7690a33f22
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().
struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).
It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.
To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Rob Clark <robdclark@gmail.com>
92 lines
2.0 KiB
C
92 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2013 Red Hat
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* Author: Rob Clark <robdclark@gmail.com>
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*/
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#include "msm_drv.h"
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#include "msm_mmu.h"
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struct msm_iommu {
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struct msm_mmu base;
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struct iommu_domain *domain;
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};
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#define to_msm_iommu(x) container_of(x, struct msm_iommu, base)
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static int msm_fault_handler(struct iommu_domain *domain, struct device *dev,
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unsigned long iova, int flags, void *arg)
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{
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struct msm_iommu *iommu = arg;
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if (iommu->base.handler)
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return iommu->base.handler(iommu->base.arg, iova, flags);
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pr_warn_ratelimited("*** fault: iova=%16lx, flags=%d\n", iova, flags);
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return 0;
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}
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static void msm_iommu_detach(struct msm_mmu *mmu)
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{
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struct msm_iommu *iommu = to_msm_iommu(mmu);
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iommu_detach_device(iommu->domain, mmu->dev);
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}
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static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
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struct sg_table *sgt, size_t len, int prot)
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{
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struct msm_iommu *iommu = to_msm_iommu(mmu);
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size_t ret;
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ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot);
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WARN_ON(!ret);
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return (ret == len) ? 0 : -EINVAL;
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}
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static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova, size_t len)
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{
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struct msm_iommu *iommu = to_msm_iommu(mmu);
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iommu_unmap(iommu->domain, iova, len);
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return 0;
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}
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static void msm_iommu_destroy(struct msm_mmu *mmu)
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{
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struct msm_iommu *iommu = to_msm_iommu(mmu);
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iommu_domain_free(iommu->domain);
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kfree(iommu);
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}
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static const struct msm_mmu_funcs funcs = {
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.detach = msm_iommu_detach,
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.map = msm_iommu_map,
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.unmap = msm_iommu_unmap,
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.destroy = msm_iommu_destroy,
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};
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struct msm_mmu *msm_iommu_new(struct device *dev, struct iommu_domain *domain)
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{
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struct msm_iommu *iommu;
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int ret;
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if (!domain)
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return ERR_PTR(-ENODEV);
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iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
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if (!iommu)
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return ERR_PTR(-ENOMEM);
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iommu->domain = domain;
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msm_mmu_init(&iommu->base, dev, &funcs);
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iommu_set_fault_handler(domain, msm_fault_handler, iommu);
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ret = iommu_attach_device(iommu->domain, dev);
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if (ret) {
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kfree(iommu);
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return ERR_PTR(ret);
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}
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return &iommu->base;
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}
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