/*
* 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->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.
*
* At this point the segments are already laid out by iommu_dma_map_sg() to
* avoid individually crossing any boundaries, so we merely need to check a
* segment's start address to avoid concatenating across one.
*/
static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
dma_addr_t dma_addr)
{
struct scatterlist *s, *cur = sg;
unsigned long seg_mask = dma_get_seg_boundary(dev);
unsigned int cur_len = 0, max_len = dma_get_max_seg_size(dev);
int i, count = 0;
for_each_sg(sg, s, nents, i) {
/* Restore this segment's original unaligned fields first */
unsigned int s_iova_off = sg_dma_address(s);
unsigned int s_length = sg_dma_len(s);
unsigned int s_iova_len = s->length;
s->offset += s_iova_off;
s->length = s_length;
sg_dma_address(s) = DMA_ERROR_CODE;
sg_dma_len(s) = 0;
/*
* Now fill in the real DMA data. If...
* - there is a valid output segment to append to
* - and this segment starts on an IOVA page boundary
* - but doesn't fall at a segment boundary
* - and wouldn't make the resulting output segment too long
*/
if (cur_len && !s_iova_off && (dma_addr & seg_mask) &&
(cur_len + s_length <= max_len)) {
/* ...then concatenate it with the previous one */
cur_len += s_length;
} else {
/* Otherwise start the next output segment */
if (i > 0)
cur = sg_next(cur);
cur_len = s_length;
count++;
sg_dma_address(cur) = dma_addr + s_iova_off;
}
sg_dma_len(cur) = cur_len;
dma_addr += s_iova_len;
if (s_length + s_iova_off < s_iova_len)
cur_len = 0;
}
return count;
}
/*
* 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;
unsigned long mask = dma_get_seg_boundary(dev);
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
* stashing the unaligned parts in the as-yet-unused DMA fields.
*/
for_each_sg(sg, s, nents, i) {
size_t s_iova_off = iova_offset(iovad, s->offset);
size_t s_length = s->length;
size_t pad_len = (mask - iova_len + 1) & mask;
sg_dma_address(s) = s_iova_off;
sg_dma_len(s) = s_length;
s->offset -= s_iova_off;
s_length = iova_align(iovad, s_length + s_iova_off);
s->length = s_length;
/*
* Due to the alignment of our single IOVA allocation, we can
* depend on these assumptions about the segment boundary mask:
* - If mask size >= IOVA size, then the IOVA range cannot
* possibly fall across a boundary, so we don't care.
* - If mask size < IOVA size, then the IOVA range must start
* exactly on a boundary, therefore we can lay things out
* based purely on segment lengths without needing to know
* the actual addresses beforehand.
* - The mask must be a power of 2, so pad_len == 0 if
* iova_len == 0, thus we cannot dereference prev the first
* time through here (i.e. before it has a meaningful value).
*/
if (pad_len && pad_len < s_length - 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;
}
