net: add Xilinx emac lite device driver

This patch adds support for the Xilinx Ethernet Lite device.  The
soft logic core from Xilinx is typically used on Virtex and Spartan
designs attached to either a PowerPC or a Microblaze processor.

Signed-off-by: Sadanand M <sadanan@xilinx.com>
Signed-off-by: John Linn <john.linn@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1041 insertions, 0 deletions

diff --git a/drivers/net/xilinx_emaclite.c b/drivers/net/xilinx_emaclite.c
new file mode 100755
index 000000000000..7e05b40ae36b
--- /dev/null
+++ b/drivers/net/xilinx_emaclite.c
@@ -0,0 +1,1041 @@
+/*
+ * 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@petalogix.com>.
+ *
+ * 2007-2009 (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/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/io.h>
+
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+
+#define DRIVER_NAME "xilinx_emaclite"
+
+/* Register offsets for the EmacLite Core */
+#define XEL_TXBUFF_OFFSET 	0x0		/* Transmit Buffer */
+#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 */
+
+/* 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
+ */
+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;
+};
+
+
+/*************************/
+/* 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 = in_be32(drvdata->base_addr + XEL_TSR_OFFSET);
+	out_be32(drvdata->base_addr + XEL_TSR_OFFSET,
+		 reg_data | XEL_TSR_XMIT_IE_MASK);
+
+	/* Enable the Tx interrupts for the second Buffer if
+	 * configured in HW */
+	if (drvdata->tx_ping_pong != 0) {
+		reg_data = in_be32(drvdata->base_addr +
+				   XEL_BUFFER_OFFSET + XEL_TSR_OFFSET);
+		out_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+			 XEL_TSR_OFFSET,
+			 reg_data | XEL_TSR_XMIT_IE_MASK);
+	}
+
+	/* Enable the Rx interrupts for the first buffer */
+	reg_data = in_be32(drvdata->base_addr + XEL_RSR_OFFSET);
+	out_be32(drvdata->base_addr + XEL_RSR_OFFSET,
+		 reg_data | XEL_RSR_RECV_IE_MASK);
+
+	/* Enable the Rx interrupts for the second Buffer if
+	 * configured in HW */
+	if (drvdata->rx_ping_pong != 0) {
+		reg_data = in_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+				   XEL_RSR_OFFSET);
+		out_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+			 XEL_RSR_OFFSET,
+			 reg_data | XEL_RSR_RECV_IE_MASK);
+	}
+
+	/* Enable the Global Interrupt Enable */
+	out_be32(drvdata->base_addr + XEL_GIER_OFFSET, XEL_GIER_GIE_MASK);
+}
+
+/**
+ * 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 */
+	out_be32(drvdata->base_addr + XEL_GIER_OFFSET, XEL_GIER_GIE_MASK);
+
+	/* Disable the Tx interrupts for the first buffer */
+	reg_data = in_be32(drvdata->base_addr + XEL_TSR_OFFSET);
+	out_be32(drvdata->base_addr + XEL_TSR_OFFSET,
+		 reg_data & (~XEL_TSR_XMIT_IE_MASK));
+
+	/* Disable the Tx interrupts for the second Buffer
+	 * if configured in HW */
+	if (drvdata->tx_ping_pong != 0) {
+		reg_data = in_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+				   XEL_TSR_OFFSET);
+		out_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+			 XEL_TSR_OFFSET,
+			 reg_data & (~XEL_TSR_XMIT_IE_MASK));
+	}
+
+	/* Disable the Rx interrupts for the first buffer */
+	reg_data = in_be32(drvdata->base_addr + XEL_RSR_OFFSET);
+	out_be32(drvdata->base_addr + XEL_RSR_OFFSET,
+		 reg_data & (~XEL_RSR_RECV_IE_MASK));
+
+	/* Disable the Rx interrupts for the second buffer
+	 * if configured in HW */
+	if (drvdata->rx_ping_pong != 0) {
+
+		reg_data = in_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+				   XEL_RSR_OFFSET);
+		out_be32(drvdata->base_addr + XEL_BUFFER_OFFSET +
+			 XEL_RSR_OFFSET,
+			 reg_data & (~XEL_RSR_RECV_IE_MASK));
+	}
+}
+
+/**
+ * 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 = (u16 *) src_ptr;
+	align_buffer = 0;
+
+	for (; length > 3; length -= 4) {
+		to_u16_ptr = (u16 *) ((void *) &align_buffer);
+		*to_u16_ptr++ = *from_u16_ptr++;
+		*to_u16_ptr++ = *from_u16_ptr++;
+
+		/* 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++;
