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Date:	Fri, 23 Jan 2015 10:07:01 +0000
From:	Stathis Voukelatos <stathisv70@...il.com>
To:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Cc:	Stathis Voukelatos <stathis.voukelatos@...n.co.uk>,
	abrestic@...omium.org
Subject: [PATCH] net: Linn Ethernet Packet Sniffer driver

This patch adds support the Ethernet Packet Sniffer H/W module
developed by Linn Products Ltd and found in the IMG Pistachio SoC.
The module allows Ethernet packets to be parsed, matched against
a user-defined pattern and timestamped. It sits between a 100M
Ethernet MAC and PHY and is completely passive with respect to
Ethernet frames.

Matched packet bytes and timestamp values are returned through a
FIFO. Timestamps are provided to the module through an externally
generated Gray-encoded counter.

The command pattern for packet matching is stored in module RAM
and consists of a sequence of 16-bit entries. Each entry includes
an 8-bit command code and and 8-bit data value. Valid command
codes are:
0 - Don't care
1 - Match: packet data must match command string byte
2 - Copy: packet data will be copied to FIFO
3 - Match/Stamp: if packet data matches string byte, a timestamp
                 is copied into the FIFO
4 - Copy/Done: packet data will be copied into the FIFO.
               This command terminates the command string.

The driver consists of two modules:
- Core: it provides an API to user space using the Generic Netlink
        framework. Specific backend implementations, like the
        Ethernet Packet Sniffer, register one or more channels
        with the Core. For each channel a Genl family is created.
        User space can access a channel by sending Genl messages
        to the Genl family associated with the channel. Packet
        matching events are multicast.

- Ethernet Packet Sniffer backend: provides the driver for the
        Linn Ethernet Packet Sniffer H/W modules.

The split between a core and backend modules allows software-only
implementations to be added for platforms where no H/W support
is available.

Based on 3.19-rc5

Signed-off-by: Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
---
 .../bindings/net/linn-ether-packet-sniffer.txt     |  27 ++
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 MAINTAINERS                                        |   7 +
 drivers/net/Kconfig                                |   2 +
 drivers/net/Makefile                               |   1 +
 drivers/net/pkt-sniffer/Kconfig                    |  23 ++
 drivers/net/pkt-sniffer/Makefile                   |   8 +
 drivers/net/pkt-sniffer/backends/ether/channel.c   | 366 ++++++++++++++++++
 drivers/net/pkt-sniffer/backends/ether/channel.h   |  76 ++++
 drivers/net/pkt-sniffer/backends/ether/hw.h        |  46 +++
 drivers/net/pkt-sniffer/backends/ether/platform.c  | 231 +++++++++++
 drivers/net/pkt-sniffer/core/dev_table.c           | 124 ++++++
 drivers/net/pkt-sniffer/core/module.c              |  37 ++
 drivers/net/pkt-sniffer/core/nl.c                  | 427 +++++++++++++++++++++
 drivers/net/pkt-sniffer/core/nl.h                  |  34 ++
 drivers/net/pkt-sniffer/core/snf_core.h            |  64 +++
 include/linux/pkt_sniffer.h                        |  89 +++++
 17 files changed, 1563 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/linn-ether-packet-sniffer.txt
 create mode 100644 drivers/net/pkt-sniffer/Kconfig
 create mode 100644 drivers/net/pkt-sniffer/Makefile
 create mode 100644 drivers/net/pkt-sniffer/backends/ether/channel.c
 create mode 100644 drivers/net/pkt-sniffer/backends/ether/channel.h
 create mode 100644 drivers/net/pkt-sniffer/backends/ether/hw.h
 create mode 100644 drivers/net/pkt-sniffer/backends/ether/platform.c
 create mode 100644 drivers/net/pkt-sniffer/core/dev_table.c
 create mode 100644 drivers/net/pkt-sniffer/core/module.c
 create mode 100644 drivers/net/pkt-sniffer/core/nl.c
 create mode 100644 drivers/net/pkt-sniffer/core/nl.h
 create mode 100644 drivers/net/pkt-sniffer/core/snf_core.h
 create mode 100644 include/linux/pkt_sniffer.h

diff --git a/Documentation/devicetree/bindings/net/linn-ether-packet-sniffer.txt b/Documentation/devicetree/bindings/net/linn-ether-packet-sniffer.txt
new file mode 100644
index 0000000..6b6e105
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/linn-ether-packet-sniffer.txt
@@ -0,0 +1,27 @@
+* Linn Products Ethernet Packet Sniffer
+
+Required properties:
+- compatible : must be "linn,eth-sniffer"
+- reg : physical addresses and sizes of registers. Must contain 3 entries:
+          first entry: registers memory space
+          second entry: TX command memory
+          third entry: RX command memory
+- reg-names : must contain the following 3 entries:
+                  "regs", "tx-ram", "rx-ram"
+- interrupts : sniffer interrupt specifier
+- clocks : specify the system clock for the peripheral
+- clock-names : must contain the "sys" entry
+- fifo-block-words : number of words in one data FIFO entry
+
+Example:
+
+sniffer@...4a000 {
+        compatible = "linn,eth-sniffer";
+        reg = <0x1814a000 0x100>, <0x1814a400 0x400>, <0x1814a800 0x400>;
+        reg-names = "regs", "tx-ram", "rx-ram";
+        interrupts = <GIC_SHARED 58 IRQ_TYPE_LEVEL_HIGH>;
+        interrupt-names = "eth-sniffer-irq";
+        clocks = <&system_clk>;
+        clock-names = "sys";
+        fifo-block-words = <4>;
+    };
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index b1df0ad..2c96f35 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -90,6 +90,7 @@ lacie	LaCie
 lantiq	Lantiq Semiconductor
 lenovo	Lenovo Group Ltd.
 lg	LG Corporation
+linn	Linn Products Ltd.
 linux	Linux-specific binding
 lsi	LSI Corp. (LSI Logic)
 lltc	Linear Technology Corporation
diff --git a/MAINTAINERS b/MAINTAINERS
index 2fa3853..7dbc6e7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5708,6 +5708,13 @@ M:	Sasha Levin <sasha.levin@...cle.com>
 S:	Maintained
 F:	tools/lib/lockdep/
 
+LINN PACKET SNIFFER DRIVER
+M: Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+S: Maintained
+F: include/linux/pkt_sniffer.h
+F: drivers/net/pkt-sniffer/
+F: Documentation/devicetree/bindings/net/linn-ether-packet-sniffer.txt
+
 LINUX FOR IBM pSERIES (RS/6000)
 M:	Paul Mackerras <paulus@...ibm.com>
 W:	http://www.ibm.com/linux/ltc/projects/ppc
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index d6607ee..219c786 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -380,4 +380,6 @@ config VMXNET3
 
 source "drivers/net/hyperv/Kconfig"
 
+source "drivers/net/pkt-sniffer/Kconfig"
+
 endif # NETDEVICES
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index e25fdd7..441111b 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -66,3 +66,4 @@ obj-$(CONFIG_USB_NET_DRIVERS) += usb/
 
 obj-$(CONFIG_HYPERV_NET) += hyperv/
 obj-$(CONFIG_NTB_NETDEV) += ntb_netdev.o
+obj-$(CONFIG_PKT_SNIFFER) += pkt-sniffer/
diff --git a/drivers/net/pkt-sniffer/Kconfig b/drivers/net/pkt-sniffer/Kconfig
new file mode 100644
index 0000000..26b4f98
--- /dev/null
+++ b/drivers/net/pkt-sniffer/Kconfig
@@ -0,0 +1,23 @@
+menuconfig PKT_SNIFFER
+    tristate "Linn packet sniffer support"
+    ---help---
+    Say Y to add support for Linn packet sniffer drivers.
