of: MSI: Simplify irqdomain lookup

[linux/fpc-iii.git] / drivers / iommu / dma-iommu.c

/*
 * A fairly generic DMA-API to IOMMU-API glue layer.
 *
 * Copyright (C) 2014-2015 ARM Ltd.
 *
 * based in part on arch/arm/mm/dma-mapping.c:
 * Copyright (C) 2000-2004 Russell King
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/device.h>
#include <linux/dma-iommu.h>
#include <linux/gfp.h>
#include <linux/huge_mm.h>
#include <linux/iommu.h>
#include <linux/iova.h>
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/vmalloc.h>

int iommu_dma_init(void)
{
        return iova_cache_get();
}

/**
 * iommu_get_dma_cookie - Acquire DMA-API resources for a domain
 * @domain: IOMMU domain to prepare for DMA-API usage
 *
 * IOMMU drivers should normally call this from their domain_alloc
 * callback when domain->type == IOMMU_DOMAIN_DMA.
 */
int iommu_get_dma_cookie(struct iommu_domain *domain)
{
        struct iova_domain *iovad;

        if (domain->iova_cookie)
                return -EEXIST;

        iovad = kzalloc(sizeof(*iovad), GFP_KERNEL);
        domain->iova_cookie = iovad;

        return iovad ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(iommu_get_dma_cookie);

/**
 * iommu_put_dma_cookie - Release a domain's DMA mapping resources
 * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
 *
 * IOMMU drivers should normally call this from their domain_free callback.
 */
void iommu_put_dma_cookie(struct iommu_domain *domain)
{
        struct iova_domain *iovad = domain->iova_cookie;

        if (!iovad)
                return;

        put_iova_domain(iovad);
        kfree(iovad);
        domain->iova_cookie = NULL;
}
EXPORT_SYMBOL(iommu_put_dma_cookie);

/**
 * iommu_dma_init_domain - Initialise a DMA mapping domain
 * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
 * @base: IOVA at which the mappable address space starts
 * @size: Size of IOVA space
 *
 * @base and @size should be exact multiples of IOMMU page granularity to
 * avoid rounding surprises. If necessary, we reserve the page at address 0
 * to ensure it is an invalid IOVA. It is safe to reinitialise a domain, but
 * any change which could make prior IOVAs invalid will fail.
 */
int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, u64 size)
{
        struct iova_domain *iovad = domain->iova_cookie;
        unsigned long order, base_pfn, end_pfn;

        if (!iovad)
                return -ENODEV;

        /* Use the smallest supported page size for IOVA granularity */
        order = __ffs(domain->ops->pgsize_bitmap);
        base_pfn = max_t(unsigned long, 1, base >> order);
        end_pfn = (base + size - 1) >> order;

        /* Check the domain allows at least some access to the device... */
        if (domain->geometry.force_aperture) {
                if (base > domain->geometry.aperture_end ||
                    base + size <= domain->geometry.aperture_start) {
                        pr_warn("specified DMA range outside IOMMU capability\n");
                        return -EFAULT;
                }
                /* ...then finally give it a kicking to make sure it fits */
                base_pfn = max_t(unsigned long, base_pfn,
                                domain->geometry.aperture_start >> order);
                end_pfn = min_t(unsigned long, end_pfn,
                                domain->geometry.aperture_end >> order);
        }

        /* All we can safely do with an existing domain is enlarge it */
        if (iovad->start_pfn) {
                if (1UL << order != iovad->granule ||
                    base_pfn != iovad->start_pfn ||
                    end_pfn < iovad->dma_32bit_pfn) {
                        pr_warn("Incompatible range for DMA domain\n");
                        return -EFAULT;
                }
                iovad->dma_32bit_pfn = end_pfn;
        } else {
                init_iova_domain(iovad, 1UL << order, base_pfn, end_pfn);
        }
        return 0;
}
EXPORT_SYMBOL(iommu_dma_init_domain);

