misc: Add CARMA DATA-FPGA Programmer support

This adds support for programming the data processing FPGAs on the OVRO
CARMA board. These FPGAs have a special programming sequence that
requires that we program the Freescale DMA engine, which is only
available inside the kernel.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 1150 insertions, 0 deletions

diff --git a/drivers/misc/carma/Kconfig b/drivers/misc/carma/Kconfig
index 4be183f..c90370e 100644
--- a/drivers/misc/carma/Kconfig
+++ b/drivers/misc/carma/Kconfig
@@ -7,3 +7,11 @@ config CARMA_FPGA
 	  Say Y here to include support for communicating with the data
 	  processing FPGAs on the OVRO CARMA board.
 
+config CARMA_FPGA_PROGRAM
+	tristate "CARMA DATA-FPGA Programmer"
+	depends on FSL_SOC && PPC_83xx && MEDIA_SUPPORT && HAS_DMA && FSL_DMA
+	select VIDEOBUF_DMA_SG
+	default n
+	help
+	  Say Y here to include support for programming the data processing
+	  FPGAs on the OVRO CARMA board.
diff --git a/drivers/misc/carma/Makefile b/drivers/misc/carma/Makefile
index 0b69fa7..ff36ac2 100644
--- a/drivers/misc/carma/Makefile
+++ b/drivers/misc/carma/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_CARMA_FPGA)		+= carma-fpga.o
+obj-$(CONFIG_CARMA_FPGA_PROGRAM)	+= carma-fpga-program.o
diff --git a/drivers/misc/carma/carma-fpga-program.c b/drivers/misc/carma/carma-fpga-program.c
new file mode 100644
index 0000000..7ce6065
--- /dev/null
+++ b/drivers/misc/carma/carma-fpga-program.c
@@ -0,0 +1,1141 @@
+/*
+ * CARMA Board DATA-FPGA Programmer
+ *
+ * Copyright (c) 2009-2011 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.
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/of_platform.h>
+#include <linux/completion.h>
+#include <linux/miscdevice.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/slab.h>
+#include <linux/kref.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+
+#include <media/videobuf-dma-sg.h>
+
+/* MPC8349EMDS specific get_immrbase() */
+#include <sysdev/fsl_soc.h>
+
+static const char drv_name[] = "carma-fpga-program";
+
+/*
+ * Firmware images are always this exact size
+ *
+ * 12849552 bytes for a CARMA Digitizer Board (EP2S90 FPGAs)
+ * 18662880 bytes for a CARMA Correlator Board (EP2S130 FPGAs)
+ */
+#define FW_SIZE_EP2S90		12849552
+#define FW_SIZE_EP2S130		18662880
+
+struct fpga_dev {
+	struct miscdevice miscdev;
+
+	/* Reference count */
+	struct kref ref;
+
+	/* Device Registers */
+	struct device *dev;
+	void __iomem *regs;
+	void __iomem *immr;
+
+	/* Freescale DMA Device */
+	struct dma_chan *chan;
+
+	/* Interrupts */
+	int irq, status;
+	struct completion completion;
+
+	/* FPGA Bitfile */
+	struct mutex lock;
+
+	struct videobuf_dmabuf vb;
+	bool vb_allocated;
+
+	/* max size and written bytes */
+	size_t fw_size;
+	size_t bytes;
+};
+
+/*
+ * FPGA Bitfile Helpers
+ */
+
+/**
+ * fpga_drop_firmware_data() - drop the bitfile image from memory
+ * @priv: the driver's private data structure
+ *
+ * LOCKING: must hold priv->lock
+ */
+static void fpga_drop_firmware_data(struct fpga_dev *priv)
+{
+	videobuf_dma_free(&priv->vb);
+	priv->vb_allocated = false;
+	priv->bytes = 0;
+}
+
+/*
+ * Private Data Reference Count
+ */
+
+static void fpga_dev_remove(struct kref *ref)
+{
+	struct fpga_dev *priv = container_of(ref, struct fpga_dev, ref);
+
+	/* free any firmware image that was not programmed */
+	fpga_drop_firmware_data(priv);
+
+	mutex_destroy(&priv->lock);
+	kfree(priv);
+}
+
+/*
+ * LED Trigger (could be a seperate module)
+ */
+
+/*
+ * NOTE: this whole thing does have the problem that whenever the led's are
