subr_busdma_bounce.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 1997, 1998 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.
 */
 
/*
 * Common code for managing bounce pages for bus_dma backends.  As
 * this code currently assumes it can access internal members of
 * opaque types like bus_dma_tag_t and bus_dmamap it is #include'd in
 * backends rather than being compiled standalone.
 *
 * Prerequisites:
 *
 * - M_BUSDMA malloc type
 * - struct bus_dmamap
 * - hw_busdma SYSCTL_NODE
 * - macros to access the following fields of bus_dma_tag_t:
 *   - dmat_alignment()
 *   - dmat_flags()
 *   - dmat_lowaddr()
 *   - dmat_lockfunc()
 *   - dmat_lockarg()
 */
 
struct bounce_page {
        vm_offset_t     vaddr;          /* kva of bounce buffer */
        bus_addr_t      busaddr;        /* Physical address */
        vm_offset_t     datavaddr;      /* kva of client data */
#if defined(__amd64__) || defined(__i386__)
        vm_page_t       datapage[2];    /* physical page(s) of client data */
#else
        vm_page_t       datapage;       /* physical page of client data */
#endif
        vm_offset_t     dataoffs;       /* page offset of client data */
        bus_size_t      datacount;      /* client data count */
        STAILQ_ENTRY(bounce_page) links;
};
 
struct bounce_zone {
        STAILQ_ENTRY(bounce_zone) links;
        STAILQ_HEAD(, bounce_page) bounce_page_list;
        int             total_bpages;
        int             free_bpages;
        int             reserved_bpages;
        int             active_bpages;
        int             total_bounced;
        int             total_deferred;
        int             map_count;
#ifdef dmat_domain
        int             domain;
#endif
        bus_size_t      alignment;
        bus_addr_t      lowaddr;
        char            zoneid[8];
        char            lowaddrid[20];
        struct sysctl_ctx_list sysctl_tree;
        struct sysctl_oid *sysctl_tree_top;
};
 
static struct mtx bounce_lock;
static int total_bpages;
static int busdma_zonecount;
 
static STAILQ_HEAD(, bounce_zone) bounce_zone_list;
static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
static void *busdma_ih;
 
static MALLOC_DEFINE(M_BOUNCE, "bounce", "busdma bounce pages");
 
SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
   "Total bounce pages");
 
static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
    int commit);
 
static int
_bus_dmamap_reserve_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int flags)
{
 
        /* Reserve Necessary Bounce Pages */
        mtx_lock(&bounce_lock);
        if (flags & BUS_DMA_NOWAIT) {
                if (reserve_bounce_pages(dmat, map, 0) != 0) {
                        map->pagesneeded = 0;
                        mtx_unlock(&bounce_lock);
                        return (ENOMEM);
                }
        } else {
                if (reserve_bounce_pages(dmat, map, 1) != 0) {
                        /* Queue us for resources */
                        STAILQ_INSERT_TAIL(&bounce_map_waitinglist, map, links);
                        mtx_unlock(&bounce_lock);
                        return (EINPROGRESS);
                }
        }
        mtx_unlock(&bounce_lock);
 
        return (0);
}
 
static void
init_bounce_pages(void *dummy __unused)
{
 
        total_bpages = 0;
        STAILQ_INIT(&bounce_zone_list);
        STAILQ_INIT(&bounce_map_waitinglist);
        STAILQ_INIT(&bounce_map_callbacklist);
        mtx_init(&bounce_lock, "bounce pages lock", NULL, MTX_DEF);
}
SYSINIT(bpages, SI_SUB_LOCK, SI_ORDER_ANY, init_bounce_pages, NULL);
 
static struct sysctl_ctx_list *
busdma_sysctl_tree(struct bounce_zone *bz)
{
 
        return (&bz->sysctl_tree);
}
 
static struct sysctl_oid *
busdma_sysctl_tree_top(struct bounce_zone *bz)
{
 
        return (bz->sysctl_tree_top);
}
 
static int
alloc_bounce_zone(bus_dma_tag_t dmat)
{
        struct bounce_zone *bz;
 
        /* Check to see if we already have a suitable zone */
        STAILQ_FOREACH(bz, &bounce_zone_list, links) {
                if ((dmat_alignment(dmat) <= bz->alignment) &&
#ifdef dmat_domain
                    dmat_domain(dmat) == bz->domain &&
#endif
                    (dmat_lowaddr(dmat) >= bz->lowaddr)) {
                        dmat->bounce_zone = bz;
                        return (0);
                }
        }
 
        if ((bz = (struct bounce_zone *)malloc(sizeof(*bz), M_BUSDMA,
            M_NOWAIT | M_ZERO)) == NULL)
                return (ENOMEM);
 
