/* -*- linux-c -*-
 *
 *  iSeries Virtual I/O Message Path code
 *
 *  Authors: Dave Boutcher <boutcher@us.ibm.com>
 *           Ryan Arnold <ryanarn@us.ibm.com>
 *           Colin Devilbiss <devilbis@us.ibm.com>
 *
 * (C) Copyright 2000-2005 IBM Corporation
 *
 * This code is used by the iSeries virtual disk, cd,
 * tape, and console to communicate with OS/400 in another
 * partition.
 *
 * 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 of the
 * License, or (at your option) anyu 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/vmalloc.h>
#include <linux/string.h>
#include <linux/proc_fs.h>
#include <linux/dma-mapping.h>
#include <linux/wait.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/completion.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/iseries/hv_types.h>
#include <asm/iseries/hv_lp_event.h>
#include <asm/iseries/hv_lp_config.h>
#include <asm/iseries/mf.h>
#include <asm/iseries/vio.h>

/* Status of the path to each other partition in the system.
 * This is overkill, since we will only ever establish connections
 * to our hosting partition and the primary partition on the system.
 * But this allows for other support in the future.
 */
static struct viopathStatus {
        int isOpen;             /* Did we open the path?            */
        int isActive;           /* Do we have a mon msg outstanding */
        int users[VIO_MAX_SUBTYPES];
        HvLpInstanceId mSourceInst;
        HvLpInstanceId mTargetInst;
        int numberAllocated;
} viopathStatus[HVMAXARCHITECTEDLPS];

static DEFINE_SPINLOCK(statuslock);

/*
 * For each kind of event we allocate a buffer that is
 * guaranteed not to cross a page boundary
 */
static unsigned char event_buffer[VIO_MAX_SUBTYPES * 256]
        __attribute__((__aligned__(4096)));
static atomic_t event_buffer_available[VIO_MAX_SUBTYPES];
static int event_buffer_initialised;

static void handleMonitorEvent(struct HvLpEvent *event);

/*
 * We use this structure to handle asynchronous responses.  The caller
 * blocks on the semaphore and the handler posts the semaphore.  However,
 * if system_state is not SYSTEM_RUNNING, then wait_atomic is used ...
 */
struct alloc_parms {
        struct completion done;
        int number;
        atomic_t wait_atomic;
        int used_wait_atomic;
};

/* Put a sequence number in each mon msg.  The value is not
 * important.  Start at something other than 0 just for
 * readability.  wrapping this is ok.
 */
static u8 viomonseq = 22;

/* Our hosting logical partition.  We get this at startup
 * time, and different modules access this variable directly.
 */
HvLpIndex viopath_hostLp = HvLpIndexInvalid;
EXPORT_SYMBOL(viopath_hostLp);
HvLpIndex viopath_ourLp = HvLpIndexInvalid;
EXPORT_SYMBOL(viopath_ourLp);

/* For each kind of incoming event we set a pointer to a
 * routine to call.
 */
static vio_event_handler_t *vio_handler[VIO_MAX_SUBTYPES];

#define VIOPATH_KERN_WARN       KERN_WARNING "viopath: "
#define VIOPATH_KERN_INFO       KERN_INFO "viopath: "

static int proc_viopath_show(struct seq_file *m, void *v)
{
        char *buf;
        u16 vlanMap;
        dma_addr_t handle;
        HvLpEvent_Rc hvrc;
        DECLARE_COMPLETION(done);
        struct device_node *node;
        const char *sysid;

        buf = kzalloc(HW_PAGE_SIZE, GFP_KERNEL);
        if (!buf)
                return 0;

        handle = iseries_hv_map(buf, HW_PAGE_SIZE, DMA_FROM_DEVICE);

        hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_config | vioconfigget,
                        HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(viopath_hostLp),
                        viopath_targetinst(viopath_hostLp),
                        (u64)(unsigned long)&done, VIOVERSION << 16,
                        ((u64)handle) << 32, HW_PAGE_SIZE, 0, 0);

