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/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* 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.
*/
#include <linux/dma-noncoherent.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
/*
* ARCH specific callbacks for generic noncoherent DMA ops (dma/noncoherent.c)
* - 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_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs)
{
unsigned long order = get_order(size);
struct page *page;
phys_addr_t paddr;
void *kvaddr;
/*
* __GFP_HIGHMEM flag is cleared by upper layer functions
* (in include/linux/dma-mapping.h) so we should never get a
* __GFP_HIGHMEM here.
*/
BUG_ON(gfp & __GFP_HIGHMEM);
page = alloc_pages(gfp | __GFP_ZERO, order);
if (!page)
return NULL;
/* This is linear addr (0x8000_0000 based) */
paddr = page_to_phys(page);
*dma_handle = paddr;
/*
* A coherent buffer needs MMU mapping to enforce non-cachability.
* kvaddr is kernel Virtual address (0x7000_0000 based).
*/
kvaddr = ioremap_nocache(paddr, size);
if (kvaddr == NULL) {
__free_pages(page, order);
return NULL;
}
/*
* 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(paddr, size);
return kvaddr;
}
void arch_dma_free(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, unsigned long attrs)
{
phys_addr_t paddr = dma_handle;
struct page *page = virt_to_page(paddr);
iounmap((void __force __iomem *)vaddr);
__free_pages(page, get_order(size));
}
long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
dma_addr_t dma_addr)
{
return __phys_to_pfn(dma_addr);
}
/*
* Cache operations depending on function and direction argument, inspired by
* https://lkml.org/lkml/2018/5/18/979
* "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(struct device *dev, 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(struct device *dev, 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, u64 dma_base, u64 size,
const struct iommu_ops *iommu, 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 %sncoherent DMA ops\n",
dev->dma_coherent ? "" : "non");
}
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