Patchwork [RFCv1,2/3] fpga: add CARMA DATA-FPGA Access Driver

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Submitter Ira Snyder
Date Sept. 3, 2010, 10:30 p.m.
Message ID <1283553052-23576-3-git-send-email-iws@ovro.caltech.edu>
Download mbox | patch
Permalink /patch/63730/
State Superseded
Headers show

Comments

Ira Snyder - Sept. 3, 2010, 10:30 p.m.
This driver allows userspace to access the data processing FPGAs on the
OVRO CARMA board. It has two modes of operation:

1) random access

This allows users to poke any DATA-FPGA registers by using mmap to map
the address region directly into their memory map.

2) correlation dumping

When correlating, the DATA-FPGA's have special requirements for getting
the data out of their memory before the next correlation. This nominally
happens at 64Hz (every 15.625ms). If the data is not dumped before the
next correlation, data is lost.

The data dumping driver handles buffering up to 1 second worth of
correlation data from the FPGAs. This lowers the realtime scheduling
requirements for the userspace process reading the device.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
---
 drivers/fpga/carma/Kconfig      |    9 +
 drivers/fpga/carma/Makefile     |    1 +
 drivers/fpga/carma/carma-fpga.c | 1447 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 1457 insertions(+), 0 deletions(-)
 create mode 100644 drivers/fpga/carma/carma-fpga.c
Randy.Dunlap - Sept. 3, 2010, 10:44 p.m.
On Fri,  3 Sep 2010 15:30:51 -0700 Ira W. Snyder wrote:

> This driver allows userspace to access the data processing FPGAs on the
> OVRO CARMA board. It has two modes of operation:
> 
> 1) random access
> 
> This allows users to poke any DATA-FPGA registers by using mmap to map
> the address region directly into their memory map.
> 
> 2) correlation dumping
> 
> When correlating, the DATA-FPGA's have special requirements for getting
> the data out of their memory before the next correlation. This nominally
> happens at 64Hz (every 15.625ms). If the data is not dumped before the
> next correlation, data is lost.
> 
> The data dumping driver handles buffering up to 1 second worth of
> correlation data from the FPGAs. This lowers the realtime scheduling
> requirements for the userspace process reading the device.
> 
> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
> ---
>  drivers/fpga/carma/Kconfig      |    9 +
>  drivers/fpga/carma/Makefile     |    1 +
>  drivers/fpga/carma/carma-fpga.c | 1447 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1457 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/fpga/carma/carma-fpga.c
> 
> diff --git a/drivers/fpga/carma/Kconfig b/drivers/fpga/carma/Kconfig
> index 448885e..5592f73 100644
> --- a/drivers/fpga/carma/Kconfig
> +++ b/drivers/fpga/carma/Kconfig
> @@ -18,4 +18,13 @@ config CARMA
>  	  Say Y here to include basic support for the CARMA System Controller
>  	  FPGA. This option allows the other more advanced drivers to be built.
>  
> +config CARMA_FPGA
> +	tristate "CARMA DATA-FPGA Access Driver"
> +	depends on CARMA
> +	select VIDEOBUF_DMA_SG

You can't safely select VIDEOBUF_DMA_SG unless MEDIA_SUPPORT && HAS_DMA are
enabled, so I would add
	depends on MEDIA_SUPPORT && HAS_DMA
to this config symbol.


> +	default n
> +	help
> +	  Say Y here to include support for communicating with the data
> +	  processing FPGAs on the CARMA board.
> +
>  endif # FPGA_DRIVERS

> diff --git a/drivers/fpga/carma/carma-fpga.c b/drivers/fpga/carma/carma-fpga.c
> new file mode 100644
> index 0000000..ab1b536
> --- /dev/null
> +++ b/drivers/fpga/carma/carma-fpga.c
> @@ -0,0 +1,1447 @@
> +/*
> + * Free a single data buffer and all allocated pages
> + *
> + * This will free all of the pages allocated to the given data buffer, and
> + * then free the structure itself
> + *
> + * @dev: the DMA device to map for
> + * @buf: the buffer to free
> + */
> +static void data_free_buffer(struct device *dev, struct data_buf *buf)
> +{

The comments above are OK, but please don't add the (doxygen?) style comments
as below (this is just one example of multiple occurrences).
Specifically, the "@param" parts.
It would be better to use the style above (if not using kernel-doc notation).


> +/*
> + * Prepare and submit a DMA_SLAVE transaction for a correlation data buffer
> + *
> + * LOCKING: must hold dev->lock
> + * CONTEXT: hardirq only
> + *
> + * @param priv the driver's private data structure
> + * @param buf the data buffer to DMA into
> + * @return 0 on success, -ERRNO otherwise
> + */
> +static int data_submit_dma(struct fpga_device *priv, struct data_buf *buf)
> +{


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Patch

diff --git a/drivers/fpga/carma/Kconfig b/drivers/fpga/carma/Kconfig
index 448885e..5592f73 100644
--- a/drivers/fpga/carma/Kconfig
+++ b/drivers/fpga/carma/Kconfig
@@ -18,4 +18,13 @@  config CARMA
 	  Say Y here to include basic support for the CARMA System Controller
 	  FPGA. This option allows the other more advanced drivers to be built.
 