+ * NOTE: first set to use the fpga trigger, they could be in the wrong state
+ */
+
+DEFINE_LED_TRIGGER(ledtrig_fpga);
+
+static void ledtrig_fpga_programmed(bool enabled)
+{
+	if (enabled)
+		led_trigger_event(ledtrig_fpga, LED_FULL);
+	else
+		led_trigger_event(ledtrig_fpga, LED_OFF);
+}
+
+/*
+ * FPGA Register Helpers
+ */
+
+/* Register Definitions */
+#define FPGA_CONFIG_CONTROL		0x40
+#define FPGA_CONFIG_STATUS		0x44
+#define FPGA_CONFIG_FIFO_SIZE		0x48
+#define FPGA_CONFIG_FIFO_USED		0x4C
+#define FPGA_CONFIG_TOTAL_BYTE_COUNT	0x50
+#define FPGA_CONFIG_CUR_BYTE_COUNT	0x54
+
+#define FPGA_FIFO_ADDRESS		0x3000
+
+static int fpga_fifo_size(void __iomem *regs)
+{
+	return ioread32be(regs + FPGA_CONFIG_FIFO_SIZE);
+}
+
+#define CFG_STATUS_ERR_MASK	0xfffe
+
+static int fpga_config_error(void __iomem *regs)
+{
+	return ioread32be(regs + FPGA_CONFIG_STATUS) & CFG_STATUS_ERR_MASK;
+}
+
+static int fpga_fifo_empty(void __iomem *regs)
+{
+	return ioread32be(regs + FPGA_CONFIG_FIFO_USED) == 0;
+}
+
+static void fpga_fifo_write(void __iomem *regs, u32 val)
+{
+	iowrite32be(val, regs + FPGA_FIFO_ADDRESS);
+}
+
+static void fpga_set_byte_count(void __iomem *regs, u32 count)
+{
+	iowrite32be(count, regs + FPGA_CONFIG_TOTAL_BYTE_COUNT);
+}
+
+#define CFG_CTL_ENABLE	(1 << 0)
+#define CFG_CTL_RESET	(1 << 1)
+#define CFG_CTL_DMA	(1 << 2)
+
+static void fpga_programmer_enable(struct fpga_dev *priv, bool dma)
+{
+	u32 val;
+
+	val = (dma) ? (CFG_CTL_ENABLE | CFG_CTL_DMA) : CFG_CTL_ENABLE;
+	iowrite32be(val, priv->regs + FPGA_CONFIG_CONTROL);
+}
+
+static void fpga_programmer_disable(struct fpga_dev *priv)
+{
+	iowrite32be(0x0, priv->regs + FPGA_CONFIG_CONTROL);
+}
+
+static void fpga_dump_registers(struct fpga_dev *priv)
+{
+	u32 control, status, size, used, total, curr;
+
+	/* good status: do nothing */
+	if (priv->status == 0)
+		return;
+
+	/* Dump all status registers */
+	control = ioread32be(priv->regs + FPGA_CONFIG_CONTROL);
+	status = ioread32be(priv->regs + FPGA_CONFIG_STATUS);
+	size = ioread32be(priv->regs + FPGA_CONFIG_FIFO_SIZE);
+	used = ioread32be(priv->regs + FPGA_CONFIG_FIFO_USED);
+	total = ioread32be(priv->regs + FPGA_CONFIG_TOTAL_BYTE_COUNT);
+	curr = ioread32be(priv->regs + FPGA_CONFIG_CUR_BYTE_COUNT);
+
+	dev_err(priv->dev, "Configuration failed, dumping status registers\n");
+	dev_err(priv->dev, "Control:    0x%.8x\n", control);
+	dev_err(priv->dev, "Status:     0x%.8x\n", status);
+	dev_err(priv->dev, "FIFO Size:  0x%.8x\n", size);
+	dev_err(priv->dev, "FIFO Used:  0x%.8x\n", used);
+	dev_err(priv->dev, "FIFO Total: 0x%.8x\n", total);
+	dev_err(priv->dev, "FIFO Curr:  0x%.8x\n", curr);
+}
+
+/*
+ * FPGA Power Supply Code
+ */
+
+#define CTL_PWR_CONTROL		0x2006
+#define CTL_PWR_STATUS		0x200A
+#define CTL_PWR_FAIL		0x200B
+
+#define PWR_CONTROL_ENABLE	0x01
+
+#define PWR_STATUS_ERROR_MASK	0x10
+#define PWR_STATUS_GOOD		0x0f
+
+/*
+ * Determine if the FPGA power is good for all supplies
+ */
+static bool fpga_power_good(struct fpga_dev *priv)
+{
+	u8 val;
+
+	val = ioread8(priv->regs + CTL_PWR_STATUS);
+	if (val & PWR_STATUS_ERROR_MASK)
+		return false;
+
+	return val == PWR_STATUS_GOOD;
+}
+
+/*
+ * Disable the FPGA power supplies
+ */
+static void fpga_disable_power_supplies(struct fpga_dev *priv)
+{
+	unsigned long start;
+	u8 val;
+
+	iowrite8(0x0, priv->regs + CTL_PWR_CONTROL);
+
+	/*
+	 * Wait 500ms for the power rails to discharge
+	 *
+	 * Without this delay, the CTL-CPLD state machine can get into a
+	 * state where it is waiting for the power-goods to assert, but they
+	 * never do. This only happens when enabling and disabling the
+	 * power sequencer very rapidly.
