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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*/
#include <linux/dma-map-ops.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
/*
* ARCH specific callbacks for generic noncoherent DMA ops
* - hardware IOC not available (or "dma-coherent" not set for device in DT)
* - But still handle both coherent and non-coherent requests from caller
*
* For DMA coherent hardware (IOC) generic code suffices
*/
void arch_dma_prep_coherent(struct page *page, size_t size)
{
/*
* Evict any existing L1 and/or L2 lines for the backing page
* in case it was used earlier as a normal "cached" page.
* Yeah this bit us - STAR 9000898266
*
* Although core does call flush_cache_vmap(), it gets kvaddr hence
* can't be used to efficiently flush L1 and/or L2 which need paddr
* Currently flush_cache_vmap nukes the L1 cache completely which
* will be optimized as a separate commit
*/
dma_cache_wback_inv(page_to_phys(page), size);
}
/*
* Cache operations depending on function and direction argument, inspired by
* https://lore.kernel.org/lkml/20180518175004.GF17671@n2100.armlinux.org.uk
* "dma_sync_*_for_cpu and direction=TO_DEVICE (was Re: [PATCH 02/20]
* dma-mapping: provide a generic dma-noncoherent implementation)"
*
* | map == for_device | unmap == for_cpu
* |----------------------------------------------------------------
* TO_DEV | writeback writeback | none none
* FROM_DEV | invalidate invalidate | invalidate* invalidate*
* BIDIR | writeback+inv writeback+inv | invalidate invalidate
*
* [*] needed for CPU speculative prefetches
*
* NOTE: we don't check the validity of direction argument as it is done in
* upper layer functions (in include/linux/dma-mapping.h)
*/
void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
{
switch (dir) {
case DMA_TO_DEVICE:
dma_cache_wback(paddr, size);
break;
case DMA_FROM_DEVICE:
dma_cache_inv(paddr, size);
break;
case DMA_BIDIRECTIONAL:
dma_cache_wback_inv(paddr, size);
break;
default:
break;
}
}
void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
enum dma_data_direction dir)
{
switch (dir) {
case DMA_TO_DEVICE:
break;
/* FROM_DEVICE invalidate needed if speculative CPU prefetch only */
case DMA_FROM_DEVICE:
case DMA_BIDIRECTIONAL:
dma_cache_inv(paddr, size);
break;
default:
break;
}
}
/*
* Plug in direct dma map ops.
*/
void arch_setup_dma_ops(struct device *dev, bool coherent)
{
/*
* IOC hardware snoops all DMA traffic keeping the caches consistent
* with memory - eliding need for any explicit cache maintenance of
* DMA buffers.
*/
if (is_isa_arcv2() && ioc_enable && coherent)
dev->dma_coherent = true;
dev_info(dev, "use %scoherent DMA ops\n",
dev->dma_coherent ? "" : "non");
}
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