rx_buf_to_use ^= XEL_BUFFER_OFFSET;
  	} else {
  		/* The instance is out of sync, try other buffer if other
  		 * buffer is configured, return 0 otherwise. If the instance is
  		 * out of sync, do not update the 'next_rx_buf_to_use' since it
  		 * will correct on subsequent calls */
  		if (drvdata->rx_ping_pong != 0)
  			addr = (void __iomem __force *)((u32 __force)addr ^
  							 XEL_BUFFER_OFFSET);
  		else
  			return 0;	/* No data was available */
  
  		/* Verify that buffer has valid data */
  		reg_data = __raw_readl(addr + XEL_RSR_OFFSET);
  		if ((reg_data & XEL_RSR_RECV_DONE_MASK) !=
  		     XEL_RSR_RECV_DONE_MASK)
  			return 0;	/* No data was available */
  	}
  
  	/* Get the protocol type of the ethernet frame that arrived */
  	proto_type = ((ntohl(__raw_readl(addr + XEL_HEADER_OFFSET +
  			XEL_RXBUFF_OFFSET)) >> XEL_HEADER_SHIFT) &
  			XEL_RPLR_LENGTH_MASK);
  
  	/* Check if received ethernet frame is a raw ethernet frame
  	 * or an IP packet or an ARP packet */
  	if (proto_type > (ETH_FRAME_LEN + ETH_FCS_LEN)) {
  
  		if (proto_type == ETH_P_IP) {
  			length = ((ntohl(__raw_readl(addr +
  					XEL_HEADER_IP_LENGTH_OFFSET +
  					XEL_RXBUFF_OFFSET)) >>
  					XEL_HEADER_SHIFT) &
  					XEL_RPLR_LENGTH_MASK);
  			length += ETH_HLEN + ETH_FCS_LEN;
  
  		} else if (proto_type == ETH_P_ARP)
  			length = XEL_ARP_PACKET_SIZE + ETH_HLEN + ETH_FCS_LEN;
  		else
  			/* Field contains type other than IP or ARP, use max
  			 * frame size and let user parse it */
  			length = ETH_FRAME_LEN + ETH_FCS_LEN;
  	} else
  		/* Use the length in the frame, plus the header and trailer */
  		length = proto_type + ETH_HLEN + ETH_FCS_LEN;
  
  	/* Read from the EmacLite device */
  	xemaclite_aligned_read((u32 __force *) (addr + XEL_RXBUFF_OFFSET),
  				data, length);
  
  	/* Acknowledge the frame */
  	reg_data = __raw_readl(addr + XEL_RSR_OFFSET);
  	reg_data &= ~XEL_RSR_RECV_DONE_MASK;
  	__raw_writel(reg_data, addr + XEL_RSR_OFFSET);
  
  	return length;
  }
  
  /**
   * xemaclite_update_address - Update the MAC address in the device
   * @drvdata:	Pointer to the Emaclite device private data
   * @address_ptr:Pointer to the MAC address (MAC address is a 48-bit value)
   *
   * Tx must be idle and Rx should be idle for deterministic results.
   * It is recommended that this function should be called after the
   * initialization and before transmission of any packets from the device.
   * The MAC address can be programmed using any of the two transmit
   * buffers (if configured).
   */
  static void xemaclite_update_address(struct net_local *drvdata,
  				     u8 *address_ptr)
  {
  	void __iomem *addr;
  	u32 reg_data;
  
  	/* Determine the expected Tx buffer address */
  	addr = drvdata->base_addr + drvdata->next_tx_buf_to_use;
  
  	xemaclite_aligned_write(address_ptr, (u32 __force *) addr, ETH_ALEN);
  
  	__raw_writel(ETH_ALEN, addr + XEL_TPLR_OFFSET);
  
  	/* Update the MAC address in the EmacLite */
  	reg_data = __raw_readl(addr + XEL_TSR_OFFSET);
  	__raw_writel(reg_data | XEL_TSR_PROG_MAC_ADDR, addr + XEL_TSR_OFFSET);
  