/**
 * dma_direction_to_prot - Translate DMA API directions to IOMMU API page flags
 * @dir: Direction of DMA transfer
 * @coherent: Is the DMA master cache-coherent?
 *
 * Return: corresponding IOMMU API page protection flags
 */
int dma_direction_to_prot(enum dma_data_direction dir, bool coherent)
{
        int prot = coherent ? IOMMU_CACHE : 0;

        switch (dir) {
        case DMA_BIDIRECTIONAL:
                return prot | IOMMU_READ | IOMMU_WRITE;
        case DMA_TO_DEVICE:
                return prot | IOMMU_READ;
        case DMA_FROM_DEVICE:
                return prot | IOMMU_WRITE;
        default:
                return 0;
        }
}

static struct iova *__alloc_iova(struct iova_domain *iovad, size_t size,
                dma_addr_t dma_limit)
{
        unsigned long shift = iova_shift(iovad);
        unsigned long length = iova_align(iovad, size) >> shift;

        /*
         * Enforce size-alignment to be safe - there could perhaps be an
         * attribute to control this per-device, or at least per-domain...
         */
        return alloc_iova(iovad, length, dma_limit >> shift, true);
}

/* The IOVA allocator knows what we mapped, so just unmap whatever that was */
static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t dma_addr)
{
        struct iova_domain *iovad = domain->iova_cookie;
        unsigned long shift = iova_shift(iovad);
        unsigned long pfn = dma_addr >> shift;
        struct iova *iova = find_iova(iovad, pfn);
        size_t size;

        if (WARN_ON(!iova))
                return;

        size = iova_size(iova) << shift;
        size -= iommu_unmap(domain, pfn << shift, size);
        /* ...and if we can't, then something is horribly, horribly wrong */
        WARN_ON(size > 0);
        __free_iova(iovad, iova);
}

static void __iommu_dma_free_pages(struct page **pages, int count)
{
        while (count--)
                __free_page(pages[count]);
        kvfree(pages);
}

static struct page **__iommu_dma_alloc_pages(unsigned int count, gfp_t gfp)
{
        struct page **pages;
        unsigned int i = 0, array_size = count * sizeof(*pages);
        unsigned int order = MAX_ORDER;

        if (array_size <= PAGE_SIZE)
                pages = kzalloc(array_size, GFP_KERNEL);
        else
                pages = vzalloc(array_size);
        if (!pages)
                return NULL;

        /* IOMMU can map any pages, so himem can also be used here */
        gfp |= __GFP_NOWARN | __GFP_HIGHMEM;

        while (count) {
                struct page *page = NULL;
                int j;

                /*
                 * Higher-order allocations are a convenience rather
                 * than a necessity, hence using __GFP_NORETRY until
                 * falling back to single-page allocations.
                 */
                for (order = min_t(unsigned int, order, __fls(count));
                     order > 0; order--) {
                        page = alloc_pages(gfp | __GFP_NORETRY, order);
                        if (!page)
                                continue;
                        if (PageCompound(page)) {
                                if (!split_huge_page(page))
                                        break;
                                __free_pages(page, order);
                        } else {
                                split_page(page, order);
                                break;
                        }
                }
                if (!page)
                        page = alloc_page(gfp);
                if (!page) {
                        __iommu_dma_free_pages(pages, i);
                        return NULL;
                }
                j = 1 << order;
                count -= j;
                while (j--)
                        pages[i++] = page++;
        }
        return pages;
}

/**
 * iommu_dma_free - Free a buffer allocated by iommu_dma_alloc()
 * @dev: Device which owns this buffer
 * @pages: Array of buffer pages as returned by iommu_dma_alloc()
 * @size: Size of buffer in bytes
 * @handle: DMA address of buffer
 *
 * Frees both the pages associated with the buffer, and the array
 * describing them
 */
void iommu_dma_free(struct device *dev, struct page **pages, size_t size,
                dma_addr_t *handle)
{
        __iommu_dma_unmap(iommu_get_domain_for_dev(dev), *handle);
        __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
        *handle = DMA_ERROR_CODE;
}