+
+    The core driver can also be built as a module. If so, the module
+    will be called snf_core.
+
+if PKT_SNIFFER
+
+config PKT_SNIFFER_ETHER
+    tristate "Ethernet packet sniffer"
+    depends on MIPS
+    default n
+    help
+        Say Y here if you want to use the Linn Ethernet packet sniffer
+        module. It can be found in the upcoming Pistachio SoC by
+        Imagination Technologies.
+
+        The driver can also be built as a module. If so, the module
+        will be called snf_ether.
+
+endif # PKT_SNIFFER
diff --git a/drivers/net/pkt-sniffer/Makefile b/drivers/net/pkt-sniffer/Makefile
new file mode 100644
index 0000000..07e7339
--- /dev/null
+++ b/drivers/net/pkt-sniffer/Makefile
@@ -0,0 +1,8 @@
+snf_core-y += core/nl.o
+snf_core-y += core/dev_table.o
+snf_core-y += core/module.o
+obj-$(CONFIG_PKT_SNIFFER) += snf_core.o
+
+snf_ether-y += backends/ether/platform.o
+snf_ether-y += backends/ether/channel.o
+obj-$(CONFIG_PKT_SNIFFER_ETHER) += snf_ether.o
diff --git a/drivers/net/pkt-sniffer/backends/ether/channel.c b/drivers/net/pkt-sniffer/backends/ether/channel.c
new file mode 100644
index 0000000..d483b58
--- /dev/null
+++ b/drivers/net/pkt-sniffer/backends/ether/channel.c
@@ -0,0 +1,366 @@
+/*
+ * Ethernet Mii packet sniffer driver
+ *  - channel functions
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/pkt_sniffer.h>
+#include "../../core/snf_core.h"
+#include "hw.h"
+#include "channel.h"
+
+#define to_ether_snf_chan(dev) container_of(dev, struct ether_snf_chan, chan)
+
+static int esnf_start(struct snf_chan *dev);
+static int esnf_stop(struct snf_chan *dev);
+static int esnf_set_pattern(struct snf_chan *dev, const u8 *pattern, int count);
+static int esnf_num_recs_avail(struct snf_chan *dev);
+static int esnf_max_ptn_entries(struct snf_chan *dev);
+static int esnf_max_match_bytes(struct snf_chan *dev);
+static int validate_pattern(
+			struct ether_snf_chan *ch,
+			const u8 *buf,
+			int count);
+static void read_fifo_data(struct ether_snf_chan *ch);
+static u32 gray_decode(u32 gray);
+
+/* Initialises a sniffer channel */
+int channel_init(
+	struct ether_snf_chan *ch,
+	struct platform_device *pdev,
+	void *regs,
+	int fifo_blk_words,
+	int tx)
+{
+	struct resource *res;
+	u32 *ptr;
+	int i;
+
+	ch->regs = regs;
+	ch->dev = &pdev->dev;
+	ch->data_irq_bit = tx ? TX_DATA_IRQ_BIT : RX_DATA_IRQ_BIT;
+	ch->full_irq_bit = tx ? TX_FULL_IRQ_BIT : RX_FULL_IRQ_BIT;
+	ch->reg_enable = ch->regs +
+			 (tx ? TX_SNIFFER_ENABLE : RX_SNIFFER_ENABLE);
+	ch->reg_occ = ch->regs + (tx ? TX_FIFO_OCC : RX_FIFO_OCC);
+	ch->reg_fifo = ch->regs + (tx ? TX_FIFO_DAT : RX_FIFO_DAT);
+
+	/* Retrieve and remap the address space for the command memory */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   tx ? "tx-ram" : "rx-ram");
+	if (!res)
+		return -ENOSYS;
+	ch->cmd_ram = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ch->cmd_ram))
+		return PTR_ERR(ch->cmd_ram);
+
+	/* It is 2 bytes/command, hence divide by 2 */
+	ch->max_cmds = resource_size(res) / 2;
+
+	/* Initialise the command pattern RAM */
+	for (i = 0, ptr = ch->cmd_ram; i < resource_size(res); i += 4)
+		iowrite32((PTN_CMD_DONTCARE << 24) | (PTN_CMD_DONTCARE << 8),
+			  ptr++);
+
+	ch->fifo_blk_words = fifo_blk_words;
+	ch->started = 0;
+
+	/* Register the channel methods */
+	ch->chan.start = esnf_start;
+	ch->chan.stop = esnf_stop;
+	ch->chan.set_pattern = esnf_set_pattern;
+	ch->chan.num_recs_avail = esnf_num_recs_avail;
+	ch->chan.max_ptn_entries = esnf_max_ptn_entries;
+	ch->chan.max_match_bytes = esnf_max_match_bytes;
+
+	strncpy(ch->name, tx ? "TX" : "RX", MAX_CHAN_NAME_SIZE - 1);
+
+	dev_dbg(ch->dev, "%s channel initialized\n", ch->name);
+
+	return 0;
+}
+
+/* Registers the channel with the sniffer core module */
+int channel_register(struct ether_snf_chan *ch, const char *name)
+{
+	int id;
+
+	id = snf_channel_add(&ch->chan, name);
+	if (id < 0)
+		return id;
+
+	ch->id = id;
+	dev_info(ch->dev, "%s channel added\n", ch->name);
+	return 0;
+}
+
+/* Unregisters the channel */
+int channel_unregister(struct ether_snf_chan *ch)
+{
+	int ret;
+
+	ch->chan.stop(&ch->chan);
+	ret = snf_channel_remove(ch->id);
+	if (!ret)
+		dev_info(ch->dev, "%s channel removed\n", ch->name);
+	return ret;
+}
+
+/* Process match event data */
+void channel_data_available(struct ether_snf_chan *ch)
+{
+	int ret;
+
+	dev_dbg(ch->dev, "%s match event\n", ch->name);
+
+	read_fifo_data(ch);
+	ret = snf_channel_notify_match(&ch->chan, &ch->evt);
+	if (ret < 0)
+		dev_err(ch->dev, "%s: event notification failed\n", ch->name);
+}
+
+/* Channel methods */
+
+/* Enables the channel */
+static int esnf_start(struct snf_chan *dev)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+
+	if (!ch->started) {
+		/* Enable interrupts */
+		iowrite32(ch->data_irq_bit | ch->full_irq_bit,
+			  ch->regs + SET_INTERRUPT_ENABLE);
+		/* Enable the packet matching logic */
+		iowrite32(ENABLE_BIT, ch->reg_enable);
+
+		ch->started = 1;
+		dev_info(ch->dev, "%s channel started\n", ch->name);
+	} else {
+		dev_dbg(ch->dev, "%s channel already running\n", ch->name);
+	}
+
+	return 0;
+}
+
+/* Disables the channel */
+static int esnf_stop(struct snf_chan *dev)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+
+	if (ch->started) {
+		/* Disable interrupts */
+		iowrite32(ch->data_irq_bit | ch->full_irq_bit,
+			  ch->regs + CLEAR_INTERRUPT_ENABLE);
+		/* Stop the sniffer channel */