  	/* Wait for EmacLite to finish with the MAC address update */
  	while ((__raw_readl(addr + XEL_TSR_OFFSET) &
  		XEL_TSR_PROG_MAC_ADDR) != 0)
  		;
  }
  
  /**
   * xemaclite_set_mac_address - Set the MAC address for this device
   * @dev:	Pointer to the network device instance
   * @addr:	Void pointer to the sockaddr structure
   *
   * This function copies the HW address from the sockaddr strucutre to the
   * net_device structure and updates the address in HW.
   *
   * Return:	Error if the net device is busy or 0 if the addr is set
   *		successfully
   */
  static int xemaclite_set_mac_address(struct net_device *dev, void *address)
  {
  	struct net_local *lp = netdev_priv(dev);
  	struct sockaddr *addr = address;
  
  	if (netif_running(dev))
  		return -EBUSY;
  
  	memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
  	xemaclite_update_address(lp, dev->dev_addr);
  	return 0;
  }
  
  /**
   * xemaclite_tx_timeout - Callback for Tx Timeout
   * @dev:	Pointer to the network device
   *
   * This function is called when Tx time out occurs for Emaclite device.
   */
  static void xemaclite_tx_timeout(struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  	unsigned long flags;
  
  	dev_err(&lp->ndev->dev, "Exceeded transmit timeout of %lu ms
  ",
  		TX_TIMEOUT * 1000UL / HZ);
  
  	dev->stats.tx_errors++;
  
  	/* Reset the device */
  	spin_lock_irqsave(&lp->reset_lock, flags);
  
  	/* Shouldn't really be necessary, but shouldn't hurt */
  	netif_stop_queue(dev);
  
  	xemaclite_disable_interrupts(lp);
  	xemaclite_enable_interrupts(lp);
  
  	if (lp->deferred_skb) {
  		dev_kfree_skb(lp->deferred_skb);
  		lp->deferred_skb = NULL;
  		dev->stats.tx_errors++;
  	}
  
  	/* To exclude tx timeout */
  	dev->trans_start = jiffies; /* prevent tx timeout */
  
  	/* We're all ready to go. Start the queue */
  	netif_wake_queue(dev);
  	spin_unlock_irqrestore(&lp->reset_lock, flags);
  }
  
  /**********************/
  /* Interrupt Handlers */
  /**********************/
  
  /**
   * xemaclite_tx_handler - Interrupt handler for frames sent
   * @dev:	Pointer to the network device
   *
   * This function updates the number of packets transmitted and handles the
   * deferred skb, if there is one.
   */
  static void xemaclite_tx_handler(struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  
  	dev->stats.tx_packets++;
  	if (lp->deferred_skb) {
  		if (xemaclite_send_data(lp,
  					(u8 *) lp->deferred_skb->data,
  					lp->deferred_skb->len) != 0)
  			return;
  		else {
  			dev->stats.tx_bytes += lp->deferred_skb->len;
  			dev_kfree_skb_irq(lp->deferred_skb);
  			lp->deferred_skb = NULL;
  			dev->trans_start = jiffies; /* prevent tx timeout */
  			netif_wake_queue(dev);
  		}
  	}
  }
  
  /**
   * xemaclite_rx_handler- Interrupt handler for frames received
   * @dev:	Pointer to the network device
   *
   * This function allocates memory for a socket buffer, fills it with data
   * received and hands it over to the TCP/IP stack.
   */
  static void xemaclite_rx_handler(struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  	struct sk_buff *skb;
  	unsigned int align;
  	u32 len;
  
  	len = ETH_FRAME_LEN + ETH_FCS_LEN;
  	skb = netdev_alloc_skb(dev, len + ALIGNMENT);
  	if (!skb) {
  		/* Couldn't get memory. */
  		dev->stats.rx_dropped++;
  		dev_err(&lp->ndev->dev, "Could not allocate receive buffer
  ");
  		return;
  	}
  