/**
 * iommu_dma_alloc - Allocate and map a buffer contiguous in IOVA space
 * @dev: Device to allocate memory for. Must be a real device
 *       attached to an iommu_dma_domain
 * @size: Size of buffer in bytes
 * @gfp: Allocation flags
 * @prot: IOMMU mapping flags
 * @handle: Out argument for allocated DMA handle
 * @flush_page: Arch callback which must ensure PAGE_SIZE bytes from the
 *              given VA/PA are visible to the given non-coherent device.
 *
 * If @size is less than PAGE_SIZE, then a full CPU page will be allocated,
 * but an IOMMU which supports smaller pages might not map the whole thing.
 *
 * Return: Array of struct page pointers describing the buffer,
 *         or NULL on failure.
 */
struct page **iommu_dma_alloc(struct device *dev, size_t size,
                gfp_t gfp, int prot, dma_addr_t *handle,
                void (*flush_page)(struct device *, const void *, phys_addr_t))
{
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
        struct iova_domain *iovad = domain->iova_cookie;
        struct iova *iova;
        struct page **pages;
        struct sg_table sgt;
        dma_addr_t dma_addr;
        unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;

        *handle = DMA_ERROR_CODE;

        pages = __iommu_dma_alloc_pages(count, gfp);
        if (!pages)
                return NULL;

        iova = __alloc_iova(iovad, size, dev->coherent_dma_mask);
        if (!iova)
                goto out_free_pages;

        size = iova_align(iovad, size);
        if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
                goto out_free_iova;

        if (!(prot & IOMMU_CACHE)) {
                struct sg_mapping_iter miter;
                /*
                 * The CPU-centric flushing implied by SG_MITER_TO_SG isn't
                 * sufficient here, so skip it by using the "wrong" direction.
                 */
                sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG);
                while (sg_miter_next(&miter))
                        flush_page(dev, miter.addr, page_to_phys(miter.page));
                sg_miter_stop(&miter);
        }

        dma_addr = iova_dma_addr(iovad, iova);
        if (iommu_map_sg(domain, dma_addr, sgt.sgl, sgt.orig_nents, prot)
                        < size)
                goto out_free_sg;

        *handle = dma_addr;
        sg_free_table(&sgt);
        return pages;

out_free_sg:
        sg_free_table(&sgt);
out_free_iova:
        __free_iova(iovad, iova);
out_free_pages:
        __iommu_dma_free_pages(pages, count);
        return NULL;
}

/**
 * iommu_dma_mmap - Map a buffer into provided user VMA
 * @pages: Array representing buffer from iommu_dma_alloc()
 * @size: Size of buffer in bytes
 * @vma: VMA describing requested userspace mapping
 *
 * Maps the pages of the buffer in @pages into @vma. The caller is responsible
 * for verifying the correct size and protection of @vma beforehand.
 */

int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
{
        unsigned long uaddr = vma->vm_start;
        unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        int ret = -ENXIO;

        for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
                ret = vm_insert_page(vma, uaddr, pages[i]);
                if (ret)
                        break;
                uaddr += PAGE_SIZE;
        }
        return ret;
}

dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
                unsigned long offset, size_t size, int prot)
{
        dma_addr_t dma_addr;
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
        struct iova_domain *iovad = domain->iova_cookie;
        phys_addr_t phys = page_to_phys(page) + offset;
        size_t iova_off = iova_offset(iovad, phys);
        size_t len = iova_align(iovad, size + iova_off);
        struct iova *iova = __alloc_iova(iovad, len, dma_get_mask(dev));

        if (!iova)
                return DMA_ERROR_CODE;

        dma_addr = iova_dma_addr(iovad, iova);
        if (iommu_map(domain, dma_addr, phys - iova_off, len, prot)) {
                __free_iova(iovad, iova);
                return DMA_ERROR_CODE;
        }
        return dma_addr + iova_off;
}

void iommu_dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
                enum dma_data_direction dir, struct dma_attrs *attrs)
{
        __iommu_dma_unmap(iommu_get_domain_for_dev(dev), handle);
}