+		iowrite32(0, ch->reg_enable);
+		/* Clear any pending interrupts */
+		iowrite32(ch->data_irq_bit | ch->full_irq_bit,
+			  ch->regs + INTERRUPT_STATUS);
+
+		ch->started = 0;
+		dev_info(ch->dev, "%s channel stopped\n", ch->name);
+	} else {
+		dev_dbg(ch->dev, "%s channel already stopped\n", ch->name);
+	}
+
+	return 0;
+}
+
+/* Sets the command string (pattern) for the channel
+ * The bytes in the pattern buffer are in the following order:
+ */
+static int esnf_set_pattern(struct snf_chan *dev, const u8 *pattern, int count)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+	int i, shift = 0;
+	u32  val = 0, *ptr;
+
+	if (ch->started) {
+		dev_err(ch->dev,
+			"cannot apply cmd pattern. %s channel is active\n",
+			ch->name);
+		return -EBUSY;
+	}
+
+	if (!validate_pattern(ch, pattern, count)) {
+		dev_err(ch->dev,
+			"invalid cmd pattern for %s channel\n",
+			ch->name);
+		return -EINVAL;
+	}
+
+	for (ptr = ch->cmd_ram, i = 0, shift = 24; i < (2*count); i++) {
+		val |= ((u32)pattern[i]) << shift;
+		if (!shift) {
+			iowrite32(val, ptr++);
+			val = 0;
+			shift = 24;
+		} else {
+			shift -= 8;
+		}
+	}
+	if (shift)
+		iowrite32(val, ptr);
+
+	return 0;
+}
+
+/* Returns the number of pending match events that are
+ * available to retrieve
+ */
+static int esnf_num_recs_avail(struct snf_chan *dev)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+
+	return ioread32(ch->reg_occ);
+}
+
+/* Returns max number of commands supported by the channel */
+static int esnf_max_ptn_entries(struct snf_chan *dev)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+
+	return ch->max_cmds;
+}
+
+/* Returns max number of bytes that can be returned by a match */
+static int esnf_max_match_bytes(struct snf_chan *dev)
+{
+	struct ether_snf_chan *ch = to_ether_snf_chan(dev);
+
+	/* Subtract the word that may be used for the timestamp */
+	return (ch->fifo_blk_words - 1) * 4;
+}
+
+/* Checks if the supplied command string is compatible with the
+ * capabilities of the H/W
+ */
+static int validate_pattern(struct ether_snf_chan *ch, const u8 *buf, int count)
+{
+	int i, complete, max_copy_bytes;
+	int ts = 0;
+	int copy_before = 0;
+	int copy_after = 0;
+
+	if (count > ch->max_cmds)
+		return 0;
+
+	/* Iterate through the commands in the string */
+	for (i = 0, complete = 0; (i < count) && !complete; i++) {
+		u8 cmd = buf[2*i];
+
+		switch (cmd) {
+		case PTN_CMD_DONTCARE:
+		case PTN_CMD_MATCH:
+			break;
+
+		case PTN_CMD_MATCHSTAMP:
+			/* The timestamp needs to be word-aligned in the FIFO
+			 * therefore, the number of 'copy' commands before it
+			 * needs to be a multiple of 4
+			 */
+			if (copy_before & 3)
+				return 0;
+			/* Signal that a timestamp will be present */
+			ts = 1;
+			break;
+
+		case PTN_CMD_COPY:
+			/* Increment count of bytes that will be returned */
+			if (ts)
+				copy_after++;
+			else
+				copy_before++;
+			break;
+
+		case PTN_CMD_COPYDONE:
+			/* Increment count of bytes that will be returned
+			 * This command terminates the string
+			 */
+			if (ts)
+				copy_after++;
+			else
+				copy_before++;
+			complete = 1;
+			break;
+
+		default:
+			return 0;
+		}
+	}
+
+	/* Check if the string was properly terminated
+	 * and contained valid number of commands
+	 */
+	if (complete) {
+		max_copy_bytes = ch->fifo_blk_words * 4;
+		if (ts)
+			max_copy_bytes -= 4;
+		if ((copy_before + copy_after) > max_copy_bytes)
+			return 0;
+		ch->ts_present = ts;
+		ch->nfb_before = copy_before;
+		ch->nfb_after = copy_after;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+/* Read a block from the data FIFO */
+static void read_fifo_data(struct ether_snf_chan *ch)
+{
+	int i;
+	u32 val, *ptr;
+	int ts = ch->ts_present;
+	int dw = ch->fifo_blk_words;
+	int bytes_before = ch->nfb_before;
+	int bytes_after = ch->nfb_after;
+
+	ptr = (u32 *)ch->evt.data;
+	for (i = 0; i < dw; i++) {
+		val = ioread32(ch->reg_fifo);
+		if (bytes_before > 0) {
+			/* Bytes before the timestamp */
+			*ptr++ = cpu_to_be32(val);
+			bytes_before -= 4;
+		} else if (ts) {
+			/* Timestamp is Gray encoded */
+			ch->evt.ts = (u64)gray_decode(val);
+			ts = 0;
+		} else if (bytes_after > 0) {
+			/* Bytes after the timestamp */
+			*ptr++ = cpu_to_be32(val);
+			bytes_after -= 4;
+		}
+	}
+
+	ch->evt.ts_valid = ch->ts_present;
+	ch->evt.len = ch->nfb_before + ch->nfb_after;
+}
+
+/* Gray decoder */
+static u32 gray_decode(u32 gray)
+{
+	gray ^= (gray >> 16);
+	gray ^= (gray >> 8);
+	gray ^= (gray >> 4);
+	gray ^= (gray >> 2);
+	gray ^= (gray >> 1);
+	return gray;
+}
+
diff --git a/drivers/net/pkt-sniffer/backends/ether/channel.h b/drivers/net/pkt-sniffer/backends/ether/channel.h
new file mode 100644
index 0000000..4f00b33
--- /dev/null
+++ b/drivers/net/pkt-sniffer/backends/ether/channel.h
@@ -0,0 +1,76 @@
+/*
+ * Ethernet Mii packet sniffer driver
+ *  - channel interface
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#ifndef _ETHER_SNIFFER_CHANNEL_H_
+#define _ETHER_SNIFFER_CHANNEL_H_
+
+#include <linux/platform_device.h>
+#include "../../core/snf_core.h"
+
+#define MAX_CHAN_NAME_SIZE 5
+
+struct ether_snf_chan {
+	/* Sniffer core structure */
+	struct snf_chan chan;
+	/* Pointer to device struct */
+	struct device *dev;
+	/* Registers */
+	u8 __iomem *regs;
+	/* Command string memory */
+	u32 __iomem *cmd_ram;
+	/* Bit number for the data IRQ */
+	int data_irq_bit;
+	/* Bit number for the FIFO full IRQ */
+	int full_irq_bit;
+	/* Channel enable register */
