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().
  ...

1 files changed, 980 insertions, 0 deletions

diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
new file mode 100644
index 000000000..9fb567524
--- /dev/null
+++ b/drivers/net/hamradio/6pack.c
@@ -0,0 +1,980 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 6pack.c	This module implements the 6pack protocol for kernel-based
+ *		devices like TTY. It interfaces between a raw TTY and the
+ *		kernel's AX.25 protocol layers.
+ *
+ * Authors:	Andreas Könsgen <ajk@comnets.uni-bremen.de>
+ *              Ralf Baechle DL5RB <ralf@linux-mips.org>
+ *
+ * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
+ *
+ *		Laurence Culhane, <loz@holmes.demon.co.uk>
+ *		Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/in.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/timer.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
+#include <linux/spinlock.h>
+#include <linux/if_arp.h>
+#include <linux/init.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/semaphore.h>
+#include <linux/refcount.h>
+
+#define SIXPACK_VERSION    "Revision: 0.3.0"
+
+/* sixpack priority commands */
+#define SIXP_SEOF		0x40	/* start and end of a 6pack frame */
+#define SIXP_TX_URUN		0x48	/* transmit overrun */
+#define SIXP_RX_ORUN		0x50	/* receive overrun */
+#define SIXP_RX_BUF_OVL		0x58	/* receive buffer overflow */
+
+#define SIXP_CHKSUM		0xFF	/* valid checksum of a 6pack frame */
+
+/* masks to get certain bits out of the status bytes sent by the TNC */
+
+#define SIXP_CMD_MASK		0xC0
+#define SIXP_CHN_MASK		0x07
+#define SIXP_PRIO_CMD_MASK	0x80
+#define SIXP_STD_CMD_MASK	0x40
+#define SIXP_PRIO_DATA_MASK	0x38
+#define SIXP_TX_MASK		0x20
+#define SIXP_RX_MASK		0x10
+#define SIXP_RX_DCD_MASK	0x18
+#define SIXP_LEDS_ON		0x78
+#define SIXP_LEDS_OFF		0x60
+#define SIXP_CON		0x08
+#define SIXP_STA		0x10
+
+#define SIXP_FOUND_TNC		0xe9
+#define SIXP_CON_ON		0x68
+#define SIXP_DCD_MASK		0x08
+#define SIXP_DAMA_OFF		0
+
+/* default level 2 parameters */
+#define SIXP_TXDELAY			25	/* 250 ms */
+#define SIXP_PERSIST			50	/* in 256ths */
+#define SIXP_SLOTTIME			10	/* 100 ms */
+#define SIXP_INIT_RESYNC_TIMEOUT	(3*HZ/2) /* in 1 s */
+#define SIXP_RESYNC_TIMEOUT		5*HZ	/* in 1 s */
+
+/* 6pack configuration. */
+#define SIXP_NRUNIT			31      /* MAX number of 6pack channels */
+#define SIXP_MTU			256	/* Default MTU */
+
+enum sixpack_flags {
+	SIXPF_ERROR,	/* Parity, etc. error	*/
+};
+
+struct sixpack {
+	/* Various fields. */
+	struct tty_struct	*tty;		/* ptr to TTY structure	*/
+	struct net_device	*dev;		/* easy for intr handling  */
+
+	/* These are pointers to the malloc()ed frame buffers. */
+	unsigned char		*rbuff;		/* receiver buffer	*/
+	int			rcount;         /* received chars counter  */
+	unsigned char		*xbuff;		/* transmitter buffer	*/
+	unsigned char		*xhead;         /* next byte to XMIT */
+	int			xleft;          /* bytes left in XMIT queue  */
+
+	unsigned char		raw_buf[4];
+	unsigned char		cooked_buf[400];
+
+	unsigned int		rx_count;
+	unsigned int		rx_count_cooked;
+	spinlock_t		rxlock;
+
+	int			mtu;		/* Our mtu (to spot changes!) */
+	int			buffsize;       /* Max buffers sizes */
+
+	unsigned long		flags;		/* Flag values/ mode etc */
+	unsigned char		mode;		/* 6pack mode */
+
+	/* 6pack stuff */
+	unsigned char		tx_delay;
+	unsigned char		persistence;
+	unsigned char		slottime;
+	unsigned char		duplex;
+	unsigned char		led_state;
+	unsigned char		status;
+	unsigned char		status1;
+	unsigned char		status2;
+	unsigned char		tx_enable;
+	unsigned char		tnc_state;
+
+	struct timer_list	tx_t;
+	struct timer_list	resync_t;
+	refcount_t		refcnt;
+	struct completion	dead;
+	spinlock_t		lock;
+};
+
+#define AX25_6PACK_HEADER_LEN 0
+
+static void sixpack_decode(struct sixpack *, const unsigned char[], int);
+static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
+
+/*
+ * Perform the persistence/slottime algorithm for CSMA access. If the
+ * persistence check was successful, write the data to the serial driver.
