Merge remote-tracking branch 'origin/master'

[unleashed/lotheac.git] / usr / src / uts / common / io / hotplug / hpcsvc / hpcsvc.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * hot-plug services module
 */

#include <sys/modctl.h>
#include <sys/kmem.h>
#include <sys/sunddi.h>
#include <sys/sunndi.h>
#include <sys/disp.h>
#include <sys/stat.h>
#include <sys/hotplug/hpcsvc.h>
#include <sys/callb.h>

/*
 * debug macros:
 */
#if defined(DEBUG)

int hpcsvc_debug = 0;

static void debug(char *, uintptr_t, uintptr_t, uintptr_t,
        uintptr_t, uintptr_t);

#define DEBUG0(fmt)     \
        debug(fmt, 0, 0, 0, 0, 0);
#define DEBUG1(fmt, a1) \
        debug(fmt, (uintptr_t)(a1), 0, 0, 0, 0);
#define DEBUG2(fmt, a1, a2)     \
        debug(fmt, (uintptr_t)(a1), (uintptr_t)(a2), 0, 0, 0);
#define DEBUG3(fmt, a1, a2, a3) \
        debug(fmt, (uintptr_t)(a1), (uintptr_t)(a2), (uintptr_t)(a3), 0, 0);
#else
#define DEBUG0(fmt)
#define DEBUG1(fmt, a1)
#define DEBUG2(fmt, a1, a2)
#define DEBUG3(fmt, a1, a2, a3)
#endif

/*
 * Definitions for the bus node registration list:
 *
 * The hot-plug service module maintains a linked list of items
 * representing the device bus nodes that have been registered via
 * hpc_nexus_register, or identified as candidates for registration
 * by the bus argument to hpc_slot_register.
 *
 * The head of the linked listed is stored in hpc_bus_list_head. Insertions
 * and removals from the list should be locked with mutex hpc_bus_mutex.
 *
 * Items in the list are allocated/freed with the macros hpc_alloc_bus_entry()
 * and hpc_free_bus_entry().
 *
 * Each item in the list contains the following fields:
 *
 *      bus_dip - pointer to devinfo node of the registering bus
 *
 *      bus_name - device path name of the bus (ie /pci@1f,4000)
 *
 *      bus_callback - bus nexus driver callback function registered
 *              with the bus
 *
 *      bus_registered - a boolean value which is true if the bus has
 *              been registered with hpc_nexus_register, false otherwise
 *
 *      bus_mutex - mutex lock to be held while updating this list entry
 *
 *      bus_slot_list - linked list of the slots registered for this
 *              bus node (see slot list details below)
 *
 *      bus_thread - kernel thread for running slot event handlers for
 *              slots associated with this bus
 *
 *      bus_thread_cv - condition variable for synchronization between
 *              the service routines and the thread for running slot
 *              event handlers
 *
 *      bus_thread_exit - a boolean value used to instruct the thread
 *              for invoking the slot event handlers to exit
 *
 *      bus_slot_event_list_head - the head of the linked list of instances
 *              of slot event handlers to be run
 *              handlers to be invoked
 *
 *      bus_next - pointer to next list entry
 */

typedef struct hpc_bus_entry hpc_bus_entry_t;
typedef struct hpc_slot_entry hpc_slot_entry_t;
typedef struct hpc_event_entry hpc_event_entry_t;

struct hpc_event_entry {
        hpc_slot_entry_t *slotp;
        int event;
        hpc_event_entry_t *next;
};

#define hpc_alloc_event_entry() \
        (hpc_event_entry_t *)kmem_zalloc(sizeof (hpc_event_entry_t), KM_SLEEP)

#define hpc_free_event_entry(a) \
        kmem_free((a), sizeof (hpc_event_entry_t))

struct hpc_bus_entry {
        dev_info_t *bus_dip;
        char bus_name[MAXPATHLEN + 1];
        boolean_t bus_registered;
        kmutex_t bus_mutex;
        int (* bus_callback)(dev_info_t *dip, hpc_slot_t hdl,
                hpc_slot_info_t *slot_info, int slot_state);
        hpc_slot_entry_t *bus_slot_list;
        kthread_t *bus_thread;
        kcondvar_t bus_thread_cv;
        boolean_t bus_thread_exit;
        hpc_event_entry_t *bus_slot_event_list_head;
        hpc_bus_entry_t *bus_next;
};