  	/*
  	 * A new skb should have the data halfword aligned, but this code is
  	 * here just in case that isn't true. Calculate how many
  	 * bytes we should reserve to get the data to start on a word
  	 * boundary */
  	align = BUFFER_ALIGN(skb->data);
  	if (align)
  		skb_reserve(skb, align);
  
  	skb_reserve(skb, 2);
  
  	len = xemaclite_recv_data(lp, (u8 *) skb->data);
  
  	if (!len) {
  		dev->stats.rx_errors++;
  		dev_kfree_skb_irq(skb);
  		return;
  	}
  
  	skb_put(skb, len);	/* Tell the skb how much data we got */
  
  	skb->protocol = eth_type_trans(skb, dev);
  	skb_checksum_none_assert(skb);
  
  	dev->stats.rx_packets++;
  	dev->stats.rx_bytes += len;
  
  	if (!skb_defer_rx_timestamp(skb))
  		netif_rx(skb);	/* Send the packet upstream */
  }
  
  /**
   * xemaclite_interrupt - Interrupt handler for this driver
   * @irq:	Irq of the Emaclite device
   * @dev_id:	Void pointer to the network device instance used as callback
   *		reference
   *
   * This function handles the Tx and Rx interrupts of the EmacLite device.
   */
  static irqreturn_t xemaclite_interrupt(int irq, void *dev_id)
  {
  	bool tx_complete = false;
  	struct net_device *dev = dev_id;
  	struct net_local *lp = netdev_priv(dev);
  	void __iomem *base_addr = lp->base_addr;
  	u32 tx_status;
  
  	/* Check if there is Rx Data available */
  	if ((__raw_readl(base_addr + XEL_RSR_OFFSET) &
  			 XEL_RSR_RECV_DONE_MASK) ||
  	    (__raw_readl(base_addr + XEL_BUFFER_OFFSET + XEL_RSR_OFFSET)
  			 & XEL_RSR_RECV_DONE_MASK))
  
  		xemaclite_rx_handler(dev);
  
  	/* Check if the Transmission for the first buffer is completed */
  	tx_status = __raw_readl(base_addr + XEL_TSR_OFFSET);
  	if (((tx_status & XEL_TSR_XMIT_BUSY_MASK) == 0) &&
  		(tx_status & XEL_TSR_XMIT_ACTIVE_MASK) != 0) {
  
  		tx_status &= ~XEL_TSR_XMIT_ACTIVE_MASK;
  		__raw_writel(tx_status, base_addr + XEL_TSR_OFFSET);
  
  		tx_complete = true;
  	}
  
  	/* Check if the Transmission for the second buffer is completed */
  	tx_status = __raw_readl(base_addr + XEL_BUFFER_OFFSET + XEL_TSR_OFFSET);
  	if (((tx_status & XEL_TSR_XMIT_BUSY_MASK) == 0) &&
  		(tx_status & XEL_TSR_XMIT_ACTIVE_MASK) != 0) {
  
  		tx_status &= ~XEL_TSR_XMIT_ACTIVE_MASK;
  		__raw_writel(tx_status, base_addr + XEL_BUFFER_OFFSET +
  			     XEL_TSR_OFFSET);
  
  		tx_complete = true;
  	}
  
  	/* If there was a Tx interrupt, call the Tx Handler */
  	if (tx_complete != 0)
  		xemaclite_tx_handler(dev);
  
  	return IRQ_HANDLED;
  }
  
  /**********************/
  /* MDIO Bus functions */
  /**********************/
  
  /**
   * xemaclite_mdio_wait - Wait for the MDIO to be ready to use
   * @lp:		Pointer to the Emaclite device private data
   *
   * This function waits till the device is ready to accept a new MDIO
   * request.
   *
   * Return:	0 for success or ETIMEDOUT for a timeout
   */
  
  static int xemaclite_mdio_wait(struct net_local *lp)
  {
  	unsigned long end = jiffies + 2;
  
  	/* wait for the MDIO interface to not be busy or timeout
  	   after some time.
  	*/
  	while (__raw_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET) &
  			XEL_MDIOCTRL_MDIOSTS_MASK) {
  		if (time_before_eq(end, jiffies)) {
  			WARN_ON(1);
  			return -ETIMEDOUT;
  		}
  		msleep(1);
  	}
  	return 0;
  }
  