+	u8 __iomem *reg_enable;
+	/* Data FIFO register */
+	u8 __iomem *reg_fifo;
+	/* FIFO occupancy register */
+	u8 __iomem *reg_occ;
+	/* Max number of commands in the string */
+	int max_cmds;
+	/* Max matching bytes that can fit in a FIFO block */
+	int fifo_blk_words;
+	/* Number of bytes in the FIFO before the timestamp */
+	int nfb_before;
+	/* Number of bytes in the FIFO after the timestamp */
+	int nfb_after;
+	/* Timestamp present flag */
+	int ts_present;
+	/* ID assigned to channel by the sniffer core */
+	int id;
+	/* Channel active flag */
+	int started;
+	/* Channel name (only used by debug messages) */
+	char name[MAX_CHAN_NAME_SIZE];
+	/* Struct to hold data from a packet match */
+	struct snf_match_evt evt;
+};
+
+int channel_init(
+		struct ether_snf_chan *ch,
+		struct platform_device *pdev,
+		void *regs,
+		int fifo_blk_words,
+		int tx);
+int channel_register(struct ether_snf_chan *ch, const char *name);
+int channel_unregister(struct ether_snf_chan *ch);
+void channel_data_available(struct ether_snf_chan *ch);
+
+#endif
diff --git a/drivers/net/pkt-sniffer/backends/ether/hw.h b/drivers/net/pkt-sniffer/backends/ether/hw.h
new file mode 100644
index 0000000..edb1093
--- /dev/null
+++ b/drivers/net/pkt-sniffer/backends/ether/hw.h
@@ -0,0 +1,46 @@
+/*
+ * Ethernet Mii packet sniffer driver
+ *  - register map
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#ifndef _ETHER_SNIFFER_HW_H_
+#define _ETHER_SNIFFER_HW_H_
+
+#include <linux/bitops.h>
+
+/* Registers */
+#define INTERRUPT_ENABLE        0x00
+#define SET_INTERRUPT_ENABLE    0x04
+#define CLEAR_INTERRUPT_ENABLE  0x08
+#define INTERRUPT_STATUS        0x0c
+#define TX_FIFO_DAT             0x10
+#define RX_FIFO_DAT             0x14
+#define TX_FIFO_OCC             0x18
+#define RX_FIFO_OCC             0x1c
+#define TX_SNIFFER_ENABLE       0x20
+#define RX_SNIFFER_ENABLE       0x24
+
+/* IRQ register bits */
+#define TX_DATA_IRQ_BIT         BIT(0)
+#define RX_DATA_IRQ_BIT         BIT(1)
+#define TX_FULL_IRQ_BIT         BIT(2)
+#define RX_FULL_IRQ_BIT         BIT(3)
+
+/* Enable register bits */
+#define ENABLE_BIT              BIT(0)
+
+#endif
+
diff --git a/drivers/net/pkt-sniffer/backends/ether/platform.c b/drivers/net/pkt-sniffer/backends/ether/platform.c
new file mode 100644
index 0000000..78e7e1c
--- /dev/null
+++ b/drivers/net/pkt-sniffer/backends/ether/platform.c
@@ -0,0 +1,231 @@
+/*
+ * Ethernet Mii packet sniffer driver
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include "../../core/snf_core.h"
+#include "hw.h"
+#include "channel.h"
+
+static const char esnf_driver_name[] = "eth-sniffer";
+
+/* Names for the TX and RX channel.
+ * User space will used these names to access the channels
+ * through the generic netlink interface
+ */
+static const char tx_channel_name[] = "snf_ether_tx";
+static const char rx_channel_name[] = "snf_ether_rx";
+
+struct ether_snf {
+	u8 __iomem *regs;
+	int irq;
+	struct clk *sys_clk;
+	struct ether_snf_chan txc;
+	struct ether_snf_chan rxc;
+};
+
+/* Interrupt thread function */
+static irqreturn_t esnf_irq_thread(int irq, void *dev_id)
+{
+	struct platform_device *pdev = (struct platform_device *)dev_id;
+	struct ether_snf *esnf = (struct ether_snf *)platform_get_drvdata(pdev);
+	u32 irq_status;
+
+	if (unlikely(esnf->irq != irq))
+		return IRQ_NONE;
+
+	irq_status = ioread32(esnf->regs + INTERRUPT_STATUS) &
+				 ioread32(esnf->regs + INTERRUPT_ENABLE);
+
+	dev_dbg(&pdev->dev, "irq: 0x%08x\n", irq_status);
+
+	/* TX FIFO full */
+	if (unlikely(irq_status & TX_FULL_IRQ_BIT))
+		dev_notice(&pdev->dev, "TX FIFO full");
+
+	/* RX FIFO full */
+	if (unlikely(irq_status & RX_FULL_IRQ_BIT))
+		dev_notice(&pdev->dev, "RX FIFO full");
+
+	/* TX match data available */
+	if (irq_status & TX_DATA_IRQ_BIT) {
+		dev_dbg(&pdev->dev, "TX data");
+		channel_data_available(&esnf->txc);
+	}
+
+	/* RX match data available */
+	if (irq_status & RX_DATA_IRQ_BIT) {
+		dev_dbg(&pdev->dev, "RX data");
+		channel_data_available(&esnf->rxc);
+	}
+
+	/* Clear interrupts */
+	iowrite32(irq_status, esnf->regs + INTERRUPT_STATUS);
+
+	return IRQ_HANDLED;
+}
+
+/* Called when the packet sniffer device is bound with the driver */
+static int esnf_driver_probe(struct platform_device *pdev)
+{
+	struct ether_snf *esnf;
+	struct resource *res;
+	int ret, irq;
+	u32 fifo_blk_words;
+	void __iomem *regs;
+	struct device_node *ofn = pdev->dev.of_node;
+
+	/* Allocate the device data structure */
+	esnf = devm_kzalloc(&pdev->dev, sizeof(*esnf), GFP_KERNEL);
+	if (!esnf)
+		return -ENOMEM;
+
+	/* Retrieve and remap register memory space */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
+	if (!res)
+		return -ENODEV;
+
+	regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	esnf->regs = regs;
+
+	/* Read the FIFO block size from the DT */
+	if (!ofn)
+		return -ENODEV;
+
+	ret = of_property_read_u32(
+				ofn,
+				"fifo-block-words",
+				&fifo_blk_words);
+	if (ret < 0)
+		return ret;
+
+	if (((fifo_blk_words - 1)*4) > MAX_MATCH_BYTES) {
+		dev_err(&pdev->dev,
+			"Invalid FIFO block size entry in device tree\n");
+		return -EINVAL;
+	}
+
+	esnf->sys_clk = devm_clk_get(&pdev->dev, "sys");
+	if (IS_ERR(esnf->sys_clk)) {
+		ret = PTR_ERR(esnf->sys_clk);
+		return ret;
+	}
+	ret = clk_prepare_enable(esnf->sys_clk);
+	if (ret < 0)
+		return ret;
+
+	/* Initialise the TX and RX channels */