#define hpc_alloc_bus_entry()   \
        (hpc_bus_entry_t *)kmem_zalloc(sizeof (hpc_bus_entry_t), KM_SLEEP)

#define hpc_free_bus_entry(a)   \
        kmem_free((a), sizeof (hpc_bus_entry_t))


/*
 * Definitions for the per-bus node slot registration list:
 *
 * For each bus node in the bus list, the hot-plug service module maintains
 * a doubly linked link list of items representing the slots that have been
 * registered (by hot-plug controllers) for that bus.
 *
 * The head of the linked listed is stored in bus_slot_list field of the bus
 * node.  Insertions and removals from this list should locked with the mutex
 * in the bus_mutex field of the bus node.
 *
 * Items in the list are allocated/freed with the macros hpc_alloc_slot_entry()
 * and hpc_free_slot_entry().
 *
 * Each item in the list contains the following fields:
 *
 *      slot_handle - handle for slot (hpc_slot_t)
 *
 *      slot_info - information registered with the slot (hpc_slot_info_t)
 *
 *      slot_ops - ops vector registered with the slot (hpc_slot_ops_t)
 *
 *      slot_ops_arg - argument to be passed to ops routines (caddr_t)
 *
 *      slot_event_handler - handler registered for slot events
 *
 *      slot_event_handler_arg - argument to be passed to event handler
 *
 *      slot_event_mask - the set of events for which the event handler
 *              gets invoked
 *
 *      slot_bus - pointer to bus node for the slot
 *
 *      slot_hpc_dip  -  devinfo node pointer to the HPC driver instance
 *                       that controls this slot
 *
 *      slot_{prev,next} - point to {previous,next} node in the list
 */

struct hpc_slot_entry {
        hpc_slot_t slot_handle;
        hpc_slot_info_t slot_info;      /* should be static & copied */
        hpc_slot_ops_t slot_ops;
        caddr_t slot_ops_arg;
        int (* slot_event_handler)(caddr_t, uint_t);
        caddr_t slot_event_handler_arg;
        uint_t slot_event_mask;
        hpc_bus_entry_t *slot_bus;
        dev_info_t *slot_hpc_dip;
        hpc_slot_entry_t *slot_next, *slot_prev;
};

#define hpc_alloc_slot_entry()  \
        (hpc_slot_entry_t *)kmem_zalloc(sizeof (hpc_slot_entry_t), KM_SLEEP)

#define hpc_free_slot_entry(a)  \
        kmem_free((a), sizeof (hpc_slot_entry_t))


/*
 * Definitions for slot registration callback table.
 */

typedef struct hpc_callback_entry hpc_callback_entry_t;

struct hpc_callback_entry {
        int (* callback)(dev_info_t *dip, hpc_slot_t hdl,
                hpc_slot_info_t *slot_info, int slot_state);
        dev_info_t *dip;
        hpc_slot_t hdl;
        hpc_slot_info_t *slot_info;
        int slot_state;
        hpc_callback_entry_t *next;
};

#define hpc_alloc_callback_entry()      \
        (hpc_callback_entry_t *)        \
                kmem_zalloc(sizeof (hpc_callback_entry_t), KM_SLEEP)

#define hpc_free_callback_entry(a)      \
        kmem_free((a), sizeof (hpc_callback_entry_t))



/*
 * Mutex lock for bus registration table and table head.
 */
static kmutex_t hpc_bus_mutex;
static hpc_bus_entry_t *hpc_bus_list_head;


/*
 * Forward function declarations.
 */
static hpc_bus_entry_t *hpc_find_bus_by_name(char *name);
static void hpc_slot_event_dispatcher(hpc_bus_entry_t *busp);


/*
 * loadable module definitions:
 */
extern struct mod_ops mod_miscops;

static struct modlmisc modlmisc = {
        &mod_miscops,   /* Type of module */
        "hot-plug controller services"
};

static struct modlinkage modlinkage = {
        MODREV_1, (void *)&modlmisc, NULL
};

int
_init(void)
{
        int e;

        mutex_init(&hpc_bus_mutex, NULL, MUTEX_DRIVER, NULL);

