Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

3 files changed, 1485 insertions, 0 deletions

diff --git a/drivers/net/plip/Kconfig b/drivers/net/plip/Kconfig
new file mode 100644
index 000000000..67bfb01de
--- /dev/null
+++ b/drivers/net/plip/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Parallel Line Internet Protocol (PLIP) network device configuration
+#
+
+config PLIP
+	tristate "PLIP (parallel port) support"
+	depends on PARPORT
+	help
+	  PLIP (Parallel Line Internet Protocol) is used to create a
+	  reasonably fast mini network consisting of two (or, rarely, more)
+	  local machines.  A PLIP link from a Linux box is a popular means to
+	  install a Linux distribution on a machine which doesn't have a
+	  CD-ROM drive (a minimal system has to be transferred with floppies
+	  first). The kernels on both machines need to have this PLIP option
+	  enabled for this to work.
+
+	  The PLIP driver has two modes, mode 0 and mode 1.  The parallel
+	  ports (the connectors at the computers with 25 holes) are connected
+	  with "null printer" or "Turbo Laplink" cables which can transmit 4
+	  bits at a time (mode 0) or with special PLIP cables, to be used on
+	  bidirectional parallel ports only, which can transmit 8 bits at a
+	  time (mode 1); you can find the wiring of these cables in
+	  <file:Documentation/networking/plip.rst>.  The cables can be up to
+	  15m long.  Mode 0 works also if one of the machines runs DOS/Windows
+	  and has some PLIP software installed, e.g. the Crynwr PLIP packet
+	  driver (<http://oak.oakland.edu/simtel.net/msdos/pktdrvr-pre.html>)
+	  and winsock or NCSA's telnet.
+
+	  If you want to use PLIP, say Y and read the PLIP mini-HOWTO as well
+	  as the NET-3-HOWTO, both available from
+	  <http://www.tldp.org/docs.html#howto>.  Note that the PLIP
+	  protocol has been changed and this PLIP driver won't work together
+	  with the PLIP support in Linux versions 1.0.x.  This option enlarges
+	  your kernel by about 8 KB.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called plip. If unsure, say Y or M, in case you buy
+	  a laptop later.
diff --git a/drivers/net/plip/Makefile b/drivers/net/plip/Makefile
new file mode 100644
index 000000000..8d4df7290
--- /dev/null
+++ b/drivers/net/plip/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the PLIP network device drivers.
+#
+
+obj-$(CONFIG_PLIP) += plip.o
diff --git a/drivers/net/plip/plip.c b/drivers/net/plip/plip.c
new file mode 100644
index 000000000..40ce8abe6
--- /dev/null
+++ b/drivers/net/plip/plip.c
@@ -0,0 +1,1440 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* $Id: plip.c,v 1.3.6.2 1997/04/16 15:07:56 phil Exp $ */
+/* PLIP: A parallel port "network" driver for Linux. */
+/* This driver is for parallel port with 5-bit cable (LapLink (R) cable). */
+/*
+ * Authors:	Donald Becker <becker@scyld.com>
+ *		Tommy Thorn <thorn@daimi.aau.dk>
+ *		Tanabe Hiroyasu <hiro@sanpo.t.u-tokyo.ac.jp>
+ *		Alan Cox <gw4pts@gw4pts.ampr.org>
+ *		Peter Bauer <100136.3530@compuserve.com>
+ *		Niibe Yutaka <gniibe@mri.co.jp>
+ *		Nimrod Zimerman <zimerman@mailandnews.com>
+ *
+ * Enhancements:
+ *		Modularization and ifreq/ifmap support by Alan Cox.
+ *		Rewritten by Niibe Yutaka.
+ *		parport-sharing awareness code by Philip Blundell.
+ *		SMP locking by Niibe Yutaka.
+ *		Support for parallel ports with no IRQ (poll mode),
+ *		Modifications to use the parallel port API
+ *		by Nimrod Zimerman.
+ *
+ * Fixes:
+ *		Niibe Yutaka
+ *		  - Module initialization.
+ *		  - MTU fix.
+ *		  - Make sure other end is OK, before sending a packet.
+ *		  - Fix immediate timer problem.
+ *
+ *		Al Viro
+ *		  - Changed {enable,disable}_irq handling to make it work
+ *		    with new ("stack") semantics.
+ */
+
+/*
+ * Original version and the name 'PLIP' from Donald Becker <becker@scyld.com>
+ * inspired by Russ Nelson's parallel port packet driver.
+ *
+ * NOTE:
+ *     Tanabe Hiroyasu had changed the protocol, and it was in Linux v1.0.
+ *     Because of the necessity to communicate to DOS machines with the
+ *     Crynwr packet driver, Peter Bauer changed the protocol again
+ *     back to original protocol.
+ *
+ *     This version follows original PLIP protocol.
+ *     So, this PLIP can't communicate the PLIP of Linux v1.0.
+ */
+
+/*
+ *     To use with DOS box, please do (Turn on ARP switch):
+ *	# ifconfig plip[0-2] arp
+ */
+static const char version[] = "NET3 PLIP version 2.4-parport gniibe@mri.co.jp\n";
+
+/*
+  Sources:
+	Ideas and protocols came from Russ Nelson's <nelson@crynwr.com>
+	"parallel.asm" parallel port packet driver.
+
+  The "Crynwr" parallel port standard specifies the following protocol:
+    Trigger by sending nibble '0x8' (this causes interrupt on other end)
+    count-low octet
+    count-high octet
+    ... data octets
+    checksum octet
+  Each octet is sent as <wait for rx. '0x1?'> <send 0x10+(octet&0x0F)>
+			<wait for rx. '0x0?'> <send 0x00+((octet>>4)&0x0F)>
+
+  The packet is encapsulated as if it were ethernet.
