FreeBSD/Linux Kernel Cross Reference
sys/dev/altera/sdcard/altera_sdcard.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2012 Robert N. M. Watson
      * All rights reserved.
      *
      * This software was developed by SRI International and the University of
      * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
      * ("CTSRD"), as part of the DARPA CRASH research programme.
     *
     * 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.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * 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 "opt_altera_sdcard.h"
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/condvar.h>
    #include <sys/conf.h>
    #include <sys/bio.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/mutex.h>
    #include <sys/rman.h>
    #include <sys/systm.h>
    #include <sys/taskqueue.h>
    
    #include <machine/bus.h>
    #include <machine/resource.h>
    
    #include <geom/geom_disk.h>
    
    #include <dev/altera/sdcard/altera_sdcard.h>
    
    /*
     * Device driver for the Altera University Program Secure Data Card IP Core,
     * as described in the similarly named SOPC Builder IP Core specification.
     * This soft core is not a full SD host controller interface (SDHCI) but
     * instead provides a set of memory mapped registers and memory buffer that
     * mildly abstract the SD Card protocol, but without providing DMA or
     * interrupts.  However, it does hide the details of voltage and
     * communications negotiation.  This driver implements disk(9), but due to the
     * lack of interrupt support, must rely on timer-driven polling to determine
     * when I/Os have completed.
     *
     * TODO:
     *
     * 1. Implement DISKFLAG_CANDELETE / SD Card sector erase support.
     * 2. Implement d_ident from SD Card CID serial number field.
     * 3. Handle read-only SD Cards.
     * 4. Tune timeouts based on real-world SD Card speeds.
     */
    devclass_t      altera_sdcard_devclass;
    
    void
    altera_sdcard_attach(struct altera_sdcard_softc *sc)
    {
    
            ALTERA_SDCARD_LOCK_INIT(sc);
            ALTERA_SDCARD_CONDVAR_INIT(sc);
            sc->as_disk = NULL;
            bioq_init(&sc->as_bioq);
            sc->as_currentbio = NULL;
            sc->as_state = ALTERA_SDCARD_STATE_NOCARD;
            sc->as_taskqueue = taskqueue_create("altera_sdcardc taskq", M_WAITOK,
                taskqueue_thread_enqueue, &sc->as_taskqueue);
            taskqueue_start_threads(&sc->as_taskqueue, 1, PI_DISK,
                "altera_sdcardc%d taskqueue", sc->as_unit);
            TIMEOUT_TASK_INIT(sc->as_taskqueue, &sc->as_task, 0,
                altera_sdcard_task, sc);
    
            /*
             * Kick off timer-driven processing with a manual poll so that we
             * synchronously detect an already-inserted SD Card during the boot or
             * other driver attach point.
            */
           altera_sdcard_task(sc, 1);
   }
   
   void
   altera_sdcard_detach(struct altera_sdcard_softc *sc)
   {
   
           KASSERT(sc->as_taskqueue != NULL, ("%s: taskqueue not present",
               __func__));
   
           /*
            * Winding down the driver on detach is a bit complex.  Update the
            * flags to indicate that a detach has been requested, and then wait
            * for in-progress I/O to wind down before continuing.
            */
           ALTERA_SDCARD_LOCK(sc);
           sc->as_flags |= ALTERA_SDCARD_FLAG_DETACHREQ;
           while (sc->as_state != ALTERA_SDCARD_STATE_DETACHED)
                   ALTERA_SDCARD_CONDVAR_WAIT(sc);
           ALTERA_SDCARD_UNLOCK(sc);
   
           /*
            * Now wait for the possibly still executing taskqueue to drain.  In
            * principle no more events will be scheduled as we've transitioned to
            * a detached state, but there might still be a request in execution.
            */
           while (taskqueue_cancel_timeout(sc->as_taskqueue, &sc->as_task, NULL))
                   taskqueue_drain_timeout(sc->as_taskqueue, &sc->as_task);
   
           /*
            * Simulate a disk removal if one is present to deal with any pending
            * or queued I/O.
            */
           if (sc->as_disk != NULL)
                   altera_sdcard_disk_remove(sc);
           KASSERT(bioq_first(&sc->as_bioq) == NULL,
               ("%s: non-empty bioq", __func__));
   
           /*
            * Free any remaining allocated resources.
            */
           taskqueue_free(sc->as_taskqueue);
           sc->as_taskqueue = NULL;
           ALTERA_SDCARD_CONDVAR_DESTROY(sc);
           ALTERA_SDCARD_LOCK_DESTROY(sc);
   }
   