+ * Note that in case of DAMA operation, the data is not sent here.
+ */
+
+static void sp_xmit_on_air(struct timer_list *t)
+{
+	struct sixpack *sp = from_timer(sp, t, tx_t);
+	int actual, when = sp->slottime;
+	static unsigned char random;
+
+	random = random * 17 + 41;
+
+	if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
+		sp->led_state = 0x70;
+		sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+		sp->tx_enable = 1;
+		actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
+		sp->xleft -= actual;
+		sp->xhead += actual;
+		sp->led_state = 0x60;
+		sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+		sp->status2 = 0;
+	} else
+		mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
+}
+
+/* ----> 6pack timer interrupt handler and friends. <---- */
+
+/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
+static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
+{
+	unsigned char *msg, *p = icp;
+	int actual, count;
+
+	if (len > sp->mtu) {	/* sp->mtu = AX25_MTU = max. PACLEN = 256 */
+		msg = "oversized transmit packet!";
+		goto out_drop;
+	}
+
+	if (p[0] > 5) {
+		msg = "invalid KISS command";
+		goto out_drop;
+	}
+
+	if ((p[0] != 0) && (len > 2)) {
+		msg = "KISS control packet too long";
+		goto out_drop;
+	}
+
+	if ((p[0] == 0) && (len < 15)) {
+		msg = "bad AX.25 packet to transmit";
+		goto out_drop;
+	}
+
+	count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
+	set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
+
+	switch (p[0]) {
+	case 1:	sp->tx_delay = p[1];
+		return;
+	case 2:	sp->persistence = p[1];
+		return;
+	case 3:	sp->slottime = p[1];
+		return;
+	case 4:	/* ignored */
+		return;
+	case 5:	sp->duplex = p[1];
+		return;
+	}
+
+	if (p[0] != 0)
+		return;
+
+	/*
+	 * In case of fullduplex or DAMA operation, we don't take care about the
+	 * state of the DCD or of any timers, as the determination of the
+	 * correct time to send is the job of the AX.25 layer. We send
+	 * immediately after data has arrived.
+	 */
+	if (sp->duplex == 1) {
+		sp->led_state = 0x70;
+		sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+		sp->tx_enable = 1;
+		actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
+		sp->xleft = count - actual;
+		sp->xhead = sp->xbuff + actual;
+		sp->led_state = 0x60;
+		sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+	} else {
+		sp->xleft = count;
+		sp->xhead = sp->xbuff;
+		sp->status2 = count;
+		sp_xmit_on_air(&sp->tx_t);
+	}
+
+	return;
+
+out_drop:
+	sp->dev->stats.tx_dropped++;
+	netif_start_queue(sp->dev);
+	if (net_ratelimit())
+		printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
+}
+
+/* Encapsulate an IP datagram and kick it into a TTY queue. */
+
+static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct sixpack *sp = netdev_priv(dev);
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return ax25_ip_xmit(skb);
+
+	spin_lock_bh(&sp->lock);
+	/* We were not busy, so we are now... :-) */
+	netif_stop_queue(dev);
+	dev->stats.tx_bytes += skb->len;
+	sp_encaps(sp, skb->data, skb->len);
+	spin_unlock_bh(&sp->lock);
+
+	dev_kfree_skb(skb);
+
+	return NETDEV_TX_OK;
+}
+
+static int sp_open_dev(struct net_device *dev)
+{
+	struct sixpack *sp = netdev_priv(dev);
+
