Subject: [PATCH] [V3] net: add Xilinx emac lite device driver

From: John Linn <[email-masked]>
Date: Thu, 20 Aug 2009 03:49:51 -0600

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.

CC: Grant Likely <[email-masked]>
CC: Josh Boyer <[email-masked]>
CC: John Williams <[email-masked]>
CC: Michal Simek <[email-masked]>
Signed-off-by: Sadanand M <[email-masked]>
Signed-off-by: John Linn <[email-masked]>

---

V2 - cleanup based on review, added depends for ppc and mb in Kconfig
V3 - fixed bug, spin lock was not initialized
---
 drivers/net/Kconfig           |    6 +
 drivers/net/Makefile          |    1 +
 drivers/net/xilinx_emaclite.c | 1041 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1048 insertions(+), 0 deletions(-)
 create mode 100755 drivers/net/xilinx_emaclite.c

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 5f6509a..ec77b69 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -1926,6 +1926,12 @@ config ATL2
 	  To compile this driver as a module, choose M here.  The module
 	  will be called atl2.
 
+config XILINX_EMACLITE
+	tristate "Xilinx 10/100 Ethernet Lite support"
+	depends on PPC32 || MICROBLAZE
+	help
+	  This driver supports the 10/100 Ethernet Lite from Xilinx.
+
 source "drivers/net/fs_enet/Kconfig"
 
 endif # NET_ETHERNET
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index ead8cab..99ae6d7 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -142,6 +142,7 @@ obj-$(CONFIG_TSI108_ETH) += tsi108_eth.o
 obj-$(CONFIG_MV643XX_ETH) += mv643xx_eth.o
 ll_temac-objs := ll_temac_main.o ll_temac_mdio.o
 obj-$(CONFIG_XILINX_LL_TEMAC) += ll_temac.o
+obj-$(CONFIG_XILINX_EMACLITE) += xilinx_emaclite.o
 obj-$(CONFIG_QLA3XXX) += qla3xxx.o
 obj-$(CONFIG_QLGE) += qlge/
 
diff --git a/drivers/net/xilinx_emaclite.c b/drivers/net/xilinx_emaclite.c
new file mode 100755
index 0000000..7e05b40
--- /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 <[email-masked]>.
+ *
+ * 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");
-- 
1.6.2.1

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