+config CARMA_FPGA
+	tristate "CARMA DATA-FPGA Access Driver"
+	depends on CARMA
+	select VIDEOBUF_DMA_SG
+	default n
+	help
+	  Say Y here to include support for communicating with the data
+	  processing FPGAs on the CARMA board.
+
 endif # FPGA_DRIVERS
diff --git a/drivers/fpga/carma/Makefile b/drivers/fpga/carma/Makefile
index 90d0594..c175d34 100644
--- a/drivers/fpga/carma/Makefile
+++ b/drivers/fpga/carma/Makefile
@@ -1 +1,2 @@ 
 obj-$(CONFIG_CARMA)			+= carma.o
+obj-$(CONFIG_CARMA_FPGA)		+= carma-fpga.o
diff --git a/drivers/fpga/carma/carma-fpga.c b/drivers/fpga/carma/carma-fpga.c
new file mode 100644
index 0000000..ab1b536
--- /dev/null
+++ b/drivers/fpga/carma/carma-fpga.c
@@ -0,0 +1,1447 @@ 
+/*
+ * CARMA DATA-FPGA Access Driver
+ *
+ * Copyright (c) 2009-2010 Ira W. Snyder <iws@ovro.caltech.edu>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+/*
+ * FPGA Memory Dump Format
+ *
+ * FPGA #0 control registers (32 x 32-bit words)
+ * FPGA #1 control registers (32 x 32-bit words)
+ * FPGA #2 control registers (32 x 32-bit words)
+ * FPGA #3 control registers (32 x 32-bit words)
+ * SYSFPGA control registers (32 x 32-bit words)
+ * FPGA #0 correlation array (NUM_CORL0 correlation blocks)
+ * FPGA #1 correlation array (NUM_CORL1 correlation blocks)
+ * FPGA #2 correlation array (NUM_CORL2 correlation blocks)
+ * FPGA #3 correlation array (NUM_CORL3 correlation blocks)
+ *
+ * Each correlation array consists of:
+ *
+ * Correlation Data      (2 x NUM_LAGSn x 32-bit words)
+ * Pipeline Metadata     (2 x NUM_METAn x 32-bit words)
+ * Quantization Counters (2 x NUM_QCNTn x 32-bit words)
+ *
+ * The NUM_CORLn, NUM_LAGSn, NUM_METAn, and NUM_QCNTn values come from
+ * the FPGA configuration registers. They do not change once the FPGA's
+ * have been programmed, they only change on re-programming.
+ */
+
+/*
+ * Basic Description:
+ *
+ * This driver is used to capture correlation spectra off of the four data
+ * processing FPGAs. The FPGAs are often reprogrammed at runtime, therefore
+ * this driver supports dynamic enable/disable of capture while the device
+ * remains open.
+ *
+ * The nominal capture rate is 64Hz (every 15.625ms). To facilitate this fast
+ * capture rate, all buffers are pre-allocated to avoid any potentially long
+ * running memory allocations while capturing.
+ *
+ * There are three lists which are used to keep track of the different states
+ * of data buffers.
+ *
+ * 1) free list
+ * This list holds all empty data buffers which are ready to receive data.
+ *
+ * 2) inflight list
+ * This list holds data buffers which are currently waiting for a DMA operation
+ * to complete.
+ *
+ * 3) used list
+ * This list holds data buffers which have been filled, and are waiting to be
+ * read by userspace.
+ *
+ * All buffers start life on the free list, then move successively to the
+ * inflight list, and then to the used list. After they have been read by
+ * userspace, they are moved back to the free list. The cycle repeats as long
+ * as necessary.
+ */
+
+/*
+ * Notes on the IRQ masking scheme:
+ *
+ * The IRQ masking scheme here is different than most other hardware. The only
+ * way for the DATA-FPGAs to detect if the kernel has taken too long to copy
+ * the data is if the status registers are not cleared before the next
+ * correlation data dump is ready.
+ *
+ * The interrupt line is connected to the status registers, such that when they
+ * are cleared, the interrupt is de-asserted. Therein lies our problem. We need
+ * to schedule a long-running DMA operation and return from the interrupt
+ * handler quickly, but we cannot clear the status registers.
+ *
+ * To handle this, the system controller FPGA has the capability to connect the
+ * interrupt line to a user-controlled GPIO pin. This pin is driven high
+ * (unasserted) and left that way. To mask the interrupt, we change the
+ * interrupt source to the GPIO pin. Tada, we hid the interrupt. :)
+ */
+
+#include <linux/of_platform.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/dmaengine.h>
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <media/videobuf-dma-sg.h>
+#include <asm/fsldma.h>
+
+#include "carma.h"
+
+/* system controller registers */
+#define SYS_IRQ_SOURCE_CTL	0x24
+#define SYS_IRQ_OUTPUT_EN	0x28
+#define SYS_IRQ_OUTPUT_DATA	0x2C
+#define SYS_IRQ_INPUT_DATA	0x30
+
+/* GPIO IRQ line assignment */
+#define IRQ_CORL_DONE		0x10
+
+/* FPGA registers */
+#define MMAP_REG_CORL_CONF1	0x08
+#define MMAP_REG_CORL_CONF2	0x0C
+#define MMAP_REG_STATUS		0x48
+
+#define SYS_FPGA_BLOCK		0xF0000000
+
+static const char drv_name[] = "carma-fpga";
+
+#define NUM_FPGA	4
+
+#define MIN_DATA_BUFS	8
+#define MAX_DATA_BUFS	64
+
+struct fpga_info {
+	unsigned int num_corl;
+	unsigned int blk_size;
+};
+
+struct data_buf {
+	struct list_head entry;
+	struct videobuf_dmabuf vb;
+	bool mapped;
+	size_t size;
+};
+
+struct fpga_device {
+	struct cdev cdev;
+	dev_t devno;
+
+	struct device *dev;
+	struct mutex mutex;
+
+	/* FPGA registers and information */
+	struct fpga_info info[NUM_FPGA];
+	void __iomem *regs;
+	int irq;
+
+	/* FPGA Physical Address/Size Information */
+	resource_size_t phys_addr;
+	size_t phys_size;
+
+	/* DMA structures */
+	struct fsl_dma_slave *slave;
+	struct dma_chan *chan;
+	struct device *dmadev;
+
+	/* Protection for all members below */
