FreeBSD/Linux Kernel Cross Reference
sys/cam/cam_sim.c

     /*-
      * Common functions for SCSI Interface Modules (SIMs).
      *
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 1997 Justin T. Gibbs.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions, and the following disclaimer,
     *    without modification, immediately at the beginning of the file.
     * 2. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
     * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    
    #include <cam/cam.h>
    #include <cam/cam_ccb.h>
    #include <cam/cam_queue.h>
    #include <cam/cam_sim.h>
    #include <cam/cam_xpt.h>
    
    #define CAM_PATH_ANY (u_int32_t)-1
    
    static MALLOC_DEFINE(M_CAMSIM, "CAM SIM", "CAM SIM buffers");
    
    static struct mtx cam_sim_free_mtx;
    MTX_SYSINIT(cam_sim_free_init, &cam_sim_free_mtx, "CAM SIM free lock", MTX_DEF);
    
    struct cam_devq *
    cam_simq_alloc(u_int32_t max_sim_transactions)
    {
            return (cam_devq_alloc(/*size*/0, max_sim_transactions));
    }
    
    void
    cam_simq_free(struct cam_devq *devq)
    {
            cam_devq_free(devq);
    }
    
    
    
    /**
     * @brief allocate a new sim and fill in the details
     *
     * A Storage Interface Module (SIM) is the interface between CAM and
     * hardware. SIM receives CCBs from CAM via @p sim_action callback and
     * translates them into DMA or other hardware transactions.  During system
     * dumps, it can be polled with the @p sim_poll callback. CCB processing is
     * terminated by calling @c xpt_done().
     *
     * The @p mtx acts as a perimeter lock for the SIM. All calls into the SIM's
     * @p sim_action are made with this lock held. It is also used to hold/release
     * a SIM, managing its reference count. When the lock is NULL, the SIM is 100%
     * responsible for locking (and the reference counting is done with a shared
     * lock.
     *
     * The cam_devq passed in (@c queue) is used to arbitrate the number of
     * outstanding transactions to the SIM. For HBAs that have global limits shared
     * between the different buses, the same devq should be specified for each bus
     * attached to the SIM.
     *
     * @param sim_action    Function to call to process CCBs
     * @param sim_poll      Function to poll the hardware for completions
     * @param sim_name      Name of SIM class
     * @param softc         Software context associated with the SIM
     * @param unit          Unit number of SIM
     * @param mtx           Mutex to lock while interacting with the SIM, or NULL
     *                      for a SIM that handle its own locking to enable multi
     *                      queue support.
     * @param max_dev_transactions Maximum number of concurrent untagged
     *                      transactions possible
     * @param max_tagged_dev_transactions Maximum number of concurrent tagged
     *                      transactions possible.
    * @param queue         The cam_devq to use for this SIM.
    */
   struct cam_sim *
   cam_sim_alloc(sim_action_func sim_action, sim_poll_func sim_poll,
                 const char *sim_name, void *softc, u_int32_t unit,
                 struct mtx *mtx, int max_dev_transactions,
                 int max_tagged_dev_transactions, struct cam_devq *queue)
   {
           struct cam_sim *sim;
   
           sim = malloc(sizeof(struct cam_sim), M_CAMSIM, M_ZERO | M_NOWAIT);
           if (sim == NULL)
                   return (NULL);
   
           sim->sim_action = sim_action;
           sim->sim_poll = sim_poll;
           sim->sim_name = sim_name;
           sim->softc = softc;
           sim->path_id = CAM_PATH_ANY;
           sim->unit_number = unit;
           sim->bus_id = 0;        /* set in xpt_bus_register */
           sim->max_tagged_dev_openings = max_tagged_dev_transactions;
           sim->max_dev_openings = max_dev_transactions;
           sim->flags = 0;
           sim->refcount = 1;
           sim->devq = queue;
           sim->mtx = mtx;
           return (sim);
   }
   
   /**
    * @brief frees up the sim
    *
    * Frees up the CAM @c sim and optionally the devq. If a mutex is associated
    * with the sim, it must be locked on entry. It will remain locked on
    * return.
    *
    * This function will wait for all outstanding reference to the sim to clear
    * before returning.
    *
    * @param sim          The sim to free
    * @param free_devq    Free the devq associated with the sim at creation.
    */
   void
   cam_sim_free(struct cam_sim *sim, int free_devq)
   {
           struct mtx *mtx;
           int error __diagused;
   
           if (sim->mtx == NULL) {
                   mtx = &cam_sim_free_mtx;
                   mtx_lock(mtx);
           } else {
                   mtx = sim->mtx;
                   mtx_assert(mtx, MA_OWNED);
           }
           KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
           sim->refcount--;
           if (sim->refcount > 0) {
                   error = msleep(sim, mtx, PRIBIO, "simfree", 0);
                   KASSERT(error == 0, ("invalid error value for msleep(9)"));
           }
           KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
           if (mtx == &cam_sim_free_mtx)   /* sim->mtx == NULL */
                   mtx_unlock(mtx);
   
           if (free_devq)
                   cam_simq_free(sim->devq);
           free(sim, M_CAMSIM);
   }
   
   void
   cam_sim_release(struct cam_sim *sim)
   {
           struct mtx *mtx;
   
           if (sim->mtx == NULL)
                   mtx = &cam_sim_free_mtx;
           else if (!mtx_owned(sim->mtx))
                   mtx = sim->mtx;
           else
                   mtx = NULL;     /* We hold the lock. */
           if (mtx)
                   mtx_lock(mtx);
           KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
           sim->refcount--;
           if (sim->refcount == 0)
                   wakeup(sim);
           if (mtx)
                   mtx_unlock(mtx);
   }
   
   void
   cam_sim_hold(struct cam_sim *sim)
   {
           struct mtx *mtx;
   
           if (sim->mtx == NULL)
                   mtx = &cam_sim_free_mtx;
           else if (!mtx_owned(sim->mtx))
                   mtx = sim->mtx;
           else
                   mtx = NULL;     /* We hold the lock. */
           if (mtx)
                   mtx_lock(mtx);
           KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
           sim->refcount++;
           if (mtx)
                   mtx_unlock(mtx);
   }
   
   void
   cam_sim_set_path(struct cam_sim *sim, u_int32_t path_id)
   {
           sim->path_id = path_id;
   }

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