/*
 * 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.
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#include <sys/types.h>
#include <sys/modctl.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/kmem.h>
#include <sys/file.h>
#include <sys/rsm/rsm_common.h>
#include <sys/rsm/rsmpi.h>
#include <sys/rsm/rsmpi_driver.h>

/* lint -w2 */
static struct modlmisc modlmisc = {
        &mod_miscops, "RSMOPS module",
};

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

static kmutex_t rsmops_lock;

static rsmops_drv_t *rsmops_drv_head = NULL;

static int rsmops_threads_started = 0;

int
_init(void)
{
        int     err;

        mutex_init(&rsmops_lock, NULL, MUTEX_DEFAULT, NULL);

        if ((err = mod_install(&modlinkage)) != 0)
                mutex_destroy(&rsmops_lock);

        return (err);
}

int
_fini(void)
{
        int     err;

        mutex_enter(&rsmops_lock);
        if (rsmops_drv_head) {
                /* Somebody is still registered with us - we cannot unload */
                mutex_exit(&rsmops_lock);
                return (EBUSY);
        }
        if (rsmops_threads_started) {
                /*
                 * Some threads have been started.  We do not have any
                 * well-supported way of checking whether they have all
                 * exited.  For now, fail attempt to unload if we have
                 * ever started any threads.  This is overkill, but ...
                 */
                mutex_exit(&rsmops_lock);
                return (EBUSY);
        }
        mutex_exit(&rsmops_lock);

        if ((err = mod_remove(&modlinkage)) == 0)
                mutex_destroy(&rsmops_lock);
        return (err);
}

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

static void
rsmops_thread_entry(rsmops_drv_t *p_drv)
{
        /* p_drv->ctrl_cnt has already been increased by the time we get here */
        ASSERT(p_drv->drv.rsm_thread_entry_pt);

        /* call the driver with the thread */
        (*(p_drv->drv.rsm_thread_entry_pt))(p_drv->drv.drv_name);

        /* thread has returned */
        mutex_enter(&rsmops_lock);
        p_drv->ctrl_cnt--;
        mutex_exit(&rsmops_lock);
}

/* This is expected to be called from the driver's init function */
int
rsm_register_driver(rsmops_registry_t *p_registry)
{
        rsmops_drv_t **pp_tail;
        rsmops_drv_t *p;

        if (p_registry->rsm_version > RSM_VERSION) {
                /* The driver is up-rev than me.  Fail attempt to register */
                return (RSMERR_BAD_DRIVER_VERSION);
        }

        /*
         * RSM_VERSION: Since this is the first version, there cannot be any
         * down-rev drivers - this will be an issue in the future
         */
        if (p_registry->rsm_version != RSM_VERSION)
                return (RSMERR_BAD_DRIVER_VERSION);

        mutex_enter(&rsmops_lock);
        /* First, search that this driver is not already registered */
        pp_tail = &rsmops_drv_head;
        while (*pp_tail) {
                if (strcmp((*pp_tail)->drv.drv_name, p_registry->drv_name)
                    == 0) {
                        mutex_exit(&rsmops_lock);
                        return (RSMERR_DRIVER_NAME_IN_USE);
                }
                pp_tail = &((*pp_tail)->next);
        }

        p = kmem_alloc(sizeof (rsmops_drv_t), KM_SLEEP);
        p->drv = *p_registry;   /* copy entire rsmops_registry_t structure */
        p->next = NULL;
        p->ctrl_cnt = 0;
        p->ctrl_head = NULL;

        if (p->drv.rsm_thread_entry_pt) {
                /* thread entry point is defined - we need to create a thread */
                extern  pri_t   minclsyspri;

                p->ctrl_cnt++;  /* bump up the count right now */
                p->thread_id = thread_create(NULL, 0, rsmops_thread_entry,
                    p, 0, &p0, TS_RUN, minclsyspri);
                rsmops_threads_started++;
        } else
                p->thread_id = NULL;

        *pp_tail = p;
        mutex_exit(&rsmops_lock);
        return (RSM_SUCCESS);
}

/*
 * This is expected to be called from the driver's fini function
 * if this function returns EBUSY, the driver is supposed to fail
 * its own fini operation
 */
int
rsm_unregister_driver(rsmops_registry_t *p_registry)
{
        rsmops_drv_t **pp_tail;
        rsmops_drv_t *p;

        mutex_enter(&rsmops_lock);

