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, 849 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp_vt220.c b/drivers/s390/char/sclp_vt220.c
new file mode 100644
index 000000000..a32f34a1c
--- /dev/null
+++ b/drivers/s390/char/sclp_vt220.c
@@ -0,0 +1,849 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCLP VT220 terminal driver.
+ *
+ * Copyright IBM Corp. 2003, 2009
+ *
+ * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/panic_notifier.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/timer.h>
+#include <linux/kernel.h>
+#include <linux/sysrq.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/major.h>
+#include <linux/console.h>
+#include <linux/kdev_t.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+
+#include <linux/uaccess.h>
+#include "sclp.h"
+#include "ctrlchar.h"
+
+#define SCLP_VT220_MAJOR		TTY_MAJOR
+#define SCLP_VT220_MINOR		65
+#define SCLP_VT220_DRIVER_NAME		"sclp_vt220"
+#define SCLP_VT220_DEVICE_NAME		"ttysclp"
+#define SCLP_VT220_CONSOLE_NAME		"ttysclp"
+#define SCLP_VT220_CONSOLE_INDEX	0	/* console=ttysclp0 */
+
+/* Representation of a single write request */
+struct sclp_vt220_request {
+	struct list_head list;
+	struct sclp_req sclp_req;
+	int retry_count;
+};
+
+/* VT220 SCCB */
+struct sclp_vt220_sccb {
+	struct sccb_header header;
+	struct evbuf_header evbuf;
+};
+
+#define SCLP_VT220_MAX_CHARS_PER_BUFFER	(PAGE_SIZE - \
+					 sizeof(struct sclp_vt220_request) - \
+					 sizeof(struct sclp_vt220_sccb))
+
+/* Structures and data needed to register tty driver */
+static struct tty_driver *sclp_vt220_driver;
+
+static struct tty_port sclp_vt220_port;
+
+/* Lock to protect internal data from concurrent access */
+static DEFINE_SPINLOCK(sclp_vt220_lock);
+
+/* List of empty pages to be used as write request buffers */
+static LIST_HEAD(sclp_vt220_empty);
+
+/* List of pending requests */
+static LIST_HEAD(sclp_vt220_outqueue);
+
+/* Flag that output queue is currently running */
+static int sclp_vt220_queue_running;
+
+/* Timer used for delaying write requests to merge subsequent messages into
+ * a single buffer */
+static struct timer_list sclp_vt220_timer;
+
+/* Pointer to current request buffer which has been partially filled but not
+ * yet sent */
+static struct sclp_vt220_request *sclp_vt220_current_request;
+
+/* Number of characters in current request buffer */
+static int sclp_vt220_buffered_chars;
+
+/* Counter controlling core driver initialization. */
+static int __initdata sclp_vt220_init_count;
+
+/* Flag indicating that sclp_vt220_current_request should really
+ * have been already queued but wasn't because the SCLP was processing
+ * another buffer */
+static int sclp_vt220_flush_later;
+
+static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
+static int __sclp_vt220_emit(struct sclp_vt220_request *request);
+static void sclp_vt220_emit_current(void);
+
+/* Registration structure for SCLP output event buffers */
+static struct sclp_register sclp_vt220_register = {
+	.send_mask		= EVTYP_VT220MSG_MASK,
+};
+
+/* Registration structure for SCLP input event buffers */
+static struct sclp_register sclp_vt220_register_input = {
+	.receive_mask		= EVTYP_VT220MSG_MASK,
+	.receiver_fn		= sclp_vt220_receiver_fn,
+};
+
+
+/*
+ * Put provided request buffer back into queue and check emit pending
+ * buffers if necessary.
+ */
+static void
+sclp_vt220_process_queue(struct sclp_vt220_request *request)
+{
+	unsigned long flags;
+	void *page;
+
+	do {
+		/* Put buffer back to list of empty buffers */
+		page = request->sclp_req.sccb;
+		spin_lock_irqsave(&sclp_vt220_lock, flags);
+		/* Move request from outqueue to empty queue */
+		list_del(&request->list);
+		list_add_tail((struct list_head *) page, &sclp_vt220_empty);
+		/* Check if there is a pending buffer on the out queue. */
+		request = NULL;
+		if (!list_empty(&sclp_vt220_outqueue))
+			request = list_entry(sclp_vt220_outqueue.next,
+					     struct sclp_vt220_request, list);
+		if (!request) {
+			sclp_vt220_queue_running = 0;
+			spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+			break;
+		}
+		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+	} while (__sclp_vt220_emit(request));
+	if (request == NULL && sclp_vt220_flush_later)
+		sclp_vt220_emit_current();
+	tty_port_tty_wakeup(&sclp_vt220_port);
+}
+
+#define SCLP_BUFFER_MAX_RETRY		1
+
+/*
+ * Callback through which the result of a write request is reported by the
+ * SCLP.
