omap-iovmm.c

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/*
 * omap iommu: simple virtual address space management
 *
 * Copyright (C) 2008-2009 Nokia Corporation
 *
 * Written by Hiroshi DOYU <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/device.h>
#include <linux/scatterlist.h>
#include <linux/iommu.h>

#include <asm/cacheflush.h>
#include <asm/mach/map.h>

#include <plat/iommu.h>
#include <plat/iovmm.h>

#include <plat/iopgtable.h>

static struct kmem_cache *iovm_area_cachep;

/* return the offset of the first scatterlist entry in a sg table */
static unsigned int sgtable_offset(const struct sg_table *sgt)
{
    if (!sgt || !sgt->nents)
        return 0;

    return sgt->sgl->offset;
}

/* return total bytes of sg buffers */
static size_t sgtable_len(const struct sg_table *sgt)
{
    unsigned int i, total = 0;
    struct scatterlist *sg;

    if (!sgt)
        return 0;

    for_each_sg(sgt->sgl, sg, sgt->nents, i) {
        size_t bytes;

        bytes = sg->length + sg->offset;

        if (!iopgsz_ok(bytes)) {
            pr_err("%s: sg[%d] not iommu pagesize(%u %u)\n",
                   __func__, i, bytes, sg->offset);
            return 0;
        }

        if (i && sg->offset) {
            pr_err("%s: sg[%d] offset not allowed in internal "
                    "entries\n", __func__, i);
            return 0;
        }

        total += bytes;
    }

    return total;
}
#define sgtable_ok(x)   (!!sgtable_len(x))

static unsigned max_alignment(u32 addr)
{
    int i;
    unsigned pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
    for (i = 0; i < ARRAY_SIZE(pagesize) && addr & (pagesize[i] - 1); i++)
        ;
    return (i < ARRAY_SIZE(pagesize)) ? pagesize[i] : 0;
}

/*
 * calculate the optimal number sg elements from total bytes based on
 * iommu superpages
 */
static unsigned sgtable_nents(size_t bytes, u32 da, u32 pa)
{
    unsigned nr_entries = 0, ent_sz;

    if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
        pr_err("%s: wrong size %08x\n", __func__, bytes);
        return 0;
    }

    while (bytes) {
        ent_sz = max_alignment(da | pa);
        ent_sz = min_t(unsigned, ent_sz, iopgsz_max(bytes));
        nr_entries++;
        da += ent_sz;
        pa += ent_sz;
        bytes -= ent_sz;
    }

    return nr_entries;
}

/* allocate and initialize sg_table header(a kind of 'superblock') */
static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags,
                            u32 da, u32 pa)
{
    unsigned int nr_entries;
    int err;
    struct sg_table *sgt;

    if (!bytes)
        return ERR_PTR(-EINVAL);

    if (!IS_ALIGNED(bytes, PAGE_SIZE))
        return ERR_PTR(-EINVAL);

    if (flags & IOVMF_LINEAR) {
        nr_entries = sgtable_nents(bytes, da, pa);
        if (!nr_entries)
            return ERR_PTR(-EINVAL);
    } else
        nr_entries =  bytes / PAGE_SIZE;

    sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
    if (!sgt)
        return ERR_PTR(-ENOMEM);

    err = sg_alloc_table(sgt, nr_entries, GFP_KERNEL);
    if (err) {
        kfree(sgt);
        return ERR_PTR(err);
    }

    pr_debug("%s: sgt:%p(%d entries)\n", __func__, sgt, nr_entries);

    return sgt;
}

/* free sg_table header(a kind of superblock) */
static void sgtable_free(struct sg_table *sgt)
{
    if (!sgt)
        return;

    sg_free_table(sgt);
    kfree(sgt);

    pr_debug("%s: sgt:%p\n", __func__, sgt);
}

/* map 'sglist' to a contiguous mpu virtual area and return 'va' */
static void *vmap_sg(const struct sg_table *sgt)
{
    u32 va;
    size_t total;
    unsigned int i;
    struct scatterlist *sg;
    struct vm_struct *new;
    const struct mem_type *mtype;

    mtype = get_mem_type(MT_DEVICE);
    if (!mtype)
        return ERR_PTR(-EINVAL);

    total = sgtable_len(sgt);
    if (!total)
        return ERR_PTR(-EINVAL);

    new = __get_vm_area(total, VM_IOREMAP, VMALLOC_START, VMALLOC_END);
    if (!new)
        return ERR_PTR(-ENOMEM);
    va = (u32)new->addr;

    for_each_sg(sgt->sgl, sg, sgt->nents, i) {
        size_t bytes;
        u32 pa;
        int err;

        pa = sg_phys(sg) - sg->offset;
        bytes = sg->length + sg->offset;

