[S390]: Rewrite of the IUCV base code, part 2

Add rewritten IUCV base code to net/iucv.

Signed-off-by: Frank Pavlic <fpavlic@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 1633 insertions, 0 deletions

diff --git a/net/Kconfig b/net/Kconfig
index 7dfc94920697..915657832d94 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -37,6 +37,7 @@ config NETDEBUG
 source "net/packet/Kconfig"
 source "net/unix/Kconfig"
 source "net/xfrm/Kconfig"
+source "net/iucv/Kconfig"
 
 config INET
         bool "TCP/IP networking"
diff --git a/net/Makefile b/net/Makefile
index ad4d14f4bb29..4854ac506313 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_IP_SCTP)		+= sctp/
 obj-$(CONFIG_IEEE80211)         += ieee80211/
 obj-$(CONFIG_TIPC)              += tipc/
 obj-$(CONFIG_NETLABEL)          += netlabel/
+obj-$(CONFIG_IUCV)              += iucv/
 
 ifeq ($(CONFIG_NET),y)
 obj-$(CONFIG_SYSCTL)            += sysctl_net.o
diff --git a/net/iucv/Kconfig b/net/iucv/Kconfig
new file mode 100644
index 000000000000..45ecf0b62d52
--- /dev/null
+++ b/net/iucv/Kconfig
@@ -0,0 +1,7 @@
+config IUCV
+        tristate "IUCV support (VM only)"
+        depends on S390
+        help
+          Select this option if you want to use inter-user communication under
+          VM or VIF sockets. If you run on z/VM, say "Y" to enable a fast
+          communication link between VM guests.
diff --git a/net/iucv/Makefile b/net/iucv/Makefile
new file mode 100644
index 000000000000..875941720d6a
--- /dev/null
+++ b/net/iucv/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for IUCV
+#
+
+obj-$(CONFIG_IUCV)      += iucv.o
diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
new file mode 100644
index 000000000000..1b10d576f222
--- /dev/null
+++ b/net/iucv/iucv.c
@@ -0,0 +1,1619 @@
+/*
+ * IUCV base infrastructure.
+ *
+ * Copyright 2001, 2006 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ * Author(s):
+ *    Original source:
+ *      Alan Altmark (Alan_Altmark@us.ibm.com)  Sept. 2000
+ *      Xenia Tkatschow (xenia@us.ibm.com)
+ *    2Gb awareness and general cleanup:
+ *      Fritz Elfert (elfert@de.ibm.com, felfert@millenux.com)
+ *    Rewritten for af_iucv:
+ *      Martin Schwidefsky <schwidefsky@de.ibm.com>
+ *
+ * Documentation used:
+ *    The original source
+ *    CP Programming Service, IBM document # SC24-5760
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include <linux/spinlock.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/cpu.h>
+#include <net/iucv/iucv.h>
+#include <asm/atomic.h>
+#include <asm/ebcdic.h>
+#include <asm/io.h>
+#include <asm/s390_ext.h>
+#include <asm/s390_rdev.h>
+#include <asm/smp.h>
+
+/*
+ * FLAGS:
+ * All flags are defined in the field IPFLAGS1 of each function
+ * and can be found in CP Programming Services.
+ * IPSRCCLS - Indicates you have specified a source class.
+ * IPTRGCLS - Indicates you have specified a target class.
+ * IPFGPID  - Indicates you have specified a pathid.
+ * IPFGMID  - Indicates you have specified a message ID.
+ * IPNORPY  - Indicates a one-way message. No reply expected.
+ * IPALL    - Indicates that all paths are affected.
+ */
+#define IUCV_IPSRCCLS   0x01
+#define IUCV_IPTRGCLS   0x01
+#define IUCV_IPFGPID    0x02
+#define IUCV_IPFGMID    0x04
+#define IUCV_IPNORPY    0x10
+#define IUCV_IPALL      0x80
+
+static int iucv_bus_match (struct device *dev, struct device_driver *drv)
+{
+        return 0;
+}
+
+struct bus_type iucv_bus = {
+        .name = "iucv",
+        .match = iucv_bus_match,
+};
+
+struct device *iucv_root;
+static int iucv_available;
+
+/* General IUCV interrupt structure */
+struct iucv_irq_data {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iptype;
+        u32 res2[8];
+};
+
+struct iucv_work {
+        struct list_head list;
+        struct iucv_irq_data data;
+};
+
+static LIST_HEAD(iucv_work_queue);
+static DEFINE_SPINLOCK(iucv_work_lock);
+
+static struct iucv_irq_data *iucv_irq_data;
+static cpumask_t iucv_buffer_cpumask = CPU_MASK_NONE;
+static cpumask_t iucv_irq_cpumask = CPU_MASK_NONE;
+
+static void iucv_tasklet_handler(unsigned long);
+static DECLARE_TASKLET(iucv_tasklet, iucv_tasklet_handler,0);
+
+enum iucv_command_codes {
+        IUCV_QUERY = 0,
+        IUCV_RETRIEVE_BUFFER = 2,
+        IUCV_SEND = 4,
+        IUCV_RECEIVE = 5,
+        IUCV_REPLY = 6,
+        IUCV_REJECT = 8,
+        IUCV_PURGE = 9,
+        IUCV_ACCEPT = 10,
+        IUCV_CONNECT = 11,
+        IUCV_DECLARE_BUFFER = 12,
+        IUCV_QUIESCE = 13,
+        IUCV_RESUME = 14,
+        IUCV_SEVER = 15,
+        IUCV_SETMASK = 16,
+};
+
+/*
+ * Error messages that are used with the iucv_sever function. They get
+ * converted to EBCDIC.
+ */
+static char iucv_error_no_listener[16] = "NO LISTENER";
+static char iucv_error_no_memory[16] = "NO MEMORY";
+static char iucv_error_pathid[16] = "INVALID PATHID";
+
+/*
+ * iucv_handler_list: List of registered handlers.
+ */
+static LIST_HEAD(iucv_handler_list);
+
+/*
+ * iucv_path_table: an array of iucv_path structures.
+ */
+static struct iucv_path **iucv_path_table;
+static unsigned long iucv_max_pathid;
+
+/*
+ * iucv_lock: spinlock protecting iucv_handler_list and iucv_pathid_table
+ */
+static DEFINE_SPINLOCK(iucv_table_lock);
+
+/*
+ * iucv_tasklet_cpu: contains the number of the cpu executing the tasklet.
+ * Needed for iucv_path_sever called from tasklet.
+ */
+static int iucv_tasklet_cpu = -1;
+
+/*
+ * Mutex and wait queue for iucv_register/iucv_unregister.