+
+  The cable used is a de facto standard parallel null cable -- sold as
+  a "LapLink" cable by various places.  You'll need a 12-conductor cable to
+  make one yourself.  The wiring is:
+    SLCTIN	17 - 17
+    GROUND	25 - 25
+    D0->ERROR	2 - 15		15 - 2
+    D1->SLCT	3 - 13		13 - 3
+    D2->PAPOUT	4 - 12		12 - 4
+    D3->ACK	5 - 10		10 - 5
+    D4->BUSY	6 - 11		11 - 6
+  Do not connect the other pins.  They are
+    D5,D6,D7 are 7,8,9
+    STROBE is 1, FEED is 14, INIT is 16
+    extra grounds are 18,19,20,21,22,23,24
+*/
+
+#include <linux/compat.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/interrupt.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_plip.h>
+#include <linux/workqueue.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/parport.h>
+#include <linux/bitops.h>
+
+#include <net/neighbour.h>
+
+#include <asm/irq.h>
+#include <asm/byteorder.h>
+
+/* Maximum number of devices to support. */
+#define PLIP_MAX  8
+
+/* Use 0 for production, 1 for verification, >2 for debug */
+#ifndef NET_DEBUG
+#define NET_DEBUG 1
+#endif
+static const unsigned int net_debug = NET_DEBUG;
+
+#define ENABLE(irq)  if (irq != -1) enable_irq(irq)
+#define DISABLE(irq) if (irq != -1) disable_irq(irq)
+
+/* In micro second */
+#define PLIP_DELAY_UNIT		   1
+
+/* Connection time out = PLIP_TRIGGER_WAIT * PLIP_DELAY_UNIT usec */
+#define PLIP_TRIGGER_WAIT	 500
+
+/* Nibble time out = PLIP_NIBBLE_WAIT * PLIP_DELAY_UNIT usec */
+#define PLIP_NIBBLE_WAIT        3000
+
+/* Bottom halves */
+static void plip_kick_bh(struct work_struct *work);
+static void plip_bh(struct work_struct *work);
+static void plip_timer_bh(struct work_struct *work);
+
+/* Interrupt handler */
+static void plip_interrupt(void *dev_id);
+
+/* Functions for DEV methods */
+static netdev_tx_t plip_tx_packet(struct sk_buff *skb, struct net_device *dev);
+static int plip_hard_header(struct sk_buff *skb, struct net_device *dev,
+                            unsigned short type, const void *daddr,
+			    const void *saddr, unsigned len);
+static int plip_hard_header_cache(const struct neighbour *neigh,
+                                  struct hh_cache *hh, __be16 type);
+static int plip_open(struct net_device *dev);
+static int plip_close(struct net_device *dev);
+static int plip_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
+			       void __user *data, int cmd);
+static int plip_preempt(void *handle);
+static void plip_wakeup(void *handle);
+
+enum plip_connection_state {
+	PLIP_CN_NONE=0,
+	PLIP_CN_RECEIVE,
+	PLIP_CN_SEND,
+	PLIP_CN_CLOSING,
+	PLIP_CN_ERROR
+};
+
+enum plip_packet_state {
+	PLIP_PK_DONE=0,
+	PLIP_PK_TRIGGER,
+	PLIP_PK_LENGTH_LSB,
+	PLIP_PK_LENGTH_MSB,
+	PLIP_PK_DATA,
+	PLIP_PK_CHECKSUM
+};
+
+enum plip_nibble_state {
+	PLIP_NB_BEGIN,
+	PLIP_NB_1,
+	PLIP_NB_2,
+};
+
+struct plip_local {
+	enum plip_packet_state state;
+	enum plip_nibble_state nibble;
+	union {
+		struct {
+#if defined(__LITTLE_ENDIAN)
+			unsigned char lsb;
+			unsigned char msb;
+#elif defined(__BIG_ENDIAN)
+			unsigned char msb;
+			unsigned char lsb;
+#else
+#error	"Please fix the endianness defines in <asm/byteorder.h>"
+#endif
+		} b;
+		unsigned short h;
+	} length;
+	unsigned short byte;
+	unsigned char  checksum;
+	unsigned char  data;
+	struct sk_buff *skb;
+};
+
+struct net_local {
+	struct net_device *dev;
+	struct work_struct immediate;
+	struct delayed_work deferred;
+	struct delayed_work timer;
+	struct plip_local snd_data;
+	struct plip_local rcv_data;
+	struct pardevice *pardev;
+	unsigned long  trigger;
+	unsigned long  nibble;
+	enum plip_connection_state connection;
+	unsigned short timeout_count;
+	int is_deferred;
+	int port_owner;
+	int should_relinquish;
+	spinlock_t lock;
+	atomic_t kill_timer;
+	struct completion killed_timer_cmp;
+};
+
+static inline void enable_parport_interrupts (struct net_device *dev)
+{
+	if (dev->irq != -1)
+	{
+		struct parport *port =
+		   ((struct net_local *)netdev_priv(dev))->pardev->port;
+		port->ops->enable_irq (port);
+	}
+}
+
+static inline void disable_parport_interrupts (struct net_device *dev)
+{
+	if (dev->irq != -1)
+	{
+		struct parport *port =
+		   ((struct net_local *)netdev_priv(dev))->pardev->port;
+		port->ops->disable_irq (port);
+	}
+}
+
+static inline void write_data (struct net_device *dev, unsigned char data)
+{
+	struct parport *port =
+	   ((struct net_local *)netdev_priv(dev))->pardev->port;
+
+	port->ops->write_data (port, data);
+}
+
+static inline unsigned char read_status (struct net_device *dev)
+{
+	struct parport *port =
+	   ((struct net_local *)netdev_priv(dev))->pardev->port;
+
+	return port->ops->read_status (port);
+}
+
+static const struct header_ops plip_header_ops = {
+	.create	= plip_hard_header,
+	.cache  = plip_hard_header_cache,
+};
+
+static const struct net_device_ops plip_netdev_ops = {
+	.ndo_open		 = plip_open,
+	.ndo_stop		 = plip_close,
+	.ndo_start_xmit		 = plip_tx_packet,
+	.ndo_siocdevprivate	 = plip_siocdevprivate,
+	.ndo_set_mac_address	 = eth_mac_addr,
+	.ndo_validate_addr	 = eth_validate_addr,
+};
+
+/* Entry point of PLIP driver.
+   Probe the hardware, and register/initialize the driver.
+
+   PLIP is rather weird, because of the way it interacts with the parport
+   system.  It is _not_ initialised from Space.c.  Instead, plip_init()
+   is called, and that function makes up a "struct net_device" for each port, and
+   then calls us here.
