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 <asm/io.h> /* need byte IO */ 15 16 /* 17 * This is only to be defined if we have PC-like DMA. 18 * By default this is not true on an Xtensa processor, 19 * however on boards with a PCI bus, such functionality 20 * might be emulated externally. 21 * 22 * NOTE: there still exists driver code that assumes 23 * this is defined, eg. drivers/sound/soundcard.c (as of 2.4). 24 */ 25 #define MAX_DMA_CHANNELS 8 26 27 /* 28 * The maximum virtual address to which DMA transfers 29 * can be performed on this platform. 30 * 31 * NOTE: This is board (platform) specific, not processor-specific! 32 * 33 * NOTE: This assumes DMA transfers can only be performed on 34 * the section of physical memory contiguously mapped in virtual 35 * space for the kernel. For the Xtensa architecture, this 36 * means the maximum possible size of this DMA area is 37 * the size of the statically mapped kernel segment 38 * (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB. 39 * 40 * NOTE: When the entire KSEG area is DMA capable, we subtract 41 * one from the max address so that the virt_to_phys() macro 42 * works correctly on the address (otherwise the address 43 * enters another area, and virt_to_phys() may not return 44 * the value desired). 45 */ 46 47 #ifndef MAX_DMA_ADDRESS 48 #define MAX_DMA_ADDRESS (PAGE_OFFSET + XCHAL_KIO_SIZE - 1) 49 #endif 50 51 /* Reserve and release a DMA channel */ 52 extern int request_dma(unsigned int dmanr, const char * device_id); 53 extern void free_dma(unsigned int dmanr); 54 55 #endif 56