1/*
2 * Copyright (c) 2004 Hewlett-Packard Development Company, L.P.
3 *   Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4 *
5 * This is a pseudo I/O MMU which dispatches to the hardware I/O MMU
6 * whenever possible.  We assume that the hardware I/O MMU requires
7 * full 32-bit addressability, as is the case, e.g., for HP zx1-based
8 * systems (there, the I/O MMU window is mapped at 3-4GB).  If a
9 * device doesn't provide full 32-bit addressability, we fall back on
10 * the sw I/O TLB.  This is good enough to let us support broken
11 * hardware such as soundcards which have a DMA engine that can
12 * address only 28 bits.
13 */
14
15#include <linux/device.h>
16#include <linux/dma-mapping.h>
17#include <linux/swiotlb.h>
18#include <linux/export.h>
19#include <asm/machvec.h>
20
21extern struct dma_map_ops sba_dma_ops, swiotlb_dma_ops;
22
23/* swiotlb declarations & definitions: */
24extern int swiotlb_late_init_with_default_size (size_t size);
25
26/*
27 * Note: we need to make the determination of whether or not to use
28 * the sw I/O TLB based purely on the device structure.  Anything else
29 * would be unreliable or would be too intrusive.
30 */
31static inline int use_swiotlb(struct device *dev)
32{
33	return dev && dev->dma_mask &&
34		!sba_dma_ops.dma_supported(dev, *dev->dma_mask);
35}
36
37struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
38{
39	if (use_swiotlb(dev))
40		return &swiotlb_dma_ops;
41	return &sba_dma_ops;
42}
43EXPORT_SYMBOL(hwsw_dma_get_ops);
44
45void __init
46hwsw_init (void)
47{
48	/* default to a smallish 2MB sw I/O TLB */
49	if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) {
50#ifdef CONFIG_IA64_GENERIC
51		/* Better to have normal DMA than panic */
52		printk(KERN_WARNING "%s: Failed to initialize software I/O TLB,"
53		       " reverting to hpzx1 platform vector\n", __func__);
54		machvec_init("hpzx1");
55#else
56		panic("Unable to initialize software I/O TLB services");
57#endif
58	}
59}
60