  /**
   * xemaclite_mdio_read - Read from a given MII management register
   * @bus:	the mii_bus struct
   * @phy_id:	the phy address
   * @reg:	register number to read from
   *
   * This function waits till the device is ready to accept a new MDIO
   * request and then writes the phy address to the MDIO Address register
   * and reads data from MDIO Read Data register, when its available.
   *
   * Return:	Value read from the MII management register
   */
  static int xemaclite_mdio_read(struct mii_bus *bus, int phy_id, int reg)
  {
  	struct net_local *lp = bus->priv;
  	u32 ctrl_reg;
  	u32 rc;
  
  	if (xemaclite_mdio_wait(lp))
  		return -ETIMEDOUT;
  
  	/* Write the PHY address, register number and set the OP bit in the
  	 * MDIO Address register. Set the Status bit in the MDIO Control
  	 * register to start a MDIO read transaction.
  	 */
  	ctrl_reg = __raw_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET);
  	__raw_writel(XEL_MDIOADDR_OP_MASK |
  		     ((phy_id << XEL_MDIOADDR_PHYADR_SHIFT) | reg),
  		     lp->base_addr + XEL_MDIOADDR_OFFSET);
  	__raw_writel(ctrl_reg | XEL_MDIOCTRL_MDIOSTS_MASK,
  		     lp->base_addr + XEL_MDIOCTRL_OFFSET);
  
  	if (xemaclite_mdio_wait(lp))
  		return -ETIMEDOUT;
  
  	rc = __raw_readl(lp->base_addr + XEL_MDIORD_OFFSET);
  
  	dev_dbg(&lp->ndev->dev,
  		"xemaclite_mdio_read(phy_id=%i, reg=%x) == %x
  ",
  		phy_id, reg, rc);
  
  	return rc;
  }
  
  /**
   * xemaclite_mdio_write - Write to a given MII management register
   * @bus:	the mii_bus struct
   * @phy_id:	the phy address
   * @reg:	register number to write to
   * @val:	value to write to the register number specified by reg
   *
   * This function waits till the device is ready to accept a new MDIO
   * request and then writes the val to the MDIO Write Data register.
   */
  static int xemaclite_mdio_write(struct mii_bus *bus, int phy_id, int reg,
  				u16 val)
  {
  	struct net_local *lp = bus->priv;
  	u32 ctrl_reg;
  
  	dev_dbg(&lp->ndev->dev,
  		"xemaclite_mdio_write(phy_id=%i, reg=%x, val=%x)
  ",
  		phy_id, reg, val);
  
  	if (xemaclite_mdio_wait(lp))
  		return -ETIMEDOUT;
  
  	/* Write the PHY address, register number and clear the OP bit in the
  	 * MDIO Address register and then write the value into the MDIO Write
  	 * Data register. Finally, set the Status bit in the MDIO Control
  	 * register to start a MDIO write transaction.
  	 */
  	ctrl_reg = __raw_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET);
  	__raw_writel(~XEL_MDIOADDR_OP_MASK &
  		     ((phy_id << XEL_MDIOADDR_PHYADR_SHIFT) | reg),
  		     lp->base_addr + XEL_MDIOADDR_OFFSET);
  	__raw_writel(val, lp->base_addr + XEL_MDIOWR_OFFSET);
  	__raw_writel(ctrl_reg | XEL_MDIOCTRL_MDIOSTS_MASK,
  		     lp->base_addr + XEL_MDIOCTRL_OFFSET);
  
  	return 0;
  }
  
  /**
   * xemaclite_mdio_setup - Register mii_bus for the Emaclite device
   * @lp:		Pointer to the Emaclite device private data
   * @ofdev:	Pointer to OF device structure
   *
   * This function enables MDIO bus in the Emaclite device and registers a
   * mii_bus.
   *
   * Return:	0 upon success or a negative error upon failure
   */
  static int xemaclite_mdio_setup(struct net_local *lp, struct device *dev)
  {
  	struct mii_bus *bus;
  	int rc;
  	struct resource res;
  	struct device_node *np = of_get_parent(lp->phy_node);
  	struct device_node *npp;
  