+ */
+static DEFINE_MUTEX(iucv_register_mutex);
+
+/*
+ * Counter for number of non-smp capable handlers.
+ */
+static int iucv_nonsmp_handler;
+
+/*
+ * IUCV control data structure. Used by iucv_path_accept, iucv_path_connect,
+ * iucv_path_quiesce and iucv_path_sever.
+ */
+struct iucv_cmd_control {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iprcode;
+        u16 ipmsglim;
+        u16 res1;
+        u8  ipvmid[8];
+        u8  ipuser[16];
+        u8  iptarget[8];
+} __attribute__ ((packed,aligned(8)));
+
+/*
+ * Data in parameter list iucv structure. Used by iucv_message_send,
+ * iucv_message_send2way and iucv_message_reply.
+ */
+struct iucv_cmd_dpl {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iprcode;
+        u32 ipmsgid;
+        u32 iptrgcls;
+        u8  iprmmsg[8];
+        u32 ipsrccls;
+        u32 ipmsgtag;
+        u32 ipbfadr2;
+        u32 ipbfln2f;
+        u32 res;
+} __attribute__ ((packed,aligned(8)));
+
+/*
+ * Data in buffer iucv structure. Used by iucv_message_receive,
+ * iucv_message_reject, iucv_message_send, iucv_message_send2way
+ * and iucv_declare_cpu.
+ */
+struct iucv_cmd_db {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iprcode;
+        u32 ipmsgid;
+        u32 iptrgcls;
+        u32 ipbfadr1;
+        u32 ipbfln1f;
+        u32 ipsrccls;
+        u32 ipmsgtag;
+        u32 ipbfadr2;
+        u32 ipbfln2f;
+        u32 res;
+} __attribute__ ((packed,aligned(8)));
+
+/*
+ * Purge message iucv structure. Used by iucv_message_purge.
+ */
+struct iucv_cmd_purge {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iprcode;
+        u32 ipmsgid;
+        u8  ipaudit[3];
+        u8  res1[5];
+        u32 res2;
+        u32 ipsrccls;
+        u32 ipmsgtag;
+        u32 res3[3];
+} __attribute__ ((packed,aligned(8)));
+
+/*
+ * Set mask iucv structure. Used by iucv_enable_cpu.
+ */
+struct iucv_cmd_set_mask {
+        u8  ipmask;
+        u8  res1[2];
+        u8  iprcode;
+        u32 res2[9];
+} __attribute__ ((packed,aligned(8)));
+
+union iucv_param {
+        struct iucv_cmd_control ctrl;
+        struct iucv_cmd_dpl dpl;
+        struct iucv_cmd_db db;
+        struct iucv_cmd_purge purge;
+        struct iucv_cmd_set_mask set_mask;
+};
+
+/*
+ * Anchor for per-cpu IUCV command parameter block.
+ */
+static union iucv_param *iucv_param;
+
+/**
+ * iucv_call_b2f0
+ * @code: identifier of IUCV call to CP.
+ * @parm: pointer to a struct iucv_parm block
+ *
+ * Calls CP to execute IUCV commands.
+ *
+ * Returns the result of the CP IUCV call.
+ */
+static inline int iucv_call_b2f0(int command, union iucv_param *parm)
+{
+        register unsigned long reg0 asm ("0");
+        register unsigned long reg1 asm ("1");
+        int ccode;
+
+        reg0 = command;
+        reg1 = virt_to_phys(parm);
+        asm volatile(
+                "       .long 0xb2f01000\n"
+                "       ipm     %0\n"
+                "       srl     %0,28\n"
+                : "=d" (ccode), "=m" (*parm), "+d" (reg0), "+a" (reg1)
+                :  "m" (*parm) : "cc");
+        return (ccode == 1) ? parm->ctrl.iprcode : ccode;
+}
+
+/**
+ * iucv_query_maxconn
+ *
+ * Determines the maximum number of connections that may be established.
+ *
+ * Returns the maximum number of connections or -EPERM is IUCV is not
+ * available.
+ */
+static int iucv_query_maxconn(void)
+{
+        register unsigned long reg0 asm ("0");
+        register unsigned long reg1 asm ("1");
+        void *param;
+        int ccode;
+
+        param = kzalloc(sizeof(union iucv_param), GFP_KERNEL|GFP_DMA);
+        if (!param)
+                return -ENOMEM;
+        reg0 = IUCV_QUERY;
+        reg1 = (unsigned long) param;
+        asm volatile (
+                "       .long   0xb2f01000\n"
+                "       ipm     %0\n"
+                "       srl     %0,28\n"
+                : "=d" (ccode), "+d" (reg0), "+d" (reg1) : : "cc");
+        if (ccode == 0)
+                iucv_max_pathid = reg0;
+        kfree(param);
+        return ccode ? -EPERM : 0;
+}
+
+/**
+ * iucv_allow_cpu
+ * @data: unused
+ *
+ * Allow iucv interrupts on this cpu.
+ */
+static void iucv_allow_cpu(void *data)
+{
+        int cpu = smp_processor_id();
+        union iucv_param *parm;
+
+        /*
+         * Enable all iucv interrupts.
+         * ipmask contains bits for the different interrupts
+         *      0x80 - Flag to allow nonpriority message pending interrupts
+         *      0x40 - Flag to allow priority message pending interrupts
+         *      0x20 - Flag to allow nonpriority message completion interrupts
+         *      0x10 - Flag to allow priority message completion interrupts
+         *      0x08 - Flag to allow IUCV control interrupts
+         */
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->set_mask.ipmask = 0xf8;
+        iucv_call_b2f0(IUCV_SETMASK, parm);
+
+        /* Set indication that iucv interrupts are allowed for this cpu. */
+        cpu_set(cpu, iucv_irq_cpumask);
+}
+
+/**
+ * iucv_block_cpu
+ * @data: unused
+ *
+ * Block iucv interrupts on this cpu.
+ */
+static void iucv_block_cpu(void *data)
+{
+        int cpu = smp_processor_id();
+        union iucv_param *parm;
+
+        /* Disable all iucv interrupts. */
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        iucv_call_b2f0(IUCV_SETMASK, parm);
+
+        /* Clear indication that iucv interrupts are allowed for this cpu. */
+        cpu_clear(cpu, iucv_irq_cpumask);
+}
+
+/**
+ * iucv_declare_cpu
+ * @data: unused
+ *
+ * Declare a interupt buffer on this cpu.