+
+   */
+static void
+plip_init_netdev(struct net_device *dev)
+{
+	static const u8 addr_init[ETH_ALEN] = {
+		0xfc, 0xfc, 0xfc,
+		0xfc, 0xfc, 0xfc,
+	};
+	struct net_local *nl = netdev_priv(dev);
+
+	/* Then, override parts of it */
+	dev->tx_queue_len 	 = 10;
+	dev->flags	         = IFF_POINTOPOINT|IFF_NOARP;
+	eth_hw_addr_set(dev, addr_init);
+
+	dev->netdev_ops		 = &plip_netdev_ops;
+	dev->header_ops          = &plip_header_ops;
+
+
+	nl->port_owner = 0;
+
+	/* Initialize constants */
+	nl->trigger	= PLIP_TRIGGER_WAIT;
+	nl->nibble	= PLIP_NIBBLE_WAIT;
+
+	/* Initialize task queue structures */
+	INIT_WORK(&nl->immediate, plip_bh);
+	INIT_DELAYED_WORK(&nl->deferred, plip_kick_bh);
+
+	if (dev->irq == -1)
+		INIT_DELAYED_WORK(&nl->timer, plip_timer_bh);
+
+	spin_lock_init(&nl->lock);
+}
+
+/* Bottom half handler for the delayed request.
+   This routine is kicked by do_timer().
+   Request `plip_bh' to be invoked. */
+static void
+plip_kick_bh(struct work_struct *work)
+{
+	struct net_local *nl =
+		container_of(work, struct net_local, deferred.work);
+
+	if (nl->is_deferred)
+		schedule_work(&nl->immediate);
+}
+
+/* Forward declarations of internal routines */
+static int plip_none(struct net_device *, struct net_local *,
+		     struct plip_local *, struct plip_local *);
+static int plip_receive_packet(struct net_device *, struct net_local *,
+			       struct plip_local *, struct plip_local *);
+static int plip_send_packet(struct net_device *, struct net_local *,
+			    struct plip_local *, struct plip_local *);
+static int plip_connection_close(struct net_device *, struct net_local *,
+				 struct plip_local *, struct plip_local *);
+static int plip_error(struct net_device *, struct net_local *,
+		      struct plip_local *, struct plip_local *);
+static int plip_bh_timeout_error(struct net_device *dev, struct net_local *nl,
+				 struct plip_local *snd,
+				 struct plip_local *rcv,
+				 int error);
+
+#define OK        0
+#define TIMEOUT   1
+#define ERROR     2
+#define HS_TIMEOUT	3
+
+typedef int (*plip_func)(struct net_device *dev, struct net_local *nl,
+			 struct plip_local *snd, struct plip_local *rcv);
+
+static const plip_func connection_state_table[] =
+{
+	plip_none,
+	plip_receive_packet,
+	plip_send_packet,
+	plip_connection_close,
+	plip_error
+};
+
+/* Bottom half handler of PLIP. */
+static void
+plip_bh(struct work_struct *work)
+{
+	struct net_local *nl = container_of(work, struct net_local, immediate);
+	struct plip_local *snd = &nl->snd_data;
+	struct plip_local *rcv = &nl->rcv_data;
+	plip_func f;
+	int r;
+
+	nl->is_deferred = 0;
+	f = connection_state_table[nl->connection];
+	if ((r = (*f)(nl->dev, nl, snd, rcv)) != OK &&
+	    (r = plip_bh_timeout_error(nl->dev, nl, snd, rcv, r)) != OK) {
+		nl->is_deferred = 1;
+		schedule_delayed_work(&nl->deferred, 1);
+	}
+}
+
+static void
+plip_timer_bh(struct work_struct *work)
+{
+	struct net_local *nl =
+		container_of(work, struct net_local, timer.work);
+
+	if (!(atomic_read (&nl->kill_timer))) {
+		plip_interrupt (nl->dev);
+
+		schedule_delayed_work(&nl->timer, 1);
+	}
+	else {
+		complete(&nl->killed_timer_cmp);
+	}
+}
+
+static int
+plip_bh_timeout_error(struct net_device *dev, struct net_local *nl,
+		      struct plip_local *snd, struct plip_local *rcv,
+		      int error)
+{
+	unsigned char c0;
+	/*
+	 * This is tricky. If we got here from the beginning of send (either
+	 * with ERROR or HS_TIMEOUT) we have IRQ enabled. Otherwise it's
+	 * already disabled. With the old variant of {enable,disable}_irq()
+	 * extra disable_irq() was a no-op. Now it became mortal - it's
+	 * unbalanced and thus we'll never re-enable IRQ (until rmmod plip,
+	 * that is). So we have to treat HS_TIMEOUT and ERROR from send
+	 * in a special way.
+	 */
+
+	spin_lock_irq(&nl->lock);
+	if (nl->connection == PLIP_CN_SEND) {
+
+		if (error != ERROR) { /* Timeout */
+			nl->timeout_count++;
+			if ((error == HS_TIMEOUT && nl->timeout_count <= 10) ||
+			    nl->timeout_count <= 3) {
+				spin_unlock_irq(&nl->lock);
+				/* Try again later */
+				return TIMEOUT;
+			}
+			c0 = read_status(dev);
+			printk(KERN_WARNING "%s: transmit timeout(%d,%02x)\n",
+			       dev->name, snd->state, c0);
+		} else
+			error = HS_TIMEOUT;
+		dev->stats.tx_errors++;
+		dev->stats.tx_aborted_errors++;
+	} else if (nl->connection == PLIP_CN_RECEIVE) {
+		if (rcv->state == PLIP_PK_TRIGGER) {
+			/* Transmission was interrupted. */
+			spin_unlock_irq(&nl->lock);
+			return OK;
+		}
+		if (error != ERROR) { /* Timeout */
+			if (++nl->timeout_count <= 3) {
+				spin_unlock_irq(&nl->lock);
+				/* Try again later */
+				return TIMEOUT;
+			}
+			c0 = read_status(dev);
+			printk(KERN_WARNING "%s: receive timeout(%d,%02x)\n",
+			       dev->name, rcv->state, c0);
+		}
+		dev->stats.rx_dropped++;
+	}
+	rcv->state = PLIP_PK_DONE;
+	if (rcv->skb) {
+		dev_kfree_skb_irq(rcv->skb);
+		rcv->skb = NULL;
+	}
+	snd->state = PLIP_PK_DONE;
+	if (snd->skb) {
+		dev_consume_skb_irq(snd->skb);
+		snd->skb = NULL;
+	}
+	spin_unlock_irq(&nl->lock);
+	if (error == HS_TIMEOUT) {
+		DISABLE(dev->irq);
+		synchronize_irq(dev->irq);
+	}
+	disable_parport_interrupts (dev);
+	netif_stop_queue (dev);
+	nl->connection = PLIP_CN_ERROR;
+	write_data (dev, 0x00);
+
+	return TIMEOUT;
+}
+
+static int
+plip_none(struct net_device *dev, struct net_local *nl,
+	  struct plip_local *snd, struct plip_local *rcv)
+{
+	return OK;
+}
+
+/* PLIP_RECEIVE --- receive a byte(two nibbles)
+   Returns OK on success, TIMEOUT on timeout */
+static inline int
+plip_receive(unsigned short nibble_timeout, struct net_device *dev,
+	     enum plip_nibble_state *ns_p, unsigned char *data_p)
+{
+	unsigned char c0, c1;
+	unsigned int cx;
+
+	switch (*ns_p) {
+	case PLIP_NB_BEGIN:
+		cx = nibble_timeout;
+		while (1) {
+			c0 = read_status(dev);
+			udelay(PLIP_DELAY_UNIT);
+			if ((c0 & 0x80) == 0) {
+				c1 = read_status(dev);
+				if (c0 == c1)
+					break;
+			}
+			if (--cx == 0)
+				return TIMEOUT;
+		}
+		*data_p = (c0 >> 3) & 0x0f;
+		write_data (dev, 0x10); /* send ACK */
+		*ns_p = PLIP_NB_1;
+		fallthrough;
+
+	case PLIP_NB_1:
+		cx = nibble_timeout;
+		while (1) {
+			c0 = read_status(dev);
+			udelay(PLIP_DELAY_UNIT);
+			if (c0 & 0x80) {
+				c1 = read_status(dev);
+				if (c0 == c1)
+					break;
+			}
+			if (--cx == 0)
+				return TIMEOUT;
+		}
+		*data_p |= (c0 << 1) & 0xf0;
+		write_data (dev, 0x00); /* send ACK */
+		*ns_p = PLIP_NB_BEGIN;
+		break;
+	case PLIP_NB_2:
+		break;
+	}
+	return OK;
+}
+
+/*
+ *	Determine the packet's protocol ID. The rule here is that we
+ *	assume 802.3 if the type field is short enough to be a length.