        BUG_ON(bytes != PAGE_SIZE);

        err = ioremap_page(va,  pa, mtype);
        if (err)
            goto err_out;

        va += bytes;
    }

    flush_cache_vmap((unsigned long)new->addr,
                (unsigned long)(new->addr + total));
    return new->addr;

err_out:
    WARN_ON(1); /* FIXME: cleanup some mpu mappings */
    vunmap(new->addr);
    return ERR_PTR(-EAGAIN);
}

static inline void vunmap_sg(const void *va)
{
    vunmap(va);
}

static struct iovm_struct *__find_iovm_area(struct omap_iommu *obj,
                            const u32 da)
{
    struct iovm_struct *tmp;

    list_for_each_entry(tmp, &obj->mmap, list) {
        if ((da >= tmp->da_start) && (da < tmp->da_end)) {
            size_t len;

            len = tmp->da_end - tmp->da_start;

            dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n",
                __func__, tmp->da_start, da, tmp->da_end, len,
                tmp->flags);

            return tmp;
        }
    }

    return NULL;
}

struct iovm_struct *omap_find_iovm_area(struct device *dev, u32 da)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    struct iovm_struct *area;

    mutex_lock(&obj->mmap_lock);
    area = __find_iovm_area(obj, da);
    mutex_unlock(&obj->mmap_lock);

    return area;
}
EXPORT_SYMBOL_GPL(omap_find_iovm_area);

/*
 * This finds the hole(area) which fits the requested address and len
 * in iovmas mmap, and returns the new allocated iovma.
 */
static struct iovm_struct *alloc_iovm_area(struct omap_iommu *obj, u32 da,
                       size_t bytes, u32 flags)
{
    struct iovm_struct *new, *tmp;
    u32 start, prev_end, alignment;

    if (!obj || !bytes)
        return ERR_PTR(-EINVAL);

    start = da;
    alignment = PAGE_SIZE;

    if (~flags & IOVMF_DA_FIXED) {
        /* Don't map address 0 */
        start = obj->da_start ? obj->da_start : alignment;

        if (flags & IOVMF_LINEAR)
            alignment = iopgsz_max(bytes);
        start = roundup(start, alignment);
    } else if (start < obj->da_start || start > obj->da_end ||
                    obj->da_end - start < bytes) {
        return ERR_PTR(-EINVAL);
    }

    tmp = NULL;
    if (list_empty(&obj->mmap))
        goto found;

    prev_end = 0;
    list_for_each_entry(tmp, &obj->mmap, list) {

        if (prev_end > start)
            break;

        if (tmp->da_start > start && (tmp->da_start - start) >= bytes)
            goto found;

        if (tmp->da_end >= start && ~flags & IOVMF_DA_FIXED)
            start = roundup(tmp->da_end + 1, alignment);

        prev_end = tmp->da_end;
    }

    if ((start >= prev_end) && (obj->da_end - start >= bytes))
        goto found;

    dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n",
        __func__, da, bytes, flags);

    return ERR_PTR(-EINVAL);

found:
    new = kmem_cache_zalloc(iovm_area_cachep, GFP_KERNEL);
    if (!new)
        return ERR_PTR(-ENOMEM);

    new->iommu = obj;
    new->da_start = start;
    new->da_end = start + bytes;
    new->flags = flags;

    /*
     * keep ascending order of iovmas
     */
    if (tmp)
        list_add_tail(&new->list, &tmp->list);
    else
        list_add(&new->list, &obj->mmap);

    dev_dbg(obj->dev, "%s: found %08x-%08x-%08x(%x) %08x\n",
        __func__, new->da_start, start, new->da_end, bytes, flags);

    return new;
}

static void free_iovm_area(struct omap_iommu *obj, struct iovm_struct *area)
{
    size_t bytes;

    BUG_ON(!obj || !area);

    bytes = area->da_end - area->da_start;

    dev_dbg(obj->dev, "%s: %08x-%08x(%x) %08x\n",
        __func__, area->da_start, area->da_end, bytes, area->flags);

    list_del(&area->list);
    kmem_cache_free(iovm_area_cachep, area);
}

void *omap_da_to_va(struct device *dev, u32 da)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    void *va = NULL;
    struct iovm_struct *area;

    mutex_lock(&obj->mmap_lock);

    area = __find_iovm_area(obj, da);
    if (!area) {
        dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
        goto out;
    }
    va = area->va;
out:
    mutex_unlock(&obj->mmap_lock);

    return va;
}
EXPORT_SYMBOL_GPL(omap_da_to_va);

static void sgtable_fill_vmalloc(struct sg_table *sgt, void *_va)
{
    unsigned int i;
    struct scatterlist *sg;
    void *va = _va;
    void *va_end;

    for_each_sg(sgt->sgl, sg, sgt->nents, i) {
        struct page *pg;
        const size_t bytes = PAGE_SIZE;