+ */
+static void iucv_declare_cpu(void *data)
+{
+        int cpu = smp_processor_id();
+        union iucv_param *parm;
+        int rc;
+
+        if (cpu_isset(cpu, iucv_buffer_cpumask))
+                return;
+
+        /* Declare interrupt buffer. */
+        parm = percpu_ptr(iucv_param, cpu);
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->db.ipbfadr1 = virt_to_phys(percpu_ptr(iucv_irq_data, cpu));
+        rc = iucv_call_b2f0(IUCV_DECLARE_BUFFER, parm);
+        if (rc) {
+                char *err = "Unknown";
+                switch(rc) {
+                case 0x03:
+                        err = "Directory error";
+                        break;
+                case 0x0a:
+                        err = "Invalid length";
+                        break;
+                case 0x13:
+                        err = "Buffer already exists";
+                        break;
+                case 0x3e:
+                        err = "Buffer overlap";
+                        break;
+                case 0x5c:
+                        err = "Paging or storage error";
+                        break;
+                }
+                printk(KERN_WARNING "iucv_register: iucv_declare_buffer "
+                       "on cpu %i returned error 0x%02x (%s)\n", cpu, rc, err);
+                return;
+        }
+
+        /* Set indication that an iucv buffer exists for this cpu. */
+        cpu_set(cpu, iucv_buffer_cpumask);
+
+        if (iucv_nonsmp_handler == 0 || cpus_empty(iucv_irq_cpumask))
+                /* Enable iucv interrupts on this cpu. */
+                iucv_allow_cpu(NULL);
+        else
+                /* Disable iucv interrupts on this cpu. */
+                iucv_block_cpu(NULL);
+}
+
+/**
+ * iucv_retrieve_cpu
+ * @data: unused
+ *
+ * Retrieve interrupt buffer on this cpu.
+ */
+static void iucv_retrieve_cpu(void *data)
+{
+        int cpu = smp_processor_id();
+        union iucv_param *parm;
+
+        if (!cpu_isset(cpu, iucv_buffer_cpumask))
+                return;
+
+        /* Block iucv interrupts. */
+        iucv_block_cpu(NULL);
+
+        /* Retrieve interrupt buffer. */
+        parm = percpu_ptr(iucv_param, cpu);
+        iucv_call_b2f0(IUCV_RETRIEVE_BUFFER, parm);
+
+        /* Clear indication that an iucv buffer exists for this cpu. */
+        cpu_clear(cpu, iucv_buffer_cpumask);
+}
+
+/**
+ * iucv_setmask_smp
+ *
+ * Allow iucv interrupts on all cpus.
+ */
+static void iucv_setmask_mp(void)
+{
+        int cpu;
+
+        for_each_online_cpu(cpu)
+                /* Enable all cpus with a declared buffer. */
+                if (cpu_isset(cpu, iucv_buffer_cpumask) &&
+                    !cpu_isset(cpu, iucv_irq_cpumask))
+                        smp_call_function_on(iucv_allow_cpu, NULL, 0, 1, cpu);
+}
+
+/**
+ * iucv_setmask_up
+ *
+ * Allow iucv interrupts on a single cpus.
+ */
+static void iucv_setmask_up(void)
+{
+        cpumask_t cpumask;
+        int cpu;
+
+        /* Disable all cpu but the first in cpu_irq_cpumask. */
+        cpumask = iucv_irq_cpumask;
+        cpu_clear(first_cpu(iucv_irq_cpumask), cpumask);
+        for_each_cpu_mask(cpu, cpumask)
+                smp_call_function_on(iucv_block_cpu, NULL, 0, 1, cpu);
+}
+
+/**
+ * iucv_enable
+ *
+ * This function makes iucv ready for use. It allocates the pathid
+ * table, declares an iucv interrupt buffer and enables the iucv
+ * interrupts. Called when the first user has registered an iucv
+ * handler.
+ */
+static int iucv_enable(void)
+{
+        size_t alloc_size;
+        int cpu, rc;
+
+        rc = -ENOMEM;
+        alloc_size = iucv_max_pathid * sizeof(struct iucv_path);
+        iucv_path_table = kzalloc(alloc_size, GFP_KERNEL);
+        if (!iucv_path_table)
+                goto out;
+        /* Declare per cpu buffers. */
+        rc = -EIO;
+        for_each_online_cpu(cpu)
+                smp_call_function_on(iucv_declare_cpu, NULL, 0, 1, cpu);
+        if (cpus_empty(iucv_buffer_cpumask))
+                /* No cpu could declare an iucv buffer. */
+                goto out_path;
+        return 0;
+
+out_path:
+        kfree(iucv_path_table);
+out:
+        return rc;
+}
+
+/**
+ * iucv_disable
+ *
+ * This function shuts down iucv. It disables iucv interrupts, retrieves
+ * the iucv interrupt buffer and frees the pathid table. Called after the
+ * last user unregister its iucv handler.
+ */
+static void iucv_disable(void)
+{
+        on_each_cpu(iucv_retrieve_cpu, NULL, 0, 1);
+        kfree(iucv_path_table);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
+                                     unsigned long action, void *hcpu)
+{
+        cpumask_t cpumask;
+        long cpu = (long) hcpu;
+
+        switch (action) {
+        case CPU_UP_PREPARE:
+                if (!percpu_populate(iucv_irq_data,
+                                     sizeof(struct iucv_irq_data),
+                                     GFP_KERNEL|GFP_DMA, cpu))
+                        return NOTIFY_BAD;
+                if (!percpu_populate(iucv_param, sizeof(union iucv_param),
+                                     GFP_KERNEL|GFP_DMA, cpu)) {
+                        percpu_depopulate(iucv_irq_data, cpu);
+                        return NOTIFY_BAD;
+                }
+                break;
+        case CPU_UP_CANCELED:
+        case CPU_DEAD:
+                percpu_depopulate(iucv_param, cpu);
+                percpu_depopulate(iucv_irq_data, cpu);
+                break;
+        case CPU_ONLINE:
+        case CPU_DOWN_FAILED:
+                smp_call_function_on(iucv_declare_cpu, NULL, 0, 1, cpu);
+                break;
+        case CPU_DOWN_PREPARE:
+                cpumask = iucv_buffer_cpumask;
+                cpu_clear(cpu, cpumask);
+                if (cpus_empty(cpumask))
+                        /* Can't offline last IUCV enabled cpu. */
+                        return NOTIFY_BAD;
+                smp_call_function_on(iucv_retrieve_cpu, NULL, 0, 1, cpu);
+                if (cpus_empty(iucv_irq_cpumask))
+                        smp_call_function_on(iucv_allow_cpu, NULL, 0, 1,
+                                             first_cpu(iucv_buffer_cpumask));
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block iucv_cpu_notifier = {
+        .notifier_call = iucv_cpu_notify,
+};
+#endif
+
+/**
+ * iucv_sever_pathid
+ * @pathid: path identification number.