+ */
+static void
+sclp_vt220_callback(struct sclp_req *request, void *data)
+{
+	struct sclp_vt220_request *vt220_request;
+	struct sclp_vt220_sccb *sccb;
+
+	vt220_request = (struct sclp_vt220_request *) data;
+	if (request->status == SCLP_REQ_FAILED) {
+		sclp_vt220_process_queue(vt220_request);
+		return;
+	}
+	sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
+
+	/* Check SCLP response code and choose suitable action	*/
+	switch (sccb->header.response_code) {
+	case 0x0020 :
+		break;
+
+	case 0x05f0: /* Target resource in improper state */
+		break;
+
+	case 0x0340: /* Contained SCLP equipment check */
+		if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
+			break;
+		/* Remove processed buffers and requeue rest */
+		if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
+			/* Not all buffers were processed */
+			sccb->header.response_code = 0x0000;
+			vt220_request->sclp_req.status = SCLP_REQ_FILLED;
+			if (sclp_add_request(request) == 0)
+				return;
+		}
+		break;
+
+	case 0x0040: /* SCLP equipment check */
+		if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
+			break;
+		sccb->header.response_code = 0x0000;
+		vt220_request->sclp_req.status = SCLP_REQ_FILLED;
+		if (sclp_add_request(request) == 0)
+			return;
+		break;
+
+	default:
+		break;
+	}
+	sclp_vt220_process_queue(vt220_request);
+}
+
+/*
+ * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
+ * otherwise.
+ */
+static int
+__sclp_vt220_emit(struct sclp_vt220_request *request)
+{
+	request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
+	request->sclp_req.status = SCLP_REQ_FILLED;
+	request->sclp_req.callback = sclp_vt220_callback;
+	request->sclp_req.callback_data = (void *) request;
+
+	return sclp_add_request(&request->sclp_req);
+}
+
+/*
+ * Queue and emit current request.
+ */
+static void
+sclp_vt220_emit_current(void)
+{
+	unsigned long flags;
+	struct sclp_vt220_request *request;
+	struct sclp_vt220_sccb *sccb;
+
+	spin_lock_irqsave(&sclp_vt220_lock, flags);
+	if (sclp_vt220_current_request) {
+		sccb = (struct sclp_vt220_sccb *) 
+				sclp_vt220_current_request->sclp_req.sccb;
+		/* Only emit buffers with content */
+		if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
+			list_add_tail(&sclp_vt220_current_request->list,
+				      &sclp_vt220_outqueue);
+			sclp_vt220_current_request = NULL;
+			del_timer(&sclp_vt220_timer);
+		}
+		sclp_vt220_flush_later = 0;
+	}
+	if (sclp_vt220_queue_running)
+		goto out_unlock;
+	if (list_empty(&sclp_vt220_outqueue))
+		goto out_unlock;
+	request = list_first_entry(&sclp_vt220_outqueue,
+				   struct sclp_vt220_request, list);
+	sclp_vt220_queue_running = 1;
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+
+	if (__sclp_vt220_emit(request))
+		sclp_vt220_process_queue(request);
+	return;
+out_unlock:
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+}
+
+#define SCLP_NORMAL_WRITE	0x00
+
+/*
+ * Helper function to initialize a page with the sclp request structure.