        /*
         * Install the module.
         */
        e = mod_install(&modlinkage);
        if (e != 0) {
                mutex_destroy(&hpc_bus_mutex);
        }
        return (e);
}

int
_fini(void)
{
        int e;

        e = mod_remove(&modlinkage);
        if (e == 0) {
                mutex_destroy(&hpc_bus_mutex);
        }
        return (e);
}

int
_info(struct modinfo *modinfop)
{
        return (mod_info(&modlinkage, modinfop));
}



hpc_slot_ops_t *
hpc_alloc_slot_ops(int flag)
{
        hpc_slot_ops_t *ops;

        ops = (hpc_slot_ops_t *)kmem_zalloc(sizeof (hpc_slot_ops_t), flag);
        return (ops);
}


void
hpc_free_slot_ops(hpc_slot_ops_t *ops)
{
        kmem_free((void *)ops, sizeof (hpc_slot_ops_t));
}


/*ARGSUSED2*/
int
hpc_nexus_register_bus(dev_info_t *dip,
        int (* callback)(dev_info_t *dip, hpc_slot_t hdl,
        hpc_slot_info_t *slot_info, int slot_state), uint_t flags)
{
        hpc_bus_entry_t *busp;
        hpc_slot_entry_t *slotp;
        char bus_path[MAXPATHLEN + 1];

        DEBUG2("hpc_nexus_register_bus: %s%d",
            ddi_node_name(dip), ddi_get_instance(dip));
        mutex_enter(&hpc_bus_mutex);
        (void) ddi_pathname(dip, bus_path);
        busp = hpc_find_bus_by_name(bus_path);
        if (busp == NULL) {

                /*
                 * Initialize the new bus node and link it at the head
                 * of the bus list.
                 */
                DEBUG0("hpc_nexus_register_bus: not in bus list");
                busp = hpc_alloc_bus_entry();
                busp->bus_dip = dip;
                busp->bus_registered = B_TRUE;
                (void) strcpy(busp->bus_name, bus_path);
                mutex_init(&busp->bus_mutex, NULL, MUTEX_DRIVER, NULL);
                busp->bus_callback = callback;
                busp->bus_slot_list = NULL;
                busp->bus_next = hpc_bus_list_head;
                hpc_bus_list_head = busp;

        } else {

                /*
                 * The bus is in the bus list but isn't registered yet.
                 * Mark it as registered, and run the registration callbacks
                 * for it slots.
                 */
                DEBUG0("hpc_nexus_register_bus: in list, but not registered");
                mutex_enter(&busp->bus_mutex);
                if (busp->bus_registered == B_TRUE) {
                        mutex_exit(&busp->bus_mutex);
                        mutex_exit(&hpc_bus_mutex);
                        return (HPC_ERR_BUS_DUPLICATE);
                }
                busp->bus_dip = dip;
                busp->bus_callback = callback;
                busp->bus_registered = B_TRUE;

                mutex_exit(&busp->bus_mutex);
                mutex_exit(&hpc_bus_mutex);
                if (callback) {
                        DEBUG0("hpc_nexus_register_bus: running callbacks");
                        for (slotp = busp->bus_slot_list; slotp;
                            slotp = slotp->slot_next) {
                                (void) callback(dip, slotp, &slotp->slot_info,
                                    HPC_SLOT_ONLINE);
                        }
                }
                return (HPC_SUCCESS);
        }
        mutex_exit(&hpc_bus_mutex);
        return (HPC_SUCCESS);
}


int
hpc_nexus_unregister_bus(dev_info_t *dip)
{
        hpc_bus_entry_t *busp, *busp_prev;
        hpc_slot_entry_t *slotp;

        /*
         * Search the list for the bus node and remove it.
         */
        DEBUG2("hpc_nexus_unregister_bus: %s%d",
            ddi_node_name(dip), ddi_get_instance(dip));
        mutex_enter(&hpc_bus_mutex);
        for (busp = hpc_bus_list_head; busp != NULL; busp_prev = busp,
            busp = busp->bus_next) {
                if (busp->bus_dip == dip)
                        break;
        }
        if (busp == NULL) {
                mutex_exit(&hpc_bus_mutex);
                return (HPC_ERR_BUS_NOTREGISTERED);
        }

        /*
         * If the bus has slots, mark the bus as unregistered, otherwise
         * remove the bus entry from the list.
         */
        mutex_enter(&busp->bus_mutex);
        if (busp->bus_slot_list == NULL) {
                if (busp == hpc_bus_list_head)
                        hpc_bus_list_head = busp->bus_next;
                else
                        busp_prev->bus_next = busp->bus_next;
                mutex_exit(&busp->bus_mutex);
                mutex_destroy(&busp->bus_mutex);
                hpc_free_bus_entry(busp);
                mutex_exit(&hpc_bus_mutex);
                return (HPC_SUCCESS);
        }