        /* Search for the driver */
        pp_tail = &rsmops_drv_head;
        while (*pp_tail) {
                if (strcmp((*pp_tail)->drv.drv_name, p_registry->drv_name)) {
                        pp_tail = &((*pp_tail)->next);
                        continue;
                }
                /* check ref count - if somebody is using it, return EBUSY */
                if ((*pp_tail)->ctrl_cnt) {
                        mutex_exit(&rsmops_lock);
                        return (RSMERR_CTLRS_REGISTERED);
                }
                /* Nobody is using it - we can allow the unregister to happen */
                p = *pp_tail;

                /* Stomp the guy out of our linked list */
                *pp_tail = (*pp_tail)->next;

                /* release the memory */
                kmem_free(p, sizeof (rsmops_drv_t));

                mutex_exit(&rsmops_lock);
                return (RSM_SUCCESS);
        }

        /* Could not find the guy */
        mutex_exit(&rsmops_lock);
        return (RSMERR_DRIVER_NOT_REGISTERED);
}

/* Should be called holding the rsmops_lock mutex */
static rsmops_drv_t *
find_rsmpi_driver(const char *name)
{
        rsmops_drv_t *p_rsmops_list;

        ASSERT(MUTEX_HELD(&rsmops_lock));
        /* the name is of the form "sci", "wci" etc */

        for (p_rsmops_list = rsmops_drv_head; p_rsmops_list != NULL;
            p_rsmops_list = p_rsmops_list->next) {

                if (strcmp(name, p_rsmops_list->drv.drv_name) == 0) {
                        return (p_rsmops_list);
                }
        }
        return (NULL);
}


/* Should be called holding the rsmops_lock mutex */
static rsmops_ctrl_t *
find_rsmpi_controller(const char *name, uint_t number)
{
        rsmops_drv_t *p_drv;
        rsmops_ctrl_t *p;

        ASSERT(MUTEX_HELD(&rsmops_lock));

        if ((p_drv = find_rsmpi_driver(name)) == NULL)
                return (NULL);

        for (p = p_drv->ctrl_head; p != NULL; p = p->next) {
                ASSERT(p->p_drv == p_drv);
                if (p->number == number)
                        return (p);
        }
        return (NULL);
}

/* Should be called holding the rsmops_lock mutex */
static rsmops_ctrl_t *
find_rsmpi_controller_handle(rsm_controller_handle_t cntlr_handle)
{
        rsmops_drv_t *p_drv;
        rsmops_ctrl_t *p;

        ASSERT(MUTEX_HELD(&rsmops_lock));

        for (p_drv = rsmops_drv_head; p_drv != NULL; p_drv = p_drv->next) {
                for (p = p_drv->ctrl_head; p != NULL; p = p->next) {
                        if (p->handle == cntlr_handle)
                                return (p);
                }
        }

        return (NULL);
}

static vnode_t *
rsmops_device_open(const char *major_name, const minor_t minor_num);

int
rsm_get_controller(const char *name, uint_t number,
    rsm_controller_object_t *controller, uint_t version)
{
        rsmops_ctrl_t *p_ctrl;
        rsmops_drv_t *p_drv;
        vnode_t *vp;
        int error;
        int (*rsm_get_controller_handler)
            (const char *name, uint_t number,
            rsm_controller_object_t *pcontroller, uint_t version);

        mutex_enter(&rsmops_lock);