+ */
+static struct sclp_vt220_request *
+sclp_vt220_initialize_page(void *page)
+{
+	struct sclp_vt220_request *request;
+	struct sclp_vt220_sccb *sccb;
+
+	/* Place request structure at end of page */
+	request = ((struct sclp_vt220_request *)
+			((addr_t) page + PAGE_SIZE)) - 1;
+	request->retry_count = 0;
+	request->sclp_req.sccb = page;
+	/* SCCB goes at start of page */
+	sccb = (struct sclp_vt220_sccb *) page;
+	memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
+	sccb->header.length = sizeof(struct sclp_vt220_sccb);
+	sccb->header.function_code = SCLP_NORMAL_WRITE;
+	sccb->header.response_code = 0x0000;
+	sccb->evbuf.type = EVTYP_VT220MSG;
+	sccb->evbuf.length = sizeof(struct evbuf_header);
+
+	return request;
+}
+
+static inline unsigned int
+sclp_vt220_space_left(struct sclp_vt220_request *request)
+{
+	struct sclp_vt220_sccb *sccb;
+	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
+	return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
+	       sccb->header.length;
+}
+
+static inline unsigned int
+sclp_vt220_chars_stored(struct sclp_vt220_request *request)
+{
+	struct sclp_vt220_sccb *sccb;
+	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
+	return sccb->evbuf.length - sizeof(struct evbuf_header);
+}
+
+/*
+ * Add msg to buffer associated with request. Return the number of characters
+ * added.
+ */
+static int
+sclp_vt220_add_msg(struct sclp_vt220_request *request,
+		   const unsigned char *msg, int count, int convertlf)
+{
+	struct sclp_vt220_sccb *sccb;
+	void *buffer;
+	unsigned char c;
+	int from;
+	int to;
+
+	if (count > sclp_vt220_space_left(request))
+		count = sclp_vt220_space_left(request);
+	if (count <= 0)
+		return 0;
+
+	sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
+	buffer = (void *) ((addr_t) sccb + sccb->header.length);
+
+	if (convertlf) {
+		/* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
+		for (from=0, to=0;
+		     (from < count) && (to < sclp_vt220_space_left(request));
+		     from++) {
+			/* Retrieve character */
+			c = msg[from];
+			/* Perform conversion */
+			if (c == 0x0a) {
+				if (to + 1 < sclp_vt220_space_left(request)) {
+					((unsigned char *) buffer)[to++] = c;
+					((unsigned char *) buffer)[to++] = 0x0d;
+				} else
+					break;
+
+			} else
+				((unsigned char *) buffer)[to++] = c;
+		}
+		sccb->header.length += to;
+		sccb->evbuf.length += to;
+		return from;
+	} else {
+		memcpy(buffer, (const void *) msg, count);
+		sccb->header.length += count;
+		sccb->evbuf.length += count;
+		return count;
+	}
+}
+
+/*
+ * Emit buffer after having waited long enough for more data to arrive.
+ */
+static void
+sclp_vt220_timeout(struct timer_list *unused)
+{
+	sclp_vt220_emit_current();
+}
+
+#define BUFFER_MAX_DELAY	HZ/20
+
+/*
+ * Drop oldest console buffer if sclp_con_drop is set
+ */
+static int
+sclp_vt220_drop_buffer(void)
+{
+	struct list_head *list;
+	struct sclp_vt220_request *request;
+	void *page;
+
+	if (!sclp_console_drop)
+		return 0;
+	list = sclp_vt220_outqueue.next;
+	if (sclp_vt220_queue_running)
+		/* The first element is in I/O */
+		list = list->next;
+	if (list == &sclp_vt220_outqueue)
+		return 0;
+	list_del(list);
+	request = list_entry(list, struct sclp_vt220_request, list);
+	page = request->sclp_req.sccb;
+	list_add_tail((struct list_head *) page, &sclp_vt220_empty);
+	return 1;
+}
+
+/* 
+ * Internal implementation of the write function. Write COUNT bytes of data
+ * from memory at BUF
+ * to the SCLP interface. In case that the data does not fit into the current
+ * write buffer, emit the current one and allocate a new one. If there are no
+ * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
+ * is non-zero, the buffer will be scheduled for emitting after a timeout -
+ * otherwise the user has to explicitly call the flush function.
+ * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
+ * buffer should be converted to 0x0a 0x0d. After completion, return the number
+ * of bytes written.