+ * @userdata: 16-bytes of user data.
+ *
+ * Sever an iucv path to free up the pathid. Used internally.
+ */
+static int iucv_sever_pathid(u16 pathid, u8 userdata[16])
+{
+        union iucv_param *parm;
+
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (userdata)
+                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
+        parm->ctrl.ippathid = pathid;
+        return iucv_call_b2f0(IUCV_SEVER, parm);
+}
+
+/**
+ * __iucv_cleanup_pathid
+ * @dummy: unused dummy argument
+ *
+ * Nop function called via smp_call_function to force work items from
+ * pending external iucv interrupts to the work queue.
+ */
+static void __iucv_cleanup_pathid(void *dummy)
+{
+}
+
+/**
+ * iucv_cleanup_pathid
+ * @pathid: 16 bit pathid
+ *
+ * Function called after a path has been severed to find all remaining
+ * work items for the now stale pathid. The caller needs to hold the
+ * iucv_table_lock.
+ */
+static void iucv_cleanup_pathid(u16 pathid)
+{
+        struct iucv_work *p, *n;
+
+        /*
+         * Path is severed, the pathid can be reused immediatly on
+         * a iucv connect or a connection pending interrupt.
+         * iucv_path_connect and connection pending interrupt will
+         * wait until the iucv_table_lock is released before the
+         * recycled pathid enters the system.
+         * Force remaining interrupts to the work queue, then
+         * scan the work queue for items of this path.
+         */
+        smp_call_function(__iucv_cleanup_pathid, NULL, 0, 1);
+        spin_lock_irq(&iucv_work_lock);
+        list_for_each_entry_safe(p, n, &iucv_work_queue, list) {
+                /* Remove work items for pathid except connection pending */
+                if (p->data.ippathid == pathid && p->data.iptype != 0x01) {
+                        list_del(&p->list);
+                        kfree(p);
+                }
+        }
+        spin_unlock_irq(&iucv_work_lock);
+}
+
+/**
+ * iucv_register:
+ * @handler: address of iucv handler structure
+ * @smp: != 0 indicates that the handler can deal with out of order messages
+ *
+ * Registers a driver with IUCV.
+ *
+ * Returns 0 on success, -ENOMEM if the memory allocation for the pathid
+ * table failed, or -EIO if IUCV_DECLARE_BUFFER failed on all cpus.
+ */
+int iucv_register(struct iucv_handler *handler, int smp)
+{
+        int rc;
+
+        if (!iucv_available)
+                return -ENOSYS;
+        mutex_lock(&iucv_register_mutex);
+        if (!smp)
+                iucv_nonsmp_handler++;
+        if (list_empty(&iucv_handler_list)) {
+                rc = iucv_enable();
+                if (rc)
+                        goto out_mutex;
+        } else if (!smp && iucv_nonsmp_handler == 1)
+                iucv_setmask_up();
+        INIT_LIST_HEAD(&handler->paths);
+
+        spin_lock_irq(&iucv_table_lock);
+        list_add_tail(&handler->list, &iucv_handler_list);
+        spin_unlock_irq(&iucv_table_lock);
+        rc = 0;
+out_mutex:
+        mutex_unlock(&iucv_register_mutex);
+        return rc;
+}
+
+/**
+ * iucv_unregister
+ * @handler:  address of iucv handler structure
+ * @smp: != 0 indicates that the handler can deal with out of order messages
+ *
+ * Unregister driver from IUCV.
+ */
+void iucv_unregister(struct iucv_handler *handler, int smp)
+{
+        struct iucv_path *p, *n;
+
+        mutex_lock(&iucv_register_mutex);
+        spin_lock_bh(&iucv_table_lock);
+        /* Remove handler from the iucv_handler_list. */
+        list_del_init(&handler->list);
+        /* Sever all pathids still refering to the handler. */
+        list_for_each_entry_safe(p, n, &handler->paths, list) {
+                iucv_sever_pathid(p->pathid, NULL);
+                iucv_path_table[p->pathid] = NULL;
+                list_del(&p->list);
+                iucv_cleanup_pathid(p->pathid);
+                iucv_path_free(p);
+        }
+        spin_unlock_bh(&iucv_table_lock);
+        if (!smp)
+                iucv_nonsmp_handler--;
+        if (list_empty(&iucv_handler_list))
+                iucv_disable();
+        else if (!smp && iucv_nonsmp_handler == 0)
+                iucv_setmask_mp();
+        mutex_unlock(&iucv_register_mutex);
+}
+
+/**
+ * iucv_path_accept
+ * @path: address of iucv path structure
+ * @handler: address of iucv handler structure
+ * @userdata: 16 bytes of data reflected to the communication partner
+ * @private: private data passed to interrupt handlers for this path
+ *
+ * This function is issued after the user received a connection pending
+ * external interrupt and now wishes to complete the IUCV communication path.
+ *
+ * Returns the result of the CP IUCV call.
+ */
+int iucv_path_accept(struct iucv_path *path, struct iucv_handler *handler,
+                     u8 userdata[16], void *private)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        /* Prepare parameter block. */
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->ctrl.ippathid = path->pathid;
+        parm->ctrl.ipmsglim = path->msglim;
+        if (userdata)
+                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
+        parm->ctrl.ipflags1 = path->flags;
+
+        rc = iucv_call_b2f0(IUCV_ACCEPT, parm);
+        if (!rc) {
+                path->private = private;
+                path->msglim = parm->ctrl.ipmsglim;
+                path->flags = parm->ctrl.ipflags1;
+        }
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_path_connect
+ * @path: address of iucv path structure
+ * @handler: address of iucv handler structure
+ * @userid: 8-byte user identification
+ * @system: 8-byte target system identification
+ * @userdata: 16 bytes of data reflected to the communication partner
+ * @private: private data passed to interrupt handlers for this path
+ *
+ * This function establishes an IUCV path. Although the connect may complete
+ * successfully, you are not able to use the path until you receive an IUCV
+ * Connection Complete external interrupt.
+ *
+ * Returns the result of the CP IUCV call.