        if (hvrc != HvLpEvent_Rc_Good)
                printk(VIOPATH_KERN_WARN "hv error on op %d\n", (int)hvrc);

        wait_for_completion(&done);

        vlanMap = HvLpConfig_getVirtualLanIndexMap();

        buf[HW_PAGE_SIZE-1] = '\0';
        seq_printf(m, "%s", buf);

        iseries_hv_unmap(handle, HW_PAGE_SIZE, DMA_FROM_DEVICE);
        kfree(buf);

        seq_printf(m, "AVAILABLE_VETH=%x\n", vlanMap);

        node = of_find_node_by_path("/");
        sysid = NULL;
        if (node != NULL)
                sysid = of_get_property(node, "system-id", NULL);

        if (sysid == NULL)
                seq_printf(m, "SRLNBR=<UNKNOWN>\n");
        else
                /* Skip "IBM," on front of serial number, see dt.c */
                seq_printf(m, "SRLNBR=%s\n", sysid + 4);

        of_node_put(node);

        return 0;
}

static int proc_viopath_open(struct inode *inode, struct file *file)
{
        return single_open(file, proc_viopath_show, NULL);
}

static const struct file_operations proc_viopath_operations = {
        .open           = proc_viopath_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int __init vio_proc_init(void)
{
        if (!firmware_has_feature(FW_FEATURE_ISERIES))
                return 0;

        proc_create("iSeries/config", 0, NULL, &proc_viopath_operations);
        return 0;
}
__initcall(vio_proc_init);

/* See if a given LP is active.  Allow for invalid lps to be passed in
 * and just return invalid
 */
int viopath_isactive(HvLpIndex lp)
{
        if (lp == HvLpIndexInvalid)
                return 0;
        if (lp < HVMAXARCHITECTEDLPS)
                return viopathStatus[lp].isActive;
        else
                return 0;
}
EXPORT_SYMBOL(viopath_isactive);

/*
 * We cache the source and target instance ids for each
 * partition.
 */
HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
{
        return viopathStatus[lp].mSourceInst;
}
EXPORT_SYMBOL(viopath_sourceinst);

HvLpInstanceId viopath_targetinst(HvLpIndex lp)
{
        return viopathStatus[lp].mTargetInst;
}
EXPORT_SYMBOL(viopath_targetinst);

/*
 * Send a monitor message.  This is a message with the acknowledge
 * bit on that the other side will NOT explicitly acknowledge.  When
 * the other side goes down, the hypervisor will acknowledge any
 * outstanding messages....so we will know when the other side dies.
 */
static void sendMonMsg(HvLpIndex remoteLp)
{
        HvLpEvent_Rc hvrc;

        viopathStatus[remoteLp].mSourceInst =
                HvCallEvent_getSourceLpInstanceId(remoteLp,
                                HvLpEvent_Type_VirtualIo);
        viopathStatus[remoteLp].mTargetInst =
                HvCallEvent_getTargetLpInstanceId(remoteLp,
                                HvLpEvent_Type_VirtualIo);

        /*
         * Deliberately ignore the return code here.  if we call this
         * more than once, we don't care.
         */
        vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);

        hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
                        HvLpEvent_AckType_DeferredAck,
                        viopathStatus[remoteLp].mSourceInst,
                        viopathStatus[remoteLp].mTargetInst,
                        viomonseq++, 0, 0, 0, 0, 0);

        if (hvrc == HvLpEvent_Rc_Good)
                viopathStatus[remoteLp].isActive = 1;
        else {
                printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
                                remoteLp);
                viopathStatus[remoteLp].isActive = 0;
        }
}

static void handleMonitorEvent(struct HvLpEvent *event)
{
        HvLpIndex remoteLp;
        int i;

        /*
         * This handler is _also_ called as part of the loop
         * at the end of this routine, so it must be able to
         * ignore NULL events...
         */
        if (!event)
                return;