+ */
+static int
+__sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
+		   int convertlf, int may_fail)
+{
+	unsigned long flags;
+	void *page;
+	int written;
+	int overall_written;
+
+	if (count <= 0)
+		return 0;
+	overall_written = 0;
+	spin_lock_irqsave(&sclp_vt220_lock, flags);
+	do {
+		/* Create an sclp output buffer if none exists yet */
+		if (sclp_vt220_current_request == NULL) {
+			if (list_empty(&sclp_vt220_empty))
+				sclp_console_full++;
+			while (list_empty(&sclp_vt220_empty)) {
+				if (may_fail)
+					goto out;
+				if (sclp_vt220_drop_buffer())
+					break;
+				spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+
+				sclp_sync_wait();
+				spin_lock_irqsave(&sclp_vt220_lock, flags);
+			}
+			page = (void *) sclp_vt220_empty.next;
+			list_del((struct list_head *) page);
+			sclp_vt220_current_request =
+				sclp_vt220_initialize_page(page);
+		}
+		/* Try to write the string to the current request buffer */
+		written = sclp_vt220_add_msg(sclp_vt220_current_request,
+					     buf, count, convertlf);
+		overall_written += written;
+		if (written == count)
+			break;
+		/*
+		 * Not all characters could be written to the current
+		 * output buffer. Emit the buffer, create a new buffer
+		 * and then output the rest of the string.
+		 */
+		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+		sclp_vt220_emit_current();
+		spin_lock_irqsave(&sclp_vt220_lock, flags);
+		buf += written;
+		count -= written;
+	} while (count > 0);
+	/* Setup timer to output current console buffer after some time */
+	if (sclp_vt220_current_request != NULL &&
+	    !timer_pending(&sclp_vt220_timer) && do_schedule) {
+		sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
+		add_timer(&sclp_vt220_timer);
+	}
+out:
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+	return overall_written;
+}
+
+/*
+ * This routine is called by the kernel to write a series of
+ * characters to the tty device.  The characters may come from
+ * user space or kernel space.  This routine will return the
+ * number of characters actually accepted for writing.
+ */
+static int
+sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
+{
+	return __sclp_vt220_write(buf, count, 1, 0, 1);
+}
+
+#define SCLP_VT220_SESSION_ENDED	0x01
+#define	SCLP_VT220_SESSION_STARTED	0x80
+#define SCLP_VT220_SESSION_DATA		0x00
+
+#ifdef CONFIG_MAGIC_SYSRQ
+
+static int sysrq_pressed;
+static struct sysrq_work sysrq;
+
+static void sclp_vt220_reset_session(void)
+{
+	sysrq_pressed = 0;
+}
+
+static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		/* Handle magic sys request */
+		if (buffer[i] == ('O' ^ 0100)) { /* CTRL-O */
+			/*
+			 * If pressed again, reset sysrq_pressed
+			 * and flip CTRL-O character
+			 */
+			sysrq_pressed = !sysrq_pressed;
+			if (sysrq_pressed)
+				continue;
+		} else if (sysrq_pressed) {
+			sysrq.key = buffer[i];
+			schedule_sysrq_work(&sysrq);
+			sysrq_pressed = 0;
+			continue;
+		}
+		tty_insert_flip_char(&sclp_vt220_port, buffer[i], 0);
+	}
+}
+
+#else
+
+static void sclp_vt220_reset_session(void)
+{
+}
+
+static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
+{
+	tty_insert_flip_string(&sclp_vt220_port, buffer, count);
+}
+
+#endif
+
+/*
+ * Called by the SCLP to report incoming event buffers.
+ */
+static void
+sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
+{
+	char *buffer;
+	unsigned int count;
+
+	buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
+	count = evbuf->length - sizeof(struct evbuf_header);
+
+	switch (*buffer) {
+	case SCLP_VT220_SESSION_ENDED:
+	case SCLP_VT220_SESSION_STARTED:
+		sclp_vt220_reset_session();
+		break;
+	case SCLP_VT220_SESSION_DATA:
+		/* Send input to line discipline */
+		buffer++;
+		count--;
+		sclp_vt220_handle_input(buffer, count);
+		tty_flip_buffer_push(&sclp_vt220_port);
+		break;
+	}
+}
+
+/*
+ * This routine is called when a particular tty device is opened.
+ */
+static int
+sclp_vt220_open(struct tty_struct *tty, struct file *filp)
+{
+	if (tty->count == 1) {
+		tty_port_tty_set(&sclp_vt220_port, tty);
+		if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
+			tty->winsize.ws_row = 24;
+			tty->winsize.ws_col = 80;
+		}
+	}
+	return 0;
+}
+
+/*
+ * This routine is called when a particular tty device is closed.