        /*
         * unregister event handlers for all the slots on this bus.
         */
        for (slotp = busp->bus_slot_list; slotp != NULL;
                slotp = slotp->slot_next) {
                slotp->slot_event_handler = NULL;
                slotp->slot_event_handler_arg = NULL;
        }
        busp->bus_registered = B_FALSE;
        mutex_exit(&busp->bus_mutex);
        mutex_exit(&hpc_bus_mutex);
        return (HPC_SUCCESS);
}


/*ARGSUSED5*/
int
hpc_slot_register(dev_info_t *hpc_dip, char *bus, hpc_slot_info_t *infop,
        hpc_slot_t *handlep, hpc_slot_ops_t *opsp,
        caddr_t ops_arg, uint_t flags)
{
        hpc_bus_entry_t *busp;
        hpc_slot_entry_t *slotp, *slot_list_head;
        boolean_t run_callback = B_FALSE;
        int (* callback)(dev_info_t *dip, hpc_slot_t hdl,
                hpc_slot_info_t *slot_info, int slot_state);
        dev_info_t *dip;
        kthread_t *t;

        /*
         * Validate the arguments.
         */
        DEBUG1("hpc_slot_register: %s", bus);
        if (handlep == NULL || infop == NULL || opsp == NULL || hpc_dip == NULL)
                return (HPC_ERR_INVALID);

        /*
         * The bus for the slot may or may not be in the bus list.  If it's
         * not, we create a node for the bus in the bus list and mark it as
         * not registered.
         */
        mutex_enter(&hpc_bus_mutex);
        busp = hpc_find_bus_by_name(bus);
        if (busp == NULL) {

                /*
                 * Initialize the new bus node and link it at the
                 * head of the bus list.
                 */
                DEBUG1("hpc_slot_register: %s not in bus list", bus);
                busp = hpc_alloc_bus_entry();
                busp->bus_registered = B_FALSE;
                (void) strcpy(busp->bus_name, bus);
                mutex_init(&busp->bus_mutex, NULL, MUTEX_DRIVER, NULL);
                busp->bus_slot_list = NULL;
                busp->bus_next = hpc_bus_list_head;
                hpc_bus_list_head = busp;

        } else {
                if (busp->bus_registered == B_TRUE) {
                        run_callback = B_TRUE;
                        callback = busp->bus_callback;
                        dip = busp->bus_dip;
                }
        }

        mutex_enter(&busp->bus_mutex);
        slot_list_head = busp->bus_slot_list;
        if (slot_list_head == NULL) {

                /*
                 * The slot list was empty, so this is the first slot
                 * registered for the bus.  Create a per-bus thread
                 * for running the slot event handlers.
                 */
                DEBUG0("hpc_slot_register: creating event callback thread");
                cv_init(&busp->bus_thread_cv, NULL, CV_DRIVER, NULL);
                busp->bus_thread_exit = B_FALSE;
                t = thread_create(NULL, 0, hpc_slot_event_dispatcher,
                    (caddr_t)busp, 0, &p0, TS_RUN, minclsyspri);
                busp->bus_thread = t;
        }

        /*
         * Create and initialize a new entry in the slot list for the bus.
         */
        slotp = hpc_alloc_slot_entry();
        slotp->slot_handle = (hpc_slot_t)slotp;
        slotp->slot_info = *infop;
        slotp->slot_ops = *opsp;
        slotp->slot_ops_arg = ops_arg;
        slotp->slot_bus = busp;
        slotp->slot_hpc_dip = hpc_dip;
        slotp->slot_prev = NULL;
        busp->bus_slot_list = slotp;
        slotp->slot_next = slot_list_head;
        if (slot_list_head != NULL)
                slot_list_head->slot_prev = slotp;
        mutex_exit(&busp->bus_mutex);
        mutex_exit(&hpc_bus_mutex);

        /*
         * Return the handle to the caller prior to return to avoid recursion.
         */
        *handlep = (hpc_slot_t)slotp;

        /*
         * If the bus was registered, we run the callback registered by
         * the bus node.
         */
        if (run_callback) {
                DEBUG0("hpc_slot_register: running callback");