+ */
+int iucv_path_connect(struct iucv_path *path, struct iucv_handler *handler,
+                      u8 userid[8], u8 system[8], u8 userdata[16],
+                      void *private)
+{
+        union iucv_param *parm;
+        int rc;
+
+        preempt_disable();
+        if (iucv_tasklet_cpu != smp_processor_id())
+                spin_lock_bh(&iucv_table_lock);
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->ctrl.ipmsglim = path->msglim;
+        parm->ctrl.ipflags1 = path->flags;
+        if (userid) {
+                memcpy(parm->ctrl.ipvmid, userid, sizeof(parm->ctrl.ipvmid));
+                ASCEBC(parm->ctrl.ipvmid, sizeof(parm->ctrl.ipvmid));
+                EBC_TOUPPER(parm->ctrl.ipvmid, sizeof(parm->ctrl.ipvmid));
+        }
+        if (system) {
+                memcpy(parm->ctrl.iptarget, system,
+                       sizeof(parm->ctrl.iptarget));
+                ASCEBC(parm->ctrl.iptarget, sizeof(parm->ctrl.iptarget));
+                EBC_TOUPPER(parm->ctrl.iptarget, sizeof(parm->ctrl.iptarget));
+        }
+        if (userdata)
+                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
+
+        rc = iucv_call_b2f0(IUCV_CONNECT, parm);
+        if (!rc) {
+                if (parm->ctrl.ippathid < iucv_max_pathid) {
+                        path->pathid = parm->ctrl.ippathid;
+                        path->msglim = parm->ctrl.ipmsglim;
+                        path->flags = parm->ctrl.ipflags1;
+                        path->handler = handler;
+                        path->private = private;
+                        list_add_tail(&path->list, &handler->paths);
+                        iucv_path_table[path->pathid] = path;
+                } else {
+                        iucv_sever_pathid(parm->ctrl.ippathid,
+                                          iucv_error_pathid);
+                        rc = -EIO;
+                }
+        }
+        if (iucv_tasklet_cpu != smp_processor_id())
+                spin_unlock_bh(&iucv_table_lock);
+        preempt_enable();
+        return rc;
+}
+
+/**
+ * iucv_path_quiesce:
+ * @path: address of iucv path structure
+ * @userdata: 16 bytes of data reflected to the communication partner
+ *
+ * This function temporarily suspends incoming messages on an IUCV path.
+ * You can later reactivate the path by invoking the iucv_resume function.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_path_quiesce(struct iucv_path *path, u8 userdata[16])
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (userdata)
+                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
+        parm->ctrl.ippathid = path->pathid;
+        rc = iucv_call_b2f0(IUCV_QUIESCE, parm);
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_path_resume:
+ * @path: address of iucv path structure
+ * @userdata: 16 bytes of data reflected to the communication partner
+ *
+ * This function resumes incoming messages on an IUCV path that has
+ * been stopped with iucv_path_quiesce.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_path_resume(struct iucv_path *path, u8 userdata[16])
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (userdata)
+                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
+        parm->ctrl.ippathid = path->pathid;
+        rc = iucv_call_b2f0(IUCV_RESUME, parm);
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_path_sever
+ * @path: address of iucv path structure
+ * @userdata: 16 bytes of data reflected to the communication partner
+ *
+ * This function terminates an IUCV path.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_path_sever(struct iucv_path *path, u8 userdata[16])
+{
+        int rc;
+
+
+        preempt_disable();
+        if (iucv_tasklet_cpu != smp_processor_id())
+                spin_lock_bh(&iucv_table_lock);
+        rc = iucv_sever_pathid(path->pathid, userdata);
+        if (!rc) {
+                iucv_path_table[path->pathid] = NULL;
+                list_del_init(&path->list);
+                iucv_cleanup_pathid(path->pathid);
+        }
+        if (iucv_tasklet_cpu != smp_processor_id())
+                spin_unlock_bh(&iucv_table_lock);
+        preempt_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_purge
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @srccls: source class of message
+ *
+ * Cancels a message you have sent.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_purge(struct iucv_path *path, struct iucv_message *msg,
+                       u32 srccls)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->purge.ippathid = path->pathid;
+        parm->purge.ipmsgid = msg->id;
+        parm->purge.ipsrccls = srccls;
+        parm->purge.ipflags1 = IUCV_IPSRCCLS | IUCV_IPFGMID | IUCV_IPFGPID;
+        rc = iucv_call_b2f0(IUCV_PURGE, parm);
+        if (!rc) {
+                msg->audit = (*(u32 *) &parm->purge.ipaudit) >> 8;
+                msg->tag = parm->purge.ipmsgtag;
+        }
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_receive
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is received (IUCV_IPBUFLST)
+ * @buffer: address of data buffer or address of struct iucv_array
+ * @size: length of data buffer
+ * @residual:
+ *
+ * This function receives messages that are being sent to you over
+ * established paths. This function will deal with RMDATA messages
+ * embedded in struct iucv_message as well.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
+                         u8 flags, void *buffer, size_t size, size_t *residual)
+{
+        union iucv_param *parm;
+        struct iucv_array *array;
+        u8 *rmmsg;
+        size_t copy;
+        int rc;
+
+        if (msg->flags & IUCV_IPRMDATA) {
+                /*
+                 * Message is 8 bytes long and has been stored to the
+                 * message descriptor itself.
