59 строки
1.8 KiB
C
59 строки
1.8 KiB
C
/*
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* Copyright (c) 2004 Hewlett-Packard Development Company, L.P.
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* Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
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*
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* This is a pseudo I/O MMU which dispatches to the hardware I/O MMU
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* whenever possible. We assume that the hardware I/O MMU requires
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* full 32-bit addressability, as is the case, e.g., for HP zx1-based
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* systems (there, the I/O MMU window is mapped at 3-4GB). If a
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* device doesn't provide full 32-bit addressability, we fall back on
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* the sw I/O TLB. This is good enough to let us support broken
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* hardware such as soundcards which have a DMA engine that can
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* address only 28 bits.
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*/
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#include <linux/device.h>
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#include <linux/dma-mapping.h>
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#include <linux/swiotlb.h>
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#include <asm/machvec.h>
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extern struct dma_map_ops sba_dma_ops, swiotlb_dma_ops;
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/* swiotlb declarations & definitions: */
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extern int swiotlb_late_init_with_default_size (size_t size);
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/*
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* Note: we need to make the determination of whether or not to use
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* the sw I/O TLB based purely on the device structure. Anything else
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* would be unreliable or would be too intrusive.
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*/
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static inline int use_swiotlb(struct device *dev)
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{
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return dev && dev->dma_mask &&
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!sba_dma_ops.dma_supported(dev, *dev->dma_mask);
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}
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struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
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{
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if (use_swiotlb(dev))
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return &swiotlb_dma_ops;
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return &sba_dma_ops;
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}
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EXPORT_SYMBOL(hwsw_dma_get_ops);
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void __init
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hwsw_init (void)
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{
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/* default to a smallish 2MB sw I/O TLB */
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if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) {
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#ifdef CONFIG_IA64_GENERIC
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/* Better to have normal DMA than panic */
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printk(KERN_WARNING "%s: Failed to initialize software I/O TLB,"
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" reverting to hpzx1 platform vector\n", __func__);
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machvec_init("hpzx1");
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#else
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panic("Unable to initialize software I/O TLB services");
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#endif
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}
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}
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