+	spinlock_t lock;
+
+	/* Device enable/disable flag */
+	bool enabled;
+
+	/* Correlation data buffers */
+	wait_queue_head_t wait;
+	struct list_head free;
+	struct list_head used;
+	struct list_head inflight;
+
+	/* Information about data buffers */
+	unsigned int num_dropped;
+	unsigned int num_buffers;
+	size_t bufsize;
+};
+
+struct fpga_reader {
+	struct fpga_device *priv;
+	struct data_buf *buf;
+	off_t buf_start;
+};
+
+#define inode_to_dev(inode) container_of(inode->i_cdev, struct fpga_device, cdev)
+
+/*
+ * Data Buffer Allocation Helpers
+ */
+
+static int data_map_buffer(struct device *dev, struct data_buf *buf)
+{
+	int ret;
+
+	/* if the buffer is already mapped, we're done */
+	if (buf->mapped)
+		return 0;
+
+	ret = videobuf_dma_map(dev, &buf->vb);
+	if (ret)
+		return ret;
+
+	buf->mapped = true;
+	return 0;
+}
+
+static void data_unmap_buffer(struct device *dev, struct data_buf *buf)
+{
+	/* the buffer is already unmapped, we're done */
+	if (!buf->mapped)
+		return;
+
+	videobuf_dma_unmap(dev, &buf->vb);
+	buf->mapped = false;
+}
+
+/*
+ * Free a single data buffer and all allocated pages
+ *
+ * This will free all of the pages allocated to the given data buffer, and
+ * then free the structure itself
+ *
+ * @dev: the DMA device to map for
+ * @buf: the buffer to free
+ */
+static void data_free_buffer(struct device *dev, struct data_buf *buf)
+{
+	/* It is ok to free a NULL buffer */
+	if (!buf)
+		return;
+
+	/* Make sure the buffer is not on any list */
+	list_del_init(&buf->entry);
+
+	/* unmap it for DMA */
+	data_unmap_buffer(dev, buf);
+
+	/* free all memory */
+	videobuf_dma_free(&buf->vb);
+	kfree(buf);
+}
+
+/*
+ * Allocate and fill a data buffer
+ *
+ * This allocates all space needed for a data buffer, and gets it ready to be
+ * used in a DMA transaction. It only needs to be used, never mapped before
+ * use. This avoids calling vmalloc in hardirq context.
+ *
+ * @dev: the DMA device to map for
+ * @bytes: the number of bytes required
+ * @return: a new buffer or NULL on failure
+ */
+static struct data_buf *data_alloc_buffer(struct device *dev, const size_t bytes)
+{
+	unsigned int nr_pages;
+	struct data_buf *buf;
+	int ret;
+
+	/* calculate the number of pages necessary */
+	nr_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
+
+	/* allocate the buffer structure */
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto out_return;
+
+	/* initialize internal fields */
+	INIT_LIST_HEAD(&buf->entry);
+	buf->size = bytes;
+
+	/* allocate the videobuf */
+	videobuf_dma_init(&buf->vb);
+	ret = videobuf_dma_init_kernel(&buf->vb, DMA_FROM_DEVICE, nr_pages);
+	if (ret)
+		goto out_free_buf;
+
+	/* map it for DMA */
+	ret = data_map_buffer(dev, buf);
+	if (ret)
+		goto out_free_videobuf;
+
+	return buf;
+
+out_free_videobuf:
+	videobuf_dma_free(&buf->vb);
+out_free_buf:
+	kfree(buf);
+out_return:
+	return NULL;
+}
+
+/*
+ * Free all of the buffers allocated for correlation data
+ *
+ * This routine will free all data buffers that are being used by the driver.
+ *
+ * REQUIREMENTS: all list manipulation must have ceased
+ * REQUIREMENTS: all DMA must be complete, and the engine stopped
+ *
+ * CONTEXT: user
+ *
+ * @param priv the driver's private data structure
+ */
+static void data_free_buffers(struct fpga_device *priv)
+{
+	struct device *dev = priv->dmadev;
+	struct data_buf *buf, *tmp;
+
+	spin_lock_irq(&priv->lock);
+	BUG_ON(!list_empty(&priv->inflight));
+
+	list_for_each_entry_safe(buf, tmp, &priv->free, entry) {
+		list_del_init(&buf->entry);
+		spin_unlock_irq(&priv->lock);
+		data_free_buffer(dev, buf);
+		spin_lock_irq(&priv->lock);
+	}
+
+	list_for_each_entry_safe(buf, tmp, &priv->used, entry) {
+		list_del_init(&buf->entry);
+		spin_unlock_irq(&priv->lock);
+		data_free_buffer(dev, buf);
+		spin_lock_irq(&priv->lock);
+	}
+
+	priv->num_buffers = 0;
+	priv->bufsize = 0;
+
+	spin_unlock_irq(&priv->lock);
+}
+
+/*
+ * Allocate enough buffers for a whole second worth of data
+ *
+ * This routine will attempt to degrade nicely by succeeding even if a full
+ * second worth of data buffers could not be allocated, as long as a minimum
+ * number were allocated. In this case, it will print a message to the kernel
+ * log.
+ *
+ * CONTEXT: user
+ *
+ * @param priv the driver's private data structure
+ * @return 0 on success, -ERRNO otherwise
+ */
+static int data_alloc_buffers(struct fpga_device *priv)
+{
+	struct device *dev = priv->dmadev;
+	struct data_buf *buf;
+	int i;
+
+	for (i = 0; i < MAX_DATA_BUFS; i++) {
+		buf = data_alloc_buffer(dev, priv->bufsize);
+		if (!buf)
+			break;
+
+		spin_lock_irq(&priv->lock);
+		list_add_tail(&buf->entry, &priv->free);
+		spin_unlock_irq(&priv->lock);
+	}
+
+	/* Make sure we allocated the minimum required number of buffers */
+	if (i < MIN_DATA_BUFS) {
+		dev_err(priv->dev, "Unable to allocate enough data buffers\n");
+		data_free_buffers(priv);
+		return -ENOMEM;
+	}
+
+	/* Warn if we are running in a degraded state, but do not fail */
+	if (i < MAX_DATA_BUFS) {
+		dev_warn(priv->dev, "Unable to allocate one second worth of "
+				   "buffers, using %d buffers instead\n", i);
+	}
+
+	priv->num_buffers = i;
+	return 0;
+}
+
+/*
+ * DMA Operations Helpers
+ */
+
+/*
+ * Calculate the physical address of the start of FPGA memory