  	/* Don't register the MDIO bus if the phy_node or its parent node
  	 * can't be found.
  	 */
  	if (!np) {
  		dev_err(dev, "Failed to register mdio bus.
  ");
  		return -ENODEV;
  	}
  	npp = of_get_parent(np);
  
  	of_address_to_resource(npp, 0, &res);
  	if (lp->ndev->mem_start != res.start) {
  		struct phy_device *phydev;
  		phydev = of_phy_find_device(lp->phy_node);
  		if (!phydev)
  			dev_info(dev,
  				 "MDIO of the phy is not registered yet
  ");
  		else
  			put_device(&phydev->dev);
  		return 0;
  	}
  
  	/* Enable the MDIO bus by asserting the enable bit in MDIO Control
  	 * register.
  	 */
  	__raw_writel(XEL_MDIOCTRL_MDIOEN_MASK,
  		     lp->base_addr + XEL_MDIOCTRL_OFFSET);
  
  	bus = mdiobus_alloc();
  	if (!bus) {
  		dev_err(dev, "Failed to allocate mdiobus
  ");
  		return -ENOMEM;
  	}
  
  	snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx",
  		 (unsigned long long)res.start);
  	bus->priv = lp;
  	bus->name = "Xilinx Emaclite MDIO";
  	bus->read = xemaclite_mdio_read;
  	bus->write = xemaclite_mdio_write;
  	bus->parent = dev;
  	bus->irq = lp->mdio_irqs; /* preallocated IRQ table */
  
  	lp->mii_bus = bus;
  
  	rc = of_mdiobus_register(bus, np);
  	if (rc) {
  		dev_err(dev, "Failed to register mdio bus.
  ");
  		goto err_register;
  	}
  
  	return 0;
  
  err_register:
  	mdiobus_free(bus);
  	return rc;
  }
  
  /**
   * xemaclite_adjust_link - Link state callback for the Emaclite device
   * @ndev: pointer to net_device struct
   *
   * There's nothing in the Emaclite device to be configured when the link
   * state changes. We just print the status.
   */
  static void xemaclite_adjust_link(struct net_device *ndev)
  {
  	struct net_local *lp = netdev_priv(ndev);
  	struct phy_device *phy = lp->phy_dev;
  	int link_state;
  
  	/* hash together the state values to decide if something has changed */
  	link_state = phy->speed | (phy->duplex << 1) | phy->link;
  
  	if (lp->last_link != link_state) {
  		lp->last_link = link_state;
  		phy_print_status(phy);
  	}
  }
  
  /**
   * xemaclite_open - Open the network device
   * @dev:	Pointer to the network device
   *
   * This function sets the MAC address, requests an IRQ and enables interrupts
   * for the Emaclite device and starts the Tx queue.
   * It also connects to the phy device, if MDIO is included in Emaclite device.
   */
  static int xemaclite_open(struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  	int retval;
  
  	/* Just to be safe, stop the device first */
  	xemaclite_disable_interrupts(lp);
  
  	if (lp->phy_node) {
  		u32 bmcr;
  
  		lp->phy_dev = of_phy_connect(lp->ndev, lp->phy_node,
  					     xemaclite_adjust_link, 0,
  					     PHY_INTERFACE_MODE_MII);
  		if (!lp->phy_dev) {
  			dev_err(&lp->ndev->dev, "of_phy_connect() failed
  ");
  			return -ENODEV;
  		}
  
  		/* EmacLite doesn't support giga-bit speeds */
  		lp->phy_dev->supported &= (PHY_BASIC_FEATURES);
  		lp->phy_dev->advertising = lp->phy_dev->supported;
  
  		/* Don't advertise 1000BASE-T Full/Half duplex speeds */
  		phy_write(lp->phy_dev, MII_CTRL1000, 0);
  