+	 *
+	 * The loop below will also wait for the power goods to de-assert,
+	 * but testing has shown that they are always disabled by the time
+	 * the sleep completes. However, omitting the sleep and only waiting
+	 * for the power-goods to de-assert was not sufficient to ensure
+	 * that the power sequencer would not wedge itself.
+	 */
+	msleep(500);
+
+	start = jiffies;
+	while (time_before(jiffies, start + HZ)) {
+		val = ioread8(priv->regs + CTL_PWR_STATUS);
+		if (!(val & PWR_STATUS_GOOD))
+			break;
+
+		usleep_range(5000, 10000);
+	}
+
+	val = ioread8(priv->regs + CTL_PWR_STATUS);
+	if (val & PWR_STATUS_GOOD) {
+		dev_err(priv->dev, "power disable failed: "
+				   "power goods: status 0x%.2x\n", val);
+	}
+
+	if (val & PWR_STATUS_ERROR_MASK) {
+		dev_err(priv->dev, "power disable failed: "
+				   "alarm bit set: status 0x%.2x\n", val);
+	}
+}
+
+/**
+ * fpga_enable_power_supplies() - enable the DATA-FPGA power supplies
+ * @priv: the driver's private data structure
+ *
+ * Enable the DATA-FPGA power supplies, waiting up to 1 second for
+ * them to enable successfully.
+ *
+ * Returns 0 on success, -ERRNO otherwise
+ */
+static int fpga_enable_power_supplies(struct fpga_dev *priv)
+{
+	unsigned long start = jiffies;
+
+	if (fpga_power_good(priv)) {
+		dev_dbg(priv->dev, "power was already good\n");
+		return 0;
+	}
+
+	iowrite8(PWR_CONTROL_ENABLE, priv->regs + CTL_PWR_CONTROL);
+	while (time_before(jiffies, start + HZ)) {
+		if (fpga_power_good(priv))
+			return 0;
+
+		usleep_range(5000, 10000);
+	}
+
+	return fpga_power_good(priv) ? 0 : -ETIMEDOUT;
+}
+
+/*
+ * Determine if the FPGA power supplies are all enabled
+ */
+static bool fpga_power_enabled(struct fpga_dev *priv)
+{
+	u8 val;
+
+	val = ioread8(priv->regs + CTL_PWR_CONTROL);
+	if (val & PWR_CONTROL_ENABLE)
+		return true;
+
+	return false;
+}
+
+/*
+ * Determine if the FPGA's are programmed and running correctly
+ */
+static bool fpga_running(struct fpga_dev *priv)
+{
+	if (!fpga_power_good(priv))
+		return false;
+
+	/* Check the config done bit */
+	return ioread32be(priv->regs + FPGA_CONFIG_STATUS) & (1 << 18);
+}
+
+/*
+ * FPGA Programming Code
+ */
+
+/**
+ * fpga_program_block() - put a block of data into the programmer's FIFO
+ * @priv: the driver's private data structure
+ * @buf: the data to program
+ * @count: the length of data to program (must be a multiple of 4 bytes)
+ *
+ * Returns 0 on success, -ERRNO otherwise
+ */
+static int fpga_program_block(struct fpga_dev *priv, void *buf, size_t count)
+{
+	u32 *data = buf;
+	int size = fpga_fifo_size(priv->regs);
+	int i, len;
+	unsigned long timeout;
+
+	/* enforce correct data length for the FIFO */
+	BUG_ON(count % 4 != 0);
+
+	while (count > 0) {
+
+		/* Get the size of the block to write (maximum is FIFO_SIZE) */
+		len = min_t(size_t, count, size);
+		timeout = jiffies + HZ / 4;
+
+		/* Write the block */
+		for (i = 0; i < len / 4; i++)
+			fpga_fifo_write(priv->regs, data[i]);
+
+		/* Update the amounts left */
+		count -= len;
+		data += len / 4;
+
+		/* Wait for the fifo to empty */
+		while (true) {
+
+			if (fpga_fifo_empty(priv->regs)) {
+				break;
+			} else {