+
+		*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 = in_be32(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 = in_be32(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);
+
+	out_be32(addr + XEL_TPLR_OFFSET, (byte_count & XEL_TPLR_LENGTH_MASK));
+
+	/* 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 = in_be32(addr + XEL_TSR_OFFSET);
+	reg_data |= (XEL_TSR_XMIT_BUSY_MASK | XEL_TSR_XMIT_ACTIVE_MASK);
+	out_be32(addr + XEL_TSR_OFFSET, reg_data);
+
+	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 = in_be32(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 = in_be32(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 = ((in_be32(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 = ((in_be32(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 = in_be32(addr + XEL_RSR_OFFSET);
+	reg_data &= ~XEL_RSR_RECV_DONE_MASK;
+	out_be32(addr + XEL_RSR_OFFSET, reg_data);
+
+	return length;
+}
+
+/**
+ * xemaclite_set_mac_address - Set the MAC address for this 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_set_mac_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);
+
+	out_be32(addr + XEL_TPLR_OFFSET, ETH_ALEN);
+
+	/* Update the MAC address in the EmacLite */
+	reg_data = in_be32(addr + XEL_TSR_OFFSET);
+	out_be32(addr + XEL_TSR_OFFSET, reg_data | XEL_TSR_PROG_MAC_ADDR);
+
+	/* Wait for EmacLite to finish with the MAC address update */
+	while ((in_be32(addr + XEL_TSR_OFFSET) &
+		XEL_TSR_PROG_MAC_ADDR) != 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 = (struct net_local *) netdev_priv(dev);
+	unsigned long flags;
+
+	dev_err(&lp->ndev->dev, "Exceeded transmit timeout of %lu ms\n",
+		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 = 0xffffffff - TX_TIMEOUT - 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 = (struct net_local *) 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;
+			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 = (struct net_local *) netdev_priv(dev);
+	struct sk_buff *skb;
+	unsigned int align;
+	u32 len;
+
+	len = ETH_FRAME_LEN + ETH_FCS_LEN;
+	skb = dev_alloc_skb(len + ALIGNMENT);
+	if (!skb) {
+		/* Couldn't get memory. */
+		dev->stats.rx_dropped++;
+		dev_err(&lp->ndev->dev, "Could not allocate receive buffer\n");
+		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->dev = dev;		/* Fill out required meta-data */
+
+	skb->protocol = eth_type_trans(skb, dev);
+	skb->ip_summed = CHECKSUM_NONE;
+
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += len;
+	dev->last_rx = jiffies;
+
+	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 = 0;
+	struct net_device *dev = dev_id;
+	struct net_local *lp = (struct net_local *) netdev_priv(dev);
+	void __iomem *base_addr = lp->base_addr;
+	u32 tx_status;
+
+	/* Check if there is Rx Data available */
+	if ((in_be32(base_addr + XEL_RSR_OFFSET) & XEL_RSR_RECV_DONE_MASK) ||
+			(in_be32(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 = in_be32(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;
+		out_be32(base_addr + XEL_TSR_OFFSET, tx_status);
+
+		tx_complete = 1;
+	}
+
+	/* Check if the Transmission for the second buffer is completed */
+	tx_status = in_be32(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;
+		out_be32(base_addr + XEL_BUFFER_OFFSET + XEL_TSR_OFFSET,
+			 tx_status);
+
+		tx_complete = 1;
+	}
+
+	/* If there was a Tx interrupt, call the Tx Handler */
+	if (tx_complete != 0)
+		xemaclite_tx_handler(dev);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * 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.
+ */
+static int xemaclite_open(struct net_device *dev)
+{
+	struct net_local *lp = (struct net_local *) netdev_priv(dev);
+	int retval;
+
+	/* Just to be safe, stop the device first */
+	xemaclite_disable_interrupts(lp);
+
+	/* Set the MAC address each time opened */
+	xemaclite_set_mac_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\n",
+			dev->irq);
+		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.