+	ret = channel_init(&esnf->txc, pdev, regs, fifo_blk_words, 1);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to init TX channel (%d)\n", ret);
+		goto fail1;
+	}
+	ret = channel_init(&esnf->rxc, pdev, regs, fifo_blk_words, 0);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to init RX channel (%d)\n", ret);
+		goto fail1;
+	}
+
+	/* Register the channels with the sniffer core module */
+	ret = channel_register(&esnf->txc, tx_channel_name);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register TX chan (%d)\n", ret);
+		goto fail1;
+	}
+	ret = channel_register(&esnf->rxc, rx_channel_name);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register RX chan (%d)\n", ret);
+		goto fail2;
+	}
+
+	platform_set_drvdata(pdev, esnf);
+
+	/* Register the interrupt handler */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		goto fail3;
+	esnf->irq = irq;
+	ret = devm_request_threaded_irq(
+				&pdev->dev,
+				irq,
+				NULL,
+				esnf_irq_thread,
+				IRQF_ONESHOT,
+				esnf_driver_name,
+				pdev);
+	if (ret < 0)
+		goto fail3;
+
+	return 0;
+
+fail3:
+	channel_unregister(&esnf->rxc);
+fail2:
+	channel_unregister(&esnf->txc);
+fail1:
+	clk_disable_unprepare(esnf->sys_clk);
+	return ret;
+}
+
+/* Called when the packet sniffer device unregisters with the driver */
+static int esnf_driver_remove(struct platform_device *pdev)
+{
+	struct ether_snf *esnf = (struct ether_snf *)platform_get_drvdata(pdev);
+	int ret;
+
+	ret = channel_unregister(&esnf->txc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to unregister TX chan (%d)\n", ret);
+		return ret;
+	}
+	ret = channel_unregister(&esnf->rxc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to unregister RX chan (%d)\n", ret);
+		return ret;
+	}
+	clk_disable_unprepare(esnf->sys_clk);
+	return 0;
+}
+
+static const struct of_device_id esnf_of_match_table[] = {
+	{ .compatible = "linn,eth-sniffer", .data = NULL },
+	{},
+};
+MODULE_DEVICE_TABLE(of, esnf_of_match_table);
+
+static struct platform_driver esnf_platform_driver = {
+	.driver = {
+		.name = esnf_driver_name,
+		.of_match_table = esnf_of_match_table,
+	},
+	.probe = esnf_driver_probe,
+	.remove = esnf_driver_remove,
+};
+
+module_platform_driver(esnf_platform_driver);
+
+MODULE_DESCRIPTION("Linn Ethernet Packet Sniffer");
+MODULE_AUTHOR("Linn Products Ltd");
+MODULE_LICENSE("GPL v2");
+
diff --git a/drivers/net/pkt-sniffer/core/dev_table.c b/drivers/net/pkt-sniffer/core/dev_table.c
new file mode 100644
index 0000000..3a07838
--- /dev/null
+++ b/drivers/net/pkt-sniffer/core/dev_table.c
@@ -0,0 +1,124 @@
+/*
+ * Packet sniffer core driver: channel management
+ *
+ * Copyright (C) 2014 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include "snf_core.h"
+#include "nl.h"
+
+#define MAX_CHANNELS   256
+
+static DEFINE_MUTEX(tlock);
+
+static struct snf_chan *dev_tab[MAX_CHANNELS];
+static unsigned int ref_count[MAX_CHANNELS];
+
+static inline int verify_args(int id)
+{
+	return (id < MAX_CHANNELS);
+}
+
+/* Registers a sniffer channel and returns and id for it */
+int snf_channel_add(struct snf_chan *dev, const char *name)
+{
+	int i;
+	int ret = -EEXIST;
+
+	mutex_lock(&tlock);
+
+	for (i = 0; i < MAX_CHANNELS; i++) {
+		if (!dev_tab[i]) {
+			/* Initialise the netlink interface for the channel */
+			ret = snf_netlink_init(i, dev, name);
+			if (ret < 0)
+				goto fail;
+
+			dev_tab[i] = dev;
+			ref_count[i] = 0;
+			mutex_unlock(&tlock);
+			return i;
+		}
+	}
+
+fail:
+	mutex_unlock(&tlock);
+	return ret;
+}
+EXPORT_SYMBOL(snf_channel_add);
+
+/* Removes a sniffer channel */
+int snf_channel_remove(int id)
+{
+	int ret = 0;
+	struct snf_chan *dev;
+
+	if (!verify_args(id))
+		return -EINVAL;
+
+	mutex_lock(&tlock);
+
+	dev = dev_tab[id];
+
+	if (!dev) {
+		ret = -ENODEV;
+		goto fail;
+	}
+
+	if (ref_count[id] > 0) {
+		ret = -EBUSY;
+		goto fail;
+	}
+
+	dev_tab[id] = NULL;
+
+	/* Release netlink API resources */
+	snf_netlink_release(dev);
+
+fail:
+	mutex_unlock(&tlock);
+	return ret;
+}
+EXPORT_SYMBOL(snf_channel_remove);
+
+/* Returns a pointer to the specified sniffer channel
+ * and increments its reference counter
+ */
+struct snf_chan *snf_channel_get(int id)
+{
+	struct snf_chan *dev;
+
+	if (!verify_args(id))
+		return NULL;
+
+	mutex_lock(&tlock);
+	dev = dev_tab[id];
+	if (dev)
+		ref_count[id]++;
+	mutex_unlock(&tlock);
+
+	return dev;
+}
+
+/* Decrements the reference counter for the channel */
+void snf_channel_put(int id)
+{
+	mutex_lock(&tlock);
+	if (ref_count[id] > 0)
+		ref_count[id]--;
+	mutex_unlock(&tlock);
+}
+
diff --git a/drivers/net/pkt-sniffer/core/module.c b/drivers/net/pkt-sniffer/core/module.c
new file mode 100644
index 0000000..af6a1aa
--- /dev/null
+++ b/drivers/net/pkt-sniffer/core/module.c
@@ -0,0 +1,37 @@
+/*
+ * Packet sniffer core driver:
+ *  - backend channel management
+ *  - interface to userland via generic netlink
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+
+static int __init snf_core_init(void)
+{
+	return 0;
+}
+
+static void __exit snf_core_cleanup(void)
+{
+}
+
+module_init(snf_core_init);
+module_exit(snf_core_cleanup);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Core packet sniffer driver");
+MODULE_AUTHOR("Linn Products Ltd");
diff --git a/drivers/net/pkt-sniffer/core/nl.c b/drivers/net/pkt-sniffer/core/nl.c
new file mode 100644
index 0000000..6839147
--- /dev/null
+++ b/drivers/net/pkt-sniffer/core/nl.c
@@ -0,0 +1,427 @@
+/*
+ * Packet sniffer core driver: generic netlink interface