+				dev_dbg(priv->dev, "Fifo not empty\n");
+				cpu_relax();
+			}
+
+			if (fpga_config_error(priv->regs)) {
+				dev_err(priv->dev, "Error detected\n");
+				return -EIO;
+			}
+
+			if (time_after(jiffies, timeout)) {
+				dev_err(priv->dev, "Fifo drain timeout\n");
+				return -ETIMEDOUT;
+			}
+
+			usleep_range(5000, 10000);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * fpga_program_cpu() - program the DATA-FPGA's using the CPU
+ * @priv: the driver's private data structure
+ *
+ * This is useful when the DMA programming method fails. It is possible to
+ * wedge the Freescale DMA controller such that the DMA programming method
+ * always fails. This method has always succeeded.
+ *
+ * Returns 0 on success, -ERRNO otherwise
+ */
+static noinline int fpga_program_cpu(struct fpga_dev *priv)
+{
+	int ret;
+
+	/* Disable the programmer */
+	fpga_programmer_disable(priv);
+
+	/* Set the total byte count */
+	fpga_set_byte_count(priv->regs, priv->bytes);
+	dev_dbg(priv->dev, "total byte count %u bytes\n", priv->bytes);
+
+	/* Enable the controller for programming */
+	fpga_programmer_enable(priv, false);
+	dev_dbg(priv->dev, "enabled the controller\n");
+
+	/* Write each chunk of the FPGA bitfile to FPGA programmer */
+	ret = fpga_program_block(priv, priv->vb.vaddr, priv->bytes);
+	if (ret)
+		goto out_disable_controller;
+
+	/* Wait for the interrupt handler to signal that programming finished */
+	ret = wait_for_completion_timeout(&priv->completion, 2 * HZ);
+	if (!ret) {
+		dev_err(priv->dev, "Timed out waiting for completion\n");
+		ret = -ETIMEDOUT;
+		goto out_disable_controller;
+	}
+
+	/* Retrieve the status from the interrupt handler */
+	ret = priv->status;
+
+out_disable_controller:
+	fpga_programmer_disable(priv);
+	return ret;
+}
+
+#define FIFO_DMA_ADDRESS	0xf0003000
+#define FIFO_MAX_LEN		4096
+
+/**
+ * fpga_program_dma() - program the DATA-FPGA's using the DMA engine
+ * @priv: the driver's private data structure
+ *
+ * Program the DATA-FPGA's using the Freescale DMA engine. This requires that
+ * the engine is programmed such that the hardware DMA request lines can
+ * control the entire DMA transaction. The system controller FPGA then
+ * completely offloads the programming from the CPU.
+ *
+ * Returns 0 on success, -ERRNO otherwise
+ */
+static noinline int fpga_program_dma(struct fpga_dev *priv)
+{
+	struct videobuf_dmabuf *vb = &priv->vb;
+	struct dma_chan *chan = priv->chan;
+	struct dma_async_tx_descriptor *tx;
+	size_t num_pages, len, avail = 0;
+	struct dma_slave_config config;
+	struct scatterlist *sg;
+	struct sg_table table;
+	dma_cookie_t cookie;
+	int ret, i;
+
+	/* Disable the programmer */
+	fpga_programmer_disable(priv);
+
+	/* Allocate a scatterlist for the DMA destination */
+	num_pages = DIV_ROUND_UP(priv->bytes, FIFO_MAX_LEN);
+	ret = sg_alloc_table(&table, num_pages, GFP_KERNEL);
+	if (ret) {
+		dev_err(priv->dev, "Unable to allocate dst scatterlist\n");
+		ret = -ENOMEM;
+		goto out_return;
+	}
+
+	/*
+	 * This is an ugly hack
+	 *
+	 * We fill in a scatterlist as if it were mapped for DMA. This is
+	 * necessary because there exists no better structure for this
+	 * inside the kernel code.