+ *	This is normal practice and works for any 'now in use' protocol.
+ *
+ *	PLIP is ethernet ish but the daddr might not be valid if unicast.
+ *	PLIP fortunately has no bus architecture (its Point-to-point).
+ *
+ *	We can't fix the daddr thing as that quirk (more bug) is embedded
+ *	in far too many old systems not all even running Linux.
+ */
+
+static __be16 plip_type_trans(struct sk_buff *skb, struct net_device *dev)
+{
+	struct ethhdr *eth;
+	unsigned char *rawp;
+
+	skb_reset_mac_header(skb);
+	skb_pull(skb,dev->hard_header_len);
+	eth = eth_hdr(skb);
+
+	if(is_multicast_ether_addr(eth->h_dest))
+	{
+		if(ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
+			skb->pkt_type=PACKET_BROADCAST;
+		else
+			skb->pkt_type=PACKET_MULTICAST;
+	}
+
+	/*
+	 *	This ALLMULTI check should be redundant by 1.4
+	 *	so don't forget to remove it.
+	 */
+
+	if (ntohs(eth->h_proto) >= ETH_P_802_3_MIN)
+		return eth->h_proto;
+
+	rawp = skb->data;
+
+	/*
+	 *	This is a magic hack to spot IPX packets. Older Novell breaks
+	 *	the protocol design and runs IPX over 802.3 without an 802.2 LLC
+	 *	layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
+	 *	won't work for fault tolerant netware but does for the rest.
+	 */
+	if (*(unsigned short *)rawp == 0xFFFF)
+		return htons(ETH_P_802_3);
+
+	/*
+	 *	Real 802.2 LLC
+	 */
+	return htons(ETH_P_802_2);
+}
+
+/* PLIP_RECEIVE_PACKET --- receive a packet */
+static int
+plip_receive_packet(struct net_device *dev, struct net_local *nl,
+		    struct plip_local *snd, struct plip_local *rcv)
+{
+	unsigned short nibble_timeout = nl->nibble;
+	unsigned char *lbuf;
+
+	switch (rcv->state) {
+	case PLIP_PK_TRIGGER:
+		DISABLE(dev->irq);
+		/* Don't need to synchronize irq, as we can safely ignore it */
+		disable_parport_interrupts (dev);
+		write_data (dev, 0x01); /* send ACK */
+		if (net_debug > 2)
+			printk(KERN_DEBUG "%s: receive start\n", dev->name);
+		rcv->state = PLIP_PK_LENGTH_LSB;
+		rcv->nibble = PLIP_NB_BEGIN;
+		fallthrough;
+
+	case PLIP_PK_LENGTH_LSB:
+		if (snd->state != PLIP_PK_DONE) {
+			if (plip_receive(nl->trigger, dev,
+					 &rcv->nibble, &rcv->length.b.lsb)) {
+				/* collision, here dev->tbusy == 1 */
+				rcv->state = PLIP_PK_DONE;
+				nl->is_deferred = 1;
+				nl->connection = PLIP_CN_SEND;
+				schedule_delayed_work(&nl->deferred, 1);
+				enable_parport_interrupts (dev);
+				ENABLE(dev->irq);
+				return OK;
+			}
+		} else {
+			if (plip_receive(nibble_timeout, dev,
+					 &rcv->nibble, &rcv->length.b.lsb))
+				return TIMEOUT;
+		}
+		rcv->state = PLIP_PK_LENGTH_MSB;
+		fallthrough;
+
+	case PLIP_PK_LENGTH_MSB:
+		if (plip_receive(nibble_timeout, dev,
+				 &rcv->nibble, &rcv->length.b.msb))
+			return TIMEOUT;
+		if (rcv->length.h > dev->mtu + dev->hard_header_len ||
+		    rcv->length.h < 8) {
+			printk(KERN_WARNING "%s: bogus packet size %d.\n", dev->name, rcv->length.h);
+			return ERROR;
+		}
+		/* Malloc up new buffer. */
+		rcv->skb = dev_alloc_skb(rcv->length.h + 2);
+		if (rcv->skb == NULL) {
+			printk(KERN_ERR "%s: Memory squeeze.\n", dev->name);
+			return ERROR;
+		}
+		skb_reserve(rcv->skb, 2);	/* Align IP on 16 byte boundaries */
+		skb_put(rcv->skb,rcv->length.h);
+		rcv->skb->dev = dev;
+		rcv->state = PLIP_PK_DATA;
+		rcv->byte = 0;
+		rcv->checksum = 0;
+		fallthrough;
+
+	case PLIP_PK_DATA:
+		lbuf = rcv->skb->data;
+		do {
+			if (plip_receive(nibble_timeout, dev,
+					 &rcv->nibble, &lbuf[rcv->byte]))
