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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;
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);
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, order = __fls(count);
/*
* Higher-order allocations are a convenience rather
* than a necessity, hence using __GFP_NORETRY until
* falling back to single-page allocations.
*/
for (order = min(order, MAX_ORDER); 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;
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