tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * include/asm-xtensa/dma.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2003 - 2005 Tensilica Inc.
9 */
10
11#ifndef _XTENSA_DMA_H
12#define _XTENSA_DMA_H
13
14#include <linux/config.h>
15#include <asm/io.h> /* need byte IO */
16#include <xtensa/config/core.h>
17
18/*
19 * This is only to be defined if we have PC-like DMA.
20 * By default this is not true on an Xtensa processor,
21 * however on boards with a PCI bus, such functionality
22 * might be emulated externally.
23 *
24 * NOTE: there still exists driver code that assumes
25 * this is defined, eg. drivers/sound/soundcard.c (as of 2.4).
26 */
27#define MAX_DMA_CHANNELS 8
28
29/*
30 * The maximum virtual address to which DMA transfers
31 * can be performed on this platform.
32 *
33 * NOTE: This is board (platform) specific, not processor-specific!
34 *
35 * NOTE: This assumes DMA transfers can only be performed on
36 * the section of physical memory contiguously mapped in virtual
37 * space for the kernel. For the Xtensa architecture, this
38 * means the maximum possible size of this DMA area is
39 * the size of the statically mapped kernel segment
40 * (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB.
41 *
42 * NOTE: When the entire KSEG area is DMA capable, we substract
43 * one from the max address so that the virt_to_phys() macro
44 * works correctly on the address (otherwise the address
45 * enters another area, and virt_to_phys() may not return
46 * the value desired).
47 */
48#define MAX_DMA_ADDRESS (PAGE_OFFSET + XCHAL_KSEG_CACHED_SIZE - 1)
49
50/* Reserve and release a DMA channel */
51extern int request_dma(unsigned int dmanr, const char * device_id);
52extern void free_dma(unsigned int dmanr);
53
54#ifdef CONFIG_PCI
55extern int isa_dma_bridge_buggy;
56#else
57#define isa_dma_bridge_buggy (0)
58#endif
59
60
61#endif