        /*
         * First see if this is just a normal monitor message from the
         * other partition
         */
        if (hvlpevent_is_int(event)) {
                remoteLp = event->xSourceLp;
                if (!viopathStatus[remoteLp].isActive)
                        sendMonMsg(remoteLp);
                return;
        }

        /*
         * This path is for an acknowledgement; the other partition
         * died
         */
        remoteLp = event->xTargetLp;
        if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
            (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
                printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
                return;
        }

        printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);

        viopathStatus[remoteLp].isActive = 0;

        /*
         * For each active handler, pass them a NULL
         * message to indicate that the other partition
         * died
         */
        for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
                if (vio_handler[i] != NULL)
                        (*vio_handler[i])(NULL);
        }
}

int vio_setHandler(int subtype, vio_event_handler_t *beh)
{
        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
                return -EINVAL;
        if (vio_handler[subtype] != NULL)
                return -EBUSY;
        vio_handler[subtype] = beh;
        return 0;
}
EXPORT_SYMBOL(vio_setHandler);

int vio_clearHandler(int subtype)
{
        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
                return -EINVAL;
        if (vio_handler[subtype] == NULL)
                return -EAGAIN;
        vio_handler[subtype] = NULL;
        return 0;
}
EXPORT_SYMBOL(vio_clearHandler);

static void handleConfig(struct HvLpEvent *event)
{
        if (!event)
                return;
        if (hvlpevent_is_int(event)) {
                printk(VIOPATH_KERN_WARN
                       "unexpected config request from partition %d",
                       event->xSourceLp);

                if (hvlpevent_need_ack(event)) {
                        event->xRc = HvLpEvent_Rc_InvalidSubtype;
                        HvCallEvent_ackLpEvent(event);
                }
                return;
        }

        complete((struct completion *)event->xCorrelationToken);
}

/*
 * Initialization of the hosting partition
 */
void vio_set_hostlp(void)
{
        /*
         * If this has already been set then we DON'T want to either change
         * it or re-register the proc file system
         */
        if (viopath_hostLp != HvLpIndexInvalid)
                return;

        /*
         * Figure out our hosting partition.  This isn't allowed to change
         * while we're active
         */
        viopath_ourLp = HvLpConfig_getLpIndex();
        viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);

        if (viopath_hostLp != HvLpIndexInvalid)
                vio_setHandler(viomajorsubtype_config, handleConfig);
}
EXPORT_SYMBOL(vio_set_hostlp);

static void vio_handleEvent(struct HvLpEvent *event)
{
        HvLpIndex remoteLp;
        int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
                >> VIOMAJOR_SUBTYPE_SHIFT;

        if (hvlpevent_is_int(event)) {
                remoteLp = event->xSourceLp;
                /*
                 * The isActive is checked because if the hosting partition
                 * went down and came back up it would not be active but it
                 * would have different source and target instances, in which
                 * case we'd want to reset them.  This case really protects
                 * against an unauthorized active partition sending interrupts
                 * or acks to this linux partition.
                 */
                if (viopathStatus[remoteLp].isActive
                    && (event->xSourceInstanceId !=
                        viopathStatus[remoteLp].mTargetInst)) {
                        printk(VIOPATH_KERN_WARN
                               "message from invalid partition. "
                               "int msg rcvd, source inst (%d) doesnt match (%d)\n",
                               viopathStatus[remoteLp].mTargetInst,
                               event->xSourceInstanceId);
                        return;
                }

                if (viopathStatus[remoteLp].isActive
                    && (event->xTargetInstanceId !=
                        viopathStatus[remoteLp].mSourceInst)) {
                        printk(VIOPATH_KERN_WARN
                               "message from invalid partition. "
                               "int msg rcvd, target inst (%d) doesnt match (%d)\n",
                               viopathStatus[remoteLp].mSourceInst,
                               event->xTargetInstanceId);
                        return;
                }
        } else {
                remoteLp = event->xTargetLp;
                if (event->xSourceInstanceId !=
                    viopathStatus[remoteLp].mSourceInst) {
                        printk(VIOPATH_KERN_WARN
                               "message from invalid partition. "
                               "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
                               viopathStatus[remoteLp].mSourceInst,
                               event->xSourceInstanceId);
                        return;
                }