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#include <linux/version.h>
+#include <net/netlink.h>
+#include <net/genetlink.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/pkt_sniffer.h>
+#include "snf_core.h"
+#include "nl.h"
+
+/* Netlink API data for a sniffer channel */
+struct snf_netlink {
+	/* genl family */
+	struct genl_family           fml;
+	/* genl operations */
+	struct genl_ops             *ops;
+	/* genl mcast group, where sniffer match
+	 * events will be sent
+	 */
+	struct genl_multicast_group  grp;
+};
+
+/* Attribute policies */
+static struct nla_policy snf_policy[SNF_ATTR_MAX + 1] = {
+	[SNF_ATTR_PATTERN] = { .type = NLA_NESTED },
+};
+
+static struct nla_policy snf_ptn_policy[SNF_ATTR_PTN_MAX + 1] = {
+	[SNF_ATTR_PTN_ENTRY] = { .type = NLA_U16 },
+};
+
+/* Generic Netlink family template definition */
+static int pre_doit_func(const struct genl_ops *ops,
+			 struct sk_buff *skb,
+			 struct genl_info *info);
+
+static void post_doit_func(const struct genl_ops *ops,
+			   struct sk_buff *skb,
+			   struct genl_info *info);
+
+static struct genl_family snf_family_tmpl = {
+	.id = GENL_ID_GENERATE,
+	.hdrsize = 0,
+	.version = SNF_GNL_VERSION,
+	.maxattr = SNF_ATTR_MAX,
+	.pre_doit = pre_doit_func,
+	.post_doit = post_doit_func
+};
+
+static int send_reply_uint32(
+			struct genl_info *info,
+			int cmd,
+			int attr,
+			u32 val);
+
+/* Generic Netlink operations template definition */
+
+static int do_it_start(struct sk_buff *skb, struct genl_info *info);
+static int do_it_stop(struct sk_buff *skb, struct genl_info *info);
+static int do_it_set_pattern(struct sk_buff *skb, struct genl_info *info);
+static int do_it_num_rec_avail(struct sk_buff *skb, struct genl_info *info);
+static int do_it_ptn_max_cmds(struct sk_buff *skb, struct genl_info *info);
+static int do_it_max_match_bytes(struct sk_buff *skb, struct genl_info *info);
+
+#define SNF_GENL_OP(_cmd, _func)	 \
+	{				 \
+		.cmd	= _cmd,          \
+		.policy = snf_policy,    \
+		.doit   = _func,         \
+		.dumpit = NULL,          \
+		.flags  = 0,             \
+		.internal_flags = 0      \
+	}
+
+#define SNF_CHAN_OPS							   \
+	{								   \
+		SNF_GENL_OP(SNF_CMD_START,         do_it_start),	   \
+		SNF_GENL_OP(SNF_CMD_STOP,          do_it_stop),		   \
+		SNF_GENL_OP(SNF_CMD_SETPATTERN,    do_it_set_pattern),     \
+		SNF_GENL_OP(SNF_CMD_NUMRECAVAIL,   do_it_num_rec_avail),   \
+		SNF_GENL_OP(SNF_CMD_PTNMAXCMDS,    do_it_ptn_max_cmds),    \
+		SNF_GENL_OP(SNF_CMD_MAXMATCHBYTES, do_it_max_match_bytes)  \
+	}
+
+static struct genl_ops snf_ops_tmpl[] = SNF_CHAN_OPS;
+
+#define NUM_GENL_OPS ARRAY_SIZE(snf_ops_tmpl)
+
+/* Multicast a netlink event containing data from a sniffer match event.
+ * Data are included in the netlink message as a nested attribute
+ * containing the timestamp (optional) and matching packet bytes
+*/
+int snf_channel_notify_match(struct snf_chan *dev, struct snf_match_evt *mt)
+{
+	int i, ret = 0;
+	struct sk_buff *msg = NULL;
+	void *msg_hdr, *nest_hdr;
+	struct snf_netlink *nl = (struct snf_netlink *)dev->cstate;
+
+	if (!nl) {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
+	if (!msg) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	msg_hdr = genlmsg_put(msg,
+			      0,
+			      0,
+			      &nl->fml,
+			      0,
+			      SNF_CMD_MATCHEVENT);
+	if (!msg_hdr) {
+		ret = -EMSGSIZE;
+		goto fail;
+	}
+
+	/* Add the nested attribute with the data */
+	if ((mt->ts_valid) || (mt->len > 0)) {
+		nest_hdr = nla_nest_start(msg, SNF_ATTR_MATCHEVENT);
+		if (!nest_hdr) {
+			ret = -EMSGSIZE;
+			goto fail;
+		}
+		if (mt->ts_valid) {
+			ret = nla_put_u64(msg, SNF_ATTR_MATCH_TS, mt->ts);
+			if (ret < 0)
+				goto fail;
+		}
+		for (i = 0; i < mt->len; i++) {
+			ret = nla_put_u8(msg,
+					 SNF_ATTR_MATCH_PKTBYTE,
+					 mt->data[i]);
+			if (ret < 0)
+				goto fail;
+		}
+		nla_nest_end(msg, nest_hdr);
+	}
+
+	ret = genlmsg_end(msg, msg_hdr);
+	if (ret < 0)
+		goto fail;
+	ret = genlmsg_multicast(&nl->fml, msg, 0, 0, GFP_ATOMIC);
+
+	/* The ESRCH code is returned when there is no socket listening on the
+	 * multicast group, so we do not really treat is as an error
+	 */
+	if (ret == -ESRCH)
+		ret = 0;
+	return ret;
+
+fail:
+	if (msg)
+		nlmsg_free(msg);
+	return ret;
+}
+EXPORT_SYMBOL(snf_channel_notify_match);
+
+/* Initialise the generic netlink API for a sniffer channel
+ * Registers family, ops and multicast group for events
+ */
+int snf_netlink_init(int id, struct snf_chan *dev, const char *name)
+{
+	int i, ret;
+	struct snf_netlink *nl = NULL;
+
+	nl = kmalloc(sizeof(*nl), GFP_KERNEL);
+	if (!nl) {
+		ret = -ENOMEM;
+		goto fail1;
+	}
+
+	nl->fml = snf_family_tmpl;
+
+	/* Set the family name */
+	strncpy(nl->fml.name, name, GENL_NAMSIZ-1);
+
+	/* Allocate ops array and copy template data */
+	nl->ops = kmalloc(sizeof(snf_ops_tmpl), GFP_KERNEL);
+	if (!nl->ops) {
+		ret = -ENOMEM;
+		goto fail2;
+	}
+	memcpy(nl->ops, snf_ops_tmpl, sizeof(snf_ops_tmpl));
+
+	/* In the internal_flags field we store the id
+	 * of the device the ops belong to
+	 */
+	for (i = 0; i < NUM_GENL_OPS; i++)
+		nl->ops[i].internal_flags = id;
+
+	snprintf(nl->grp.name, GENL_NAMSIZ-1, SNF_EVENT_GRP);
+
+	ret = _genl_register_family_with_ops_grps(
+						&nl->fml,
+						nl->ops,
+						NUM_GENL_OPS,
+						&nl->grp,
+						1);
+	if (ret < 0) {
+		pr_err("%s: failed to register family %s (%d)\n",
+		       KBUILD_MODNAME, name, ret);
