1 /* 2 * ISA DMA support functions 3 * Copyright (c) by Jaroslav Kysela <perex@perex.cz> 4 * 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 * 20 */ 21 22 /* 23 * Defining following add some delay. Maybe this helps for some broken 24 * ISA DMA controllers. 25 */ 26 27 #undef HAVE_REALLY_SLOW_DMA_CONTROLLER 28 29 #include <sound/core.h> 30 #include <asm/dma.h> 31 32 /** 33 * snd_dma_program - program an ISA DMA transfer 34 * @dma: the dma number 35 * @addr: the physical address of the buffer 36 * @size: the DMA transfer size 37 * @mode: the DMA transfer mode, DMA_MODE_XXX 38 * 39 * Programs an ISA DMA transfer for the given buffer. 40 */ 41 void snd_dma_program(unsigned long dma, 42 unsigned long addr, unsigned int size, 43 unsigned short mode) 44 { 45 unsigned long flags; 46 47 flags = claim_dma_lock(); 48 disable_dma(dma); 49 clear_dma_ff(dma); 50 set_dma_mode(dma, mode); 51 set_dma_addr(dma, addr); 52 set_dma_count(dma, size); 53 if (!(mode & DMA_MODE_NO_ENABLE)) 54 enable_dma(dma); 55 release_dma_lock(flags); 56 } 57 58 EXPORT_SYMBOL(snd_dma_program); 59 60 /** 61 * snd_dma_disable - stop the ISA DMA transfer 62 * @dma: the dma number 63 * 64 * Stops the ISA DMA transfer. 65 */ 66 void snd_dma_disable(unsigned long dma) 67 { 68 unsigned long flags; 69 70 flags = claim_dma_lock(); 71 clear_dma_ff(dma); 72 disable_dma(dma); 73 release_dma_lock(flags); 74 } 75 76 EXPORT_SYMBOL(snd_dma_disable); 77 78 /** 79 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes 80 * @dma: the dma number 81 * @size: the dma transfer size 82 * 83 * Returns the current pointer in DMA tranfer buffer in bytes 84 */ 85 unsigned int snd_dma_pointer(unsigned long dma, unsigned int size) 86 { 87 unsigned long flags; 88 unsigned int result, result1; 89 90 flags = claim_dma_lock(); 91 clear_dma_ff(dma); 92 if (!isa_dma_bridge_buggy) 93 disable_dma(dma); 94 result = get_dma_residue(dma); 95 /* 96 * HACK - read the counter again and choose higher value in order to 97 * avoid reading during counter lower byte roll over if the 98 * isa_dma_bridge_buggy is set. 99 */ 100 result1 = get_dma_residue(dma); 101 if (!isa_dma_bridge_buggy) 102 enable_dma(dma); 103 release_dma_lock(flags); 104 if (unlikely(result < result1)) 105 result = result1; 106 #ifdef CONFIG_SND_DEBUG 107 if (result > size) 108 snd_printk(KERN_ERR "pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size); 109 #endif 110 if (result >= size || result == 0) 111 return 0; 112 else 113 return size - result; 114 } 115 116 EXPORT_SYMBOL(snd_dma_pointer); 117