+ */
+static void
+sclp_vt220_close(struct tty_struct *tty, struct file *filp)
+{
+	if (tty->count == 1)
+		tty_port_tty_set(&sclp_vt220_port, NULL);
+}
+
+/*
+ * This routine is called by the kernel to write a single
+ * character to the tty device.  If the kernel uses this routine,
+ * it must call the flush_chars() routine (if defined) when it is
+ * done stuffing characters into the driver.
+ */
+static int
+sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
+{
+	return __sclp_vt220_write(&ch, 1, 0, 0, 1);
+}
+
+/*
+ * This routine is called by the kernel after it has written a
+ * series of characters to the tty device using put_char().  
+ */
+static void
+sclp_vt220_flush_chars(struct tty_struct *tty)
+{
+	if (!sclp_vt220_queue_running)
+		sclp_vt220_emit_current();
+	else
+		sclp_vt220_flush_later = 1;
+}
+
+/*
+ * This routine returns the numbers of characters the tty driver
+ * will accept for queuing to be written.  This number is subject
+ * to change as output buffers get emptied, or if the output flow
+ * control is acted.
+ */
+static unsigned int
+sclp_vt220_write_room(struct tty_struct *tty)
+{
+	unsigned long flags;
+	struct list_head *l;
+	unsigned int count;
+
+	spin_lock_irqsave(&sclp_vt220_lock, flags);
+	count = 0;
+	if (sclp_vt220_current_request != NULL)
+		count = sclp_vt220_space_left(sclp_vt220_current_request);
+	list_for_each(l, &sclp_vt220_empty)
+		count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+	return count;
+}
+
+/*
+ * Return number of buffered chars.
+ */
+static unsigned int
+sclp_vt220_chars_in_buffer(struct tty_struct *tty)
+{
+	unsigned long flags;
+	struct list_head *l;
+	struct sclp_vt220_request *r;
+	unsigned int count = 0;
+
+	spin_lock_irqsave(&sclp_vt220_lock, flags);
+	if (sclp_vt220_current_request != NULL)
+		count = sclp_vt220_chars_stored(sclp_vt220_current_request);
+	list_for_each(l, &sclp_vt220_outqueue) {
+		r = list_entry(l, struct sclp_vt220_request, list);
+		count += sclp_vt220_chars_stored(r);
+	}
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+	return count;
+}
+
+/*
+ * Pass on all buffers to the hardware. Return only when there are no more
+ * buffers pending.
+ */
+static void
+sclp_vt220_flush_buffer(struct tty_struct *tty)
+{
+	sclp_vt220_emit_current();
+}
+
+/* Release allocated pages. */
+static void __init __sclp_vt220_free_pages(void)
+{
+	struct list_head *page, *p;
+
+	list_for_each_safe(page, p, &sclp_vt220_empty) {
+		list_del(page);
+		free_page((unsigned long) page);
+	}
+}
+
+/* Release memory and unregister from sclp core. Controlled by init counting -
+ * only the last invoker will actually perform these actions. */
+static void __init __sclp_vt220_cleanup(void)
+{
+	sclp_vt220_init_count--;
+	if (sclp_vt220_init_count != 0)
+		return;
+	sclp_unregister(&sclp_vt220_register);
+	__sclp_vt220_free_pages();
+	tty_port_destroy(&sclp_vt220_port);
+}
+
+/* Allocate buffer pages and register with sclp core. Controlled by init
+ * counting - only the first invoker will actually perform these actions. */
+static int __init __sclp_vt220_init(int num_pages)
+{
+	void *page;
+	int i;
+	int rc;
+
+	sclp_vt220_init_count++;
+	if (sclp_vt220_init_count != 1)
+		return 0;
+	timer_setup(&sclp_vt220_timer, sclp_vt220_timeout, 0);
+	tty_port_init(&sclp_vt220_port);
+	sclp_vt220_current_request = NULL;
+	sclp_vt220_buffered_chars = 0;
+	sclp_vt220_flush_later = 0;
+
+	/* Allocate pages for output buffering */
+	rc = -ENOMEM;
+	for (i = 0; i < num_pages; i++) {
+		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+		if (!page)
+			goto out;
+		list_add_tail(page, &sclp_vt220_empty);
+	}
+	rc = sclp_register(&sclp_vt220_register);
+out:
+	if (rc) {
+		__sclp_vt220_free_pages();
+		sclp_vt220_init_count--;
+		tty_port_destroy(&sclp_vt220_port);
+	}
+	return rc;
+}
+
+static const struct tty_operations sclp_vt220_ops = {
+	.open = sclp_vt220_open,
+	.close = sclp_vt220_close,
+	.write = sclp_vt220_write,
+	.put_char = sclp_vt220_put_char,
+	.flush_chars = sclp_vt220_flush_chars,
+	.write_room = sclp_vt220_write_room,
+	.chars_in_buffer = sclp_vt220_chars_in_buffer,
+	.flush_buffer = sclp_vt220_flush_buffer,
+};
+
+/*
+ * Register driver with SCLP and Linux and initialize internal tty structures.
