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ARM/nommu: use the generic dma-direct code for non-coherent devices
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Select the right options to just use the generic dma-direct code
instead of reimplementing it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dillon Min <dillon.minfei@gmail.com>
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Christoph Hellwig committed Aug 18, 2021
1 parent faf4ef8 commit 31b089b
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Showing 2 changed files with 9 additions and 169 deletions.
5 changes: 3 additions & 2 deletions arch/arm/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,8 @@ config ARM
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
select ARCH_HAS_STRICT_MODULE_RWX if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if SWIOTLB
select ARCH_HAS_SYNC_DMA_FOR_CPU if SWIOTLB
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if SWIOTLB || !MMU
select ARCH_HAS_SYNC_DMA_FOR_CPU if SWIOTLB || !MMU
select ARCH_HAS_TEARDOWN_DMA_OPS if MMU
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAVE_CUSTOM_GPIO_H
Expand All @@ -44,6 +44,7 @@ config ARM
select CPU_PM if SUSPEND || CPU_IDLE
select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
select DMA_DECLARE_COHERENT
select DMA_GLOBAL_POOL if !MMU
select DMA_OPS
select DMA_REMAP if MMU
select EDAC_SUPPORT
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173 changes: 6 additions & 167 deletions arch/arm/mm/dma-mapping-nommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,78 +5,16 @@
* Copyright (C) 2000-2004 Russell King
*/

#include <linux/export.h>
#include <linux/mm.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>
#include <linux/scatterlist.h>

#include <asm/cachetype.h>
#include <asm/cacheflush.h>
#include <asm/outercache.h>
#include <asm/cp15.h>

#include "dma.h"

/*
* The generic direct mapping code is used if
* - MMU/MPU is off
* - cpu is v7m w/o cache support
* - device is coherent
* otherwise arm_nommu_dma_ops is used.
*
* arm_nommu_dma_ops rely on consistent DMA memory (please, refer to
* [1] on how to declare such memory).
*
* [1] Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
*/

static void *arm_nommu_dma_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp,
unsigned long attrs)

{
void *ret = dma_alloc_from_global_coherent(dev, size, dma_handle);

/*
* dma_alloc_from_global_coherent() may fail because:
*
* - no consistent DMA region has been defined, so we can't
* continue.
* - there is no space left in consistent DMA region, so we
* only can fallback to generic allocator if we are
* advertised that consistency is not required.
*/

WARN_ON_ONCE(ret == NULL);
return ret;
}

static void arm_nommu_dma_free(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr,
unsigned long attrs)
{
int ret = dma_release_from_global_coherent(get_order(size), cpu_addr);

WARN_ON_ONCE(ret == 0);
}

static int arm_nommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs)
{
int ret;

if (dma_mmap_from_global_coherent(vma, cpu_addr, size, &ret))
return ret;
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;
return -ENXIO;
}


static void __dma_page_cpu_to_dev(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
{
dmac_map_area(__va(paddr), size, dir);

Expand All @@ -86,111 +24,15 @@ static void __dma_page_cpu_to_dev(phys_addr_t paddr, size_t size,
outer_clean_range(paddr, paddr + size);
}

static void __dma_page_dev_to_cpu(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
{
if (dir != DMA_TO_DEVICE) {
outer_inv_range(paddr, paddr + size);
dmac_unmap_area(__va(paddr), size, dir);
}
}

static dma_addr_t arm_nommu_dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
unsigned long attrs)
{
dma_addr_t handle = page_to_phys(page) + offset;

__dma_page_cpu_to_dev(handle, size, dir);

return handle;
}

static void arm_nommu_dma_unmap_page(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
__dma_page_dev_to_cpu(handle, size, dir);
}


static int arm_nommu_dma_map_sg(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
unsigned long attrs)
{
int i;
struct scatterlist *sg;

for_each_sg(sgl, sg, nents, i) {
sg_dma_address(sg) = sg_phys(sg);
sg_dma_len(sg) = sg->length;
__dma_page_cpu_to_dev(sg_dma_address(sg), sg_dma_len(sg), dir);
}

return nents;
}

static void arm_nommu_dma_unmap_sg(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
unsigned long attrs)
{
struct scatterlist *sg;
int i;

for_each_sg(sgl, sg, nents, i)
__dma_page_dev_to_cpu(sg_dma_address(sg), sg_dma_len(sg), dir);
}

static void arm_nommu_dma_sync_single_for_device(struct device *dev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
__dma_page_cpu_to_dev(handle, size, dir);
}

static void arm_nommu_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
__dma_page_cpu_to_dev(handle, size, dir);
}

static void arm_nommu_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;

for_each_sg(sgl, sg, nents, i)
__dma_page_cpu_to_dev(sg_dma_address(sg), sg_dma_len(sg), dir);
}

static void arm_nommu_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir)
{
struct scatterlist *sg;
int i;

for_each_sg(sgl, sg, nents, i)
__dma_page_dev_to_cpu(sg_dma_address(sg), sg_dma_len(sg), dir);
}

const struct dma_map_ops arm_nommu_dma_ops = {
.alloc = arm_nommu_dma_alloc,
.free = arm_nommu_dma_free,
.alloc_pages = dma_direct_alloc_pages,
.free_pages = dma_direct_free_pages,
.mmap = arm_nommu_dma_mmap,
.map_page = arm_nommu_dma_map_page,
.unmap_page = arm_nommu_dma_unmap_page,
.map_sg = arm_nommu_dma_map_sg,
.unmap_sg = arm_nommu_dma_unmap_sg,
.sync_single_for_device = arm_nommu_dma_sync_single_for_device,
.sync_single_for_cpu = arm_nommu_dma_sync_single_for_cpu,
.sync_sg_for_device = arm_nommu_dma_sync_sg_for_device,
.sync_sg_for_cpu = arm_nommu_dma_sync_sg_for_cpu,
};
EXPORT_SYMBOL(arm_nommu_dma_ops);

void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
const struct iommu_ops *iommu, bool coherent)
{
Expand All @@ -201,14 +43,11 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
* enough to check if MPU is in use or not since in absense of
* MPU system memory map is used.
*/
dev->archdata.dma_coherent = (cacheid) ? coherent : true;
dev->dma_coherent = cacheid ? coherent : true;
} else {
/*
* Assume coherent DMA in case MMU/MPU has not been set up.
*/
dev->archdata.dma_coherent = (get_cr() & CR_M) ? coherent : true;
dev->dma_coherent = (get_cr() & CR_M) ? coherent : true;
}

if (!dev->archdata.dma_coherent)
set_dma_ops(dev, &arm_nommu_dma_ops);
}

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