        STAILQ_INIT(&bz->bounce_page_list);
        bz->free_bpages = 0;
        bz->reserved_bpages = 0;
        bz->active_bpages = 0;
        bz->lowaddr = dmat_lowaddr(dmat);
        bz->alignment = MAX(dmat_alignment(dmat), PAGE_SIZE);
        bz->map_count = 0;
#ifdef dmat_domain
        bz->domain = dmat_domain(dmat);
#endif
        snprintf(bz->zoneid, sizeof(bz->zoneid), "zone%d", busdma_zonecount);
        busdma_zonecount++;
        snprintf(bz->lowaddrid, sizeof(bz->lowaddrid), "%#jx",
            (uintmax_t)bz->lowaddr);
        STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
        dmat->bounce_zone = bz;
 
        sysctl_ctx_init(&bz->sysctl_tree);
        bz->sysctl_tree_top = SYSCTL_ADD_NODE(&bz->sysctl_tree,
            SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
            CTLFLAG_RD | CTLFLAG_MPSAFE, 0, "");
        if (bz->sysctl_tree_top == NULL) {
                sysctl_ctx_free(&bz->sysctl_tree);
                return (0);     /* XXX error code? */
        }
 
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
            "Total bounce pages");
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
            "Free bounce pages");
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
            "Reserved bounce pages");
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
            "Active bounce pages");
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
            "Total bounce requests (pages bounced)");
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
            "Total bounce requests that were deferred");
        SYSCTL_ADD_STRING(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
        SYSCTL_ADD_UAUTO(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "alignment", CTLFLAG_RD, &bz->alignment, "");
#ifdef dmat_domain
        SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
            SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
            "domain", CTLFLAG_RD, &bz->domain, 0,
            "memory domain");
#endif
 
        return (0);
}
 
static int
alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages)
{
        struct bounce_zone *bz;
        int count;
 
        bz = dmat->bounce_zone;
        count = 0;
        while (numpages > 0) {
                struct bounce_page *bpage;
 
#ifdef dmat_domain
                bpage = malloc_domainset(sizeof(*bpage), M_BUSDMA,
                    DOMAINSET_PREF(bz->domain), M_NOWAIT | M_ZERO);
#else
                bpage = malloc(sizeof(*bpage), M_BUSDMA, M_NOWAIT | M_ZERO);
#endif
 
                if (bpage == NULL)
                        break;
#ifdef dmat_domain
                bpage->vaddr = (vm_offset_t)contigmalloc_domainset(PAGE_SIZE,
                    M_BOUNCE, DOMAINSET_PREF(bz->domain), M_NOWAIT,
                    0ul, bz->lowaddr, PAGE_SIZE, 0);
#else
                bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_BOUNCE,
                    M_NOWAIT, 0ul, bz->lowaddr, PAGE_SIZE, 0);
#endif
                if (bpage->vaddr == 0) {
                        free(bpage, M_BUSDMA);
                        break;
                }
                bpage->busaddr = pmap_kextract(bpage->vaddr);
                mtx_lock(&bounce_lock);
                STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
                total_bpages++;
                bz->total_bpages++;
                bz->free_bpages++;
                mtx_unlock(&bounce_lock);
                count++;
                numpages--;
        }
        return (count);
}
 
static int
reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
{
        struct bounce_zone *bz;
        int pages;
 
        mtx_assert(&bounce_lock, MA_OWNED);
        bz = dmat->bounce_zone;
        pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
        if (commit == 0 && map->pagesneeded > (map->pagesreserved + pages))
                return (map->pagesneeded - (map->pagesreserved + pages));
        bz->free_bpages -= pages;
        bz->reserved_bpages += pages;
        map->pagesreserved += pages;
        pages = map->pagesneeded - map->pagesreserved;
 
        return (pages);
}
 
#if defined(__amd64__) || defined(__i386__)
static bus_addr_t
add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
    vm_paddr_t addr1, vm_paddr_t addr2, bus_size_t size)
#else
static bus_addr_t
add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
    bus_addr_t addr, bus_size_t size)
#endif
{
        struct bounce_zone *bz;
        struct bounce_page *bpage;
 