+	 *
+	 * As an added bonus, we can use the DMAEngine API for all of this,
+	 * rather than inventing another extremely similar API.
+	 */
+	avail = priv->bytes;
+	for_each_sg(table.sgl, sg, num_pages, i) {
+		len = min_t(size_t, avail, FIFO_MAX_LEN);
+		sg_dma_address(sg) = FIFO_DMA_ADDRESS;
+		sg_dma_len(sg) = len;
+
+		avail -= len;
+	}
+
+	/* Map the buffer for DMA */
+	ret = videobuf_dma_map(priv->dev, &priv->vb);
+	if (ret) {
+		dev_err(priv->dev, "Unable to map buffer for DMA\n");
+		goto out_free_table;
+	}
+
+	/*
+	 * Configure the DMA channel to transfer FIFO_SIZE / 2 bytes per
+	 * transaction, and then put it under external control
+	 */
+	memset(&config, 0, sizeof(config));
+	config.direction = DMA_TO_DEVICE;
+	config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	config.dst_maxburst = fpga_fifo_size(priv->regs) / 2 / 4;
+	ret = chan->device->device_control(chan, DMA_SLAVE_CONFIG,
+					   (unsigned long)&config);
+	if (ret) {
+		dev_err(priv->dev, "DMA slave configuration failed\n");
+		goto out_dma_unmap;
+	}
+
+	ret = chan->device->device_control(chan, FSLDMA_EXTERNAL_START, 1);
+	if (ret) {
+		dev_err(priv->dev, "DMA external control setup failed\n");
+		goto out_dma_unmap;
+	}
+
+	/* setup and submit the DMA transaction */
+	tx = chan->device->device_prep_dma_sg(chan,
+					      table.sgl, num_pages,
+					      vb->sglist, vb->sglen, 0);
+	if (!tx) {
+		dev_err(priv->dev, "Unable to prep DMA transaction\n");
+		ret = -ENOMEM;
+		goto out_dma_unmap;
+	}
+
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		dev_err(priv->dev, "Unable to submit DMA transaction\n");
+		ret = -ENOMEM;
+		goto out_dma_unmap;
+	}
+
+	dma_async_memcpy_issue_pending(chan);
+
+	/* Set the total byte count */
+	fpga_set_byte_count(priv->regs, priv->bytes);
+	dev_dbg(priv->dev, "total byte count %u bytes\n", priv->bytes);
+
+	/* Enable the controller for DMA programming */
+	fpga_programmer_enable(priv, true);
+	dev_dbg(priv->dev, "enabled the controller\n");
+
+	/* Wait for the interrupt handler to signal that programming finished */
+	ret = wait_for_completion_timeout(&priv->completion, 2 * HZ);
+	if (!ret) {
+		dev_err(priv->dev, "Timed out waiting for completion\n");
+		ret = -ETIMEDOUT;
+		goto out_disable_controller;
+	}
+
+	/* Retrieve the status from the interrupt handler */
+	ret = priv->status;
+
+out_disable_controller:
+	fpga_programmer_disable(priv);
+out_dma_unmap:
+	videobuf_dma_unmap(priv->dev, vb);
+out_free_table:
+	sg_free_table(&table);
+out_return:
+	return ret;
+}
+
+/*
+ * Interrupt Handling
+ */
+
+static irqreturn_t fpga_irq(int irq, void *dev_id)
+{
+	struct fpga_dev *priv = dev_id;
+
+	/* Save the status */
+	priv->status = fpga_config_error(priv->regs) ? -EIO : 0;
+	dev_dbg(priv->dev, "INTERRUPT status %d\n", priv->status);
+	fpga_dump_registers(priv);
+
+	/* Disabling the programmer clears the interrupt */
+	fpga_programmer_disable(priv);
+
+	/* Notify any waiters */
+	complete(&priv->completion);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * SYSFS Helpers
+ */
+
+/**
+ * fpga_do_stop() - deconfigure (reset) the DATA-FPGA's
+ * @priv: the driver's private data structure