+	if (sp->tty == NULL)
+		return -ENODEV;
+	return 0;
+}
+
+/* Close the low-level part of the 6pack channel. */
+static int sp_close(struct net_device *dev)
+{
+	struct sixpack *sp = netdev_priv(dev);
+
+	spin_lock_bh(&sp->lock);
+	if (sp->tty) {
+		/* TTY discipline is running. */
+		clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
+	}
+	netif_stop_queue(dev);
+	spin_unlock_bh(&sp->lock);
+
+	return 0;
+}
+
+static int sp_set_mac_address(struct net_device *dev, void *addr)
+{
+	struct sockaddr_ax25 *sa = addr;
+
+	netif_tx_lock_bh(dev);
+	netif_addr_lock(dev);
+	__dev_addr_set(dev, &sa->sax25_call, AX25_ADDR_LEN);
+	netif_addr_unlock(dev);
+	netif_tx_unlock_bh(dev);
+
+	return 0;
+}
+
+static const struct net_device_ops sp_netdev_ops = {
+	.ndo_open		= sp_open_dev,
+	.ndo_stop		= sp_close,
+	.ndo_start_xmit		= sp_xmit,
+	.ndo_set_mac_address    = sp_set_mac_address,
+};
+
+static void sp_setup(struct net_device *dev)
+{
+	/* Finish setting up the DEVICE info. */
+	dev->netdev_ops		= &sp_netdev_ops;
+	dev->mtu		= SIXP_MTU;
+	dev->hard_header_len	= AX25_MAX_HEADER_LEN;
+	dev->header_ops 	= &ax25_header_ops;
+
+	dev->addr_len		= AX25_ADDR_LEN;
+	dev->type		= ARPHRD_AX25;
+	dev->tx_queue_len	= 10;
+
+	/* Only activated in AX.25 mode */
+	memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
+	dev_addr_set(dev, (u8 *)&ax25_defaddr);
+
+	dev->flags		= 0;
+}
+
+/* Send one completely decapsulated IP datagram to the IP layer. */
+
+/*
+ * This is the routine that sends the received data to the kernel AX.25.
+ * 'cmd' is the KISS command. For AX.25 data, it is zero.
+ */
+
+static void sp_bump(struct sixpack *sp, char cmd)
+{
+	struct sk_buff *skb;
+	int count;
+	unsigned char *ptr;
+
+	count = sp->rcount + 1;
+
+	sp->dev->stats.rx_bytes += count;
+
+	if ((skb = dev_alloc_skb(count + 1)) == NULL)
+		goto out_mem;
+
+	ptr = skb_put(skb, count + 1);
+	*ptr++ = cmd;	/* KISS command */
+
+	memcpy(ptr, sp->cooked_buf + 1, count);
+	skb->protocol = ax25_type_trans(skb, sp->dev);
+	netif_rx(skb);
+	sp->dev->stats.rx_packets++;
+
+	return;
+
+out_mem:
+	sp->dev->stats.rx_dropped++;
+}
+
+
+/* ----------------------------------------------------------------------- */
+
+/*
+ * We have a potential race on dereferencing tty->disc_data, because the tty
+ * layer provides no locking at all - thus one cpu could be running
+ * sixpack_receive_buf while another calls sixpack_close, which zeroes
+ * tty->disc_data and frees the memory that sixpack_receive_buf is using.  The
+ * best way to fix this is to use a rwlock in the tty struct, but for now we
+ * use a single global rwlock for all ttys in ppp line discipline.
+ */
+static DEFINE_RWLOCK(disc_data_lock);
+                                                                                
+static struct sixpack *sp_get(struct tty_struct *tty)
+{
+	struct sixpack *sp;
+
+	read_lock(&disc_data_lock);
+	sp = tty->disc_data;
+	if (sp)
+		refcount_inc(&sp->refcnt);
+	read_unlock(&disc_data_lock);
+
+	return sp;
+}
+
+static void sp_put(struct sixpack *sp)
+{
+	if (refcount_dec_and_test(&sp->refcnt))
+		complete(&sp->dead);
+}
+
+/*
+ * Called by the TTY driver when there's room for more data.  If we have
+ * more packets to send, we send them here.
