1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2004 Hewlett-Packard Development Company, L.P.
 4 *   Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
 5 *
 6 * This is a pseudo I/O MMU which dispatches to the hardware I/O MMU
 7 * whenever possible.  We assume that the hardware I/O MMU requires
 8 * full 32-bit addressability, as is the case, e.g., for HP zx1-based
 9 * systems (there, the I/O MMU window is mapped at 3-4GB).  If a
10 * device doesn't provide full 32-bit addressability, we fall back on
11 * the sw I/O TLB.  This is good enough to let us support broken
12 * hardware such as soundcards which have a DMA engine that can
13 * address only 28 bits.
14 */
15
16#include <linux/device.h>
17#include <linux/dma-mapping.h>
18#include <linux/swiotlb.h>
19#include <linux/export.h>
20#include <asm/machvec.h>
21
22extern const struct dma_map_ops sba_dma_ops;
23
24/* swiotlb declarations & definitions: */
25extern int swiotlb_late_init_with_default_size (size_t size);
26
27/*
28 * Note: we need to make the determination of whether or not to use
29 * the sw I/O TLB based purely on the device structure.  Anything else
30 * would be unreliable or would be too intrusive.
31 */
32static inline int use_swiotlb(struct device *dev)
33{
34	return dev && dev->dma_mask &&
35		!sba_dma_ops.dma_supported(dev, *dev->dma_mask);
36}
37
38const struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
39{
40	if (use_swiotlb(dev))
41		return &swiotlb_dma_ops;
42	return &sba_dma_ops;
43}
44EXPORT_SYMBOL(hwsw_dma_get_ops);
45
46void __init
47hwsw_init (void)
48{
49	/* default to a smallish 2MB sw I/O TLB */
50	if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) {
51#ifdef CONFIG_IA64_GENERIC
52		/* Better to have normal DMA than panic */
53		printk(KERN_WARNING "%s: Failed to initialize software I/O TLB,"
54		       " reverting to hpzx1 platform vector\n", __func__);
55		machvec_init("hpzx1");
56#else
57		panic("Unable to initialize software I/O TLB services");
58#endif
59	}
60}