                if (event->xTargetInstanceId !=
                    viopathStatus[remoteLp].mTargetInst) {
                        printk(VIOPATH_KERN_WARN
                               "message from invalid partition. "
                               "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
                               viopathStatus[remoteLp].mTargetInst,
                               event->xTargetInstanceId);
                        return;
                }
        }

        if (vio_handler[subtype] == NULL) {
                printk(VIOPATH_KERN_WARN
                       "unexpected virtual io event subtype %d from partition %d\n",
                       event->xSubtype, remoteLp);
                /* No handler.  Ack if necessary */
                if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
                        event->xRc = HvLpEvent_Rc_InvalidSubtype;
                        HvCallEvent_ackLpEvent(event);
                }
                return;
        }

        /* This innocuous little line is where all the real work happens */
        (*vio_handler[subtype])(event);
}

static void viopath_donealloc(void *parm, int number)
{
        struct alloc_parms *parmsp = parm;

        parmsp->number = number;
        if (parmsp->used_wait_atomic)
                atomic_set(&parmsp->wait_atomic, 0);
        else
                complete(&parmsp->done);
}

static int allocateEvents(HvLpIndex remoteLp, int numEvents)
{
        struct alloc_parms parms;

        if (system_state != SYSTEM_RUNNING) {
                parms.used_wait_atomic = 1;
                atomic_set(&parms.wait_atomic, 1);
        } else {
                parms.used_wait_atomic = 0;
                init_completion(&parms.done);
        }
        mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,  /* It would be nice to put a real number here! */
                            numEvents, &viopath_donealloc, &parms);
        if (system_state != SYSTEM_RUNNING) {
                while (atomic_read(&parms.wait_atomic))
                        mb();
        } else
                wait_for_completion(&parms.done);
        return parms.number;
}

int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
{
        int i;
        unsigned long flags;
        int tempNumAllocated;

        if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
                return -EINVAL;

        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
                return -EINVAL;

        spin_lock_irqsave(&statuslock, flags);

        if (!event_buffer_initialised) {
                for (i = 0; i < VIO_MAX_SUBTYPES; i++)
                        atomic_set(&event_buffer_available[i], 1);
                event_buffer_initialised = 1;
        }

        viopathStatus[remoteLp].users[subtype]++;

        if (!viopathStatus[remoteLp].isOpen) {
                viopathStatus[remoteLp].isOpen = 1;
                HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);

                /*
                 * Don't hold the spinlock during an operation that
                 * can sleep.
                 */
                spin_unlock_irqrestore(&statuslock, flags);
                tempNumAllocated = allocateEvents(remoteLp, 1);
                spin_lock_irqsave(&statuslock, flags);

                viopathStatus[remoteLp].numberAllocated += tempNumAllocated;

                if (viopathStatus[remoteLp].numberAllocated == 0) {
                        HvCallEvent_closeLpEventPath(remoteLp,
                                        HvLpEvent_Type_VirtualIo);

                        spin_unlock_irqrestore(&statuslock, flags);
                        return -ENOMEM;
                }

                viopathStatus[remoteLp].mSourceInst =
                        HvCallEvent_getSourceLpInstanceId(remoteLp,
                                        HvLpEvent_Type_VirtualIo);
                viopathStatus[remoteLp].mTargetInst =
                        HvCallEvent_getTargetLpInstanceId(remoteLp,
                                        HvLpEvent_Type_VirtualIo);
                HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
                                          &vio_handleEvent);
                sendMonMsg(remoteLp);
                printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
                                "setting sinst %d, tinst %d\n",
                                remoteLp, viopathStatus[remoteLp].mSourceInst,
                                viopathStatus[remoteLp].mTargetInst);
        }

        spin_unlock_irqrestore(&statuslock, flags);
        tempNumAllocated = allocateEvents(remoteLp, numReq);
        spin_lock_irqsave(&statuslock, flags);
        viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
        spin_unlock_irqrestore(&statuslock, flags);

        return 0;
}
EXPORT_SYMBOL(viopath_open);

int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
{
        unsigned long flags;
        int i;
        int numOpen;
        struct alloc_parms parms;

        if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
                return -EINVAL;