+				return TIMEOUT;
+		} while (++rcv->byte < rcv->length.h);
+		do {
+			rcv->checksum += lbuf[--rcv->byte];
+		} while (rcv->byte);
+		rcv->state = PLIP_PK_CHECKSUM;
+		fallthrough;
+
+	case PLIP_PK_CHECKSUM:
+		if (plip_receive(nibble_timeout, dev,
+				 &rcv->nibble, &rcv->data))
+			return TIMEOUT;
+		if (rcv->data != rcv->checksum) {
+			dev->stats.rx_crc_errors++;
+			if (net_debug)
+				printk(KERN_DEBUG "%s: checksum error\n", dev->name);
+			return ERROR;
+		}
+		rcv->state = PLIP_PK_DONE;
+		fallthrough;
+
+	case PLIP_PK_DONE:
+		/* Inform the upper layer for the arrival of a packet. */
+		rcv->skb->protocol=plip_type_trans(rcv->skb, dev);
+		netif_rx(rcv->skb);
+		dev->stats.rx_bytes += rcv->length.h;
+		dev->stats.rx_packets++;
+		rcv->skb = NULL;
+		if (net_debug > 2)
+			printk(KERN_DEBUG "%s: receive end\n", dev->name);
+
+		/* Close the connection. */
+		write_data (dev, 0x00);
+		spin_lock_irq(&nl->lock);
+		if (snd->state != PLIP_PK_DONE) {
+			nl->connection = PLIP_CN_SEND;
+			spin_unlock_irq(&nl->lock);
+			schedule_work(&nl->immediate);
+			enable_parport_interrupts (dev);
+			ENABLE(dev->irq);
+			return OK;
+		} else {
+			nl->connection = PLIP_CN_NONE;
+			spin_unlock_irq(&nl->lock);
+			enable_parport_interrupts (dev);
+			ENABLE(dev->irq);
+			return OK;
+		}
+	}
+	return OK;
+}
+
+/* PLIP_SEND --- send a byte (two nibbles)
+   Returns OK on success, TIMEOUT when timeout    */
+static inline int
+plip_send(unsigned short nibble_timeout, struct net_device *dev,
+	  enum plip_nibble_state *ns_p, unsigned char data)
+{
+	unsigned char c0;
+	unsigned int cx;
+
+	switch (*ns_p) {
+	case PLIP_NB_BEGIN:
+		write_data (dev, data & 0x0f);
+		*ns_p = PLIP_NB_1;
+		fallthrough;
+
+	case PLIP_NB_1:
+		write_data (dev, 0x10 | (data & 0x0f));
+		cx = nibble_timeout;
+		while (1) {
+			c0 = read_status(dev);
+			if ((c0 & 0x80) == 0)
+				break;
+			if (--cx == 0)
+				return TIMEOUT;
+			udelay(PLIP_DELAY_UNIT);
+		}
+		write_data (dev, 0x10 | (data >> 4));
+		*ns_p = PLIP_NB_2;
+		fallthrough;
+
+	case PLIP_NB_2:
+		write_data (dev, (data >> 4));
+		cx = nibble_timeout;
+		while (1) {
+			c0 = read_status(dev);
+			if (c0 & 0x80)
+				break;
+			if (--cx == 0)
+				return TIMEOUT;
+			udelay(PLIP_DELAY_UNIT);
+		}
+		*ns_p = PLIP_NB_BEGIN;
+		return OK;
+	}
+	return OK;
+}
+
+/* PLIP_SEND_PACKET --- send a packet */
+static int
+plip_send_packet(struct net_device *dev, struct net_local *nl,
+		 struct plip_local *snd, struct plip_local *rcv)
+{
+	unsigned short nibble_timeout = nl->nibble;
+	unsigned char *lbuf;
+	unsigned char c0;
+	unsigned int cx;
+
+	if (snd->skb == NULL || (lbuf = snd->skb->data) == NULL) {
+		printk(KERN_DEBUG "%s: send skb lost\n", dev->name);
+		snd->state = PLIP_PK_DONE;
+		snd->skb = NULL;
+		return ERROR;
+	}
+
+	switch (snd->state) {
+	case PLIP_PK_TRIGGER:
+		if ((read_status(dev) & 0xf8) != 0x80)
+			return HS_TIMEOUT;
+
+		/* Trigger remote rx interrupt. */
+		write_data (dev, 0x08);
+		cx = nl->trigger;
+		while (1) {
+			udelay(PLIP_DELAY_UNIT);
+			spin_lock_irq(&nl->lock);
+			if (nl->connection == PLIP_CN_RECEIVE) {
+				spin_unlock_irq(&nl->lock);
+				/* Interrupted. */
+				dev->stats.collisions++;
+				return OK;
+			}
+			c0 = read_status(dev);
+			if (c0 & 0x08) {
+				spin_unlock_irq(&nl->lock);
+				DISABLE(dev->irq);
+				synchronize_irq(dev->irq);
+				if (nl->connection == PLIP_CN_RECEIVE) {
+					/* Interrupted.