  		/* Advertise only 10 and 100mbps full/half duplex speeds */
  		phy_write(lp->phy_dev, MII_ADVERTISE, ADVERTISE_ALL |
  			  ADVERTISE_CSMA);
  
  		/* Restart auto negotiation */
  		bmcr = phy_read(lp->phy_dev, MII_BMCR);
  		bmcr |= (BMCR_ANENABLE | BMCR_ANRESTART);
  		phy_write(lp->phy_dev, MII_BMCR, bmcr);
  
  		phy_start(lp->phy_dev);
  	}
  
  	/* Set the MAC address each time opened */
  	xemaclite_update_address(lp, dev->dev_addr);
  
  	/* Grab the IRQ */
  	retval = request_irq(dev->irq, xemaclite_interrupt, 0, dev->name, dev);
  	if (retval) {
  		dev_err(&lp->ndev->dev, "Could not allocate interrupt %d
  ",
  			dev->irq);
  		if (lp->phy_dev)
  			phy_disconnect(lp->phy_dev);
  		lp->phy_dev = NULL;
  
  		return retval;
  	}
  
  	/* Enable Interrupts */
  	xemaclite_enable_interrupts(lp);
  
  	/* We're ready to go */
  	netif_start_queue(dev);
  
  	return 0;
  }
  
  /**
   * xemaclite_close - Close the network device
   * @dev:	Pointer to the network device
   *
   * This function stops the Tx queue, disables interrupts and frees the IRQ for
   * the Emaclite device.
   * It also disconnects the phy device associated with the Emaclite device.
   */
  static int xemaclite_close(struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  
  	netif_stop_queue(dev);
  	xemaclite_disable_interrupts(lp);
  	free_irq(dev->irq, dev);
  
  	if (lp->phy_dev)
  		phy_disconnect(lp->phy_dev);
  	lp->phy_dev = NULL;
  
  	return 0;
  }
  
  /**
   * xemaclite_send - Transmit a frame
   * @orig_skb:	Pointer to the socket buffer to be transmitted
   * @dev:	Pointer to the network device
   *
   * This function checks if the Tx buffer of the Emaclite device is free to send
   * data. If so, it fills the Tx buffer with data from socket buffer data,
   * updates the stats and frees the socket buffer. The Tx completion is signaled
   * by an interrupt. If the Tx buffer isn't free, then the socket buffer is
   * deferred and the Tx queue is stopped so that the deferred socket buffer can
   * be transmitted when the Emaclite device is free to transmit data.
   *
   * Return:	0, always.
   */
  static int xemaclite_send(struct sk_buff *orig_skb, struct net_device *dev)
  {
  	struct net_local *lp = netdev_priv(dev);
  	struct sk_buff *new_skb;
  	unsigned int len;
  	unsigned long flags;
  
  	len = orig_skb->len;
  
  	new_skb = orig_skb;
  
  	spin_lock_irqsave(&lp->reset_lock, flags);
  	if (xemaclite_send_data(lp, (u8 *) new_skb->data, len) != 0) {
  		/* If the Emaclite Tx buffer is busy, stop the Tx queue and
  		 * defer the skb for transmission during the ISR, after the
  		 * current transmission is complete */
  		netif_stop_queue(dev);
  		lp->deferred_skb = new_skb;
  		/* Take the time stamp now, since we can't do this in an ISR. */
  		skb_tx_timestamp(new_skb);
  		spin_unlock_irqrestore(&lp->reset_lock, flags);
  		return 0;
  	}
  	spin_unlock_irqrestore(&lp->reset_lock, flags);
  
  	skb_tx_timestamp(new_skb);
  
  	dev->stats.tx_bytes += len;
  	dev_consume_skb_any(new_skb);
  
  	return 0;
  }
  
  /**
   * xemaclite_remove_ndev - Free the network device
   * @ndev:	Pointer to the network device to be freed
   *
   * This function un maps the IO region of the Emaclite device and frees the net
   * device.
   */
  static void xemaclite_remove_ndev(struct net_device *ndev)
  {
  	if (ndev) {
  		free_netdev(ndev);
  	}
  }
  