+ */
+static void sixpack_write_wakeup(struct tty_struct *tty)
+{
+	struct sixpack *sp = sp_get(tty);
+	int actual;
+
+	if (!sp)
+		return;
+	if (sp->xleft <= 0)  {
+		/* Now serial buffer is almost free & we can start
+		 * transmission of another packet */
+		sp->dev->stats.tx_packets++;
+		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+		sp->tx_enable = 0;
+		netif_wake_queue(sp->dev);
+		goto out;
+	}
+
+	if (sp->tx_enable) {
+		actual = tty->ops->write(tty, sp->xhead, sp->xleft);
+		sp->xleft -= actual;
+		sp->xhead += actual;
+	}
+
+out:
+	sp_put(sp);
+}
+
+/* ----------------------------------------------------------------------- */
+
+/*
+ * Handle the 'receiver data ready' interrupt.
+ * This function is called by the tty module in the kernel when
+ * a block of 6pack data has been received, which can now be decapsulated
+ * and sent on to some IP layer for further processing.
+ */
+static void sixpack_receive_buf(struct tty_struct *tty,
+	const unsigned char *cp, const char *fp, int count)
+{
+	struct sixpack *sp;
+	int count1;
+
+	if (!count)
+		return;
+
+	sp = sp_get(tty);
+	if (!sp)
+		return;
+
+	/* Read the characters out of the buffer */
+	count1 = count;
+	while (count) {
+		count--;
+		if (fp && *fp++) {
+			if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
+				sp->dev->stats.rx_errors++;
+			continue;
+		}
+	}
+	sixpack_decode(sp, cp, count1);
+
+	sp_put(sp);
+	tty_unthrottle(tty);
+}
+
+/*
+ * Try to resync the TNC. Called by the resync timer defined in
+ * decode_prio_command
+ */
+
+#define TNC_UNINITIALIZED	0
+#define TNC_UNSYNC_STARTUP	1
+#define TNC_UNSYNCED		2
+#define TNC_IN_SYNC		3
+
+static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
+{
+	char *msg;
+
+	switch (new_tnc_state) {
+	default:			/* gcc oh piece-o-crap ... */
+	case TNC_UNSYNC_STARTUP:
+		msg = "Synchronizing with TNC";
+		break;
+	case TNC_UNSYNCED:
+		msg = "Lost synchronization with TNC\n";
+		break;
+	case TNC_IN_SYNC:
+		msg = "Found TNC";
+		break;
+	}
+
+	sp->tnc_state = new_tnc_state;
+	printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
+}
+
+static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
+{
+	int old_tnc_state = sp->tnc_state;
+
+	if (old_tnc_state != new_tnc_state)
+		__tnc_set_sync_state(sp, new_tnc_state);
+}
+
+static void resync_tnc(struct timer_list *t)
+{
+	struct sixpack *sp = from_timer(sp, t, resync_t);
+	static char resync_cmd = 0xe8;
+
+	/* clear any data that might have been received */
+
+	sp->rx_count = 0;
+	sp->rx_count_cooked = 0;
+
+	/* reset state machine */
+
+	sp->status = 1;
+	sp->status1 = 1;
+	sp->status2 = 0;
+
+	/* resync the TNC */
+
+	sp->led_state = 0x60;
+	sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+	sp->tty->ops->write(sp->tty, &resync_cmd, 1);
+
+
+	/* Start resync timer again -- the TNC might be still absent */
+	mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
+}
+
+static inline int tnc_init(struct sixpack *sp)
+{
+	unsigned char inbyte = 0xe8;
+
+	tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
+
+	sp->tty->ops->write(sp->tty, &inbyte, 1);
+
+	mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
+
+	return 0;
+}
+
+/*
+ * Open the high-level part of the 6pack channel.
+ * This function is called by the TTY module when the
+ * 6pack line discipline is called for.  Because we are
+ * sure the tty line exists, we only have to link it to
+ * a free 6pcack channel...