                (void) callback(dip, slotp, infop, HPC_SLOT_ONLINE);
        }

        /*
         * Keep hpc driver in memory
         */
        (void) ndi_hold_driver(hpc_dip);

        return (HPC_SUCCESS);
}


int
hpc_slot_unregister(hpc_slot_t *handlep)
{
        hpc_slot_entry_t *slotp;
        hpc_bus_entry_t *busp, *busp_prev;
        boolean_t run_callback;
        int (* callback)(dev_info_t *dip, hpc_slot_t hdl,
                hpc_slot_info_t *slot_info, int slot_state);
        int r;
        dev_info_t *dip;
        char *bus_name;

        DEBUG0("hpc_slot_unregister:");

        ASSERT(handlep != NULL);

        /* validate the handle */
        slotp = (hpc_slot_entry_t *)*handlep;
        if ((slotp == NULL) || slotp->slot_handle != *handlep)
                return (HPC_ERR_INVALID);

        /*
         * Get the bus list entry from the slot to grap the mutex for
         * the slot list of the bus.
         */
        mutex_enter(&hpc_bus_mutex);
        busp = slotp->slot_bus;
        DEBUG2("hpc_slot_unregister: handlep=%x, slotp=%x", handlep, slotp);
        if (busp == NULL) {
                mutex_exit(&hpc_bus_mutex);
                return (HPC_ERR_SLOT_NOTREGISTERED);
        }

        /*
         * Determine if we need to run the slot offline callback and
         * save the data necessary to do so.
         */
        callback = busp->bus_callback;
        run_callback = (busp->bus_registered == B_TRUE) && (callback != NULL);
        dip = busp->bus_dip;
        bus_name = busp->bus_name;

        /*
         * Run the slot offline callback if necessary.
         */
        if (run_callback) {
                mutex_exit(&hpc_bus_mutex);
                DEBUG0("hpc_slot_unregister: running callback");
                r = callback(dip, (hpc_slot_t)slotp, &slotp->slot_info,
                    HPC_SLOT_OFFLINE);
                DEBUG1("hpc_slot_unregister: callback returned %x", r);
                if (r != HPC_SUCCESS)
                        return (HPC_ERR_FAILED);
                mutex_enter(&hpc_bus_mutex);
        }

        /*
         * Remove the slot from list and free the memory associated with it.
         */
        mutex_enter(&busp->bus_mutex);
        DEBUG1("hpc_slot_unregister: freeing slot, bus_slot_list=%x",
                busp->bus_slot_list);
        if (slotp->slot_prev != NULL)
                slotp->slot_prev->slot_next = slotp->slot_next;
        if (slotp->slot_next != NULL)
                slotp->slot_next->slot_prev = slotp->slot_prev;
        if (slotp == busp->bus_slot_list)
                busp->bus_slot_list = slotp->slot_next;

        /*
         * Release hold from slot registration
         */
        ndi_rele_driver(slotp->slot_hpc_dip);

        /* Free the memory associated with the slot entry structure */
        hpc_free_slot_entry(slotp);

        /*
         * If the slot list is empty then stop the event handler thread.
         */
        if (busp->bus_slot_list == NULL) {
                DEBUG0("hpc_slot_unregister: stopping thread");
                busp->bus_thread_exit = B_TRUE;
                cv_signal(&busp->bus_thread_cv);
                DEBUG0("hpc_slot_unregister: waiting for thread to exit");
                cv_wait(&busp->bus_thread_cv, &busp->bus_mutex);
                DEBUG0("hpc_slot_unregister: thread exit");
                cv_destroy(&busp->bus_thread_cv);
        }

        /*
         * If the bus is unregistered and this is the last slot for this bus
         * then remove the entry from the bus list.
         */
        if (busp->bus_registered == B_FALSE && busp->bus_slot_list == NULL) {
                /* locate the previous entry in the bus list */
                for (busp = hpc_bus_list_head; busp != NULL; busp_prev = busp,
                    busp = busp->bus_next)
                        if (strcmp(bus_name, busp->bus_name) == 0)
                                break;

                if (busp == hpc_bus_list_head)
                        hpc_bus_list_head = busp->bus_next;
                else
                        busp_prev->bus_next = busp->bus_next;

                mutex_exit(&busp->bus_mutex);
                mutex_destroy(&busp->bus_mutex);
                hpc_free_bus_entry(busp);
        } else
                mutex_exit(&busp->bus_mutex);
        mutex_exit(&hpc_bus_mutex);