   /*
    * Set up and start the next I/O.  Transition to the I/O state, but allow the
    * caller to schedule the next timeout, as this may be called either from an
    * initial attach context, or from the task queue, which requires different
    * behaviour.
    */
   static void
   altera_sdcard_nextio(struct altera_sdcard_softc *sc)
   {
           struct bio *bp;
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
           KASSERT(sc->as_currentbio == NULL,
               ("%s: bio already active", __func__));
   
           bp = bioq_takefirst(&sc->as_bioq);
           if (bp == NULL)
                   panic("%s: bioq empty", __func__);
           altera_sdcard_io_start(sc, bp);
           sc->as_state = ALTERA_SDCARD_STATE_IO;
   }
   
   static void
   altera_sdcard_task_nocard(struct altera_sdcard_softc *sc)
   {
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
   
           /*
            * Handle device driver detach.
            */
           if (sc->as_flags & ALTERA_SDCARD_FLAG_DETACHREQ) {
                   sc->as_state = ALTERA_SDCARD_STATE_DETACHED;
                   return;
           }
   
           /*
            * If there is no card insertion, remain in NOCARD.
            */
           if (!(altera_sdcard_read_asr(sc) & ALTERA_SDCARD_ASR_CARDPRESENT))
                   return;
   
           /*
            * Read the CSD -- it may contain values that the driver can't handle,
            * either because of an unsupported version/feature, or because the
            * card is misbehaving.  This triggers a transition to
            * ALTERA_SDCARD_STATE_BADCARD.  We rely on the CSD read to print a
            * banner about how the card is problematic, since it has more
            * information.  The bad card state allows us to print that banner
            * once rather than each time we notice the card is there, and still
            * bad.
            */
           if (altera_sdcard_read_csd(sc) != 0) {
                   sc->as_state = ALTERA_SDCARD_STATE_BADCARD;
                   return;
           }
   
           /*
            * Process card insertion and upgrade to the IDLE state.
            */
           altera_sdcard_disk_insert(sc);
           sc->as_state = ALTERA_SDCARD_STATE_IDLE;
   }
   
   static void
   altera_sdcard_task_badcard(struct altera_sdcard_softc *sc)
   {
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
   
           /*
            * Handle device driver detach.
            */
           if (sc->as_flags & ALTERA_SDCARD_FLAG_DETACHREQ) {
                   sc->as_state = ALTERA_SDCARD_STATE_DETACHED;
                   return;
           }
   
           /*
            * Handle safe card removal -- no teardown is required, just a state
            * transition.
            */
           if (!(altera_sdcard_read_asr(sc) & ALTERA_SDCARD_ASR_CARDPRESENT))
                   sc->as_state = ALTERA_SDCARD_STATE_NOCARD;
   }
   
   static void
   altera_sdcard_task_idle(struct altera_sdcard_softc *sc)
   {
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
   
           /*
            * Handle device driver detach.
            */
           if (sc->as_flags & ALTERA_SDCARD_FLAG_DETACHREQ) {
                   sc->as_state = ALTERA_SDCARD_STATE_DETACHED;
                   return;
           }
   
           /*
            * Handle safe card removal.
            */
           if (!(altera_sdcard_read_asr(sc) & ALTERA_SDCARD_ASR_CARDPRESENT)) {
                   altera_sdcard_disk_remove(sc);
                   sc->as_state = ALTERA_SDCARD_STATE_NOCARD;
           }
   }
   
   static void
   altera_sdcard_task_io(struct altera_sdcard_softc *sc)
   {
           uint16_t asr;
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
           KASSERT(sc->as_currentbio != NULL, ("%s: no current I/O", __func__));
   
   #ifdef ALTERA_SDCARD_FAST_SIM
   recheck:
   #endif
           asr = altera_sdcard_read_asr(sc);
   
           /*
            * Check for unexpected card removal during an I/O.
            */
           if (!(asr & ALTERA_SDCARD_ASR_CARDPRESENT)) {
                   altera_sdcard_disk_remove(sc);
                   if (sc->as_flags & ALTERA_SDCARD_FLAG_DETACHREQ)
                           sc->as_state = ALTERA_SDCARD_STATE_DETACHED;
                   else
                           sc->as_state = ALTERA_SDCARD_STATE_NOCARD;
                   return;
           }
   
           /*
            * If the I/O isn't complete, remain in the IO state without further
            * action, even if DETACHREQ is in flight.
            */
           if (asr & ALTERA_SDCARD_ASR_CMDINPROGRESS)
                   return;
   