+		goto fail3;
+	}
+
+	pr_info("%s: registered genl family for channel %d: %s\n",
+		KBUILD_MODNAME, id, name);
+	dev->cstate = nl;
+
+	return 0;
+
+fail3:
+	kfree(nl->ops);
+fail2:
+	kfree(nl);
+fail1:
+	return ret;
+}
+
+/* Shuts down the netlink API for a sniffer channel
+ * and frees resources
+ */
+void snf_netlink_release(struct snf_chan *dev)
+{
+	struct snf_netlink *nl = (struct snf_netlink *)dev->cstate;
+	/* Unregister family and free ops
+	 * NOTE: this will also unregister the ops and the mcast group
+	 */
+	genl_unregister_family(&nl->fml);
+	pr_info("%s: unregistered genl family: %s\n",
+		KBUILD_MODNAME, nl->fml.name);
+
+	kfree(nl->ops);
+	kfree(nl);
+	dev->cstate = NULL;
+}
+
+/* pre_doit function that retrieves a pointer to the sniffer channel device
+ * from the instance and channel number stored in the ops internal_flag field
+ */
+static int pre_doit_func(const struct genl_ops *ops,
+			 struct sk_buff *skb,
+			 struct genl_info *info)
+{
+	info->user_ptr[0] = snf_channel_get(ops->internal_flags);
+	return info->user_ptr[0] ? 0 : -ENODEV;
+}
+
+/* post_doit function that releases a sniffer channel device */
+static void post_doit_func(const struct genl_ops *ops,
+			   struct sk_buff *skb,
+			   struct genl_info *info)
+{
+	snf_channel_put(ops->internal_flags);
+}
+
+/* doit command handlers */
+
+/* Start the sniffer channel */
+static int do_it_start(struct sk_buff *skb, struct genl_info *info)
+{
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+
+	return dev->start(dev);
+}
+
+/* Stop the sniffer channel */
+static int do_it_stop(struct sk_buff *skb, struct genl_info *info)
+{
+	int ret;
+	struct snf_match_evt mt;
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+
+	ret = dev->stop(dev);
+	if (ret < 0)
+		return ret;
+
+	/* Multicast an empty match event to notify any user-space
+	 * listeners that the sniffer is stopping
+	 */
+	memset(&mt, 0, sizeof(mt));
+	return snf_channel_notify_match(dev, &mt);
+}
+
+/* Set the command pattern. The string is received in a nested
+ * attribute containing a sequence of 16-bit valued.
+ * Each value consists of a command (8 bits) and data (8 bits)
+*/
+static int do_it_set_pattern(struct sk_buff *skb, struct genl_info *info)
+{
+	int ret = 0;
+	int rem, count;
+	struct nlattr *nla;
+	u16 entry;
+	u8 *buf = NULL;
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+	int max_entries = dev->max_ptn_entries(dev);
+
+	if (!info->attrs[SNF_ATTR_PATTERN]) {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	ret = nla_validate_nested(info->attrs[SNF_ATTR_PATTERN],
+				  SNF_ATTR_PTN_ENTRY, snf_ptn_policy);
+	if (ret < 0)
+		goto fail;
+
+	buf = kmalloc(max_entries*2, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	/* Iterate over the contents of the nested attribute
+	 * and extract into the buffer
+	 */
+	count = 0;
+	nla_for_each_nested(nla, info->attrs[SNF_ATTR_PATTERN], rem) {
+		if (count >= max_entries) {
+			ret = -EINVAL;
+			goto fail;
+		}
+		entry = nla_get_u16(nla);
+		buf[2*count] = PTNENTRY_CMD(entry);
+		buf[2*count + 1] = PTNENTRY_DATA(entry);
+		count++;
+	}
+
+	ret = dev->set_pattern(dev, buf, count);
+
+fail:
+	kfree(buf);
+	return ret;
+}
+
+/* Number of pending match events */
+static int do_it_num_rec_avail(struct sk_buff *skb, struct genl_info *info)
+{
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+
+	return send_reply_uint32(
+			info,
+			SNF_CMD_NUMRECAVAIL,
+			SNF_ATTR_NUMRECAVAIL,
+			dev->num_recs_avail(dev));
+}
+
+/* Max number of commands that are supported in the command pattern */
+static int do_it_ptn_max_cmds(struct sk_buff *skb, struct genl_info *info)
+{
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+
+	return send_reply_uint32(
+			info,
+			SNF_CMD_PTNMAXCMDS,
+			SNF_ATTR_PTNMAXCMDS,
+			dev->max_ptn_entries(dev));
+}
+
+/* Max bytes that can be returned by a packet match event */
+static int do_it_max_match_bytes(struct sk_buff *skb, struct genl_info *info)
+{
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+
+	return send_reply_uint32(
+			info,
+			SNF_CMD_MAXMATCHBYTES,
+			SNF_ATTR_MAXMATCHBYTES,
+			dev->max_match_bytes(dev));
+}
+
+/* Helper function for sending a reply containing a single u32 attribute */
+static int send_reply_uint32(struct genl_info *info, int cmd, int attr, u32 val)
+{
+	void *hdr;
+	int ret = 0;
+	struct sk_buff *msg;
+	struct snf_chan *dev = (struct snf_chan *)info->user_ptr[0];
+	struct snf_netlink *nl = (struct snf_netlink *)dev->cstate;
+
+	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!msg) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	hdr = genlmsg_put_reply(msg, info, &nl->fml, 0, cmd);
+	if (!hdr) {
+		ret = -EMSGSIZE;
+		goto fail;
+	}
+	ret = nla_put_u32(msg, attr, val);
+	if (ret < 0)
+		goto fail;
+	ret = genlmsg_end(msg, hdr);
+	if (ret < 0)
+		goto fail;
+
+	return genlmsg_reply(msg, info);
+
+fail:
+	if (msg)
+		nlmsg_free(msg);
+	return ret;
+}
+
diff --git a/drivers/net/pkt-sniffer/core/nl.h b/drivers/net/pkt-sniffer/core/nl.h
new file mode 100644
index 0000000..f7bf579
--- /dev/null
+++ b/drivers/net/pkt-sniffer/core/nl.h
@@ -0,0 +1,34 @@
+/*
+ * Packet sniffer core driver: generic netlink interface
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#ifndef __SNF_NL_H
+#define __SNF_NL_H
+
+#include <net/genetlink.h>
+#include "snf_core.h"
+
+/* Initialise netlink interface for a sniffer channel,
+ * register netlink families etc.
