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- /*
- * 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;
- if (iovad->granule)
- 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;
- }
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