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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
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> | |
917f69b8 | 17 | #include <linux/dma-mapping.h> |
9979aa77 | 18 | #include <linux/swiotlb.h> |
bd3ff194 | 19 | #include <linux/export.h> |
1da177e4 LT |
20 | #include <asm/machvec.h> |
21 | ||
5299709d | 22 | extern const struct dma_map_ops sba_dma_ops, swiotlb_dma_ops; |
c7b3aee8 | 23 | |
1da177e4 | 24 | /* swiotlb declarations & definitions: */ |
0b9afede | 25 | extern int swiotlb_late_init_with_default_size (size_t size); |
1da177e4 | 26 | |
1da177e4 LT |
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 | */ | |
c7b3aee8 | 32 | static inline int use_swiotlb(struct device *dev) |
1da177e4 | 33 | { |
c7b3aee8 | 34 | return dev && dev->dma_mask && |
160c1d8e | 35 | !sba_dma_ops.dma_supported(dev, *dev->dma_mask); |
1da177e4 LT |
36 | } |
37 | ||
5299709d | 38 | const struct dma_map_ops *hwsw_dma_get_ops(struct device *dev) |
c7b3aee8 FT |
39 | { |
40 | if (use_swiotlb(dev)) | |
41 | return &swiotlb_dma_ops; | |
42 | return &sba_dma_ops; | |
43 | } | |
44 | EXPORT_SYMBOL(hwsw_dma_get_ops); | |
4d9b977c | 45 | |
9a86bbb9 | 46 | void __init |
1da177e4 LT |
47 | hwsw_init (void) |
48 | { | |
49 | /* default to a smallish 2MB sw I/O TLB */ | |
0b9afede AW |
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," | |
d4ed8084 | 54 | " reverting to hpzx1 platform vector\n", __func__); |
0b9afede AW |
55 | machvec_init("hpzx1"); |
56 | #else | |
57 | panic("Unable to initialize software I/O TLB services"); | |
58 | #endif | |
59 | } | |
1da177e4 | 60 | } |