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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * ISA DMA support functions4 * Copyright (c) by Jaroslav Kysela <perex@perex.cz>5 */6 7/*8 * Defining following add some delay. Maybe this helps for some broken9 * ISA DMA controllers.10 */11 12#undef HAVE_REALLY_SLOW_DMA_CONTROLLER13 14#include <linux/export.h>15#include <linux/isa-dma.h>16#include <sound/core.h>17 18/**19 * snd_dma_program - program an ISA DMA transfer20 * @dma: the dma number21 * @addr: the physical address of the buffer22 * @size: the DMA transfer size23 * @mode: the DMA transfer mode, DMA_MODE_XXX24 *25 * Programs an ISA DMA transfer for the given buffer.26 */27void snd_dma_program(unsigned long dma,28 unsigned long addr, unsigned int size,29 unsigned short mode)30{31 unsigned long flags;32 33 flags = claim_dma_lock();34 disable_dma(dma);35 clear_dma_ff(dma);36 set_dma_mode(dma, mode);37 set_dma_addr(dma, addr);38 set_dma_count(dma, size);39 if (!(mode & DMA_MODE_NO_ENABLE))40 enable_dma(dma);41 release_dma_lock(flags);42}43EXPORT_SYMBOL(snd_dma_program);44 45/**46 * snd_dma_disable - stop the ISA DMA transfer47 * @dma: the dma number48 *49 * Stops the ISA DMA transfer.50 */51void snd_dma_disable(unsigned long dma)52{53 unsigned long flags;54 55 flags = claim_dma_lock();56 clear_dma_ff(dma);57 disable_dma(dma);58 release_dma_lock(flags);59}60EXPORT_SYMBOL(snd_dma_disable);61 62/**63 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes64 * @dma: the dma number65 * @size: the dma transfer size66 *67 * Return: The current pointer in DMA transfer buffer in bytes.68 */69unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)70{71 unsigned long flags;72 unsigned int result, result1;73 74 flags = claim_dma_lock();75 clear_dma_ff(dma);76 if (!isa_dma_bridge_buggy)77 disable_dma(dma);78 result = get_dma_residue(dma);79 /*80 * HACK - read the counter again and choose higher value in order to81 * avoid reading during counter lower byte roll over if the82 * isa_dma_bridge_buggy is set.83 */84 result1 = get_dma_residue(dma);85 if (!isa_dma_bridge_buggy)86 enable_dma(dma);87 release_dma_lock(flags);88 if (unlikely(result < result1))89 result = result1;90#ifdef CONFIG_SND_DEBUG91 if (result > size)92 pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size);93#endif94 if (result >= size || result == 0)95 return 0;96 else97 return size - result;98}99EXPORT_SYMBOL(snd_dma_pointer);100 101struct snd_dma_data {102 int dma;103};104 105static void __snd_release_dma(struct device *dev, void *data)106{107 struct snd_dma_data *p = data;108 109 snd_dma_disable(p->dma);110 free_dma(p->dma);111}112 113/**114 * snd_devm_request_dma - the managed version of request_dma()115 * @dev: the device pointer116 * @dma: the dma number117 * @name: the name string of the requester118 *119 * The requested DMA will be automatically released at unbinding via devres.120 *121 * Return: zero on success, or a negative error code122 */123int snd_devm_request_dma(struct device *dev, int dma, const char *name)124{125 struct snd_dma_data *p;126 127 if (request_dma(dma, name))128 return -EBUSY;129 p = devres_alloc(__snd_release_dma, sizeof(*p), GFP_KERNEL);130 if (!p) {131 free_dma(dma);132 return -ENOMEM;133 }134 p->dma = dma;135 devres_add(dev, p);136 return 0;137}138EXPORT_SYMBOL_GPL(snd_devm_request_dma);139