+ */
+int snf_netlink_init(int id, struct snf_chan *dev, const char *name);
+
+/* Shutdown netlink interface, unregister
+ * families etc.
+ */
+void snf_netlink_release(struct snf_chan *dev);
+
+#endif
diff --git a/drivers/net/pkt-sniffer/core/snf_core.h b/drivers/net/pkt-sniffer/core/snf_core.h
new file mode 100644
index 0000000..062de70
--- /dev/null
+++ b/drivers/net/pkt-sniffer/core/snf_core.h
@@ -0,0 +1,64 @@
+/*
+ * Packet sniffer core driver
+ * - this header provides the interface to specific backend packet
+ *   sniffer implementations
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#ifndef __SNF_CORE_H
+#define __SNF_CORE_H
+
+#include <linux/types.h>
+
+/* This is a global maximum. Each backend will have its own limit */
+#define MAX_MATCH_BYTES 512
+
+/* Sniffer channel data structure */
+struct snf_chan {
+	int  (*start)(struct snf_chan *dev);
+	int  (*stop)(struct snf_chan *dev);
+	int  (*set_pattern)(struct snf_chan *dev, const u8 *pattern, int count);
+	int  (*num_recs_avail)(struct snf_chan *dev);
+	int  (*max_ptn_entries)(struct snf_chan *dev);
+	int  (*max_match_bytes)(struct snf_chan *dev);
+
+	void *cstate;
+};
+
+/* Data from a sniffer match event */
+struct snf_match_evt {
+	int ts_valid;     /* flag indicating if timestamp is present */
+	u64 ts;           /* timestamp value */
+	u8 data[MAX_MATCH_BYTES]; /* packet data bytes matched by sniffer */
+	int len;          /* number of valid bytes in the 'data' buffer */
+};
+
+/* Adds a sniffer channel to the registry */
+int snf_channel_add(struct snf_chan *dev, const char *name);
+
+/* Removes the channel with the specified id from the registry */
+int snf_channel_remove(int id);
+
+/* Returns handle to a channel and increments reference count */
+struct snf_chan *snf_channel_get(int id);
+
+/* Decrements reference count for the specified channel */
+void snf_channel_put(int id);
+
+/* Multicast a notification to user space for a sniffer match event */
+int snf_channel_notify_match(struct snf_chan *dev, struct snf_match_evt *mt);
+
+#endif
+
diff --git a/include/linux/pkt_sniffer.h b/include/linux/pkt_sniffer.h
new file mode 100644
index 0000000..3e73d14
--- /dev/null
+++ b/include/linux/pkt_sniffer.h
@@ -0,0 +1,89 @@
+/*
+ * Linn packet sniffer driver interface
+ *
+ * Copyright (C) 2015 Linn Products Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Written by:
+ * Stathis Voukelatos <stathis.voukelatos@...n.co.uk>
+ */
+#ifndef __PKT_SNIFFER_H
+#define __PKT_SNIFFER_H
+
+/* Commands for the pattern string */
+#define PTN_CMD_DONTCARE    0
+#define PTN_CMD_MATCH       1
+#define PTN_CMD_COPY        2
+#define PTN_CMD_MATCHSTAMP  3
+#define PTN_CMD_COPYDONE    4
+
+/* Creates an entry for the pattern string.
+ * An entry consists of a command byte and a data byte
+*/
+#define MAKE_PTN_ENTRY(cmd, data) (((((int)cmd) & 0xff) << 8) | (data & 0xff))
+/* Gets the cmd and data portion of a pattern string entry */
+#define PTNENTRY_CMD(val)        (((val) >> 8) & 0xff)
+#define PTNENTRY_DATA(val)       ((val) & 0xff)
+
+/* Generic Netlink commands */
+enum {
+	SNF_CMD_UNSPEC,
+	SNF_CMD_START,          /* start the sniffer */
+	SNF_CMD_STOP,           /* stop the sniffer */
+	SNF_CMD_SETPATTERN,     /* set the command pattern */
+	SNF_CMD_NUMRECAVAIL,    /* number of pending match events */
+	SNF_CMD_MATCHEVENT,     /* match event notification */
+	SNF_CMD_PTNMAXCMDS,     /* max number of commands supported */
+	SNF_CMD_MAXMATCHBYTES,  /* max number of bytes in match event */
+	__SNF_CMD_MAX
+};
+#define SNF_CMD_MAX (__SNF_CMD_MAX - 1)
+
+/* Generic Netlink attributes */
+enum {
+	SNF_ATTR_UNSPEC,
+	SNF_ATTR_PTNMAXCMDS,    /* max number of commands supported */
+	SNF_ATTR_PATTERN,       /* nested attribute containing commands */
+	SNF_ATTR_NUMRECAVAIL,   /* number of pending match events */
+	SNF_ATTR_MATCHEVENT,    /* nested attribute for a match event */
+	SNF_ATTR_MAXMATCHBYTES, /* max bytes in a match event */
+	__SNF_ATTR_MAX
+};
+#define SNF_ATTR_MAX (__SNF_ATTR_MAX - 1)
+
+/* Attributes that are included in the nested attribute
+ * for the command string
+ */
+enum {
+	SNF_ATTR_PTN_UNSPEC,
+	SNF_ATTR_PTN_ENTRY,    /* command entry containing a command id */
+	__SNF_ATTR_PTN_MAX     /* and data byte */
+};
+#define SNF_ATTR_PTN_MAX (__SNF_ATTR_PTN_MAX - 1)
+
+/* Attributes included in the nested attribute
+ * of a match event notification
+ */
+enum {
+	SNF_ATTR_MATCH_UNSPEC,
+	SNF_ATTR_MATCH_TS,      /* timestamp (returned with a match event) */
+	SNF_ATTR_MATCH_PKTBYTE, /* packet data (returned with a match event) */
+	__SNF_ATTR_MATCH_MAX
+};
+#define SNF_ATTR_MATCH_MAX (__SNF_ATTR_MATCH_MAX - 1)
+
+/* Family version */
+#define SNF_GNL_VERSION 1
+
+/* Multicast group name */
+#define SNF_EVENT_GRP    "snf_evt_grp"
+
+#endif
-- 
1.9.1

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