+ */
+static int xemaclite_close(struct net_device *dev)
+{
+	struct net_local *lp = (struct net_local *) netdev_priv(dev);
+
+	netif_stop_queue(dev);
+	xemaclite_disable_interrupts(lp);
+	free_irq(dev->irq, dev);
+
+	return 0;
+}
+
+/**
+ * xemaclite_get_stats - Get the stats for the net_device
+ * @dev:	Pointer to the network device
+ *
+ * This function returns the address of the 'net_device_stats' structure for the
+ * given network device. This structure holds usage statistics for the network
+ * device.
+ *
+ * Return:	Pointer to the net_device_stats structure.
+ */
+static struct net_device_stats *xemaclite_get_stats(struct net_device *dev)
+{
+	return &dev->stats;
+}
+
+/**
+ * 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 = (struct net_local *) 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 at a later point when the
+		 * current transmission is complete */
+		netif_stop_queue(dev);
+		lp->deferred_skb = new_skb;
+		spin_unlock_irqrestore(&lp->reset_lock, flags);
+		return 0;
+	}
+	spin_unlock_irqrestore(&lp->reset_lock, flags);
+
+	dev->stats.tx_bytes += len;
+	dev_kfree_skb(new_skb);
+	dev->trans_start = jiffies;
+
+	return 0;
+}
+
+/**
+ * xemaclite_ioctl - Perform IO Control operations on the network device
+ * @dev:	Pointer to the network device
+ * @rq:		Pointer to the interface request structure
+ * @cmd:	IOCTL command
+ *
+ * The only IOCTL operation supported by this function is setting the MAC
+ * address. An error is reported if any other operations are requested.
+ *
+ * Return:	0 to indicate success, or a negative error for failure.
+ */
+static int xemaclite_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
+{
+	struct net_local *lp = (struct net_local *) netdev_priv(dev);
+	struct hw_addr_data *hw_addr = (struct hw_addr_data *) &rq->ifr_hwaddr;
+
+	switch (cmd) {
+	case SIOCETHTOOL:
+		return -EIO;
+
+	case SIOCSIFHWADDR:
+		dev_err(&lp->ndev->dev, "SIOCSIFHWADDR\n");
+
+		/* Copy MAC address in from user space */
+		copy_from_user((void __force *) dev->dev_addr,
+			       (void __user __force *) hw_addr,
+			       IFHWADDRLEN);
+		xemaclite_set_mac_address(lp, dev->dev_addr);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	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) {
+		struct net_local *lp = (struct net_local *) netdev_priv(ndev);
+
+		if (lp->base_addr)
+			iounmap((void __iomem __force *) (lp->base_addr));
+		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 of_device *ofdev, const char *s)
+{
+	u32 *p = (u32 *)of_get_property(ofdev->node, s, NULL);
+
+	if (p) {
+		return (bool)*p;
+	} else {
+		dev_warn(&ofdev->dev, "Parameter %s not found,"
+			"defaulting to false\n", s);
+		return 0;
+	}
+}
+
+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.
+ *
+ * Return:	0, if the driver is bound to the Emaclite device, or
+ *		a negative error if there is failure.