        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
                return -EINVAL;

        spin_lock_irqsave(&statuslock, flags);
        /*
         * If the viopath_close somehow gets called before a
         * viopath_open it could decrement to -1 which is a non
         * recoverable state so we'll prevent this from
         * happening.
         */
        if (viopathStatus[remoteLp].users[subtype] > 0)
                viopathStatus[remoteLp].users[subtype]--;

        spin_unlock_irqrestore(&statuslock, flags);

        parms.used_wait_atomic = 0;
        init_completion(&parms.done);
        mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
                              numReq, &viopath_donealloc, &parms);
        wait_for_completion(&parms.done);

        spin_lock_irqsave(&statuslock, flags);
        for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
                numOpen += viopathStatus[remoteLp].users[i];

        if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
                printk(VIOPATH_KERN_INFO "closing connection to partition %d\n",
                                remoteLp);

                HvCallEvent_closeLpEventPath(remoteLp,
                                             HvLpEvent_Type_VirtualIo);
                viopathStatus[remoteLp].isOpen = 0;
                viopathStatus[remoteLp].isActive = 0;

                for (i = 0; i < VIO_MAX_SUBTYPES; i++)
                        atomic_set(&event_buffer_available[i], 0);
                event_buffer_initialised = 0;
        }
        spin_unlock_irqrestore(&statuslock, flags);
        return 0;
}
EXPORT_SYMBOL(viopath_close);

void *vio_get_event_buffer(int subtype)
{
        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
                return NULL;

        if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
                return &event_buffer[subtype * 256];
        else
                return NULL;
}
EXPORT_SYMBOL(vio_get_event_buffer);

void vio_free_event_buffer(int subtype, void *buffer)
{
        subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
        if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
                printk(VIOPATH_KERN_WARN
                       "unexpected subtype %d freeing event buffer\n", subtype);
                return;
        }

        if (atomic_read(&event_buffer_available[subtype]) != 0) {
                printk(VIOPATH_KERN_WARN
                       "freeing unallocated event buffer, subtype %d\n",
                       subtype);
                return;
        }

        if (buffer != &event_buffer[subtype * 256]) {
                printk(VIOPATH_KERN_WARN
                       "freeing invalid event buffer, subtype %d\n", subtype);
        }

        atomic_set(&event_buffer_available[subtype], 1);
}
EXPORT_SYMBOL(vio_free_event_buffer);

static const struct vio_error_entry vio_no_error =
    { 0, 0, "Non-VIO Error" };
static const struct vio_error_entry vio_unknown_error =
    { 0, EIO, "Unknown Error" };

static const struct vio_error_entry vio_default_errors[] = {
        {0x0001, EIO, "No Connection"},
        {0x0002, EIO, "No Receiver"},
        {0x0003, EIO, "No Buffer Available"},
        {0x0004, EBADRQC, "Invalid Message Type"},
        {0x0000, 0, NULL},
};

const struct vio_error_entry *vio_lookup_rc(
                const struct vio_error_entry *local_table, u16 rc)
{
        const struct vio_error_entry *cur;

        if (!rc)
                return &vio_no_error;
        if (local_table)
                for (cur = local_table; cur->rc; ++cur)
                        if (cur->rc == rc)
                                return cur;
        for (cur = vio_default_errors; cur->rc; ++cur)
                if (cur->rc == rc)
                        return cur;
        return &vio_unknown_error;
}
EXPORT_SYMBOL(vio_lookup_rc);