+ */
+static int __init sclp_vt220_tty_init(void)
+{
+	struct tty_driver *driver;
+	int rc;
+
+	/* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
+	 * symmetry between VM and LPAR systems regarding ttyS1. */
+	driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW);
+	if (IS_ERR(driver))
+		return PTR_ERR(driver);
+	rc = __sclp_vt220_init(MAX_KMEM_PAGES);
+	if (rc)
+		goto out_driver;
+
+	driver->driver_name = SCLP_VT220_DRIVER_NAME;
+	driver->name = SCLP_VT220_DEVICE_NAME;
+	driver->major = SCLP_VT220_MAJOR;
+	driver->minor_start = SCLP_VT220_MINOR;
+	driver->type = TTY_DRIVER_TYPE_SYSTEM;
+	driver->subtype = SYSTEM_TYPE_TTY;
+	driver->init_termios = tty_std_termios;
+	tty_set_operations(driver, &sclp_vt220_ops);
+	tty_port_link_device(&sclp_vt220_port, driver, 0);
+
+	rc = tty_register_driver(driver);
+	if (rc)
+		goto out_init;
+	rc = sclp_register(&sclp_vt220_register_input);
+	if (rc)
+		goto out_reg;
+	sclp_vt220_driver = driver;
+	return 0;
+
+out_reg:
+	tty_unregister_driver(driver);
+out_init:
+	__sclp_vt220_cleanup();
+out_driver:
+	tty_driver_kref_put(driver);
+	return rc;
+}
+__initcall(sclp_vt220_tty_init);
+
+#ifdef CONFIG_SCLP_VT220_CONSOLE
+
+static void
+sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
+{
+	__sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
+}
+
+static struct tty_driver *
+sclp_vt220_con_device(struct console *c, int *index)
+{
+	*index = 0;
+	return sclp_vt220_driver;
+}
+
+/*
+ * This panic/reboot notifier runs in atomic context, so
+ * locking restrictions apply to prevent potential lockups.
+ */
+static int
+sclp_vt220_notify(struct notifier_block *self,
+			  unsigned long event, void *data)
+{
+	unsigned long flags;
+
+	if (spin_is_locked(&sclp_vt220_lock))
+		return NOTIFY_DONE;
+
+	sclp_vt220_emit_current();
+
+	spin_lock_irqsave(&sclp_vt220_lock, flags);
+	del_timer(&sclp_vt220_timer);
+	while (sclp_vt220_queue_running) {
+		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+		sclp_sync_wait();
+		spin_lock_irqsave(&sclp_vt220_lock, flags);
+	}
+	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block on_panic_nb = {
+	.notifier_call = sclp_vt220_notify,
+	.priority = INT_MIN + 1, /* run the callback late */
+};
+
+static struct notifier_block on_reboot_nb = {
+	.notifier_call = sclp_vt220_notify,
+	.priority = INT_MIN + 1, /* run the callback late */
+};
+
+/* Structure needed to register with printk */
+static struct console sclp_vt220_console =
+{
+	.name = SCLP_VT220_CONSOLE_NAME,
+	.write = sclp_vt220_con_write,
+	.device = sclp_vt220_con_device,
+	.flags = CON_PRINTBUFFER,
+	.index = SCLP_VT220_CONSOLE_INDEX
+};
+
+static int __init
+sclp_vt220_con_init(void)
+{
+	int rc;
+
+	rc = __sclp_vt220_init(sclp_console_pages);
+	if (rc)
+		return rc;
+	/* Attach linux console */
+	atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
+	register_reboot_notifier(&on_reboot_nb);
+	register_console(&sclp_vt220_console);
+	return 0;
+}
+
+console_initcall(sclp_vt220_con_init);
+#endif /* CONFIG_SCLP_VT220_CONSOLE */
+