+ *
+ * @param priv the driver's private data structure
+ * @param fpga the FPGA number
+ * @return the physical address of the correlation data block
+ */
+static dma_addr_t fpga_start_addr(struct fpga_device *priv, unsigned int fpga)
+{
+	return priv->phys_addr + 0x400000 + (0x80000 * fpga);
+}
+
+/*
+ * Calculate the physical address of an FPGA correlation data block
+ *
+ * @param priv the driver's private data structure
+ * @param fpga the FPGA number
+ * @param blknum the correlation data block number
+ * @return the physical address of the correlation data block
+ */
+static dma_addr_t fpga_block_addr(struct fpga_device *priv, unsigned int fpga,
+				  unsigned int blknum)
+{
+	return fpga_start_addr(priv, fpga) + (0x10000 * (1 + blknum));
+}
+
+/*
+ * Add the correlation data for a single DATA FPGA to the DMA_SLAVE structure
+ *
+ * @param priv the driver's private data structure
+ * @param slave the Freescale DMA_SLAVE structure
+ * @param fpga the FPGA number
+ * @return 0 on success, -ERRNO otherwise
+ */
+static int fpga_append_correlation_data(struct fpga_device *priv,
+					struct fsl_dma_slave *slave,
+					unsigned int fpga)
+{
+	struct fpga_info *info = &priv->info[fpga];
+	dma_addr_t addr;
+	size_t len;
+	int i, ret;
+
+	for (i = 0; i < info->num_corl; i++) {
+		addr = fpga_block_addr(priv, fpga, i);
+		len = info->blk_size;
+		ret = fsl_dma_slave_append(slave, addr, len);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Create the DMA_SLAVE structure for transferring data from the DATA FPGA's
+ *
+ * This structure will be reused for each buffer that needs to be filled
+ * with correlation data from the DATA FPGA's
+ *
+ * @param priv the driver's private data structure
+ * @return 0 on success, -ERRNO otherwise
+ */
+static int data_setup_dma_slave(struct fpga_device *priv)
+{
+	static const char prefix[] = "DMA_SLAVE: unable to";
+	struct fsl_dma_slave *slave;
+	dma_addr_t addr;
+	size_t len;
+	int i, ret;
+
+	/* Create the Freescale DMA_SLAVE structure */
+	slave = fsl_dma_slave_alloc(GFP_KERNEL);
+	if (!slave) {
+		dev_err(priv->dev, "%s allocate structure\n", prefix);
+		ret = -ENOMEM;
+		goto out_return;
+	}
+
+	/* Add the FPGA registers to the slave list */
+	for (i = 0; i < NUM_FPGA; i++) {
+		addr = fpga_start_addr(priv, i);
+		len = 32 * 4;
+		ret = fsl_dma_slave_append(slave, addr, len);
+		if (ret) {
+			dev_err(priv->dev, "%s add FPGA registers\n", prefix);
+			goto out_free_slave;
+		}
+	}
+
+	/* Add the SYS-FPGA registers to the slave list */
+	addr = SYS_FPGA_BLOCK;
+	len = 32 * 4;
+	ret = fsl_dma_slave_append(slave, addr, len);
+	if (ret) {
+		dev_err(priv->dev, "%s add SYS-FPGA registers\n", prefix);
+		goto out_free_slave;
+	}
+
+	/* Add the FPGA correlation data blocks to the slave list */
+	for (i = 0; i < NUM_FPGA; i++) {
+		ret = fpga_append_correlation_data(priv, slave, i);
+		if (ret) {
+			dev_err(priv->dev, "%s add correlation data\n", prefix);
+			goto out_free_slave;
+		}
+	}
+
+	/*
+	 * That's everything, this slave structure can be re-used for
+	 * every FPGA DATA interrupt
+	 */
+	priv->slave = slave;
+	return 0;
+
+out_free_slave:
+	fsl_dma_slave_free(slave);
+out_return:
+	return ret;
+}
+
+/*
+ * FPGA Register Access Helpers
+ */
+
+static void fpga_write_reg(struct fpga_device *priv, unsigned int fpga,
+			   unsigned int reg, u32 val)
+{
+	iowrite32be(val, priv->regs + 0x400000 + (fpga * 0x80000) + reg);
+}
+
+static u32 fpga_read_reg(struct fpga_device *priv, unsigned int fpga,
+			 unsigned int reg)
+{
+	return ioread32be(priv->regs + 0x400000 + (fpga * 0x80000) + reg);
+}
+
+/*
+ * Calculate the total buffer size needed to hold a single block
+ * of correlation data
+ *
+ * CONTEXT: user
+ *
+ * @param priv the driver's private data structure
+ * @return 0 on success, -ERRNO otherwise
+ */
+static int data_calculate_bufsize(struct fpga_device *priv)
+{
+	u32 num_corl, num_lags, num_meta, num_qcnt, blk_size;
+	u32 conf1, conf2;
+	int i;
+
+	/* Zero the total buffer size */
+	priv->bufsize = 0;
+
+	/* Read and store the configuration data for each FPGA */
+	for (i = 0; i < NUM_FPGA; i++) {
+		conf1 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF1);
+		conf2 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF2);
+
+		num_corl = (conf1 & 0x000000F0) >> 4;
+		num_lags = (conf1 & 0x000FFF00) >> 8;
+		num_meta = (conf1 & 0x7FF00000) >> 20;
+		num_qcnt = (conf2 & 0x00000FFF) >> 0;
+		blk_size = (num_lags + num_meta + num_qcnt) * 8;
+
+		priv->info[i].num_corl = num_corl;
+		priv->info[i].blk_size = blk_size;
+		priv->bufsize += num_corl * blk_size;
+
+		dev_dbg(priv->dev, "FPGA %d NUM_CORL: %d\n", i, num_corl);
+		dev_dbg(priv->dev, "FPGA %d NUM_LAGS: %d\n", i, num_lags);
+		dev_dbg(priv->dev, "FPGA %d NUM_META: %d\n", i, num_meta);
+		dev_dbg(priv->dev, "FPGA %d NUM_QCNT: %d\n", i, num_qcnt);
+		dev_dbg(priv->dev, "FPGA %d BLK_SIZE: %d\n", i, blk_size);
+	}
+
+	/* Add in the 5 FPGA register areas */
+	priv->bufsize += 5 * (32 * 4);
+	dev_dbg(priv->dev, "TOTAL BUFFER SIZE: %zu bytes\n", priv->bufsize);
+
+	return 0;
+}
+
+/*
+ * Interrupt Handling
+ */
+
+/*
+ * Hide interrupts by switching to GPIO interrupt source
+ *
+ * LOCKING: must hold dev->lock
+ */
+static void data_disable_interrupts(struct fpga_device *priv)
+{
+	/* hide the interrupt by switching the IRQ driver to GPIO */