        /* check if the controller is already registered */
        if ((p_ctrl = find_rsmpi_controller(name, number)) == NULL) {
                /*
                 * controller is not registered.  We should try to load it
                 * First check if the driver is registered
                 */
                if ((p_drv = find_rsmpi_driver(name)) == NULL) {
                        /* Cannot find the driver.  Try to load it */
                        mutex_exit(&rsmops_lock);
                        if ((error = modload("drv", (char *)name)) == -1) {
                                return (RSMERR_CTLR_NOT_PRESENT);
                        }
                        mutex_enter(&rsmops_lock);
                        if ((p_drv = find_rsmpi_driver(name)) == NULL) {
                                mutex_exit(&rsmops_lock);
                                /*
                                 * Cannot find yet - maybe the driver we loaded
                                 * was not a RSMPI driver at all.  We'll just
                                 * fail this call.
                                 */
                                return (RSMERR_CTLR_NOT_PRESENT);
                        }
                }
                ASSERT(p_drv);
                p_ctrl = find_rsmpi_controller(name, number);
                if (p_ctrl == NULL) {
                        /*
                         * controller is not registered.
                         * try to do a VOP_OPEN to force it to get registered
                         */
                        mutex_exit(&rsmops_lock);
                        vp = rsmops_device_open(name, number);
                        mutex_enter(&rsmops_lock);
                        if (vp != NULL) {
                                (void) VOP_CLOSE(vp, FREAD|FWRITE, 0, 0,
                                    CRED(), NULL);
                                VN_RELE(vp);
                        }
                        p_ctrl = find_rsmpi_controller(name, number);
                        if (p_ctrl == NULL) {
                                mutex_exit(&rsmops_lock);
                                return (RSMERR_CTLR_NOT_PRESENT);
                        }
                }
                ASSERT(p_ctrl);
        } else {
                p_drv = p_ctrl->p_drv;
        }
        ASSERT(p_drv);
        ASSERT(p_drv == p_ctrl->p_drv);

        rsm_get_controller_handler = p_drv->drv.rsm_get_controller_handler;
        /*
         * Increase the refcnt right now, so that attempts to deregister
         * while we are using this entry will fail
         */
        p_ctrl->refcnt++;
        mutex_exit(&rsmops_lock);

        error = (*rsm_get_controller_handler)(name, number, controller,
            version);
        if (error != RSM_SUCCESS) {
                /* We failed - drop the refcnt back */
                mutex_enter(&rsmops_lock);
                /*
                 * Even though we had released the global lock, we can
                 * guarantee that p_ctrl is still meaningful (and has not
                 * been deregistered, freed whatever) because we were holding
                 * refcnt on it.  So, it is okay to just use p_ctrl here
                 * after re-acquiring the global lock
                 */
                p_ctrl->refcnt--;
                mutex_exit(&rsmops_lock);
        } else {
                /*
                 * Initialize the controller handle field
                 */
                mutex_enter(&rsmops_lock);
                if ((p_ctrl = find_rsmpi_controller(name, number)) == NULL) {
                        mutex_exit(&rsmops_lock);
                        return (RSMERR_CTLR_NOT_PRESENT);
                }

                p_ctrl->handle = controller->handle;
                mutex_exit(&rsmops_lock);
        }
        return (error);
}

int
rsm_release_controller(const char *name, uint_t number,
    rsm_controller_object_t *controller)
{
        rsmops_ctrl_t *p_ctrl;
        rsmops_drv_t *p_drv;
        int error;
        int (*releaser)(const char *name, uint_t number,
            rsm_controller_object_t *controller);

        mutex_enter(&rsmops_lock);

        if ((p_ctrl = find_rsmpi_controller(name, number)) == NULL) {
                mutex_exit(&rsmops_lock);
                return (RSMERR_CTLR_NOT_PRESENT);
        }
        p_drv = find_rsmpi_driver(name);
        ASSERT(p_drv);  /* If we found controller, there MUST be a driver */

        /* Found the appropriate driver.  Forward the call to it */
        releaser = p_drv->drv.rsm_release_controller_handler;
        mutex_exit(&rsmops_lock);

        error = (*releaser)(name, number, controller);
        if (error == RSM_SUCCESS) {
                mutex_enter(&rsmops_lock);
                p_ctrl->refcnt--;
                mutex_exit(&rsmops_lock);
        }
        return (error);
}

/* This is expected to be called from the driver's attach function */
int
rsm_register_controller(const char *name, uint_t number,
    rsm_controller_attr_t *attrp)
{
        rsmops_drv_t *p_drv;
        rsmops_ctrl_t *p_ctrl;

        if (strlen(name) > MAX_DRVNAME)
                return (RSMERR_NAME_TOO_LONG);

        mutex_enter(&rsmops_lock);

        /* Check if the driver is registered with us */
        p_drv = find_rsmpi_driver(name);
        if (p_drv == NULL) {
                /*
                 * Hey! Driver is not registered, but we are getting a
                 * controller ??
                 */
                mutex_exit(&rsmops_lock);
                return (RSMERR_DRIVER_NOT_REGISTERED);
        }

