1 files changed, 99 insertions, 0 deletions
diff --git a/sound/core/isadma.c b/sound/core/isadma.c
new file mode 100644
index 000000000..c3d789ef6
--- /dev/null
+++ b/sound/core/isadma.c
@@ -0,0 +1,99 @@
+// 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);