+	iowrite32be(0x2F, priv->regs + SYS_IRQ_SOURCE_CTL);
+}
+
+/*
+ * Unhide interrupts by switching to the FPGA interrupt source
+ *
+ * LOCKING: must hold dev->lock
+ */
+static void data_enable_interrupts(struct fpga_device *priv)
+{
+	/* clear the actual FPGA corl_done interrupt */
+	fpga_write_reg(priv, 0, MMAP_REG_STATUS, 0x0);
+	fpga_write_reg(priv, 1, MMAP_REG_STATUS, 0x0);
+	fpga_write_reg(priv, 2, MMAP_REG_STATUS, 0x0);
+	fpga_write_reg(priv, 3, MMAP_REG_STATUS, 0x0);
+
+	/* flush the writes */
+	fpga_read_reg(priv, 0, MMAP_REG_STATUS);
+
+	/* switch back to the external interrupt source */
+	iowrite32be(0x3F, priv->regs + SYS_IRQ_SOURCE_CTL);
+}
+
+/*
+ * Complete a DMA transfer from the FPGA's
+ *
+ * This is called via the DMA callback mechanism, and will handle moving the
+ * completed DMA transaction to the used list, and then wake any processes
+ * waiting for new data
+ *
+ * CONTEXT: any, softirq expected
+ *
+ * @param data the driver's private data structure
+ */
+static void data_dma_cb(void *data)
+{
+	struct fpga_device *priv = data;
+	struct data_buf *buf;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	/* clear the FPGA status and re-enable interrupts */
+	data_enable_interrupts(priv);
+
+	/* If the inflight list is empty, we've got a bug */
+	BUG_ON(list_empty(&priv->inflight));
+
+	/* Grab the first buffer from the inflight list */
+	buf = list_first_entry(&priv->inflight, struct data_buf, entry);
+	list_del_init(&buf->entry);
+
+	/* Add it to the used list */
+	list_add_tail(&buf->entry, &priv->used);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	/* We've changed both the inflight and used lists, so we need
+	 * to wake up any processes that are blocking for those events */
+	wake_up(&priv->wait);
+}
+
+/*
+ * Prepare and submit a DMA_SLAVE transaction for a correlation data buffer
+ *
+ * LOCKING: must hold dev->lock
+ * CONTEXT: hardirq only
+ *
+ * @param priv the driver's private data structure
+ * @param buf the data buffer to DMA into
+ * @return 0 on success, -ERRNO otherwise
+ */
+static int data_submit_dma(struct fpga_device *priv, struct data_buf *buf)
+{
+	struct scatterlist *sg = buf->vb.sglist;
+	unsigned int nents = buf->vb.sglen;
+	struct dma_chan *chan = priv->chan;
+	struct dma_async_tx_descriptor *tx;
+	dma_cookie_t cookie;
+	dma_addr_t dst, src;
+
+	/*
+	 * All buffers passed to this function should be ready and mapped
+	 * for DMA already. Therefore, we don't need to do anything except
+	 * submit it to the Freescale DMA Engine for processing
+	 */
+
+	/* setup the DMA_SLAVE transaction */
+	chan->private = priv->slave;
+	tx = chan->device->device_prep_slave_sg(chan, sg, nents,
+						DMA_FROM_DEVICE, 0);
+	if (!tx) {
+		dev_err(priv->dev, "unable to prep slave DMA 1\n");
+		return -ENOMEM;
+	}
+
+	/* submit the transaction to the DMA controller */
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		dev_err(priv->dev, "unable to submit slave DMA 1\n");
+		return -ENOMEM;
+	}
+
+	/* Prepare the re-read of the SYS-FPGA block */
+	dst = sg_dma_address(sg) + (NUM_FPGA * 32 * 4);
+	src = SYS_FPGA_BLOCK;
+	tx = chan->device->device_prep_dma_memcpy(chan, dst, src, 32 * 4,
+						  DMA_PREP_INTERRUPT);
+	if (!tx) {
+		dev_err(priv->dev, "unable to prep slave DMA 2\n");
+		return -ENOMEM;
+	}
+
+	/* Setup the callback */
+	tx->callback = data_dma_cb;
+	tx->callback_param = priv;
+
+	/* submit the transaction to the DMA controller */
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		dev_err(priv->dev, "unable to submit slave DMA 2\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+#define CORL_DONE	0x1
+#define CORL_ERR	0x2
+
+static irqreturn_t data_irq(int irq, void *dev_id)
+{
+	struct fpga_device *priv = dev_id;
+	struct data_buf *buf;
+	u32 status;
+	int i;
+
+	/* detect spurious interrupts via FPGA status */
+	for (i = 0; i < 4; i++) {
+		status = fpga_read_reg(priv, i, MMAP_REG_STATUS);
+		if (!(status & (CORL_DONE | CORL_ERR))) {
+			dev_err(priv->dev, "spurious irq detected (FPGA)\n");
+			return IRQ_NONE;
+		}
+	}
+
+	/* detect spurious interrupts via raw IRQ pin readback */
+	status = ioread32be(priv->regs + SYS_IRQ_INPUT_DATA);
+	if (status & IRQ_CORL_DONE) {
+		dev_err(priv->dev, "spurious irq detected (IRQ)\n");
+		return IRQ_NONE;
+	}
+
+	spin_lock(&priv->lock);
+
+	/* hide the interrupt by switching the IRQ driver to GPIO */
+	data_disable_interrupts(priv);
+
+	/* Check that we actually have a free buffer */
+	if (list_empty(&priv->free)) {
+		priv->num_dropped++;
+		data_enable_interrupts(priv);
+		goto out_unlock;
+	}
+
+	buf = list_first_entry(&priv->free, struct data_buf, entry);
+	list_del_init(&buf->entry);
+
+	/* Check the buffer size */
+	BUG_ON(buf->size != priv->bufsize);
+
+	/* Submit a DMA transfer to get the correlation data */
+	if (data_submit_dma(priv, buf)) {
+		dev_err(priv->dev, "Unable to setup DMA transfer\n");
+		list_add_tail(&buf->entry, &priv->free);
+		data_enable_interrupts(priv);
+		goto out_unlock;
+	}
+
+	/* DMA setup succeeded, GO!!! */
+	list_add_tail(&buf->entry, &priv->inflight);
+	dma_async_memcpy_issue_pending(priv->chan);
+
+out_unlock:
+	spin_unlock(&priv->lock);
+	return IRQ_HANDLED;
+}
+
+/*
+ * Realtime Device Enable Helpers
+ */
+
+/*
+ * Enable the device for buffered dumping
