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mn10300: make the ASB2305's PCnet32 NIC work by using the PCI bridge's SRAM 

Access to the ASB2305's PCnet32 NIC doesn't work correctly because when
the NIC attempts to update the ring buffer flags by DMA, the change to RAM
crops up about 17uS after the interrupt line is asserted.  This is almost
certainly due to a bug in the PCI bridge FPGA on that board.

We can get around this by making dma_alloc_coherent() put the ring buffer
in the SRAM attached to the PCI bridge rather than in the SDRAM.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2010-01-08 14:43:21 -08:00 committed by Linus Torvalds
parent 112b4a0bf1
commit 012c79bad5
1 changed files with 17 additions and 0 deletions
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17
arch/mn10300/mm/dma-alloc.c
View File

@ -16,12 +16,24 @@
#include <linux/pci.h>
#include <asm/io.h>
static unsigned long pci_sram_allocated = 0xbc000000;
void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, int gfp)
{
unsigned long addr;
void *ret;
printk("dma_alloc_coherent(%s,%zu,,%x)\n", dev_name(dev), size, gfp);
if (0xbe000000 - pci_sram_allocated >= size) {
size = (size + 255) & ~255;
addr = pci_sram_allocated;
pci_sram_allocated += size;
ret = (void *) addr;
goto done;
}
/* ignore region specifiers */
gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
@ -41,7 +53,9 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
/* write back and evict all cache lines covering this region */
mn10300_dcache_flush_inv_range2(virt_to_phys((void *) addr), PAGE_SIZE);
done:
*dma_handle = virt_to_bus((void *) addr);
printk("dma_alloc_coherent() = %p [%x]\n", ret, *dma_handle);
return ret;
}
EXPORT_SYMBOL(dma_alloc_coherent);
@ -51,6 +65,9 @@ void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
{
unsigned long addr = (unsigned long) vaddr & ~0x20000000;
if (addr >= 0x9c000000)
return;
free_pages(addr, get_order(size));
}
EXPORT_SYMBOL(dma_free_coherent);