+					   We don't need to enable irq,
+					   as it is soon disabled.    */
+					/* Yes, we do. New variant of
+					   {enable,disable}_irq *counts*
+					   them.  -- AV  */
+					ENABLE(dev->irq);
+					dev->stats.collisions++;
+					return OK;
+				}
+				disable_parport_interrupts (dev);
+				if (net_debug > 2)
+					printk(KERN_DEBUG "%s: send start\n", dev->name);
+				snd->state = PLIP_PK_LENGTH_LSB;
+				snd->nibble = PLIP_NB_BEGIN;
+				nl->timeout_count = 0;
+				break;
+			}
+			spin_unlock_irq(&nl->lock);
+			if (--cx == 0) {
+				write_data (dev, 0x00);
+				return HS_TIMEOUT;
+			}
+		}
+		break;
+
+	case PLIP_PK_LENGTH_LSB:
+		if (plip_send(nibble_timeout, dev,
+			      &snd->nibble, snd->length.b.lsb))
+			return TIMEOUT;
+		snd->state = PLIP_PK_LENGTH_MSB;
+		fallthrough;
+
+	case PLIP_PK_LENGTH_MSB:
+		if (plip_send(nibble_timeout, dev,
+			      &snd->nibble, snd->length.b.msb))
+			return TIMEOUT;
+		snd->state = PLIP_PK_DATA;
+		snd->byte = 0;
+		snd->checksum = 0;
+		fallthrough;
+
+	case PLIP_PK_DATA:
+		do {
+			if (plip_send(nibble_timeout, dev,
+				      &snd->nibble, lbuf[snd->byte]))
+				return TIMEOUT;
+		} while (++snd->byte < snd->length.h);
+		do {
+			snd->checksum += lbuf[--snd->byte];
+		} while (snd->byte);
+		snd->state = PLIP_PK_CHECKSUM;
+		fallthrough;
+
+	case PLIP_PK_CHECKSUM:
+		if (plip_send(nibble_timeout, dev,
+			      &snd->nibble, snd->checksum))
+			return TIMEOUT;
+
+		dev->stats.tx_bytes += snd->skb->len;
+		dev_kfree_skb(snd->skb);
+		dev->stats.tx_packets++;
+		snd->state = PLIP_PK_DONE;
+		fallthrough;
+
+	case PLIP_PK_DONE:
+		/* Close the connection */
+		write_data (dev, 0x00);
+		snd->skb = NULL;
+		if (net_debug > 2)
+			printk(KERN_DEBUG "%s: send end\n", dev->name);
+		nl->connection = PLIP_CN_CLOSING;
+		nl->is_deferred = 1;
+		schedule_delayed_work(&nl->deferred, 1);
+		enable_parport_interrupts (dev);
+		ENABLE(dev->irq);
+		return OK;
+	}
+	return OK;
+}
+
+static int
+plip_connection_close(struct net_device *dev, struct net_local *nl,
+		      struct plip_local *snd, struct plip_local *rcv)
+{
+	spin_lock_irq(&nl->lock);
+	if (nl->connection == PLIP_CN_CLOSING) {
+		nl->connection = PLIP_CN_NONE;
+		netif_wake_queue (dev);
+	}
+	spin_unlock_irq(&nl->lock);
+	if (nl->should_relinquish) {
+		nl->should_relinquish = nl->port_owner = 0;
+		parport_release(nl->pardev);
+	}
+	return OK;
+}
+
+/* PLIP_ERROR --- wait till other end settled */
+static int
+plip_error(struct net_device *dev, struct net_local *nl,
+	   struct plip_local *snd, struct plip_local *rcv)
+{
+	unsigned char status;
+
+	status = read_status(dev);
+	if ((status & 0xf8) == 0x80) {
+		if (net_debug > 2)
+			printk(KERN_DEBUG "%s: reset interface.\n", dev->name);
+		nl->connection = PLIP_CN_NONE;
+		nl->should_relinquish = 0;
+		netif_start_queue (dev);
+		enable_parport_interrupts (dev);
+		ENABLE(dev->irq);
+		netif_wake_queue (dev);
+	} else {
+		nl->is_deferred = 1;
+		schedule_delayed_work(&nl->deferred, 1);
+	}
+
+	return OK;
+}
+
+/* Handle the parallel port interrupts. */
+static void
+plip_interrupt(void *dev_id)
+{
+	struct net_device *dev = dev_id;
+	struct net_local *nl;
+	struct plip_local *rcv;
+	unsigned char c0;
+	unsigned long flags;
+
+	nl = netdev_priv(dev);
+	rcv = &nl->rcv_data;
+
+	spin_lock_irqsave (&nl->lock, flags);
+
+	c0 = read_status(dev);
+	if ((c0 & 0xf8) != 0xc0) {
+		if ((dev->irq != -1) && (net_debug > 1))
+			printk(KERN_DEBUG "%s: spurious interrupt\n", dev->name);
+		spin_unlock_irqrestore (&nl->lock, flags);
+		return;
+	}
+
+	if (net_debug > 3)
+		printk(KERN_DEBUG "%s: interrupt.\n", dev->name);
+
+	switch (nl->connection) {
+	case PLIP_CN_CLOSING:
+		netif_wake_queue (dev);
+		fallthrough;
+	case PLIP_CN_NONE:
+	case PLIP_CN_SEND:
+		rcv->state = PLIP_PK_TRIGGER;
+		nl->connection = PLIP_CN_RECEIVE;
+		nl->timeout_count = 0;
+		schedule_work(&nl->immediate);
+		break;
+
+	case PLIP_CN_RECEIVE:
+		/* May occur because there is race condition
+		   around test and set of dev->interrupt.
+		   Ignore this interrupt. */
+		break;
+
+	case PLIP_CN_ERROR:
+		printk(KERN_ERR "%s: receive interrupt in error state\n", dev->name);
+		break;
+	}
+
+	spin_unlock_irqrestore(&nl->lock, flags);
+}
+
+static netdev_tx_t
+plip_tx_packet(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_local *nl = netdev_priv(dev);
+	struct plip_local *snd = &nl->snd_data;
+
+	if (netif_queue_stopped(dev))
+		return NETDEV_TX_BUSY;
+
+	/* We may need to grab the bus */
+	if (!nl->port_owner) {
+		if (parport_claim(nl->pardev))
+			return NETDEV_TX_BUSY;
+		nl->port_owner = 1;
+	}
+
+	netif_stop_queue (dev);
+
+	if (skb->len > dev->mtu + dev->hard_header_len) {
+		printk(KERN_WARNING "%s: packet too big, %d.\n", dev->name, (int)skb->len);
+		netif_start_queue (dev);
+		return NETDEV_TX_BUSY;
+	}
+
+	if (net_debug > 2)
+		printk(KERN_DEBUG "%s: send request\n", dev->name);
+
+	spin_lock_irq(&nl->lock);
+	snd->skb = skb;
+	snd->length.h = skb->len;
+	snd->state = PLIP_PK_TRIGGER;
+	if (nl->connection == PLIP_CN_NONE) {
+		nl->connection = PLIP_CN_SEND;
+		nl->timeout_count = 0;
+	}
+	schedule_work(&nl->immediate);
+	spin_unlock_irq(&nl->lock);
+
+	return NETDEV_TX_OK;
+}
+
+static void
+plip_rewrite_address(const struct net_device *dev, struct ethhdr *eth)
+{
+	const struct in_device *in_dev;
+
+	rcu_read_lock();
+	in_dev = __in_dev_get_rcu(dev);
+	if (in_dev) {
+		/* Any address will do - we take the first */
+		const struct in_ifaddr *ifa = rcu_dereference(in_dev->ifa_list);
+		if (ifa) {
+			memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
+			memset(eth->h_dest, 0xfc, 2);
+			memcpy(eth->h_dest+2, &ifa->ifa_address, 4);
+		}
+	}
+	rcu_read_unlock();
+}
+
+static int
+plip_hard_header(struct sk_buff *skb, struct net_device *dev,
+		 unsigned short type, const void *daddr,
+		 const void *saddr, unsigned len)
+{
+	int ret;
+
+	ret = eth_header(skb, dev, type, daddr, saddr, len);
+	if (ret >= 0)
+		plip_rewrite_address (dev, (struct ethhdr *)skb->data);
+
+	return ret;
+}
+
+static int plip_hard_header_cache(const struct neighbour *neigh,
+				  struct hh_cache *hh, __be16 type)
+{
+	int ret;
+
+	ret = eth_header_cache(neigh, hh, type);
+	if (ret == 0) {
+		struct ethhdr *eth;
+
+		eth = (struct ethhdr*)(((u8*)hh->hh_data) +
+				       HH_DATA_OFF(sizeof(*eth)));
+		plip_rewrite_address (neigh->dev, eth);
+	}
+
+	return ret;
+}
+
+/* Open/initialize the board.  This is called (in the current kernel)
+   sometime after booting when the 'ifconfig' program is run.