        KASSERT(dmat->bounce_zone != NULL, ("no bounce zone in dma tag"));
        KASSERT(map != NULL, ("add_bounce_page: bad map %p", map));
#if defined(__amd64__) || defined(__i386__)
        KASSERT(map != &nobounce_dmamap, ("add_bounce_page: bad map %p", map));
#endif
#ifdef __riscv
        KASSERT((map->flags & DMAMAP_COULD_BOUNCE) != 0,
            ("add_bounce_page: bad map %p", map));
#endif
 
        bz = dmat->bounce_zone;
        if (map->pagesneeded == 0)
                panic("add_bounce_page: map doesn't need any pages");
        map->pagesneeded--;
 
        if (map->pagesreserved == 0)
                panic("add_bounce_page: map doesn't need any pages");
        map->pagesreserved--;
 
        mtx_lock(&bounce_lock);
        bpage = STAILQ_FIRST(&bz->bounce_page_list);
        if (bpage == NULL)
                panic("add_bounce_page: free page list is empty");
 
        STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
        bz->reserved_bpages--;
        bz->active_bpages++;
        mtx_unlock(&bounce_lock);
 
        if (dmat_flags(dmat) & BUS_DMA_KEEP_PG_OFFSET) {
                /* Page offset needs to be preserved. */
#if defined(__amd64__) || defined(__i386__)
                bpage->vaddr |= addr1 & PAGE_MASK;
                bpage->busaddr |= addr1 & PAGE_MASK;
                KASSERT(addr2 == 0,
            ("Trying to bounce multiple pages with BUS_DMA_KEEP_PG_OFFSET"));
#else
                bpage->vaddr |= addr & PAGE_MASK;
                bpage->busaddr |= addr & PAGE_MASK;
#endif
        }
        bpage->datavaddr = vaddr;
#if defined(__amd64__) || defined(__i386__)
        bpage->datapage[0] = PHYS_TO_VM_PAGE(addr1);
        KASSERT((addr2 & PAGE_MASK) == 0, ("Second page is not aligned"));
        bpage->datapage[1] = PHYS_TO_VM_PAGE(addr2);
        bpage->dataoffs = addr1 & PAGE_MASK;
#else
        bpage->datapage = PHYS_TO_VM_PAGE(addr);
        bpage->dataoffs = addr & PAGE_MASK;
#endif
        bpage->datacount = size;
        STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
        return (bpage->busaddr);
}
 
static void
free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
{
        struct bus_dmamap *map;
        struct bounce_zone *bz;
        bool schedule_swi;
 
        bz = dmat->bounce_zone;
        bpage->datavaddr = 0;
        bpage->datacount = 0;
        if (dmat_flags(dmat) & BUS_DMA_KEEP_PG_OFFSET) {
                /*
                 * Reset the bounce page to start at offset 0.  Other uses
                 * of this bounce page may need to store a full page of
                 * data and/or assume it starts on a page boundary.
                 */
                bpage->vaddr &= ~PAGE_MASK;
                bpage->busaddr &= ~PAGE_MASK;
        }
 
        schedule_swi = false;
        mtx_lock(&bounce_lock);
        STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
        bz->free_bpages++;
        bz->active_bpages--;
        if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {
                if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
                        STAILQ_REMOVE_HEAD(&bounce_map_waitinglist, links);
                        STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
                            map, links);
                        bz->total_deferred++;
                        schedule_swi = true;
                }
        }
        mtx_unlock(&bounce_lock);
        if (schedule_swi)
                swi_sched(busdma_ih, 0);
}
 
static void
busdma_swi(void *dummy __unused)
{
        bus_dma_tag_t dmat;
        struct bus_dmamap *map;
 
        mtx_lock(&bounce_lock);
        while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
                STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
                mtx_unlock(&bounce_lock);
                dmat = map->dmat;
                dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_LOCK);
                bus_dmamap_load_mem(map->dmat, map, &map->mem, map->callback,
                    map->callback_arg, BUS_DMA_WAITOK);
                dmat_lockfunc(dmat)(dmat_lockfuncarg(dmat), BUS_DMA_UNLOCK);
                mtx_lock(&bounce_lock);
        }
        mtx_unlock(&bounce_lock);
}
 
static void
start_busdma_swi(void *dummy __unused)
{
        if (swi_add(NULL, "busdma", busdma_swi, NULL, SWI_BUSDMA, INTR_MPSAFE,
            &busdma_ih))
                panic("died while creating busdma swi ithread");
}
SYSINIT(start_busdma_swi, SI_SUB_SOFTINTR, SI_ORDER_ANY, start_busdma_swi,
    NULL);