+ */
+static int __devinit xemaclite_of_probe(struct of_device *ofdev,
+					const struct of_device_id *match)
+{
+	struct resource r_irq; /* Interrupt resources */
+	struct resource r_mem; /* IO mem resources */
+	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\n");
+
+	/* Get iospace for the device */
+	rc = of_address_to_resource(ofdev->node, 0, &r_mem);
+	if (rc) {
+		dev_err(dev, "invalid address\n");
+		return rc;
+	}
+
+	/* Get IRQ for the device */
+	rc = of_irq_to_resource(ofdev->node, 0, &r_irq);
+	if (rc == NO_IRQ) {
+		dev_err(dev, "no IRQ found\n");
+		return rc;
+	}
+
+	/* Create an ethernet device instance */
+	ndev = alloc_etherdev(sizeof(struct net_local));
+	if (!ndev) {
+		dev_err(dev, "Could not allocate network device\n");
+		return -ENOMEM;
+	}
+
+	dev_set_drvdata(dev, ndev);
+
+	ndev->irq = r_irq.start;
+	ndev->mem_start = r_mem.start;
+	ndev->mem_end = r_mem.end;
+
+	lp = netdev_priv(ndev);
+	lp->ndev = ndev;
+
+	if (!request_mem_region(ndev->mem_start,
+				ndev->mem_end - ndev->mem_start + 1,
+				DRIVER_NAME)) {
+		dev_err(dev, "Couldn't lock memory region at %p\n",
+			(void *)ndev->mem_start);
+		rc = -EBUSY;
+		goto error2;
+	}
+
+	/* Get the virtual base address for the device */
+	lp->base_addr = ioremap(r_mem.start, r_mem.end - r_mem.start + 1);
+	if (NULL == lp->base_addr) {
+		dev_err(dev, "EmacLite: Could not allocate iomem\n");
+		rc = -EIO;
+		goto error1;
+	}
+
+	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->node);
+
+	if (mac_address)
+		/* Set the MAC address. */
+		memcpy(ndev->dev_addr, mac_address, 6);
+	else
+		dev_warn(dev, "No MAC address found\n");
+
+	/* Clear the Tx CSR's in case this is a restart */
+	out_be32(lp->base_addr + XEL_TSR_OFFSET, 0);
+	out_be32(lp->base_addr + XEL_BUFFER_OFFSET + XEL_TSR_OFFSET, 0);
+
+	/* Set the MAC address in the EmacLite device */
+	xemaclite_set_mac_address(lp, ndev->dev_addr);
+
+	dev_info(dev,
+		 "MAC address is now %2x:%2x:%2x:%2x:%2x:%2x\n",
+		 ndev->dev_addr[0], ndev->dev_addr[1],
+		 ndev->dev_addr[2], ndev->dev_addr[3],
+		 ndev->dev_addr[4], ndev->dev_addr[5]);
+
+	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\n");
+		goto error1;
+	}
+
+	dev_info(dev,
+		 "Xilinx EmacLite at 0x%08X mapped to 0x%08X, irq=%d\n",
+		 (unsigned int __force)ndev->mem_start,
+		 (unsigned int __force)lp->base_addr, ndev->irq);
+	return 0;
+
+error1:
+	release_mem_region(ndev->mem_start, r_mem.end - r_mem.start + 1);
+
+error2:
+	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 __devexit xemaclite_of_remove(struct of_device *of_dev)
+{
+	struct device *dev = &of_dev->dev;
+	struct net_device *ndev = dev_get_drvdata(dev);
+
+	unregister_netdev(ndev);
+
+	release_mem_region(ndev->mem_start, ndev->mem_end-ndev->mem_start + 1);
+
+	xemaclite_remove_ndev(ndev);
+
+	dev_set_drvdata(dev, NULL);
+
+	return 0;
+}
+
+static struct net_device_ops xemaclite_netdev_ops = {
+	.ndo_open		= xemaclite_open,
+	.ndo_stop		= xemaclite_close,
+	.ndo_start_xmit		= xemaclite_send,
+	.ndo_do_ioctl		= xemaclite_ioctl,
+	.ndo_tx_timeout		= xemaclite_tx_timeout,
+	.ndo_get_stats		= xemaclite_get_stats,
+};
+
+/* Match table for OF platform binding */
+static struct of_device_id xemaclite_of_match[] __devinitdata = {
+	{ .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", },
+	{ /* end of list */ },
+};
+MODULE_DEVICE_TABLE(of, xemaclite_of_match);
+
+static struct of_platform_driver xemaclite_of_driver = {
+	.name		= DRIVER_NAME,
+	.match_table	= xemaclite_of_match,
+	.probe		= xemaclite_of_probe,
+	.remove		= __devexit_p(xemaclite_of_remove),
+};
+
+/**
+ * xgpiopss_init - Initial driver registration call
+ *
+ * Return:	0 upon success, or a negative error upon failure.
+ */
+static int __init xemaclite_init(void)
+{
+	/* No kernel boot options used, we just need to register the driver */
+	return of_register_platform_driver(&xemaclite_of_driver);
+}
+
+/**
+ * xemaclite_cleanup - Driver un-registration call
+ */
+static void __exit xemaclite_cleanup(void)
+{
+	of_unregister_platform_driver(&xemaclite_of_driver);
+}
+
+module_init(xemaclite_init);
+module_exit(xemaclite_cleanup);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx Ethernet MAC Lite driver");
+MODULE_LICENSE("GPL");