  /**
   * get_bool - Get a parameter from the OF device
   * @ofdev:	Pointer to OF device structure
   * @s:		Property to be retrieved
   *
   * This function looks for a property in the device node and returns the value
   * of the property if its found or 0 if the property is not found.
   *
   * Return:	Value of the parameter if the parameter is found, or 0 otherwise
   */
  static bool get_bool(struct platform_device *ofdev, const char *s)
  {
  	u32 *p = (u32 *)of_get_property(ofdev->dev.of_node, s, NULL);
  
  	if (p) {
  		return (bool)*p;
  	} else {
  		dev_warn(&ofdev->dev, "Parameter %s not found,"
  			"defaulting to false
  ", s);
  		return false;
  	}
  }
  
  static struct net_device_ops xemaclite_netdev_ops;
  
  /**
   * xemaclite_of_probe - Probe method for the Emaclite device.
   * @ofdev:	Pointer to OF device structure
   * @match:	Pointer to the structure used for matching a device
   *
   * This function probes for the Emaclite device in the device tree.
   * It initializes the driver data structure and the hardware, sets the MAC
   * address and registers the network device.
   * It also registers a mii_bus for the Emaclite device, if MDIO is included
   * in the device.
   *
   * Return:	0, if the driver is bound to the Emaclite device, or
   *		a negative error if there is failure.
   */
  static int xemaclite_of_probe(struct platform_device *ofdev)
  {
  	struct resource *res;
  	struct net_device *ndev = NULL;
  	struct net_local *lp = NULL;
  	struct device *dev = &ofdev->dev;
  	const void *mac_address;
  
  	int rc = 0;
  
  	dev_info(dev, "Device Tree Probing
  ");
  
  	/* Create an ethernet device instance */
  	ndev = alloc_etherdev(sizeof(struct net_local));
  	if (!ndev)
  		return -ENOMEM;
  
  	dev_set_drvdata(dev, ndev);
  	SET_NETDEV_DEV(ndev, &ofdev->dev);
  
  	lp = netdev_priv(ndev);
  	lp->ndev = ndev;
  
  	/* Get IRQ for the device */
  	res = platform_get_resource(ofdev, IORESOURCE_IRQ, 0);
  	if (!res) {
  		dev_err(dev, "no IRQ found
  ");
  		rc = -ENXIO;
  		goto error;
  	}
  
  	ndev->irq = res->start;
  
  	res = platform_get_resource(ofdev, IORESOURCE_MEM, 0);
  	lp->base_addr = devm_ioremap_resource(&ofdev->dev, res);
  	if (IS_ERR(lp->base_addr)) {
  		rc = PTR_ERR(lp->base_addr);
  		goto error;
  	}
  
  	ndev->mem_start = res->start;
  	ndev->mem_end = res->end;
  
  	spin_lock_init(&lp->reset_lock);
  	lp->next_tx_buf_to_use = 0x0;
  	lp->next_rx_buf_to_use = 0x0;
  	lp->tx_ping_pong = get_bool(ofdev, "xlnx,tx-ping-pong");
  	lp->rx_ping_pong = get_bool(ofdev, "xlnx,rx-ping-pong");
  	mac_address = of_get_mac_address(ofdev->dev.of_node);
  
  	if (mac_address)
  		/* Set the MAC address. */
  		memcpy(ndev->dev_addr, mac_address, ETH_ALEN);
  	else
  		dev_warn(dev, "No MAC address found
  ");
  
  	/* Clear the Tx CSR's in case this is a restart */
  	__raw_writel(0, lp->base_addr + XEL_TSR_OFFSET);
  	__raw_writel(0, lp->base_addr + XEL_BUFFER_OFFSET + XEL_TSR_OFFSET);
  
  	/* Set the MAC address in the EmacLite device */
  	xemaclite_update_address(lp, ndev->dev_addr);
  
  	lp->phy_node = of_parse_phandle(ofdev->dev.of_node, "phy-handle", 0);
  	rc = xemaclite_mdio_setup(lp, &ofdev->dev);
  	if (rc)
  		dev_warn(&ofdev->dev, "error registering MDIO bus
  ");
  
  	dev_info(dev, "MAC address is now %pM
  ", ndev->dev_addr);
  
  	ndev->netdev_ops = &xemaclite_netdev_ops;
  	ndev->flags &= ~IFF_MULTICAST;
  	ndev->watchdog_timeo = TX_TIMEOUT;
  