+                 */
+                rc = (size < 8) ? 5 : 0;
+                if (residual)
+                        *residual = abs(size - 8);
+                rmmsg = msg->rmmsg;
+                if (flags & IUCV_IPBUFLST) {
+                        /* Copy to struct iucv_array. */
+                        size = (size < 8) ? size : 8;
+                        for (array = buffer; size > 0; array++) {
+                                copy = min_t(size_t, size, array->length);
+                                memcpy((u8 *)(addr_t) array->address,
+                                       rmmsg, copy);
+                                rmmsg += copy;
+                                size -= copy;
+                        }
+                } else {
+                        /* Copy to direct buffer. */
+                        memcpy(buffer, rmmsg, min_t(size_t, size, 8));
+                }
+                return 0;
+        }
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->db.ipbfadr1 = (u32)(addr_t) buffer;
+        parm->db.ipbfln1f = (u32) size;
+        parm->db.ipmsgid = msg->id;
+        parm->db.ippathid = path->pathid;
+        parm->db.iptrgcls = msg->class;
+        parm->db.ipflags1 = (flags | IUCV_IPFGPID |
+                             IUCV_IPFGMID | IUCV_IPTRGCLS);
+        rc = iucv_call_b2f0(IUCV_RECEIVE, parm);
+        if (!rc || rc == 5) {
+                msg->flags = parm->db.ipflags1;
+                if (residual)
+                        *residual = parm->db.ipbfln1f;
+        }
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_reject
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ *
+ * The reject function refuses a specified message. Between the time you
+ * are notified of a message and the time that you complete the message,
+ * the message may be rejected.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_reject(struct iucv_path *path, struct iucv_message *msg)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        parm->db.ippathid = path->pathid;
+        parm->db.ipmsgid = msg->id;
+        parm->db.iptrgcls = msg->class;
+        parm->db.ipflags1 = (IUCV_IPTRGCLS | IUCV_IPFGMID | IUCV_IPFGPID);
+        rc = iucv_call_b2f0(IUCV_REJECT, parm);
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_reply
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the reply is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
+ * @reply: address of reply data buffer or address of struct iucv_array
+ * @size: length of reply data buffer
+ *
+ * This function responds to the two-way messages that you receive. You
+ * must identify completely the message to which you wish to reply. ie,
+ * pathid, msgid, and trgcls. Prmmsg signifies the data is moved into
+ * the parameter list.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_reply(struct iucv_path *path, struct iucv_message *msg,
+                       u8 flags, void *reply, size_t size)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (flags & IUCV_IPRMDATA) {
+                parm->dpl.ippathid = path->pathid;
+                parm->dpl.ipflags1 = flags;
+                parm->dpl.ipmsgid = msg->id;
+                parm->dpl.iptrgcls = msg->class;
+                memcpy(parm->dpl.iprmmsg, reply, min_t(size_t, size, 8));
+        } else {
+                parm->db.ipbfadr1 = (u32)(addr_t) reply;
+                parm->db.ipbfln1f = (u32) size;
+                parm->db.ippathid = path->pathid;
+                parm->db.ipflags1 = flags;
+                parm->db.ipmsgid = msg->id;
+                parm->db.iptrgcls = msg->class;
+        }
+        rc = iucv_call_b2f0(IUCV_REPLY, parm);
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_send
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
+ * @srccls: source class of message
+ * @buffer: address of send buffer or address of struct iucv_array
+ * @size: length of send buffer
+ *
+ * This function transmits data to another application. Data to be
+ * transmitted is in a buffer and this is a one-way message and the
+ * receiver will not reply to the message.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
+                      u8 flags, u32 srccls, void *buffer, size_t size)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (flags & IUCV_IPRMDATA) {
+                /* Message of 8 bytes can be placed into the parameter list. */
+                parm->dpl.ippathid = path->pathid;
+                parm->dpl.ipflags1 = flags | IUCV_IPNORPY;
+                parm->dpl.iptrgcls = msg->class;
+                parm->dpl.ipsrccls = srccls;
+                parm->dpl.ipmsgtag = msg->tag;
+                memcpy(parm->dpl.iprmmsg, buffer, 8);
+        } else {
+                parm->db.ipbfadr1 = (u32)(addr_t) buffer;
+                parm->db.ipbfln1f = (u32) size;
+                parm->db.ippathid = path->pathid;
+                parm->db.ipflags1 = flags | IUCV_IPNORPY;
+                parm->db.iptrgcls = msg->class;
+                parm->db.ipsrccls = srccls;
+                parm->db.ipmsgtag = msg->tag;
+        }
+        rc = iucv_call_b2f0(IUCV_SEND, parm);
+        if (!rc)
+                msg->id = parm->db.ipmsgid;
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_message_send2way
+ * @path: address of iucv path structure
+ * @msg: address of iucv msg structure
+ * @flags: how the message is sent and the reply is received
+ *         (IUCV_IPRMDATA, IUCV_IPBUFLST, IUCV_IPPRTY, IUCV_ANSLST)
+ * @srccls: source class of message
+ * @buffer: address of send buffer or address of struct iucv_array
+ * @size: length of send buffer
+ * @ansbuf: address of answer buffer or address of struct iucv_array
+ * @asize: size of reply buffer
+ *
+ * This function transmits data to another application. Data to be
+ * transmitted is in a buffer. The receiver of the send is expected to
+ * reply to the message and a buffer is provided into which IUCV moves
+ * the reply to this message.
+ *
+ * Returns the result from the CP IUCV call.
+ */
+int iucv_message_send2way(struct iucv_path *path, struct iucv_message *msg,
+                          u8 flags, u32 srccls, void *buffer, size_t size,
+                          void *answer, size_t asize, size_t *residual)
+{
+        union iucv_param *parm;
+        int rc;
+
+        local_bh_disable();
+        parm = percpu_ptr(iucv_param, smp_processor_id());
+        memset(parm, 0, sizeof(union iucv_param));
+        if (flags & IUCV_IPRMDATA) {
+                parm->dpl.ippathid = path->pathid;
+                parm->dpl.ipflags1 = path->flags;       /* priority message */
+                parm->dpl.iptrgcls = msg->class;
+                parm->dpl.ipsrccls = srccls;
+                parm->dpl.ipmsgtag = msg->tag;
+                parm->dpl.ipbfadr2 = (u32)(addr_t) answer;
+                parm->dpl.ipbfln2f = (u32) asize;
+                memcpy(parm->dpl.iprmmsg, buffer, 8);
+        } else {
+                parm->db.ippathid = path->pathid;
+                parm->db.ipflags1 = path->flags;        /* priority message */
+                parm->db.iptrgcls = msg->class;
+                parm->db.ipsrccls = srccls;
+                parm->db.ipmsgtag = msg->tag;
+                parm->db.ipbfadr1 = (u32)(addr_t) buffer;
+                parm->db.ipbfln1f = (u32) size;
+                parm->db.ipbfadr2 = (u32)(addr_t) answer;
+                parm->db.ipbfln2f = (u32) asize;
+        }
+        rc = iucv_call_b2f0(IUCV_SEND, parm);
+        if (!rc)
+                msg->id = parm->db.ipmsgid;
+        local_bh_enable();
+        return rc;
+}
+
+/**
+ * iucv_path_pending
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process connection pending work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_path_pending {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iptype;
+        u16 ipmsglim;
+        u16 res1;
+        u8  ipvmid[8];
+        u8  ipuser[16];
+        u32 res3;
+        u8  ippollfg;
+        u8  res4[3];
+} __attribute__ ((packed));
+
+static void iucv_path_pending(struct iucv_irq_data *data)
+{
+        struct iucv_path_pending *ipp = (void *) data;
+        struct iucv_handler *handler;
+        struct iucv_path *path;
+        char *error;
+
+        BUG_ON(iucv_path_table[ipp->ippathid]);
+        /* New pathid, handler found. Create a new path struct. */
+        error = iucv_error_no_memory;
+        path = iucv_path_alloc(ipp->ipmsglim, ipp->ipflags1, GFP_ATOMIC);
+        if (!path)
+                goto out_sever;
+        path->pathid = ipp->ippathid;
+        iucv_path_table[path->pathid] = path;
+        EBCASC(ipp->ipvmid, 8);
+
+        /* Call registered handler until one is found that wants the path. */
+        list_for_each_entry(handler, &iucv_handler_list, list) {
+                if (!handler->path_pending)
+                        continue;
+                /*
+                 * Add path to handler to allow a call to iucv_path_sever
+                 * inside the path_pending function. If the handler returns
+                 * an error remove the path from the handler again.