+ *
+ * ASSUMES: the FPGA's are powered on and reads will succeed
+ * LOCKING: dev->mutex held
+ * CONTEXT: user context only
+ */
+static int data_device_enable(struct fpga_device *priv)
+{
+	u32 val;
+	int ret;
+
+	/* multiple enables are safe: they do nothing */
+	if (priv->enabled)
+		return 0;
+
+	/* check that the FPGAs are programmed */
+	val = ioread32be(priv->regs + 0x44);
+	if (!(val & (1 << 18))) {
+		dev_err(priv->dev, "DATA-FPGAs are not enabled\n");
+		return -ENODATA;
+	}
+
+	/* read the FPGAs to calculate the buffer size */
+	ret = data_calculate_bufsize(priv);
+	if (ret) {
+		dev_err(priv->dev, "unable to calculate buffer size\n");
+		goto out_error;
+	}
+
+	/* allocate the correlation data buffers */
+	ret = data_alloc_buffers(priv);
+	if (ret) {
+		dev_err(priv->dev, "unable to allocate buffers\n");
+		goto out_error;
+	}
+
+	/* allocate the DMA_SLAVE structure for correlation data */
+	ret = data_setup_dma_slave(priv);
+	if (ret) {
+		dev_err(priv->dev, "unable to setup DMA list\n");
+		goto out_error;
+	}
+
+	/* switch to the external FPGA IRQ line */
+	data_enable_interrupts(priv);
+
+	/* hookup the irq handler */
+	ret = request_irq(priv->irq, data_irq, IRQF_SHARED, drv_name, priv);
+	if (ret) {
+		dev_err(priv->dev, "unable to request IRQ handler\n");
+		goto out_free_slave;
+	}
+
+	/* success, we're enabled */
+	priv->enabled = true;
+	return 0;
+
+out_free_slave:
+	fsl_dma_slave_free(priv->slave);
+	priv->slave = NULL;
+out_error:
+	data_free_buffers(priv);
+	return ret;
+}
+
+/*
+ * Disable the device for buffered dumping
+ *
+ * LOCKING: must hold dev->mutex
+ * CONTEXT: user only
+ */
+static int data_device_disable(struct fpga_device *priv)
+{
+	struct list_head *list;
+	int ret;
+
+	/* allow multiple disable */
+	if (!priv->enabled)
+		return 0;
+
+	/* switch to the internal GPIO IRQ line */
+	data_disable_interrupts(priv);
+
+	/* unhook the irq handler */
+	free_irq(priv->irq, priv);
+
+	/* wait for all outstanding DMA to complete */
+	list = &priv->inflight;
+
+	spin_lock_irq(&priv->lock);
+	while (!list_empty(list)) {
+		spin_unlock_irq(&priv->lock);
+
+		ret = wait_event_interruptible(priv->wait, list_empty(list));
+		if (ret)
+			return -ERESTARTSYS;
+
+		spin_lock_irq(&priv->lock);
+	}
+	spin_unlock_irq(&priv->lock);
+
+	/* free the DMA_SLAVE structure */
+	fsl_dma_slave_free(priv->slave);
+	priv->slave = NULL;
+
+	/* free all of the buffers */
+	data_free_buffers(priv);
+	priv->enabled = false;
+	return 0;
+}
+
+/*
+ * SYSFS Attributes
+ */
+
+/*
+ * Count the number of entries in the given list
+ */
+static unsigned int list_num_entries(struct list_head *list)
+{
+	struct list_head *entry;
+	unsigned int ret = 0;
+
+	list_for_each(entry, list)
+		ret++;
+
+	return ret;
+}
+
+static ssize_t data_num_buffers_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned int num;
+
+	spin_lock_irq(&priv->lock);
+	num = priv->num_buffers;
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", num);
+}
+
+static ssize_t data_bufsize_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	size_t num;
+
+	spin_lock_irq(&priv->lock);
+	num = priv->bufsize;
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%zu\n", num);
+}
+
+static ssize_t data_inflight_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned int num;
+
+	spin_lock_irq(&priv->lock);
+	num = list_num_entries(&priv->inflight);
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", num);
+}
+
+static ssize_t data_free_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned int num;
+
+	spin_lock_irq(&priv->lock);
+	num = list_num_entries(&priv->free);
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", num);
+}
+
+static ssize_t data_used_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned int num;
+
+	spin_lock_irq(&priv->lock);
+	num = list_num_entries(&priv->used);
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", num);
+}
+
+static ssize_t data_num_dropped_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned int num;
+
+	spin_lock_irq(&priv->lock);
+	num = priv->num_dropped;
+	spin_unlock_irq(&priv->lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", num);
+}
+
+static ssize_t data_en_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	ssize_t count;
+
+	if (mutex_lock_interruptible(&priv->mutex))
+		return -ERESTARTSYS;
+
+	count = snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled);
+	mutex_unlock(&priv->mutex);
+	return count;
+}
+
+static ssize_t data_en_set(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct fpga_device *priv = dev_get_drvdata(dev);
+	unsigned long enable;
+	int ret;
+
+	ret = strict_strtoul(buf, 0, &enable);
+	if (ret) {
+		dev_err(priv->dev, "unable to parse enable input\n");
+		return -EINVAL;
+	}
+
+	if (mutex_lock_interruptible(&priv->mutex))
+		return -ERESTARTSYS;
+
+	if (enable)
+		ret = data_device_enable(priv);
+	else
+		ret = data_device_disable(priv);
+
+	if (ret) {
+		dev_err(priv->dev, "device %s failed\n",
+			enable ? "enable" : "disable");
+		count = ret;
+		goto out_unlock;
+	}
+
+out_unlock:
+	mutex_unlock(&priv->mutex);
+	return count;
+}
+
+static DEVICE_ATTR(num_buffers, S_IRUGO, data_num_buffers_show, NULL);
+static DEVICE_ATTR(buffer_size, S_IRUGO, data_bufsize_show, NULL);
+static DEVICE_ATTR(num_inflight, S_IRUGO, data_inflight_show, NULL);
