012c79bad5
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>
74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
/* MN10300 Dynamic DMA mapping support
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* Derived from: arch/i386/kernel/pci-dma.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/pci.h>
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#include <asm/io.h>
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static unsigned long pci_sram_allocated = 0xbc000000;
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void *dma_alloc_coherent(struct device *dev, size_t size,
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dma_addr_t *dma_handle, int gfp)
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{
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unsigned long addr;
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void *ret;
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printk("dma_alloc_coherent(%s,%zu,,%x)\n", dev_name(dev), size, gfp);
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if (0xbe000000 - pci_sram_allocated >= size) {
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size = (size + 255) & ~255;
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addr = pci_sram_allocated;
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pci_sram_allocated += size;
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ret = (void *) addr;
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goto done;
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}
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/* ignore region specifiers */
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gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
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if (dev == NULL || dev->coherent_dma_mask < 0xffffffff)
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gfp |= GFP_DMA;
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addr = __get_free_pages(gfp, get_order(size));
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if (!addr)
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return NULL;
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/* map the coherent memory through the uncached memory window */
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ret = (void *) (addr | 0x20000000);
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/* fill the memory with obvious rubbish */
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memset((void *) addr, 0xfb, size);
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/* write back and evict all cache lines covering this region */
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mn10300_dcache_flush_inv_range2(virt_to_phys((void *) addr), PAGE_SIZE);
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done:
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*dma_handle = virt_to_bus((void *) addr);
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printk("dma_alloc_coherent() = %p [%x]\n", ret, *dma_handle);
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return ret;
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}
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EXPORT_SYMBOL(dma_alloc_coherent);
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void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
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dma_addr_t dma_handle)
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{
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unsigned long addr = (unsigned long) vaddr & ~0x20000000;
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if (addr >= 0x9c000000)
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return;
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free_pages(addr, get_order(size));
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}
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EXPORT_SYMBOL(dma_free_coherent);
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