+                 */
+                list_add(&path->list, &handler->paths);
+                path->handler = handler;
+                if (!handler->path_pending(path, ipp->ipvmid, ipp->ipuser))
+                        return;
+                list_del(&path->list);
+                path->handler = NULL;
+        }
+        /* No handler wanted the path. */
+        iucv_path_table[path->pathid] = NULL;
+        iucv_path_free(path);
+        error = iucv_error_no_listener;
+out_sever:
+        iucv_sever_pathid(ipp->ippathid, error);
+}
+
+/**
+ * iucv_path_complete
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process connection complete work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_path_complete {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iptype;
+        u16 ipmsglim;
+        u16 res1;
+        u8  res2[8];
+        u8  ipuser[16];
+        u32 res3;
+        u8  ippollfg;
+        u8  res4[3];
+} __attribute__ ((packed));
+
+static void iucv_path_complete(struct iucv_irq_data *data)
+{
+        struct iucv_path_complete *ipc = (void *) data;
+        struct iucv_path *path = iucv_path_table[ipc->ippathid];
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->path_complete)
+                path->handler->path_complete(path, ipc->ipuser);
+}
+
+/**
+ * iucv_path_severed
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process connection severed work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_path_severed {
+        u16 ippathid;
+        u8  res1;
+        u8  iptype;
+        u32 res2;
+        u8  res3[8];
+        u8  ipuser[16];
+        u32 res4;
+        u8  ippollfg;
+        u8  res5[3];
+} __attribute__ ((packed));
+
+static void iucv_path_severed(struct iucv_irq_data *data)
+{
+        struct iucv_path_severed *ips = (void *) data;
+        struct iucv_path *path = iucv_path_table[ips->ippathid];
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->path_severed)
+                path->handler->path_severed(path, ips->ipuser);
+        else {
+                iucv_sever_pathid(path->pathid, NULL);
+                iucv_path_table[path->pathid] = NULL;
+                list_del_init(&path->list);
+                iucv_cleanup_pathid(path->pathid);
+                iucv_path_free(path);
+        }
+}
+
+/**
+ * iucv_path_quiesced
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process connection quiesced work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_path_quiesced {
+        u16 ippathid;
+        u8  res1;
+        u8  iptype;
+        u32 res2;
+        u8  res3[8];
+        u8  ipuser[16];
+        u32 res4;
+        u8  ippollfg;
+        u8  res5[3];
+} __attribute__ ((packed));
+
+static void iucv_path_quiesced(struct iucv_irq_data *data)
+{
+        struct iucv_path_quiesced *ipq = (void *) data;
+        struct iucv_path *path = iucv_path_table[ipq->ippathid];
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->path_quiesced)
+                path->handler->path_quiesced(path, ipq->ipuser);
+}
+
+/**
+ * iucv_path_resumed
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process connection resumed work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_path_resumed {
+        u16 ippathid;
+        u8  res1;
+        u8  iptype;
+        u32 res2;
+        u8  res3[8];
+        u8  ipuser[16];
+        u32 res4;
+        u8  ippollfg;
+        u8  res5[3];
+} __attribute__ ((packed));
+
+static void iucv_path_resumed(struct iucv_irq_data *data)
+{
+        struct iucv_path_resumed *ipr = (void *) data;
+        struct iucv_path *path = iucv_path_table[ipr->ippathid];
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->path_resumed)
+                path->handler->path_resumed(path, ipr->ipuser);
+}
+
+/**
+ * iucv_message_complete
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process message complete work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_message_complete {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iptype;
+        u32 ipmsgid;
+        u32 ipaudit;
+        u8  iprmmsg[8];
+        u32 ipsrccls;
+        u32 ipmsgtag;
+        u32 res;
+        u32 ipbfln2f;
+        u8  ippollfg;
+        u8  res2[3];
+} __attribute__ ((packed));
+
+static void iucv_message_complete(struct iucv_irq_data *data)
+{
+        struct iucv_message_complete *imc = (void *) data;
+        struct iucv_path *path = iucv_path_table[imc->ippathid];
+        struct iucv_message msg;
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->message_complete) {
+                msg.flags = imc->ipflags1;
+                msg.id = imc->ipmsgid;
+                msg.audit = imc->ipaudit;
+                memcpy(msg.rmmsg, imc->iprmmsg, 8);
+                msg.class = imc->ipsrccls;
+                msg.tag = imc->ipmsgtag;
+                msg.length = imc->ipbfln2f;
+                path->handler->message_complete(path, &msg);
+        }
+}
+
+/**
+ * iucv_message_pending
+ * @data: Pointer to external interrupt buffer
+ *
+ * Process message pending work item. Called from tasklet while holding
+ * iucv_table_lock.
+ */
+struct iucv_message_pending {
+        u16 ippathid;
+        u8  ipflags1;
+        u8  iptype;
+        u32 ipmsgid;
+        u32 iptrgcls;
+        union {
+                u32 iprmmsg1_u32;
+                u8  iprmmsg1[4];
+        } ln1msg1;
+        union {
+                u32 ipbfln1f;
+                u8  iprmmsg2[4];
+        } ln1msg2;
+        u32 res1[3];
+        u32 ipbfln2f;
+        u8  ippollfg;
+        u8  res2[3];
+} __attribute__ ((packed));
+
+static void iucv_message_pending(struct iucv_irq_data *data)
+{
+        struct iucv_message_pending *imp = (void *) data;
+        struct iucv_path *path = iucv_path_table[imp->ippathid];
+        struct iucv_message msg;
+
+        BUG_ON(!path || !path->handler);
+        if (path->handler->message_pending) {
+                msg.flags = imp->ipflags1;
+                msg.id = imp->ipmsgid;
+                msg.class = imp->iptrgcls;
+                if (imp->ipflags1 & IUCV_IPRMDATA) {
+                        memcpy(msg.rmmsg, imp->ln1msg1.iprmmsg1, 8);
+                        msg.length = 8;
+                } else
+                        msg.length = imp->ln1msg2.ipbfln1f;
+                msg.reply_size = imp->ipbfln2f;
+                path->handler->message_pending(path, &msg);
+        }
+}
+
+/**
+ * iucv_tasklet_handler:
+ *
+ * This tasklet loops over the queue of irq buffers created by
+ * iucv_external_interrupt, calls the appropriate action handler
+ * and then frees the buffer.
