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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.
*/
/*
* DMA Coherent API Notes
*
* I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
* implemented by accessintg it using a kernel virtual address, with
* Cache bit off in the TLB entry.
*
* The default DMA address == Phy address which is 0x8000_0000 based.
*/
#include <linux/dma-mapping.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
static void *arc_dma_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, struct dma_attrs *attrs)
{
unsigned long order = get_order(size);
struct page *page;
phys_addr_t paddr;
void *kvaddr;
int need_coh = 1, need_kvaddr = 0;
page = alloc_pages(gfp, order);
if (!page)
return NULL;
/*
* IOC relies on all data (even coherent DMA data) being in cache
* Thus allocate normal cached memory
*
* The gains with IOC are two pronged:
* -For streaming data, elides need for cache maintenance, saving
* cycles in flush code, and bus bandwidth as all the lines of a
* buffer need to be flushed out to memory
* -For coherent data, Read/Write to buffers terminate early in cache
* (vs. always going to memory - thus are faster)
*/
if ((is_isa_arcv2() && ioc_exists) ||
dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs))
need_coh = 0;
/*
* - A coherent buffer needs MMU mapping to enforce non-cachability
* - A highmem page needs a virtual handle (hence MMU mapping)
* independent of cachability
*/
if (PageHighMem(page) || need_coh)
need_kvaddr = 1;
/* This is linear addr (0x8000_0000 based) */
paddr = page_to_phys(page);
/* For now bus address is exactly same as paddr */
*dma_handle = paddr;
/* This is kernel Virtual address (0x7000_0000 based) */
if (need_kvaddr) {
kvaddr = ioremap_nocache((unsigned long)paddr, size);
if (kvaddr == NULL) {
__free_pages(page, order);
return NULL;
}
} else {
kvaddr = (void *)paddr;
}
/*
* 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
*/
if (need_coh)
dma_cache_wback_inv((unsigned long)paddr, size);
return kvaddr;
}
static void arc_dma_free(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, struct dma_attrs *attrs)
{
struct page *page = virt_to_page(dma_handle);
int is_non_coh = 1;
is_non_coh = dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs) ||
(is_isa_arcv2() && ioc_exists);
if (PageHighMem(page) || !is_non_coh)
iounmap((void __force __iomem *)vaddr);
__free_pages(page, get_order(size));
}
/*
* streaming DMA Mapping API...
* CPU accesses page via normal paddr, thus needs to explicitly made
* consistent before each use
*/
static void _dma_cache_sync(unsigned long paddr, size_t size,
enum dma_data_direction dir)
{
switch (dir) {
case DMA_FROM_DEVICE:
dma_cache_inv(paddr, size);
break;
case DMA_TO_DEVICE:
dma_cache_wback(paddr, size);
break;
case DMA_BIDIRECTIONAL:
dma_cache_wback_inv(paddr, size);
break;
default:
pr_err("Invalid DMA dir [%d] for OP @ %lx\n", dir, paddr);
}
}
static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs)
{
unsigned long paddr = page_to_phys(page) + offset;
_dma_cache_sync(paddr, size, dir);
return (dma_addr_t)paddr;
}
static int arc_dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir, struct dma_attrs *attrs)
{
struct scatterlist *s;
int i;
for_each_sg(sg, s, nents, i)
s->dma_address = dma_map_page(dev, sg_page(s), s->offset,
s->length, dir);
return nents;
}
static void arc_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
{
_dma_cache_sync(dma_handle, size, DMA_FROM_DEVICE);
}
static void arc_dma_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
{
_dma_cache_sync(dma_handle, size, DMA_TO_DEVICE);
}
static void arc_dma_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sglist, int nelems,
enum dma_data_direction dir)
{
int i;
struct scatterlist *sg;
for_each_sg(sglist, sg, nelems, i)
_dma_cache_sync(sg_phys(sg), sg->length, dir);
}
static void arc_dma_sync_sg_for_device(struct device *dev,
struct scatterlist *sglist, int nelems,
enum dma_data_direction dir)
{
int i;
struct scatterlist *sg;
for_each_sg(sglist, sg, nelems, i)
_dma_cache_sync(sg_phys(sg), sg->length, dir);
}
static int arc_dma_supported(struct device *dev, u64 dma_mask)
{
/* Support 32 bit DMA mask exclusively */
return dma_mask == DMA_BIT_MASK(32);
}
struct dma_map_ops arc_dma_ops = {
.alloc = arc_dma_alloc,
.free = arc_dma_free,
.map_page = arc_dma_map_page,
.map_sg = arc_dma_map_sg,
.sync_single_for_device = arc_dma_sync_single_for_device,
.sync_single_for_cpu = arc_dma_sync_single_for_cpu,
.sync_sg_for_cpu = arc_dma_sync_sg_for_cpu,
.sync_sg_for_device = arc_dma_sync_sg_for_device,
.dma_supported = arc_dma_supported,
};
EXPORT_SYMBOL(arc_dma_ops);
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