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 <linux/export.h> 30 #include <sound/core.h> 31 #include <asm/dma.h> 32 33 /** 34 * snd_dma_program - program an ISA DMA transfer 35 * @dma: the dma number 36 * @addr: the physical address of the buffer 37 * @size: the DMA transfer size 38 * @mode: the DMA transfer mode, DMA_MODE_XXX 39 * 40 * Programs an ISA DMA transfer for the given buffer. 41 */ 42 void snd_dma_program(unsigned long dma, 43 unsigned long addr, unsigned int size, 44 unsigned short mode) 45 { 46 unsigned long flags; 47 48 flags = claim_dma_lock(); 49 disable_dma(dma); 50 clear_dma_ff(dma); 51 set_dma_mode(dma, mode); 52 set_dma_addr(dma, addr); 53 set_dma_count(dma, size); 54 if (!(mode & DMA_MODE_NO_ENABLE)) 55 enable_dma(dma); 56 release_dma_lock(flags); 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 EXPORT_SYMBOL(snd_dma_disable); 76 77 /** 78 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes 79 * @dma: the dma number 80 * @size: the dma transfer size 81 * 82 * Return: The current pointer in DMA transfer buffer in bytes. 83 */ 84 unsigned int snd_dma_pointer(unsigned long dma, unsigned int size) 85 { 86 unsigned long flags; 87 unsigned int result, result1; 88 89 flags = claim_dma_lock(); 90 clear_dma_ff(dma); 91 if (!isa_dma_bridge_buggy) 92 disable_dma(dma); 93 result = get_dma_residue(dma); 94 /* 95 * HACK - read the counter again and choose higher value in order to 96 * avoid reading during counter lower byte roll over if the 97 * isa_dma_bridge_buggy is set. 98 */ 99 result1 = get_dma_residue(dma); 100 if (!isa_dma_bridge_buggy) 101 enable_dma(dma); 102 release_dma_lock(flags); 103 if (unlikely(result < result1)) 104 result = result1; 105 #ifdef CONFIG_SND_DEBUG 106 if (result > size) 107 pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size); 108 #endif 109 if (result >= size || result == 0) 110 return 0; 111 else 112 return size - result; 113 } 114 EXPORT_SYMBOL(snd_dma_pointer); 115