        /*
         * reset the slot handle.
         */
        *handlep = NULL;
        return (HPC_SUCCESS);
}


int
hpc_install_event_handler(hpc_slot_t handle, uint_t event_mask,
        int (*event_handler)(caddr_t, uint_t), caddr_t arg)
{
        hpc_slot_entry_t *slotp;
        hpc_bus_entry_t *busp;

        DEBUG3("hpc_install_event_handler: handle=%x, mask=%x, arg=%x",
                handle, event_mask, arg);
        ASSERT((handle != NULL) && (event_handler != NULL));
        slotp = (hpc_slot_entry_t *)handle;
        busp = slotp->slot_bus;
        ASSERT(slotp == slotp->slot_handle);
        mutex_enter(&busp->bus_mutex);
        slotp->slot_event_mask = event_mask;
        slotp->slot_event_handler = event_handler;
        slotp->slot_event_handler_arg = arg;
        mutex_exit(&busp->bus_mutex);
        return (HPC_SUCCESS);
}


int
hpc_remove_event_handler(hpc_slot_t handle)
{
        hpc_slot_entry_t *slotp;
        hpc_bus_entry_t *busp;

        DEBUG1("hpc_remove_event_handler: handle=%x", handle);
        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        ASSERT(slotp == slotp->slot_handle);
        busp = slotp->slot_bus;
        mutex_enter(&busp->bus_mutex);
        slotp->slot_event_mask = 0;
        slotp->slot_event_handler = NULL;
        slotp->slot_event_handler_arg = NULL;
        mutex_exit(&busp->bus_mutex);
        return (HPC_SUCCESS);
}


/*ARGSUSED2*/
int
hpc_slot_event_notify(hpc_slot_t handle, uint_t event, uint_t flags)
{
        hpc_slot_entry_t *slotp;
        hpc_bus_entry_t *busp;
        hpc_event_entry_t *eventp;

        DEBUG2("hpc_slot_event_notify: handle=%x event=%x", handle, event);
        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        ASSERT(slotp == slotp->slot_handle);

        if (slotp->slot_event_handler == NULL)
                return (HPC_EVENT_UNCLAIMED);

        /*
         * If the request is to handle the event synchronously, then call
         * the event handler without queuing the event.
         */
        if (flags == HPC_EVENT_SYNCHRONOUS) {
                caddr_t arg;
                int (* func)(caddr_t, uint_t);

                func = slotp->slot_event_handler;
                arg = slotp->slot_event_handler_arg;
                return (func(arg, event));
        }
        /*
         * Insert the event into the bus slot event handler list and
         * signal the bus slot event handler dispatch thread.
         */
        busp = slotp->slot_bus;
        mutex_enter(&busp->bus_mutex);

        if (busp->bus_slot_event_list_head == NULL) {
                eventp = busp->bus_slot_event_list_head =
                    hpc_alloc_event_entry();
        } else {
                for (eventp = busp->bus_slot_event_list_head;
                            eventp->next != NULL; eventp = eventp->next)
                        ;
                eventp->next = hpc_alloc_event_entry();
                eventp = eventp->next;
        }
        eventp->slotp = slotp;
        eventp->event = event;
        eventp->next = NULL;
        DEBUG2("hpc_slot_event_notify: busp=%x event=%x", busp, event);
        cv_signal(&busp->bus_thread_cv);
        mutex_exit(&busp->bus_mutex);
        return (HPC_EVENT_CLAIMED);
}


int
hpc_nexus_connect(hpc_slot_t handle, void *data, uint_t flags)
{
        hpc_slot_entry_t *slotp;

        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        if (slotp->slot_ops.hpc_op_connect)
                return (slotp->slot_ops.hpc_op_connect(slotp->slot_ops_arg,
                        handle, data, flags));
        return (HPC_ERR_FAILED);
}


int
hpc_nexus_disconnect(hpc_slot_t handle, void *data, uint_t flags)
{
        hpc_slot_entry_t *slotp;

        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        if (slotp->slot_ops.hpc_op_disconnect)
                return (slotp->slot_ops.hpc_op_disconnect(slotp->slot_ops_arg,
                        handle, data, flags));
        return (HPC_ERR_FAILED);
}


int
hpc_nexus_insert(hpc_slot_t handle, void *data, uint_t flags)
{
        hpc_slot_entry_t *slotp;