+static DEVICE_ATTR(num_free, S_IRUGO, data_free_show, NULL);
+static DEVICE_ATTR(num_used, S_IRUGO, data_used_show, NULL);
+static DEVICE_ATTR(num_dropped, S_IRUGO, data_num_dropped_show, NULL);
+static DEVICE_ATTR(enable, S_IWUGO | S_IRUGO, data_en_show, data_en_set);
+
+static struct attribute *data_sysfs_attrs[] = {
+	&dev_attr_num_buffers.attr,
+	&dev_attr_buffer_size.attr,
+	&dev_attr_num_inflight.attr,
+	&dev_attr_num_free.attr,
+	&dev_attr_num_used.attr,
+	&dev_attr_num_dropped.attr,
+	&dev_attr_enable.attr,
+	NULL,
+};
+
+static const struct attribute_group rt_sysfs_attr_group = {
+	.attrs = data_sysfs_attrs,
+};
+
+/*
+ * FPGA Realtime Data Character Device
+ */
+
+static int data_open(struct inode *inode, struct file *filp)
+{
+	struct fpga_device *priv = inode_to_dev(inode);
+	struct fpga_reader *reader;
+	int ret;
+
+	/* allocate private data */
+	reader = kzalloc(sizeof(*reader), GFP_KERNEL);
+	if (!reader)
+		return -ENOMEM;
+
+	reader->priv = priv;
+	reader->buf = NULL;
+
+	filp->private_data = reader;
+	ret = nonseekable_open(inode, filp);
+	if (ret) {
+		dev_err(priv->dev, "nonseekable-open failed\n");
+		kfree(reader);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int data_release(struct inode *inode, struct file *filp)
+{
+	struct fpga_reader *reader = filp->private_data;
+	struct fpga_device *priv = reader->priv;
+
+	/* free the per-reader structure */
+	data_free_buffer(priv->dmadev, reader->buf);
+	kfree(reader);
+	return 0;
+}
+
+static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count,
+			 loff_t *f_pos)
+{
+	struct fpga_reader *reader = filp->private_data;
+	struct fpga_device *priv = reader->priv;
+	struct list_head *used = &priv->used;
+	struct data_buf *dbuf;
+	size_t avail;
+	void *data;
+	int ret;
+
+	/* check if we already have a partial buffer */
+	if (reader->buf) {
+		dbuf = reader->buf;
+		goto have_buffer;
+	}
+
+	spin_lock_irq(&priv->lock);
+
+	/* Block until there is at least one buffer on the used list */
+	while (list_empty(used)) {
+		spin_unlock_irq(&priv->lock);
+
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		if (wait_event_interruptible(priv->wait, !list_empty(used)))
+			return -ERESTARTSYS;
+
+		spin_lock_irq(&priv->lock);
+	}
+
+	/* Grab the first buffer off of the used list */
+	dbuf = list_first_entry(used, struct data_buf, entry);
+	list_del_init(&dbuf->entry);
+
+	spin_unlock_irq(&priv->lock);
+
+	/* Buffers are always mapped: unmap it */
+	data_unmap_buffer(priv->dmadev, dbuf);
+
+	/* save the buffer for later */
+	reader->buf = dbuf;
+	reader->buf_start = 0;
+
+	/* we removed a buffer from the used list: wake any waiters */
+	wake_up(&priv->wait);
+
+have_buffer:
+	/* Get the number of bytes available */
+	avail = dbuf->size - reader->buf_start;
+	data = dbuf->vb.vaddr + reader->buf_start;
+
+	/* Get the number of bytes we can transfer */
+	count = min(count, avail);
+
+	/* Copy the data to the userspace buffer */
+	if (copy_to_user(ubuf, data, count))
+		return -EFAULT;
+
+	/* Update the amount of available space */
+	avail -= count;
+
+	/* Lock against concurrent enable/disable */
+	if (mutex_lock_interruptible(&priv->mutex))
+		return -ERESTARTSYS;
+
+	/* Still some space available: save the buffer for later */
+	if (avail != 0) {
+		reader->buf_start += count;
+		reader->buf = dbuf;
+		goto out_unlock;
+	}
+
+	/*
+	 * No space is available in this buffer
+	 *
+	 * This is a complicated decision:
+	 * - if the device is not enabled: free the buffer
+	 * - if the buffer is too small: free the buffer
+	 */
+	if (!priv->enabled || dbuf->size != priv->bufsize) {
+		data_free_buffer(priv->dmadev, dbuf);
+		reader->buf = NULL;
+		goto out_unlock;
+	}
+
+	/*
+	 * The buffer is safe to recycle: remap it and finish
+	 *
+	 * If this fails, we pretend that the read never happened, and return
+	 * -EFAULT to userspace. They'll retry the read again.
+	 */
+	ret = data_map_buffer(priv->dmadev, dbuf);
+	if (ret) {
+		dev_err(priv->dev, "unable to remap buffer for DMA\n");
+		count = -EFAULT;
+		goto out_unlock;
+	}
+
+	/* Add the buffer back to the free list */
+	reader->buf = NULL;
+	spin_lock_irq(&priv->lock);
+	list_add_tail(&dbuf->entry, &priv->free);
+	spin_unlock_irq(&priv->lock);
+
+out_unlock:
+	mutex_unlock(&priv->mutex);
+	return count;
+}
+
+static unsigned int data_poll(struct file *filp, struct poll_table_struct *tbl)
+{
+	struct fpga_reader *reader = filp->private_data;
+	struct fpga_device *priv = reader->priv;
+	unsigned int mask = 0;
+
+	poll_wait(filp, &priv->wait, tbl);
+
+	spin_lock_irq(&priv->lock);
+
+	if (!list_empty(&priv->used))
+		mask |= POLLIN | POLLRDNORM;
+
+	spin_unlock_irq(&priv->lock);
+	return mask;
+}
+
+static int data_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct fpga_reader *reader = filp->private_data;
+	struct fpga_device *priv = reader->priv;
+	unsigned long offset, vsize, psize, addr;
+
+	/* VMA properties */
+	offset = vma->vm_pgoff << PAGE_SHIFT;
+	vsize = vma->vm_end - vma->vm_start;
+	psize = priv->phys_size - offset;
+	addr = (priv->phys_addr + offset) >> PAGE_SHIFT;
+
+	/* Check against the FPGA region's physical memory size */
+	if (vsize > psize) {
+		dev_err(priv->dev, "requested mmap mapping too large\n");
+		return -EINVAL;
+	}
+
+	/* IO memory (stop cacheing) */
+	vma->vm_flags |= VM_IO | VM_RESERVED;