+
+   This routine gets exclusive access to the parallel port by allocating
+   its IRQ line.
+ */
+static int
+plip_open(struct net_device *dev)
+{
+	struct net_local *nl = netdev_priv(dev);
+	struct in_device *in_dev;
+
+	/* Grab the port */
+	if (!nl->port_owner) {
+		if (parport_claim(nl->pardev)) return -EAGAIN;
+		nl->port_owner = 1;
+	}
+
+	nl->should_relinquish = 0;
+
+	/* Clear the data port. */
+	write_data (dev, 0x00);
+
+	/* Enable rx interrupt. */
+	enable_parport_interrupts (dev);
+	if (dev->irq == -1)
+	{
+		atomic_set (&nl->kill_timer, 0);
+		schedule_delayed_work(&nl->timer, 1);
+	}
+
+	/* Initialize the state machine. */
+	nl->rcv_data.state = nl->snd_data.state = PLIP_PK_DONE;
+	nl->rcv_data.skb = nl->snd_data.skb = NULL;
+	nl->connection = PLIP_CN_NONE;
+	nl->is_deferred = 0;
+
+	/* Fill in the MAC-level header.
+	   We used to abuse dev->broadcast to store the point-to-point
+	   MAC address, but we no longer do it. Instead, we fetch the
+	   interface address whenever it is needed, which is cheap enough
+	   because we use the hh_cache. Actually, abusing dev->broadcast
+	   didn't work, because when using plip_open the point-to-point
+	   address isn't yet known.
+	   PLIP doesn't have a real MAC address, but we need it to be
+	   DOS compatible, and to properly support taps (otherwise,
+	   when the device address isn't identical to the address of a
+	   received frame, the kernel incorrectly drops it).             */
+
+	in_dev=__in_dev_get_rtnl(dev);
+	if (in_dev) {
+		/* Any address will do - we take the first. We already
+		   have the first two bytes filled with 0xfc, from
+		   plip_init_dev(). */
+		const struct in_ifaddr *ifa = rtnl_dereference(in_dev->ifa_list);
+		if (ifa != NULL) {
+			dev_addr_mod(dev, 2, &ifa->ifa_local, 4);
+		}
+	}
+
+	netif_start_queue (dev);
+
+	return 0;
+}
+
+/* The inverse routine to plip_open (). */
+static int
+plip_close(struct net_device *dev)
+{
+	struct net_local *nl = netdev_priv(dev);
+	struct plip_local *snd = &nl->snd_data;
+	struct plip_local *rcv = &nl->rcv_data;
+
+	netif_stop_queue (dev);
+	DISABLE(dev->irq);
+	synchronize_irq(dev->irq);
+
+	if (dev->irq == -1)
+	{
+		init_completion(&nl->killed_timer_cmp);
+		atomic_set (&nl->kill_timer, 1);
+		wait_for_completion(&nl->killed_timer_cmp);
+	}
+
+#ifdef NOTDEF
+	outb(0x00, PAR_DATA(dev));
+#endif
+	nl->is_deferred = 0;
+	nl->connection = PLIP_CN_NONE;
+	if (nl->port_owner) {
+		parport_release(nl->pardev);
+		nl->port_owner = 0;
+	}
+
+	snd->state = PLIP_PK_DONE;
+	if (snd->skb) {
+		dev_kfree_skb(snd->skb);
+		snd->skb = NULL;
+	}
+	rcv->state = PLIP_PK_DONE;
+	if (rcv->skb) {
+		kfree_skb(rcv->skb);
+		rcv->skb = NULL;
+	}
+
+#ifdef NOTDEF
+	/* Reset. */
+	outb(0x00, PAR_CONTROL(dev));
+#endif
+	return 0;
+}
+
+static int
+plip_preempt(void *handle)
+{
+	struct net_device *dev = (struct net_device *)handle;
+	struct net_local *nl = netdev_priv(dev);
+
+	/* Stand our ground if a datagram is on the wire */
+	if (nl->connection != PLIP_CN_NONE) {
+		nl->should_relinquish = 1;
+		return 1;
+	}
+
+	nl->port_owner = 0;	/* Remember that we released the bus */
+	return 0;
+}
+
+static void
+plip_wakeup(void *handle)
+{
+	struct net_device *dev = (struct net_device *)handle;
+	struct net_local *nl = netdev_priv(dev);
+
+	if (nl->port_owner) {
+		/* Why are we being woken up? */
+		printk(KERN_DEBUG "%s: why am I being woken up?\n", dev->name);
+		if (!parport_claim(nl->pardev))
+			/* bus_owner is already set (but why?) */
+			printk(KERN_DEBUG "%s: I'm broken.\n", dev->name);
+		else
+			return;
+	}
+
+	if (!(dev->flags & IFF_UP))
+		/* Don't need the port when the interface is down */
+		return;
+
+	if (!parport_claim(nl->pardev)) {
+		nl->port_owner = 1;
+		/* Clear the data port. */
+		write_data (dev, 0x00);
+	}
+}
+
+static int
+plip_siocdevprivate(struct net_device *dev, struct ifreq *rq,
+		    void __user *data, int cmd)
+{
+	struct net_local *nl = netdev_priv(dev);
+	struct plipconf *pc = (struct plipconf *) &rq->ifr_ifru;
+
+	if (cmd != SIOCDEVPLIP)
+		return -EOPNOTSUPP;
+
+	if (in_compat_syscall())
+		return -EOPNOTSUPP;
+
+	switch(pc->pcmd) {
+	case PLIP_GET_TIMEOUT:
+		pc->trigger = nl->trigger;
+		pc->nibble  = nl->nibble;
+		break;
+	case PLIP_SET_TIMEOUT:
+		if(!capable(CAP_NET_ADMIN))
+			return -EPERM;
+		nl->trigger = pc->trigger;
+		nl->nibble  = pc->nibble;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+static int parport[PLIP_MAX] = { [0 ... PLIP_MAX-1] = -1 };