        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        if (slotp->slot_ops.hpc_op_insert)
                return (slotp->slot_ops.hpc_op_insert(slotp->slot_ops_arg,
                        handle, data, flags));
        return (HPC_ERR_FAILED);
}


int
hpc_nexus_remove(hpc_slot_t handle, void *data, uint_t flags)
{
        hpc_slot_entry_t *slotp;

        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        if (slotp->slot_ops.hpc_op_remove)
                return (slotp->slot_ops.hpc_op_remove(slotp->slot_ops_arg,
                        handle, data, flags));
        return (HPC_ERR_FAILED);
}


int
hpc_nexus_control(hpc_slot_t handle, int request, caddr_t arg)
{
        hpc_slot_entry_t *slotp;

        ASSERT(handle != NULL);
        slotp = (hpc_slot_entry_t *)handle;
        if (slotp->slot_ops.hpc_op_control)
                return (slotp->slot_ops.hpc_op_control(slotp->slot_ops_arg,
                        handle, request, arg));
        return (HPC_ERR_FAILED);
}

/*
 * The following function is run from the bus entries slot event handling
 * thread.
 */
static void
hpc_slot_event_dispatcher(hpc_bus_entry_t *busp)
{
        hpc_event_entry_t *eventp;
        hpc_slot_entry_t *slotp;
        int event;
        caddr_t arg;
        int (* func)(caddr_t, uint_t);
        callb_cpr_t cprinfo;

        /*
         * The creator of this thread is waiting to be signaled that
         * the thread has been started.
         */
        DEBUG1("hpc_slot_event_dispatcher: busp=%x", busp);

        CALLB_CPR_INIT(&cprinfo, &busp->bus_mutex, callb_generic_cpr,
            "hpc_slot_event_dispatcher");

        mutex_enter(&busp->bus_mutex);
        /*
         * Wait for events to queue and then process them.
         */
        for (;;) {

                /*
                 * Note we only hold the mutex while determining
                 * the number of entries that have been added to
                 * the event list, while updating the event list
                 * after processing the event list entries.
                 */
                if (busp->bus_slot_event_list_head == NULL) {
                        CALLB_CPR_SAFE_BEGIN(&cprinfo);
                        cv_wait(&busp->bus_thread_cv, &busp->bus_mutex);
                        CALLB_CPR_SAFE_END(&cprinfo, &busp->bus_mutex);
                        if (busp->bus_thread_exit)
                                break;
                        continue;
                }

                /*
                 * We have an event handler instance in the list to
                 * process.  Remove the head of the list, saving the
                 * information required to run the event handler.
                 * Then run the event handler while the bus mutex
                 * is released.
                 */
                eventp = busp->bus_slot_event_list_head;
                slotp = eventp->slotp;
                event = eventp->event;
                func = slotp->slot_event_handler;
                arg = slotp->slot_event_handler_arg;
                busp->bus_slot_event_list_head = eventp->next;
                hpc_free_event_entry(eventp);
                mutex_exit(&busp->bus_mutex);
                func(arg, event);
                mutex_enter(&busp->bus_mutex);

                if (busp->bus_thread_exit)
                        break;
        }

        DEBUG0("hpc_slot_event_dispatcher: thread_exit");
        cv_signal(&busp->bus_thread_cv);
        CALLB_CPR_EXIT(&cprinfo);
        thread_exit();
}


static hpc_bus_entry_t *
hpc_find_bus_by_name(char *path)
{
        hpc_bus_entry_t *busp;

        for (busp = hpc_bus_list_head; busp != NULL; busp = busp->bus_next) {
                if (strcmp(path, busp->bus_name) == 0)
                        break;
        }
        return (busp);
}

boolean_t
hpc_bus_registered(hpc_slot_t slot_hdl)
{
        hpc_slot_entry_t *slotp;
        hpc_bus_entry_t *busp;

        slotp = (hpc_slot_entry_t *)slot_hdl;
        busp = slotp->slot_bus;
        return (busp->bus_registered);
}


#ifdef DEBUG

extern void prom_printf(const char *, ...);

static void
debug(char *fmt, uintptr_t a1, uintptr_t a2, uintptr_t a3,
    uintptr_t a4, uintptr_t a5)
{
        if (hpcsvc_debug != 0) {
                cmn_err(CE_CONT, "hpcsvc: ");
                cmn_err(CE_CONT, fmt, a1, a2, a3, a4, a5);
                cmn_err(CE_CONT, "\n");
        }
}
#endif