        /*
         * iommu 'superpage' isn't supported with 'omap_iommu_vmalloc()'
         */
        pg = vmalloc_to_page(va);
        BUG_ON(!pg);
        sg_set_page(sg, pg, bytes, 0);

        va += bytes;
    }

    va_end = _va + PAGE_SIZE * i;
}

static inline void sgtable_drain_vmalloc(struct sg_table *sgt)
{
    /*
     * Actually this is not necessary at all, just exists for
     * consistency of the code readability.
     */
    BUG_ON(!sgt);
}

/* create 'da' <-> 'pa' mapping from 'sgt' */
static int map_iovm_area(struct iommu_domain *domain, struct iovm_struct *new,
            const struct sg_table *sgt, u32 flags)
{
    int err;
    unsigned int i, j;
    struct scatterlist *sg;
    u32 da = new->da_start;

    if (!domain || !sgt)
        return -EINVAL;

    BUG_ON(!sgtable_ok(sgt));

    for_each_sg(sgt->sgl, sg, sgt->nents, i) {
        u32 pa;
        size_t bytes;

        pa = sg_phys(sg) - sg->offset;
        bytes = sg->length + sg->offset;

        flags &= ~IOVMF_PGSZ_MASK;

        if (bytes_to_iopgsz(bytes) < 0)
            goto err_out;

        pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
             i, da, pa, bytes);

        err = iommu_map(domain, da, pa, bytes, flags);
        if (err)
            goto err_out;

        da += bytes;
    }
    return 0;

err_out:
    da = new->da_start;

    for_each_sg(sgt->sgl, sg, i, j) {
        size_t bytes;

        bytes = sg->length + sg->offset;

        /* ignore failures.. we're already handling one */
        iommu_unmap(domain, da, bytes);

        da += bytes;
    }
    return err;
}

/* release 'da' <-> 'pa' mapping */
static void unmap_iovm_area(struct iommu_domain *domain, struct omap_iommu *obj,
                        struct iovm_struct *area)
{
    u32 start;
    size_t total = area->da_end - area->da_start;
    const struct sg_table *sgt = area->sgt;
    struct scatterlist *sg;
    int i;
    size_t unmapped;

    BUG_ON(!sgtable_ok(sgt));
    BUG_ON((!total) || !IS_ALIGNED(total, PAGE_SIZE));

    start = area->da_start;
    for_each_sg(sgt->sgl, sg, sgt->nents, i) {
        size_t bytes;

        bytes = sg->length + sg->offset;

        unmapped = iommu_unmap(domain, start, bytes);
        if (unmapped < bytes)
            break;

        dev_dbg(obj->dev, "%s: unmap %08x(%x) %08x\n",
                __func__, start, bytes, area->flags);

        BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));

        total -= bytes;
        start += bytes;
    }
    BUG_ON(total);
}

/* template function for all unmapping */
static struct sg_table *unmap_vm_area(struct iommu_domain *domain,
                      struct omap_iommu *obj, const u32 da,
                      void (*fn)(const void *), u32 flags)
{
    struct sg_table *sgt = NULL;
    struct iovm_struct *area;

    if (!IS_ALIGNED(da, PAGE_SIZE)) {
        dev_err(obj->dev, "%s: alignment err(%08x)\n", __func__, da);
        return NULL;
    }

    mutex_lock(&obj->mmap_lock);

    area = __find_iovm_area(obj, da);
    if (!area) {
        dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
        goto out;
    }

    if ((area->flags & flags) != flags) {
        dev_err(obj->dev, "%s: wrong flags(%08x)\n", __func__,
            area->flags);
        goto out;
    }
    sgt = (struct sg_table *)area->sgt;

    unmap_iovm_area(domain, obj, area);

    fn(area->va);

    dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n", __func__,
        area->da_start, da, area->da_end,
        area->da_end - area->da_start, area->flags);

    free_iovm_area(obj, area);
out:
    mutex_unlock(&obj->mmap_lock);

    return sgt;
}

static u32 map_iommu_region(struct iommu_domain *domain, struct omap_iommu *obj,
                u32 da, const struct sg_table *sgt, void *va,
                size_t bytes, u32 flags)
{
    int err = -ENOMEM;
    struct iovm_struct *new;

    mutex_lock(&obj->mmap_lock);

    new = alloc_iovm_area(obj, da, bytes, flags);
    if (IS_ERR(new)) {
        err = PTR_ERR(new);
        goto err_alloc_iovma;
    }
    new->va = va;
    new->sgt = sgt;

    if (map_iovm_area(domain, new, sgt, new->flags))
        goto err_map;