+static int timid;
+
+module_param_array(parport, int, NULL, 0);
+module_param(timid, int, 0);
+MODULE_PARM_DESC(parport, "List of parport device numbers to use by plip");
+
+static struct net_device *dev_plip[PLIP_MAX] = { NULL, };
+
+static inline int
+plip_searchfor(int list[], int a)
+{
+	int i;
+	for (i = 0; i < PLIP_MAX && list[i] != -1; i++) {
+		if (list[i] == a) return 1;
+	}
+	return 0;
+}
+
+/* plip_attach() is called (by the parport code) when a port is
+ * available to use. */
+static void plip_attach (struct parport *port)
+{
+	static int unit;
+	struct net_device *dev;
+	struct net_local *nl;
+	char name[IFNAMSIZ];
+	struct pardev_cb plip_cb;
+
+	if ((parport[0] == -1 && (!timid || !port->devices)) ||
+	    plip_searchfor(parport, port->number)) {
+		if (unit == PLIP_MAX) {
+			printk(KERN_ERR "plip: too many devices\n");
+			return;
+		}
+
+		sprintf(name, "plip%d", unit);
+		dev = alloc_etherdev(sizeof(struct net_local));
+		if (!dev)
+			return;
+
+		strcpy(dev->name, name);
+
+		dev->irq = port->irq;
+		dev->base_addr = port->base;
+		if (port->irq == -1) {
+			printk(KERN_INFO "plip: %s has no IRQ. Using IRQ-less mode,"
+		                 "which is fairly inefficient!\n", port->name);
+		}
+
+		nl = netdev_priv(dev);
+		nl->dev = dev;
+
+		memset(&plip_cb, 0, sizeof(plip_cb));
+		plip_cb.private = dev;
+		plip_cb.preempt = plip_preempt;
+		plip_cb.wakeup = plip_wakeup;
+		plip_cb.irq_func = plip_interrupt;
+
+		nl->pardev = parport_register_dev_model(port, dev->name,
+							&plip_cb, unit);
+
+		if (!nl->pardev) {
+			printk(KERN_ERR "%s: parport_register failed\n", name);
+			goto err_free_dev;
+		}
+
+		plip_init_netdev(dev);
+
+		if (register_netdev(dev)) {
+			printk(KERN_ERR "%s: network register failed\n", name);
+			goto err_parport_unregister;
+		}
+
+		printk(KERN_INFO "%s", version);
+		if (dev->irq != -1)
+			printk(KERN_INFO "%s: Parallel port at %#3lx, "
+					 "using IRQ %d.\n",
+				         dev->name, dev->base_addr, dev->irq);
+		else
+			printk(KERN_INFO "%s: Parallel port at %#3lx, "
+					 "not using IRQ.\n",
+					 dev->name, dev->base_addr);
+		dev_plip[unit++] = dev;
+	}
+	return;
+
+err_parport_unregister:
+	parport_unregister_device(nl->pardev);
+err_free_dev:
+	free_netdev(dev);
+}
+
+/* plip_detach() is called (by the parport code) when a port is
+ * no longer available to use. */
+static void plip_detach (struct parport *port)
+{
+	/* Nothing to do */
+}
+
+static int plip_probe(struct pardevice *par_dev)
+{
+	struct device_driver *drv = par_dev->dev.driver;
+	int len = strlen(drv->name);
+
+	if (strncmp(par_dev->name, drv->name, len))
+		return -ENODEV;
+
+	return 0;
+}
+
+static struct parport_driver plip_driver = {
+	.name		= "plip",
+	.probe		= plip_probe,
+	.match_port	= plip_attach,
+	.detach		= plip_detach,
+	.devmodel	= true,
+};
+
+static void __exit plip_cleanup_module (void)
+{
+	struct net_device *dev;
+	int i;
+
+	for (i=0; i < PLIP_MAX; i++) {
+		if ((dev = dev_plip[i])) {
+			struct net_local *nl = netdev_priv(dev);
+			unregister_netdev(dev);
+			if (nl->port_owner)
+				parport_release(nl->pardev);
+			parport_unregister_device(nl->pardev);
+			free_netdev(dev);
+			dev_plip[i] = NULL;
+		}
+	}
+
+	parport_unregister_driver(&plip_driver);
+}
+
+#ifndef MODULE
+
+static int parport_ptr;
+
+static int __init plip_setup(char *str)
+{
+	int ints[4];
+
+	str = get_options(str, ARRAY_SIZE(ints), ints);
+
+	/* Ugh. */
+	if (!strncmp(str, "parport", 7)) {
+		int n = simple_strtoul(str+7, NULL, 10);
+		if (parport_ptr < PLIP_MAX)
+			parport[parport_ptr++] = n;
+		else
+			printk(KERN_INFO "plip: too many ports, %s ignored.\n",
+			       str);
+	} else if (!strcmp(str, "timid")) {
+		timid = 1;
+	} else {
+		if (ints[0] == 0 || ints[1] == 0) {
+			/* disable driver on "plip=" or "plip=0" */
+			parport[0] = -2;
+		} else {
+			printk(KERN_WARNING "warning: 'plip=0x%x' ignored\n",
+			       ints[1]);
+		}
+	}
+	return 1;
+}
+
+__setup("plip=", plip_setup);
+
+#endif /* !MODULE */
+
+static int __init plip_init (void)
+{
+	if (parport[0] == -2)
+		return 0;
+
+	if (parport[0] != -1 && timid) {
+		printk(KERN_WARNING "plip: warning, ignoring `timid' since specific ports given.\n");
+		timid = 0;
+	}
+
+	if (parport_register_driver (&plip_driver)) {
+		printk (KERN_WARNING "plip: couldn't register driver\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+module_init(plip_init);
+module_exit(plip_cleanup_module);
+MODULE_LICENSE("GPL");