+ */
+static int sixpack_open(struct tty_struct *tty)
+{
+	char *rbuff = NULL, *xbuff = NULL;
+	struct net_device *dev;
+	struct sixpack *sp;
+	unsigned long len;
+	int err = 0;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+	if (tty->ops->write == NULL)
+		return -EOPNOTSUPP;
+
+	dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
+			   sp_setup);
+	if (!dev) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	sp = netdev_priv(dev);
+	sp->dev = dev;
+
+	spin_lock_init(&sp->lock);
+	spin_lock_init(&sp->rxlock);
+	refcount_set(&sp->refcnt, 1);
+	init_completion(&sp->dead);
+
+	/* !!! length of the buffers. MTU is IP MTU, not PACLEN!  */
+
+	len = dev->mtu * 2;
+
+	rbuff = kmalloc(len + 4, GFP_KERNEL);
+	xbuff = kmalloc(len + 4, GFP_KERNEL);
+
+	if (rbuff == NULL || xbuff == NULL) {
+		err = -ENOBUFS;
+		goto out_free;
+	}
+
+	spin_lock_bh(&sp->lock);
+
+	sp->tty = tty;
+
+	sp->rbuff	= rbuff;
+	sp->xbuff	= xbuff;
+
+	sp->mtu		= AX25_MTU + 73;
+	sp->buffsize	= len;
+	sp->rcount	= 0;
+	sp->rx_count	= 0;
+	sp->rx_count_cooked = 0;
+	sp->xleft	= 0;
+
+	sp->flags	= 0;		/* Clear ESCAPE & ERROR flags */
+
+	sp->duplex	= 0;
+	sp->tx_delay    = SIXP_TXDELAY;
+	sp->persistence = SIXP_PERSIST;
+	sp->slottime    = SIXP_SLOTTIME;
+	sp->led_state   = 0x60;
+	sp->status      = 1;
+	sp->status1     = 1;
+	sp->status2     = 0;
+	sp->tx_enable   = 0;
+
+	netif_start_queue(dev);
+
+	timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
+
+	timer_setup(&sp->resync_t, resync_tnc, 0);
+
+	spin_unlock_bh(&sp->lock);
+
+	/* Done.  We have linked the TTY line to a channel. */
+	tty->disc_data = sp;
+	tty->receive_room = 65536;
+
+	/* Now we're ready to register. */
+	err = register_netdev(dev);
+	if (err)
+		goto out_free;
+
+	tnc_init(sp);
+
+	return 0;
+
+out_free:
+	kfree(xbuff);
+	kfree(rbuff);
+
+	free_netdev(dev);
+
+out:
+	return err;
+}
+
+
+/*
+ * Close down a 6pack channel.
+ * This means flushing out any pending queues, and then restoring the
+ * TTY line discipline to what it was before it got hooked to 6pack
+ * (which usually is TTY again).
+ */
+static void sixpack_close(struct tty_struct *tty)
+{
+	struct sixpack *sp;
+
+	write_lock_irq(&disc_data_lock);
+	sp = tty->disc_data;
+	tty->disc_data = NULL;
+	write_unlock_irq(&disc_data_lock);
+	if (!sp)
+		return;
+
+	/*
+	 * We have now ensured that nobody can start using ap from now on, but
+	 * we have to wait for all existing users to finish.
+	 */
+	if (!refcount_dec_and_test(&sp->refcnt))
+		wait_for_completion(&sp->dead);
+
+	/* We must stop the queue to avoid potentially scribbling
+	 * on the free buffers. The sp->dead completion is not sufficient
+	 * to protect us from sp->xbuff access.
