1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
new file mode 100644
index 000000000000..c729094298c2
--- /dev/null
+++ b/drivers/comedi/drivers/comedi_isadma.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * COMEDI ISA DMA support functions
+ * Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <asm/dma.h>
+
+#include "../comedidev.h"
+
+#include "comedi_isadma.h"
+
+/**
+ * comedi_isadma_program - program and enable an ISA DMA transfer
+ * @desc:	the ISA DMA cookie to program and enable
+ */
+void comedi_isadma_program(struct comedi_isadma_desc *desc)
+{
+	unsigned long flags;
+
+	flags = claim_dma_lock();
+	clear_dma_ff(desc->chan);
+	set_dma_mode(desc->chan, desc->mode);
+	set_dma_addr(desc->chan, desc->hw_addr);
+	set_dma_count(desc->chan, desc->size);
+	enable_dma(desc->chan);
+	release_dma_lock(flags);
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_program);
+
+/**
+ * comedi_isadma_disable - disable the ISA DMA channel
+ * @dma_chan:	the DMA channel to disable
+ *
+ * Returns the residue (remaining bytes) left in the DMA transfer.
+ */
+unsigned int comedi_isadma_disable(unsigned int dma_chan)
+{
+	unsigned long flags;
+	unsigned int residue;
+
+	flags = claim_dma_lock();
+	disable_dma(dma_chan);
+	residue = get_dma_residue(dma_chan);
+	release_dma_lock(flags);
+
+	return residue;
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_disable);
+
+/**
+ * comedi_isadma_disable_on_sample - disable the ISA DMA channel
+ * @dma_chan:	the DMA channel to disable
+ * @size:	the sample size (in bytes)
+ *
+ * Returns the residue (remaining bytes) left in the DMA transfer.
+ */
+unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan,
+					     unsigned int size)
+{
+	int stalled = 0;
+	unsigned long flags;
+	unsigned int residue;
+	unsigned int new_residue;
+
+	residue = comedi_isadma_disable(dma_chan);
+	while (residue % size) {
+		/* residue is a partial sample, enable DMA to allow more data */
+		flags = claim_dma_lock();
+		enable_dma(dma_chan);
+		release_dma_lock(flags);
+
+		udelay(2);
+		new_residue = comedi_isadma_disable(dma_chan);
+
+		/* is DMA stalled? */
+		if (new_residue == residue) {
+			stalled++;
+			if (stalled > 10)
+				break;
+		} else {
+			residue = new_residue;
+			stalled = 0;
+		}
+	}
+	return residue;
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_disable_on_sample);
+
+/**
+ * comedi_isadma_poll - poll the current DMA transfer
+ * @dma:	the ISA DMA to poll
+ *
+ * Returns the position (in bytes) of the current DMA transfer.
+ */
+unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
+{
+	struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
+	unsigned long flags;
+	unsigned int result;
+	unsigned int result1;
+
+	flags = claim_dma_lock();
+	clear_dma_ff(desc->chan);
+	if (!isa_dma_bridge_buggy)
+		disable_dma(desc->chan);
+	result = get_dma_residue(desc->chan);
+	/*
+	 * 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(desc->chan);
+	if (!isa_dma_bridge_buggy)
+		enable_dma(desc->chan);
+	release_dma_lock(flags);
+
+	if (result < result1)
+		result = result1;
+	if (result >= desc->size || result == 0)
+		return 0;
+	return desc->size - result;
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_poll);
+
+/**
+ * comedi_isadma_set_mode - set the ISA DMA transfer direction
+ * @desc:	the ISA DMA cookie to set
+ * @dma_dir:	the DMA direction
+ */
+void comedi_isadma_set_mode(struct comedi_isadma_desc *desc, char dma_dir)
+{
+	desc->mode = (dma_dir == COMEDI_ISADMA_READ) ? DMA_MODE_READ
+						     : DMA_MODE_WRITE;
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_set_mode);
+
+/**
+ * comedi_isadma_alloc - allocate and initialize the ISA DMA
+ * @dev:	comedi_device struct
+ * @n_desc:	the number of cookies to allocate
+ * @dma_chan:	DMA channel for the first cookie
+ * @dma_chan2:	DMA channel for the second cookie
+ * @maxsize:	the size of the buffer to allocate for each cookie
+ * @dma_dir:	the DMA direction
+ *
+ * Returns the allocated and initialized ISA DMA or NULL if anything fails.