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	return io_remap_pfn_range(vma, vma->vm_start, addr, vsize,
+				  vma->vm_page_prot);
+}
+
+static const struct file_operations data_fops = {
+	.owner		= THIS_MODULE,
+	.open		= data_open,
+	.release	= data_release,
+	.read		= data_read,
+	.poll		= data_poll,
+	.mmap		= data_mmap,
+	.llseek		= no_llseek,
+};
+
+/*
+ * OpenFirmware Device Subsystem
+ */
+
+static bool dma_filter(struct dma_chan *chan, void *data)
+{
+	/*
+	 * DMA Channel #0 is used for the FPGA Programmer, so ignore it
+	 *
+	 * This probably won't survive an unload/load cycle of the Freescale
+	 * DMAEngine driver, but that won't be a problem
+	 */
+	if (chan->chan_id == 0 && chan->device->dev_id == 0)
+		return false;
+
+	return true;
+}
+
+static int data_of_probe(struct platform_device *op,
+			 const struct of_device_id *match)
+{
+	struct device_node *of_node = op->dev.of_node;
+	struct fpga_device *priv;
+	struct resource res;
+	dma_cap_mask_t mask;
+	int ret;
+
+	/* Allocate private data */
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(&op->dev, "Unable to allocate device private data\n");
+		ret = -ENOMEM;
+		goto out_return;
+	}
+
+	dev_set_drvdata(&op->dev, priv);
+	priv->dmadev = &op->dev;
+
+	/* Allocate the character device */
+	ret = alloc_chrdev_region(&priv->devno, 0, 1, drv_name);
+	if (ret) {
+		dev_err(&op->dev, "Unable to allocate chardev region\n");
+		goto out_free_priv;
+	}
+
+	/* Get the physical address of the FPGA registers */
+	ret = of_address_to_resource(of_node, 0, &res);
+	if (ret) {
+		dev_err(&op->dev, "Unable to find FPGA physical address\n");
+		ret = -ENODEV;
+		goto out_unregister_chrdev_region;
+	}
+
+	priv->phys_addr = res.start;
+	priv->phys_size = resource_size(&res);
+
+	/* ioremap the registers for use */
+	priv->regs = of_iomap(of_node, 0);
+	if (!priv->regs) {
+		dev_err(&op->dev, "Unable to ioremap registers\n");
+		ret = -ENOMEM;
+		goto out_unregister_chrdev_region;
+	}
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_MEMCPY, mask);
+	dma_cap_set(DMA_INTERRUPT, mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	/* Request a DMA channel */
+	priv->chan = dma_request_channel(mask, dma_filter, NULL);
+	if (!priv->chan) {
+		dev_err(&op->dev, "Unable to request DMA channel\n");
+		ret = -ENODEV;
+		goto out_unmap_regs;
+	}
+
+	/* Find the correct IRQ number */
+	priv->irq = irq_of_parse_and_map(of_node, 0);
+	if (priv->irq == NO_IRQ) {
+		dev_err(&op->dev, "Unable to find IRQ line\n");
+		ret = -ENODEV;
+		goto out_release_dma;
+	}
+
+	priv->dev = carma_device_create(&op->dev, priv->devno, drv_name);
+	if (IS_ERR(priv->dev)) {
+		dev_err(&op->dev, "Unable to create CARMA device\n");
+		ret = PTR_ERR(priv->dev);
+		goto out_irq_dispose_mapping;
+	}
+
+	dev_set_drvdata(priv->dev, priv);
+	cdev_init(&priv->cdev, &data_fops);
+	mutex_init(&priv->mutex);
+	spin_lock_init(&priv->lock);
+	INIT_LIST_HEAD(&priv->free);
+	INIT_LIST_HEAD(&priv->used);
+	INIT_LIST_HEAD(&priv->inflight);
+	init_waitqueue_head(&priv->wait);
+
+	/* Drive the GPIO for FPGA IRQ high (no interrupt) */
+	iowrite32be(IRQ_CORL_DONE, priv->regs + SYS_IRQ_OUTPUT_DATA);
+
+	/* Register the character device */
+	ret = cdev_add(&priv->cdev, priv->devno, 1);
+	if (ret) {
+		dev_err(&op->dev, "Unable to add character device\n");
+		goto out_destroy_carma_device;
+	}
+
+	/* Create the sysfs files */
+	ret = sysfs_create_group(&priv->dev->kobj, &rt_sysfs_attr_group);
+	if (ret) {
+		dev_err(&op->dev, "Unable to create sysfs files\n");
+		goto out_cdev_del;
+	}
+
+	dev_info(&op->dev, "CARMA FPGA Realtime Data Driver Loaded\n");
+	return 0;
+
+out_cdev_del:
+	cdev_del(&priv->cdev);
+out_destroy_carma_device:
+	carma_device_destroy(priv->devno);
+out_irq_dispose_mapping:
+	irq_dispose_mapping(priv->irq);
+out_release_dma:
+	dma_release_channel(priv->chan);
+out_unmap_regs:
+	iounmap(priv->regs);
+out_unregister_chrdev_region:
+	unregister_chrdev_region(priv->devno, 1);
+out_free_priv:
+	kfree(priv);
+out_return:
+	return ret;
+}
+
+static int data_of_remove(struct platform_device *op)
+{
+	struct fpga_device *priv = dev_get_drvdata(&op->dev);
+
+	/* make sure the IRQ line is disabled */
+	mutex_lock(&priv->mutex);
+	data_device_disable(priv);
+	mutex_unlock(&priv->mutex);
+
+	sysfs_remove_group(&priv->dev->kobj, &rt_sysfs_attr_group);
+	cdev_del(&priv->cdev);
+	carma_device_destroy(priv->devno);
+
+	irq_dispose_mapping(priv->irq);
+	dma_release_channel(priv->chan);
+	iounmap(priv->regs);
+	unregister_chrdev_region(priv->devno, 1);
+	kfree(priv);
+
+	return 0;
+}
+
+static struct of_device_id data_of_match[] = {
+	{ .compatible = "carma,carma-fpga", },
+	{},
+};
+
+static struct of_platform_driver data_of_driver = {
+	.probe		= data_of_probe,
+	.remove		= data_of_remove,
+	.driver		= {
+		.name		= drv_name,
+		.of_match_table	= data_of_match,
+		.owner		= THIS_MODULE,
+	},
+};
+
+/*
+ * Module Init / Exit
+ */
+
+static int __init data_init(void)
+{
+	return of_register_platform_driver(&data_of_driver);
+}
+
+static void __exit data_exit(void)
+{
+	of_unregister_platform_driver(&data_of_driver);
+}
+
+MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
+MODULE_DESCRIPTION("CARMA DATA-FPGA Access Driver");
+MODULE_LICENSE("GPL");
+
+module_init(data_init);
+module_exit(data_exit);