    mutex_unlock(&obj->mmap_lock);

    dev_dbg(obj->dev, "%s: da:%08x(%x) flags:%08x va:%p\n",
        __func__, new->da_start, bytes, new->flags, va);

    return new->da_start;

err_map:
    free_iovm_area(obj, new);
err_alloc_iovma:
    mutex_unlock(&obj->mmap_lock);
    return err;
}

static inline u32
__iommu_vmap(struct iommu_domain *domain, struct omap_iommu *obj,
                u32 da, const struct sg_table *sgt,
                void *va, size_t bytes, u32 flags)
{
    return map_iommu_region(domain, obj, da, sgt, va, bytes, flags);
}

u32 omap_iommu_vmap(struct iommu_domain *domain, struct device *dev, u32 da,
        const struct sg_table *sgt, u32 flags)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    size_t bytes;
    void *va = NULL;

    if (!obj || !obj->dev || !sgt)
        return -EINVAL;

    bytes = sgtable_len(sgt);
    if (!bytes)
        return -EINVAL;
    bytes = PAGE_ALIGN(bytes);

    if (flags & IOVMF_MMIO) {
        va = vmap_sg(sgt);
        if (IS_ERR(va))
            return PTR_ERR(va);
    }

    flags |= IOVMF_DISCONT;
    flags |= IOVMF_MMIO;

    da = __iommu_vmap(domain, obj, da, sgt, va, bytes, flags);
    if (IS_ERR_VALUE(da))
        vunmap_sg(va);

    return da + sgtable_offset(sgt);
}
EXPORT_SYMBOL_GPL(omap_iommu_vmap);

struct sg_table *
omap_iommu_vunmap(struct iommu_domain *domain, struct device *dev, u32 da)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    struct sg_table *sgt;
    /*
     * 'sgt' is allocated before 'omap_iommu_vmalloc()' is called.
     * Just returns 'sgt' to the caller to free
     */
    da &= PAGE_MASK;
    sgt = unmap_vm_area(domain, obj, da, vunmap_sg,
                    IOVMF_DISCONT | IOVMF_MMIO);
    if (!sgt)
        dev_dbg(obj->dev, "%s: No sgt\n", __func__);
    return sgt;
}
EXPORT_SYMBOL_GPL(omap_iommu_vunmap);

u32
omap_iommu_vmalloc(struct iommu_domain *domain, struct device *dev, u32 da,
                        size_t bytes, u32 flags)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    void *va;
    struct sg_table *sgt;

    if (!obj || !obj->dev || !bytes)
        return -EINVAL;

    bytes = PAGE_ALIGN(bytes);

    va = vmalloc(bytes);
    if (!va)
        return -ENOMEM;

    flags |= IOVMF_DISCONT;
    flags |= IOVMF_ALLOC;

    sgt = sgtable_alloc(bytes, flags, da, 0);
    if (IS_ERR(sgt)) {
        da = PTR_ERR(sgt);
        goto err_sgt_alloc;
    }
    sgtable_fill_vmalloc(sgt, va);

    da = __iommu_vmap(domain, obj, da, sgt, va, bytes, flags);
    if (IS_ERR_VALUE(da))
        goto err_iommu_vmap;

    return da;

err_iommu_vmap:
    sgtable_drain_vmalloc(sgt);
    sgtable_free(sgt);
err_sgt_alloc:
    vfree(va);
    return da;
}
EXPORT_SYMBOL_GPL(omap_iommu_vmalloc);

void omap_iommu_vfree(struct iommu_domain *domain, struct device *dev,
                                const u32 da)
{
    struct omap_iommu *obj = dev_to_omap_iommu(dev);
    struct sg_table *sgt;

    sgt = unmap_vm_area(domain, obj, da, vfree,
                        IOVMF_DISCONT | IOVMF_ALLOC);
    if (!sgt)
        dev_dbg(obj->dev, "%s: No sgt\n", __func__);
    sgtable_free(sgt);
}
EXPORT_SYMBOL_GPL(omap_iommu_vfree);

static int __init iovmm_init(void)
{
    const unsigned long flags = SLAB_HWCACHE_ALIGN;
    struct kmem_cache *p;

    p = kmem_cache_create("iovm_area_cache", sizeof(struct iovm_struct), 0,
                  flags, NULL);
    if (!p)
        return -ENOMEM;
    iovm_area_cachep = p;

    return 0;
}
module_init(iovmm_init);

static void __exit iovmm_exit(void)
{
    kmem_cache_destroy(iovm_area_cachep);
}
module_exit(iovmm_exit);

MODULE_DESCRIPTION("omap iommu: simple virtual address space management");
MODULE_AUTHOR("Hiroshi DOYU <[email protected]>");
MODULE_LICENSE("GPL v2");