+ */
+static void iucv_tasklet_handler(unsigned long ignored)
+{
+        typedef void iucv_irq_fn(struct iucv_irq_data *);
+        static iucv_irq_fn *irq_fn[] = {
+                [0x01] = iucv_path_pending,
+                [0x02] = iucv_path_complete,
+                [0x03] = iucv_path_severed,
+                [0x04] = iucv_path_quiesced,
+                [0x05] = iucv_path_resumed,
+                [0x06] = iucv_message_complete,
+                [0x07] = iucv_message_complete,
+                [0x08] = iucv_message_pending,
+                [0x09] = iucv_message_pending,
+        };
+        struct iucv_work *p;
+
+        /* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
+        spin_lock(&iucv_table_lock);
+        iucv_tasklet_cpu = smp_processor_id();
+
+        spin_lock_irq(&iucv_work_lock);
+        while (!list_empty(&iucv_work_queue)) {
+                p = list_entry(iucv_work_queue.next, struct iucv_work, list);
+                list_del_init(&p->list);
+                spin_unlock_irq(&iucv_work_lock);
+                irq_fn[p->data.iptype](&p->data);
+                kfree(p);
+                spin_lock_irq(&iucv_work_lock);
+        }
+        spin_unlock_irq(&iucv_work_lock);
+
+        iucv_tasklet_cpu = -1;
+        spin_unlock(&iucv_table_lock);
+}
+
+/**
+ * iucv_external_interrupt
+ * @code: irq code
+ *
+ * Handles external interrupts coming in from CP.
+ * Places the interrupt buffer on a queue and schedules iucv_tasklet_handler().
+ */
+static void iucv_external_interrupt(u16 code)
+{
+        struct iucv_irq_data *p;
+        struct iucv_work *work;
+
+        p = percpu_ptr(iucv_irq_data, smp_processor_id());
+        if (p->ippathid >= iucv_max_pathid) {
+                printk(KERN_WARNING "iucv_do_int: Got interrupt with "
+                       "pathid %d > max_connections (%ld)\n",
+                       p->ippathid, iucv_max_pathid - 1);
+                iucv_sever_pathid(p->ippathid, iucv_error_no_listener);
+                return;
+        }
+        if (p->iptype  < 0x01 || p->iptype > 0x09) {
+                printk(KERN_ERR "iucv_do_int: unknown iucv interrupt\n");
+                return;
+        }
+        work = kmalloc(sizeof(struct iucv_work), GFP_ATOMIC);
+        if (!work) {
+                printk(KERN_WARNING "iucv_external_interrupt: out of memory\n");
+                return;
+        }
+        memcpy(&work->data, p, sizeof(work->data));
+        spin_lock(&iucv_work_lock);
+        list_add_tail(&work->list, &iucv_work_queue);
+        spin_unlock(&iucv_work_lock);
+        tasklet_schedule(&iucv_tasklet);
+}
+
+/**
+ * iucv_init
+ *
+ * Allocates and initializes various data structures.
+ */
+static int iucv_init(void)
+{
+        int rc;
+
+        if (!MACHINE_IS_VM) {
+                rc = -EPROTONOSUPPORT;
+                goto out;
+        }
+        rc = iucv_query_maxconn();
+        if (rc)
+                goto out;
+        rc = register_external_interrupt (0x4000, iucv_external_interrupt);
+        if (rc)
+                goto out;
+        rc = bus_register(&iucv_bus);
+        if (rc)
+                goto out_int;
+        iucv_root = s390_root_dev_register("iucv");
+        if (IS_ERR(iucv_root)) {
+                rc = PTR_ERR(iucv_root);
+                goto out_bus;
+        }
+        /* Note: GFP_DMA used used to get memory below 2G */
+        iucv_irq_data = percpu_alloc(sizeof(struct iucv_irq_data),
+                                     GFP_KERNEL|GFP_DMA);
+        if (!iucv_irq_data) {
+                rc = -ENOMEM;
+                goto out_root;
+        }
+        /* Allocate parameter blocks. */
+        iucv_param = percpu_alloc(sizeof(union iucv_param),
+                                  GFP_KERNEL|GFP_DMA);
+        if (!iucv_param) {
+                rc = -ENOMEM;
+                goto out_extint;
+        }
+        register_hotcpu_notifier(&iucv_cpu_notifier);
+        ASCEBC(iucv_error_no_listener, 16);
+        ASCEBC(iucv_error_no_memory, 16);
+        ASCEBC(iucv_error_pathid, 16);
+        iucv_available = 1;
+        return 0;
+
+out_extint:
+        percpu_free(iucv_irq_data);
+out_root:
+        s390_root_dev_unregister(iucv_root);
+out_bus:
+        bus_unregister(&iucv_bus);
+out_int:
+        unregister_external_interrupt(0x4000, iucv_external_interrupt);
+out:
+        return rc;
+}
+
+/**
+ * iucv_exit
+ *
+ * Frees everything allocated from iucv_init.
+ */
+static void iucv_exit(void)
+{
+        struct iucv_work *p, *n;
+
+        spin_lock_irq(&iucv_work_lock);
+        list_for_each_entry_safe(p, n, &iucv_work_queue, list)
+                kfree(p);
+        spin_unlock_irq(&iucv_work_lock);
+        unregister_hotcpu_notifier(&iucv_cpu_notifier);
+        percpu_free(iucv_param);
+        percpu_free(iucv_irq_data);
+        s390_root_dev_unregister(iucv_root);
+        bus_unregister(&iucv_bus);
+        unregister_external_interrupt(0x4000, iucv_external_interrupt);
+}
+
+subsys_initcall(iucv_init);
+module_exit(iucv_exit);
+
+/**
+ * Export all public stuff
+ */
+EXPORT_SYMBOL (iucv_bus);
+EXPORT_SYMBOL (iucv_root);
+EXPORT_SYMBOL (iucv_register);
+EXPORT_SYMBOL (iucv_unregister);
+EXPORT_SYMBOL (iucv_path_accept);
+EXPORT_SYMBOL (iucv_path_connect);
+EXPORT_SYMBOL (iucv_path_quiesce);
+EXPORT_SYMBOL (iucv_path_sever);
+EXPORT_SYMBOL (iucv_message_purge);
+EXPORT_SYMBOL (iucv_message_receive);
+EXPORT_SYMBOL (iucv_message_reject);
+EXPORT_SYMBOL (iucv_message_reply);
+EXPORT_SYMBOL (iucv_message_send);
+EXPORT_SYMBOL (iucv_message_send2way);
+
+MODULE_AUTHOR("(C) 2001 IBM Corp. by Fritz Elfert (felfert@millenux.com)");
+MODULE_DESCRIPTION("Linux for S/390 IUCV lowlevel driver");
+MODULE_LICENSE("GPL");