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-rw-r--r--sound/core/isadma.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/sound/core/isadma.c b/sound/core/isadma.c
new file mode 100644
index 000000000..28768061d
--- /dev/null
+++ b/sound/core/isadma.c
@@ -0,0 +1,138 @@
+// 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 <linux/isa-dma.h>
+#include <sound/core.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);
+
+struct snd_dma_data {
+ int dma;
+};
+
+static void __snd_release_dma(struct device *dev, void *data)
+{
+ struct snd_dma_data *p = data;
+
+ snd_dma_disable(p->dma);
+ free_dma(p->dma);
+}
+
+/**
+ * snd_devm_request_dma - the managed version of request_dma()
+ * @dev: the device pointer
+ * @dma: the dma number
+ * @name: the name string of the requester
+ *
+ * The requested DMA will be automatically released at unbinding via devres.
+ *
+ * Return: zero on success, or a negative error code
+ */
+int snd_devm_request_dma(struct device *dev, int dma, const char *name)
+{
+ struct snd_dma_data *p;
+
+ if (request_dma(dma, name))
+ return -EBUSY;
+ p = devres_alloc(__snd_release_dma, sizeof(*p), GFP_KERNEL);
+ if (!p) {
+ free_dma(dma);
+ return -ENOMEM;
+ }
+ p->dma = dma;
+ devres_add(dev, p);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_devm_request_dma);