+ */
+struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
+					  int n_desc, unsigned int dma_chan1,
+					  unsigned int dma_chan2,
+					  unsigned int maxsize, char dma_dir)
+{
+	struct comedi_isadma *dma = NULL;
+	struct comedi_isadma_desc *desc;
+	unsigned int dma_chans[2];
+	int i;
+
+	if (n_desc < 1 || n_desc > 2)
+		goto no_dma;
+
+	dma = kzalloc(sizeof(*dma), GFP_KERNEL);
+	if (!dma)
+		goto no_dma;
+
+	desc = kcalloc(n_desc, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		goto no_dma;
+	dma->desc = desc;
+	dma->n_desc = n_desc;
+	if (dev->hw_dev) {
+		dma->dev = dev->hw_dev;
+	} else {
+		/* Fall back to using the "class" device. */
+		if (!dev->class_dev)
+			goto no_dma;
+		/* Need 24-bit mask for ISA DMA. */
+		if (dma_coerce_mask_and_coherent(dev->class_dev,
+						 DMA_BIT_MASK(24))) {
+			goto no_dma;
+		}
+		dma->dev = dev->class_dev;
+	}
+
+	dma_chans[0] = dma_chan1;
+	if (dma_chan2 == 0 || dma_chan2 == dma_chan1)
+		dma_chans[1] = dma_chan1;
+	else
+		dma_chans[1] = dma_chan2;
+
+	if (request_dma(dma_chans[0], dev->board_name))
+		goto no_dma;
+	dma->chan = dma_chans[0];
+	if (dma_chans[1] != dma_chans[0]) {
+		if (request_dma(dma_chans[1], dev->board_name))
+			goto no_dma;
+	}
+	dma->chan2 = dma_chans[1];
+
+	for (i = 0; i < n_desc; i++) {
+		desc = &dma->desc[i];
+		desc->chan = dma_chans[i];
+		desc->maxsize = maxsize;
+		desc->virt_addr = dma_alloc_coherent(dma->dev, desc->maxsize,
+						     &desc->hw_addr,
+						     GFP_KERNEL);
+		if (!desc->virt_addr)
+			goto no_dma;
+		comedi_isadma_set_mode(desc, dma_dir);
+	}
+
+	return dma;
+
+no_dma:
+	comedi_isadma_free(dma);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_alloc);
+
+/**
+ * comedi_isadma_free - free the ISA DMA
+ * @dma:	the ISA DMA to free
+ */
+void comedi_isadma_free(struct comedi_isadma *dma)
+{
+	struct comedi_isadma_desc *desc;
+	int i;
+
+	if (!dma)
+		return;
+
+	if (dma->desc) {
+		for (i = 0; i < dma->n_desc; i++) {
+			desc = &dma->desc[i];
+			if (desc->virt_addr)
+				dma_free_coherent(dma->dev, desc->maxsize,
+						  desc->virt_addr,
+						  desc->hw_addr);
+		}
+		kfree(dma->desc);
+	}
+	if (dma->chan2 && dma->chan2 != dma->chan)
+		free_dma(dma->chan2);
+	if (dma->chan)
+		free_dma(dma->chan);
+	kfree(dma);
+}
+EXPORT_SYMBOL_GPL(comedi_isadma_free);
+
+static int __init comedi_isadma_init(void)
+{
+	return 0;
+}
+module_init(comedi_isadma_init);
+
+static void __exit comedi_isadma_exit(void)
+{
+}
+module_exit(comedi_isadma_exit);
+
+MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
+MODULE_DESCRIPTION("Comedi ISA DMA support");
+MODULE_LICENSE("GPL");