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99 lines
2.3 KiB
99 lines
2.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* ISA DMA support functions |
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* Copyright (c) by Jaroslav Kysela <[email protected]> |
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*/ |
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/* |
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* Defining following add some delay. Maybe this helps for some broken |
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* ISA DMA controllers. |
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*/ |
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#undef HAVE_REALLY_SLOW_DMA_CONTROLLER |
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#include <linux/export.h> |
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#include <sound/core.h> |
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#include <asm/dma.h> |
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/** |
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* snd_dma_program - program an ISA DMA transfer |
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* @dma: the dma number |
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* @addr: the physical address of the buffer |
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* @size: the DMA transfer size |
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* @mode: the DMA transfer mode, DMA_MODE_XXX |
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* |
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* Programs an ISA DMA transfer for the given buffer. |
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*/ |
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void snd_dma_program(unsigned long dma, |
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unsigned long addr, unsigned int size, |
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unsigned short mode) |
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{ |
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unsigned long flags; |
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flags = claim_dma_lock(); |
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disable_dma(dma); |
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clear_dma_ff(dma); |
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set_dma_mode(dma, mode); |
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set_dma_addr(dma, addr); |
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set_dma_count(dma, size); |
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if (!(mode & DMA_MODE_NO_ENABLE)) |
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enable_dma(dma); |
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release_dma_lock(flags); |
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} |
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EXPORT_SYMBOL(snd_dma_program); |
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/** |
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* snd_dma_disable - stop the ISA DMA transfer |
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* @dma: the dma number |
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* |
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* Stops the ISA DMA transfer. |
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*/ |
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void snd_dma_disable(unsigned long dma) |
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{ |
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unsigned long flags; |
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flags = claim_dma_lock(); |
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clear_dma_ff(dma); |
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disable_dma(dma); |
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release_dma_lock(flags); |
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} |
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EXPORT_SYMBOL(snd_dma_disable); |
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/** |
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* snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes |
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* @dma: the dma number |
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* @size: the dma transfer size |
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* |
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* Return: The current pointer in DMA transfer buffer in bytes. |
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*/ |
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unsigned int snd_dma_pointer(unsigned long dma, unsigned int size) |
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{ |
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unsigned long flags; |
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unsigned int result, result1; |
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flags = claim_dma_lock(); |
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clear_dma_ff(dma); |
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if (!isa_dma_bridge_buggy) |
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disable_dma(dma); |
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result = get_dma_residue(dma); |
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/* |
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* HACK - read the counter again and choose higher value in order to |
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* avoid reading during counter lower byte roll over if the |
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* isa_dma_bridge_buggy is set. |
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*/ |
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result1 = get_dma_residue(dma); |
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if (!isa_dma_bridge_buggy) |
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enable_dma(dma); |
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release_dma_lock(flags); |
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if (unlikely(result < result1)) |
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result = result1; |
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#ifdef CONFIG_SND_DEBUG |
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if (result > size) |
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pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size); |
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#endif |
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if (result >= size || result == 0) |
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return 0; |
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else |
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return size - result; |
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} |
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EXPORT_SYMBOL(snd_dma_pointer);
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