+	 */
+	netif_stop_queue(sp->dev);
+
+	unregister_netdev(sp->dev);
+
+	del_timer_sync(&sp->tx_t);
+	del_timer_sync(&sp->resync_t);
+
+	/* Free all 6pack frame buffers after unreg. */
+	kfree(sp->rbuff);
+	kfree(sp->xbuff);
+
+	free_netdev(sp->dev);
+}
+
+/* Perform I/O control on an active 6pack channel. */
+static int sixpack_ioctl(struct tty_struct *tty, unsigned int cmd,
+		unsigned long arg)
+{
+	struct sixpack *sp = sp_get(tty);
+	struct net_device *dev;
+	unsigned int tmp, err;
+
+	if (!sp)
+		return -ENXIO;
+	dev = sp->dev;
+
+	switch(cmd) {
+	case SIOCGIFNAME:
+		err = copy_to_user((void __user *) arg, dev->name,
+		                   strlen(dev->name) + 1) ? -EFAULT : 0;
+		break;
+
+	case SIOCGIFENCAP:
+		err = put_user(0, (int __user *) arg);
+		break;
+
+	case SIOCSIFENCAP:
+		if (get_user(tmp, (int __user *) arg)) {
+			err = -EFAULT;
+			break;
+		}
+
+		sp->mode = tmp;
+		dev->addr_len        = AX25_ADDR_LEN;
+		dev->hard_header_len = AX25_KISS_HEADER_LEN +
+		                       AX25_MAX_HEADER_LEN + 3;
+		dev->type            = ARPHRD_AX25;
+
+		err = 0;
+		break;
+
+	case SIOCSIFHWADDR: {
+			char addr[AX25_ADDR_LEN];
+
+			if (copy_from_user(&addr,
+					   (void __user *)arg, AX25_ADDR_LEN)) {
+				err = -EFAULT;
+				break;
+			}
+
+			netif_tx_lock_bh(dev);
+			__dev_addr_set(dev, &addr, AX25_ADDR_LEN);
+			netif_tx_unlock_bh(dev);
+			err = 0;
+			break;
+		}
+	default:
+		err = tty_mode_ioctl(tty, cmd, arg);
+	}
+
+	sp_put(sp);
+
+	return err;
+}
+
+static struct tty_ldisc_ops sp_ldisc = {
+	.owner		= THIS_MODULE,
+	.num		= N_6PACK,
+	.name		= "6pack",
+	.open		= sixpack_open,
+	.close		= sixpack_close,
+	.ioctl		= sixpack_ioctl,
+	.receive_buf	= sixpack_receive_buf,
+	.write_wakeup	= sixpack_write_wakeup,
+};
+
+/* Initialize 6pack control device -- register 6pack line discipline */
+
+static const char msg_banner[]  __initconst = KERN_INFO \
+	"AX.25: 6pack driver, " SIXPACK_VERSION "\n";
+static const char msg_regfail[] __initconst = KERN_ERR  \
+	"6pack: can't register line discipline (err = %d)\n";
+
+static int __init sixpack_init_driver(void)
+{
+	int status;
+
+	printk(msg_banner);
+
+	/* Register the provided line protocol discipline */
+	status = tty_register_ldisc(&sp_ldisc);
+	if (status)
+		printk(msg_regfail, status);
+
+	return status;
+}
+
+static void __exit sixpack_exit_driver(void)
+{
+	tty_unregister_ldisc(&sp_ldisc);
+}
+
+/* encode an AX.25 packet into 6pack */
+
+static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
+	int length, unsigned char tx_delay)
+{
+	int count = 0;
+	unsigned char checksum = 0, buf[400];
+	int raw_count = 0;
+
+	tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
+	tx_buf_raw[raw_count++] = SIXP_SEOF;
+
+	buf[0] = tx_delay;
+	for (count = 1; count < length; count++)
+		buf[count] = tx_buf[count];
+
+	for (count = 0; count < length; count++)
+		checksum += buf[count];
+	buf[length] = (unsigned char) 0xff - checksum;
+
+	for (count = 0; count <= length; count++) {
+		if ((count % 3) == 0) {
+			tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
+			tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
+		} else if ((count % 3) == 1) {
+			tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
+			tx_buf_raw[raw_count] =	((buf[count] >> 2) & 0x3c);
+		} else {
+			tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
+			tx_buf_raw[raw_count++] = (buf[count] >> 2);
+		}
+	}
+	if ((length % 3) != 2)
+		raw_count++;
+	tx_buf_raw[raw_count++] = SIXP_SEOF;
+	return raw_count;
+}
+
+/* decode 4 sixpack-encoded bytes into 3 data bytes */
+
+static void decode_data(struct sixpack *sp, unsigned char inbyte)
+{
+	unsigned char *buf;
+
+	if (sp->rx_count != 3) {
+		sp->raw_buf[sp->rx_count++] = inbyte;
+
+		return;
+	}
+
+	if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {
+		pr_err("6pack: cooked buffer overrun, data loss\n");
+		sp->rx_count = 0;
+		return;
+	}
+
+	buf = sp->raw_buf;
+	sp->cooked_buf[sp->rx_count_cooked++] =
+		buf[0] | ((buf[1] << 2) & 0xc0);
+	sp->cooked_buf[sp->rx_count_cooked++] =
+		(buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