/*
 * Prepare a successfully-mapped scatterlist to give back to the caller.
 * Handling IOVA concatenation can come later, if needed
 */
static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
                dma_addr_t dma_addr)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i) {
                /* Un-swizzling the fields here, hence the naming mismatch */
                unsigned int s_offset = sg_dma_address(s);
                unsigned int s_length = sg_dma_len(s);
                unsigned int s_dma_len = s->length;

                s->offset = s_offset;
                s->length = s_length;
                sg_dma_address(s) = dma_addr + s_offset;
                dma_addr += s_dma_len;
        }
        return i;
}

/*
 * If mapping failed, then just restore the original list,
 * but making sure the DMA fields are invalidated.
 */
static void __invalidate_sg(struct scatterlist *sg, int nents)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i) {
                if (sg_dma_address(s) != DMA_ERROR_CODE)
                        s->offset = sg_dma_address(s);
                if (sg_dma_len(s))
                        s->length = sg_dma_len(s);
                sg_dma_address(s) = DMA_ERROR_CODE;
                sg_dma_len(s) = 0;
        }
}

/*
 * The DMA API client is passing in a scatterlist which could describe
 * any old buffer layout, but the IOMMU API requires everything to be
 * aligned to IOMMU pages. Hence the need for this complicated bit of
 * impedance-matching, to be able to hand off a suitably-aligned list,
 * but still preserve the original offsets and sizes for the caller.
 */
int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
                int nents, int prot)
{
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
        struct iova_domain *iovad = domain->iova_cookie;
        struct iova *iova;
        struct scatterlist *s, *prev = NULL;
        dma_addr_t dma_addr;
        size_t iova_len = 0;
        int i;

        /*
         * Work out how much IOVA space we need, and align the segments to
         * IOVA granules for the IOMMU driver to handle. With some clever
         * trickery we can modify the list in-place, but reversibly, by
         * hiding the original data in the as-yet-unused DMA fields.
         */
        for_each_sg(sg, s, nents, i) {
                size_t s_offset = iova_offset(iovad, s->offset);
                size_t s_length = s->length;

                sg_dma_address(s) = s_offset;
                sg_dma_len(s) = s_length;
                s->offset -= s_offset;
                s_length = iova_align(iovad, s_length + s_offset);
                s->length = s_length;

                /*
                 * The simple way to avoid the rare case of a segment
                 * crossing the boundary mask is to pad the previous one
                 * to end at a naturally-aligned IOVA for this one's size,
                 * at the cost of potentially over-allocating a little.
                 */
                if (prev) {
                        size_t pad_len = roundup_pow_of_two(s_length);

                        pad_len = (pad_len - iova_len) & (pad_len - 1);
                        prev->length += pad_len;
                        iova_len += pad_len;
                }

                iova_len += s_length;
                prev = s;
        }

        iova = __alloc_iova(iovad, iova_len, dma_get_mask(dev));
        if (!iova)
                goto out_restore_sg;

        /*
         * We'll leave any physical concatenation to the IOMMU driver's
         * implementation - it knows better than we do.
         */
        dma_addr = iova_dma_addr(iovad, iova);
        if (iommu_map_sg(domain, dma_addr, sg, nents, prot) < iova_len)
                goto out_free_iova;

        return __finalise_sg(dev, sg, nents, dma_addr);

out_free_iova:
        __free_iova(iovad, iova);
out_restore_sg:
        __invalidate_sg(sg, nents);
        return 0;
}

void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
                enum dma_data_direction dir, struct dma_attrs *attrs)
{
        /*
         * The scatterlist segments are mapped into a single
         * contiguous IOVA allocation, so this is incredibly easy.
         */
        __iommu_dma_unmap(iommu_get_domain_for_dev(dev), sg_dma_address(sg));
}

int iommu_dma_supported(struct device *dev, u64 mask)
{
        /*
         * 'Special' IOMMUs which don't have the same addressing capability
         * as the CPU will have to wait until we have some way to query that
         * before they'll be able to use this framework.
         */
        return 1;
}

int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
        return dma_addr == DMA_ERROR_CODE;
}