           /*
            * Handle various forms of I/O completion, successful and otherwise.
            * The I/O layer may restart the transaction if an error occurred, in
            * which case remain in the IO state and reschedule.
            */
           if (!altera_sdcard_io_complete(sc, asr))
                   return;
   
           /*
            * Now that I/O is complete, process detach requests in preference to
            * starting new I/O.
            */
           if (sc->as_flags & ALTERA_SDCARD_FLAG_DETACHREQ) {
                   sc->as_state = ALTERA_SDCARD_STATE_DETACHED;
                   return;
           }
   
           /*
            * Finally, either start the next I/O or transition to the IDLE state.
            */
           if (bioq_first(&sc->as_bioq) != NULL) {
                   altera_sdcard_nextio(sc);
   #ifdef ALTERA_SDCARD_FAST_SIM
                   goto recheck;
   #endif
           } else
                   sc->as_state = ALTERA_SDCARD_STATE_IDLE;
   }
   
   static void
   altera_sdcard_task_rechedule(struct altera_sdcard_softc *sc)
   {
           int interval;
   
           /*
            * Reschedule based on new state.  Or not, if detaching the device
            * driver.  Treat a bad card as though it were no card at all.
            */
           switch (sc->as_state) {
           case ALTERA_SDCARD_STATE_NOCARD:
           case ALTERA_SDCARD_STATE_BADCARD:
                   interval = ALTERA_SDCARD_TIMEOUT_NOCARD;
                   break;
   
           case ALTERA_SDCARD_STATE_IDLE:
                   interval = ALTERA_SDCARD_TIMEOUT_IDLE;
                   break;
   
           case ALTERA_SDCARD_STATE_IO:
                   if (sc->as_flags & ALTERA_SDCARD_FLAG_IOERROR)
                           interval = ALTERA_SDCARD_TIMEOUT_IOERROR;
                   else
                           interval = ALTERA_SDCARD_TIMEOUT_IO;
                   break;
   
           default:
                   panic("%s: invalid exit state %d", __func__, sc->as_state);
           }
           taskqueue_enqueue_timeout(sc->as_taskqueue, &sc->as_task, interval);
   }
   
   /*
    * Because the Altera SD Card IP Core doesn't support interrupts, we do all
    * asynchronous work from a timeout.  Poll at two different rates -- an
    * infrequent check for card insertion status changes, and a frequent one for
    * I/O completion.  The task should never start in DETACHED, as that would
    * imply that a previous instance failed to cancel rather than reschedule.
    */
   void
   altera_sdcard_task(void *arg, int pending)
   {
           struct altera_sdcard_softc *sc;
   
           sc = arg;
           KASSERT(sc->as_state != ALTERA_SDCARD_STATE_DETACHED,
               ("%s: already in detached", __func__));
   
           ALTERA_SDCARD_LOCK(sc);
           switch (sc->as_state) {
           case ALTERA_SDCARD_STATE_NOCARD:
                   altera_sdcard_task_nocard(sc);
                   break;
   
           case ALTERA_SDCARD_STATE_BADCARD:
                   altera_sdcard_task_badcard(sc);
                   break;
   
           case ALTERA_SDCARD_STATE_IDLE:
                   altera_sdcard_task_idle(sc);
                   break;
   
           case ALTERA_SDCARD_STATE_IO:
                   altera_sdcard_task_io(sc);
                   break;
   
           default:
                   panic("%s: invalid enter state %d", __func__, sc->as_state);
           }
   
           /*
            * If we have transitioned to DETACHED, signal the detach thread and
            * cancel the timeout-driven task.  Otherwise reschedule on an
            * appropriate timeout.
            */
           if (sc->as_state == ALTERA_SDCARD_STATE_DETACHED)
                   ALTERA_SDCARD_CONDVAR_SIGNAL(sc);
           else
                   altera_sdcard_task_rechedule(sc);
           ALTERA_SDCARD_UNLOCK(sc);
   }
   
   void
   altera_sdcard_start(struct altera_sdcard_softc *sc)
   {
   
           ALTERA_SDCARD_LOCK_ASSERT(sc);
   
           KASSERT(sc->as_state == ALTERA_SDCARD_STATE_IDLE,
               ("%s: starting when not IDLE", __func__));
   
           taskqueue_cancel_timeout(sc->as_taskqueue, &sc->as_task, NULL);
           altera_sdcard_nextio(sc);
   #ifdef ALTERA_SDCARD_FAST_SIM
           altera_sdcard_task_io(sc);
   #endif
           altera_sdcard_task_rechedule(sc);
   }

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