+	sp->cooked_buf[sp->rx_count_cooked++] =
+		(buf[2] & 0x03) | (inbyte << 2);
+	sp->rx_count = 0;
+}
+
+/* identify and execute a 6pack priority command byte */
+
+static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
+{
+	int actual;
+
+	if ((cmd & SIXP_PRIO_DATA_MASK) != 0) {     /* idle ? */
+
+	/* RX and DCD flags can only be set in the same prio command,
+	   if the DCD flag has been set without the RX flag in the previous
+	   prio command. If DCD has not been set before, something in the
+	   transmission has gone wrong. In this case, RX and DCD are
+	   cleared in order to prevent the decode_data routine from
+	   reading further data that might be corrupt. */
+
+		if (((sp->status & SIXP_DCD_MASK) == 0) &&
+			((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
+				if (sp->status != 1)
+					printk(KERN_DEBUG "6pack: protocol violation\n");
+				else
+					sp->status = 0;
+				cmd &= ~SIXP_RX_DCD_MASK;
+		}
+		sp->status = cmd & SIXP_PRIO_DATA_MASK;
+	} else { /* output watchdog char if idle */
+		if ((sp->status2 != 0) && (sp->duplex == 1)) {
+			sp->led_state = 0x70;
+			sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+			sp->tx_enable = 1;
+			actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
+			sp->xleft -= actual;
+			sp->xhead += actual;
+			sp->led_state = 0x60;
+			sp->status2 = 0;
+
+		}
+	}
+
+	/* needed to trigger the TNC watchdog */
+	sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+
+        /* if the state byte has been received, the TNC is present,
+           so the resync timer can be reset. */
+
+	if (sp->tnc_state == TNC_IN_SYNC)
+		mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
+
+	sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
+}
+
+/* identify and execute a standard 6pack command byte */
+
+static void decode_std_command(struct sixpack *sp, unsigned char cmd)
+{
+	unsigned char checksum = 0, rest = 0;
+	short i;
+
+	switch (cmd & SIXP_CMD_MASK) {     /* normal command */
+	case SIXP_SEOF:
+		if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
+			if ((sp->status & SIXP_RX_DCD_MASK) ==
+				SIXP_RX_DCD_MASK) {
+				sp->led_state = 0x68;
+				sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+			}
+		} else {
+			sp->led_state = 0x60;
+			/* fill trailing bytes with zeroes */
+			sp->tty->ops->write(sp->tty, &sp->led_state, 1);
+			spin_lock_bh(&sp->rxlock);
+			rest = sp->rx_count;
+			if (rest != 0)
+				 for (i = rest; i <= 3; i++)
+					decode_data(sp, 0);
+			if (rest == 2)
+				sp->rx_count_cooked -= 2;
+			else if (rest == 3)
+				sp->rx_count_cooked -= 1;
+			for (i = 0; i < sp->rx_count_cooked; i++)
+				checksum += sp->cooked_buf[i];
+			if (checksum != SIXP_CHKSUM) {
+				printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
+			} else {
+				sp->rcount = sp->rx_count_cooked-2;
+				sp_bump(sp, 0);
+			}
+			sp->rx_count_cooked = 0;
+			spin_unlock_bh(&sp->rxlock);
+		}
+		break;
+	case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
+		break;
+	case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
+		break;
+	case SIXP_RX_BUF_OVL:
+		printk(KERN_DEBUG "6pack: RX buffer overflow\n");
+	}
+}
+
+/* decode a 6pack packet */
+
+static void
+sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
+{
+	unsigned char inbyte;
+	int count1;
+
+	for (count1 = 0; count1 < count; count1++) {
+		inbyte = pre_rbuff[count1];
+		if (inbyte == SIXP_FOUND_TNC) {
+			tnc_set_sync_state(sp, TNC_IN_SYNC);
+			del_timer(&sp->resync_t);
+		}
+		if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
+			decode_prio_command(sp, inbyte);
+		else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
+			decode_std_command(sp, inbyte);
+		else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) {
+			spin_lock_bh(&sp->rxlock);
+			decode_data(sp, inbyte);
+			spin_unlock_bh(&sp->rxlock);
+		}
+	}
+}
+
+MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
+MODULE_DESCRIPTION("6pack driver for AX.25");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_6PACK);
+
+module_init(sixpack_init_driver);
+module_exit(sixpack_exit_driver);