        /* Check if the controller is already registered with us */
        p_ctrl = find_rsmpi_controller(name, number);
        if (p_ctrl) {
                /* already registered */
                mutex_exit(&rsmops_lock);
                return (RSMERR_CTLR_ALREADY_REGISTERED);
        }

        /* WAIT: sanity check - verify that the dip matches up to name,number */

        p_ctrl = kmem_alloc(sizeof (rsmops_ctrl_t), KM_SLEEP);

        /* bump up controller count on the driver */
        p_drv->ctrl_cnt++;

        p_ctrl->p_drv = p_drv;  /* setup the back pointer */
        p_ctrl->number = number;
        p_ctrl->refcnt = 0;
        p_ctrl->attrp = attrp;
        p_ctrl->handle = NULL;

        /* Now link to head of list */
        p_ctrl->next = p_drv->ctrl_head;
        p_drv->ctrl_head = p_ctrl;

        mutex_exit(&rsmops_lock);

        return (RSM_SUCCESS);
}

/*
 * This is expected to be called from the driver's detach function
 * if this function returns EBUSY, the driver is supposed to fail
 * its own detach operation
 */
int
rsm_unregister_controller(const char *name, uint_t number)
{
        rsmops_drv_t *p_drv;
        rsmops_ctrl_t **p_prev;
        rsmops_ctrl_t *found;

        mutex_enter(&rsmops_lock);

        /* Check if the driver is registered with us */
        p_drv = find_rsmpi_driver(name);
        if (p_drv == NULL) {
                /* Hey!  Driver is not registered */
                mutex_exit(&rsmops_lock);
                return (RSMERR_DRIVER_NOT_REGISTERED);
        }

        /* Search for the controller in the list */
        for (p_prev = &p_drv->ctrl_head; *p_prev; p_prev = &((*p_prev)->next)) {
                if ((*p_prev)->number == number) {
                        /* Found the controller.  Check if it is busy */
                        found = *p_prev;

                        if (found->refcnt) {
                                /* Controller is busy -  handles outstanding */
                                mutex_exit(&rsmops_lock);
                                return (RSMERR_CTLR_IN_USE);
                        }
                        /* unlink it out */
                        *p_prev = found->next;
                        /* bump down controller count on the driver */
                        p_drv->ctrl_cnt--;

                        mutex_exit(&rsmops_lock);
                        kmem_free(found, sizeof (rsmops_ctrl_t));
                        return (RSM_SUCCESS);
                }
        }
        mutex_exit(&rsmops_lock);
        /* Could not find the right controller */
        return (RSMERR_CTLR_NOT_REGISTERED);
}


/*
 * This opens and closes the appropriate device with minor number -
 * hopefully, it will cause the driver to attach and register a controller
 * with us
 */
static vnode_t *
rsmops_device_open(const char *major_name, const minor_t minor_num)
{
        major_t maj;
        vnode_t *vp;
        int ret;

        if (minor_num == (minor_t)-1) {
                return (NULL);
        }

        maj = ddi_name_to_major((char *)major_name);
        if (maj == (major_t)-1) {
                return (NULL);
        }

        vp = makespecvp(makedevice(maj, minor_num), VCHR);

        ret = VOP_OPEN(&vp, FREAD|FWRITE, CRED(), NULL);
        if (ret == 0) {
                return (vp);
        } else {
                VN_RELE(vp);
                return (NULL);
        }
}

/*
 * Attributes for controller identified by the handle are returned
 * via *attrp. Modifications of attributes is prohibited by client!
 */
int
rsm_get_controller_attr(rsm_controller_handle_t handle,
    rsm_controller_attr_t **attrp)
{

        rsmops_ctrl_t *p_ctrl;

        if (handle == NULL)
                return (RSMERR_BAD_CTLR_HNDL);

        mutex_enter(&rsmops_lock);

        /* find controller */
        if ((p_ctrl = find_rsmpi_controller_handle(handle)) == NULL) {
                /* can't supply attributes for invalid controller */
                mutex_exit(&rsmops_lock);
                return (RSMERR_BAD_CTLR_HNDL);
        }
        *attrp =  p_ctrl->attrp;
        mutex_exit(&rsmops_lock);

        return (RSM_SUCCESS);
}