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