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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 accessing 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-noncoherent.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
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;
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_enable) ||
(attrs & DMA_ATTR_NON_CONSISTENT))
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);
*dma_handle = paddr;
/* This is kernel Virtual address (0x7000_0000 based) */
if (need_kvaddr) {
kvaddr = ioremap_nocache(paddr, size);
if (kvaddr == NULL) {
__free_pages(page, order);
return NULL;
}
} else {
kvaddr = (void *)(u32)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(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);
int is_non_coh = 1;
is_non_coh = (attrs & DMA_ATTR_NON_CONSISTENT) ||
(is_isa_arcv2() && ioc_enable);
if (PageHighMem(page) || !is_non_coh)
iounmap((void __force __iomem *)vaddr);
__free_pages(page, get_order(size));
}
int arch_dma_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs)
{
unsigned long user_count = vma_pages(vma);
unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
unsigned long pfn = __phys_to_pfn(dma_addr);
unsigned long off = vma->vm_pgoff;
int ret = -ENXIO;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;
if (off < count && user_count <= (count - off)) {
ret = remap_pfn_range(vma, vma->vm_start,
pfn + off,
user_count << PAGE_SHIFT,
vma->vm_page_prot);
}
return ret;
}
/*
* 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;
}
}
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