  	/* Finally, register the device */
  	rc = register_netdev(ndev);
  	if (rc) {
  		dev_err(dev,
  			"Cannot register network device, aborting
  ");
  		goto error;
  	}
  
  	dev_info(dev,
  		 "Xilinx EmacLite at 0x%08X mapped to 0x%08X, irq=%d
  ",
  		 (unsigned int __force)ndev->mem_start,
  		 (unsigned int __force)lp->base_addr, ndev->irq);
  	return 0;
  
  error:
  	xemaclite_remove_ndev(ndev);
  	return rc;
  }
  
  /**
   * xemaclite_of_remove - Unbind the driver from the Emaclite device.
   * @of_dev:	Pointer to OF device structure
   *
   * This function is called if a device is physically removed from the system or
   * if the driver module is being unloaded. It frees any resources allocated to
   * the device.
   *
   * Return:	0, always.
   */
  static int xemaclite_of_remove(struct platform_device *of_dev)
  {
  	struct net_device *ndev = platform_get_drvdata(of_dev);
  
  	struct net_local *lp = netdev_priv(ndev);
  
  	/* Un-register the mii_bus, if configured */
  	if (lp->has_mdio) {
  		mdiobus_unregister(lp->mii_bus);
  		kfree(lp->mii_bus->irq);
  		mdiobus_free(lp->mii_bus);
  		lp->mii_bus = NULL;
  	}
  
  	unregister_netdev(ndev);
  
  	of_node_put(lp->phy_node);
  	lp->phy_node = NULL;
  
  	xemaclite_remove_ndev(ndev);
  
  	return 0;
  }
  
  #ifdef CONFIG_NET_POLL_CONTROLLER
  static void
  xemaclite_poll_controller(struct net_device *ndev)
  {
  	disable_irq(ndev->irq);
  	xemaclite_interrupt(ndev->irq, ndev);
  	enable_irq(ndev->irq);
  }
  #endif
  
  static struct net_device_ops xemaclite_netdev_ops = {
  	.ndo_open		= xemaclite_open,
  	.ndo_stop		= xemaclite_close,
  	.ndo_start_xmit		= xemaclite_send,
  	.ndo_set_mac_address	= xemaclite_set_mac_address,
  	.ndo_tx_timeout		= xemaclite_tx_timeout,
  #ifdef CONFIG_NET_POLL_CONTROLLER
  	.ndo_poll_controller = xemaclite_poll_controller,
  #endif
  };
  
  /* Match table for OF platform binding */
  static const struct of_device_id xemaclite_of_match[] = {
  	{ .compatible = "xlnx,opb-ethernetlite-1.01.a", },
  	{ .compatible = "xlnx,opb-ethernetlite-1.01.b", },
  	{ .compatible = "xlnx,xps-ethernetlite-1.00.a", },
  	{ .compatible = "xlnx,xps-ethernetlite-2.00.a", },
  	{ .compatible = "xlnx,xps-ethernetlite-2.01.a", },
  	{ .compatible = "xlnx,xps-ethernetlite-3.00.a", },
  	{ /* end of list */ },
  };
  MODULE_DEVICE_TABLE(of, xemaclite_of_match);
  
  static struct platform_driver xemaclite_of_driver = {
  	.driver = {
  		.name = DRIVER_NAME,
  		.of_match_table = xemaclite_of_match,
  	},
  	.probe		= xemaclite_of_probe,
  	.remove		= xemaclite_of_remove,
  };
  
  module_platform_driver(xemaclite_of_driver);
  
  MODULE_AUTHOR("Xilinx, Inc.");
  MODULE_DESCRIPTION("Xilinx Ethernet MAC Lite driver");
  MODULE_LICENSE("GPL");