+ *
+ * LOCKING: must hold priv->lock
+ */
+static int fpga_do_stop(struct fpga_dev *priv)
+{
+	u32 val;
+
+	/* Set the led to unprogrammed */
+	ledtrig_fpga_programmed(false);
+
+	/* Pulse the config line to reset the FPGA's */
+	val = CFG_CTL_ENABLE | CFG_CTL_RESET;
+	iowrite32be(val, priv->regs + FPGA_CONFIG_CONTROL);
+	iowrite32be(0x0, priv->regs + FPGA_CONFIG_CONTROL);
+
+	return 0;
+}
+
+static noinline int fpga_do_program(struct fpga_dev *priv)
+{
+	int ret;
+
+	if (priv->bytes != priv->fw_size) {
+		dev_err(priv->dev, "Incorrect bitfile size: got %zu bytes, "
+				   "should be %zu bytes\n",
+				   priv->bytes, priv->fw_size);
+		return -EINVAL;
+	}
+
+	if (!fpga_power_enabled(priv)) {
+		dev_err(priv->dev, "Power not enabled\n");
+		return -EINVAL;
+	}
+
+	if (!fpga_power_good(priv)) {
+		dev_err(priv->dev, "Power not good\n");
+		return -EINVAL;
+	}
+
+	/* Set the LED to unprogrammed */
+	ledtrig_fpga_programmed(false);
+
+	/* Try to program the FPGA's using DMA */
+	ret = fpga_program_dma(priv);
+
+	/* If DMA failed or doesn't exist, try with CPU */
+	if (ret) {
+		dev_warn(priv->dev, "Falling back to CPU programming\n");
+		ret = fpga_program_cpu(priv);
+	}
+
+	if (ret) {
+		dev_err(priv->dev, "Unable to program FPGA's\n");
+		return ret;
+	}
+
+	/* Drop the firmware bitfile from memory */
+	fpga_drop_firmware_data(priv);
+
+	dev_dbg(priv->dev, "FPGA programming successful\n");
+	ledtrig_fpga_programmed(true);
+
+	return 0;
+}
+
+/*
+ * File Operations
+ */
+
+static int fpga_open(struct inode *inode, struct file *filp)
+{
+	/*
+	 * The miscdevice layer puts our struct miscdevice into the
+	 * filp->private_data field. We use this to find our private
+	 * data and then overwrite it with our own private structure.
+	 */
+	struct fpga_dev *priv = container_of(filp->private_data,
+					     struct fpga_dev, miscdev);
+	unsigned int nr_pages;
+	int ret;
+
+	/* We only allow one process at a time */
+	ret = mutex_lock_interruptible(&priv->lock);
+	if (ret)
+		return ret;
+
+	filp->private_data = priv;
+	kref_get(&priv->ref);
+
+	/* Truncation: drop any existing data */
+	if (filp->f_flags & O_TRUNC)
+		priv->bytes = 0;
+
+	/* Check if we have already allocated a buffer */
+	if (priv->vb_allocated)
+		return 0;
+
+	/* Allocate a buffer to hold enough data for the bitfile */
+	nr_pages = DIV_ROUND_UP(priv->fw_size, PAGE_SIZE);
+	ret = videobuf_dma_init_kernel(&priv->vb, DMA_TO_DEVICE, nr_pages);
+	if (ret) {
+		dev_err(priv->dev, "unable to allocate data buffer\n");
+		mutex_unlock(&priv->lock);
+		kref_put(&priv->ref, fpga_dev_remove);
+		return ret;
+	}
+
+	priv->vb_allocated = true;
+	return 0;
+}
+
+static int fpga_release(struct inode *inode, struct file *filp)
+{
+	struct fpga_dev *priv = filp->private_data;
+
+	mutex_unlock(&priv->lock);
+	kref_put(&priv->ref, fpga_dev_remove);
+	return 0;
+}
+
+static ssize_t fpga_write(struct file *filp, const char __user *buf,
+			  size_t count, loff_t *f_pos)
+{
+	struct fpga_dev *priv = filp->private_data;
+
+	/* FPGA bitfiles have an exact size: disallow anything else */
+	if (priv->bytes >= priv->fw_size)
+		return -ENOSPC;
+
+	count = min_t(size_t, priv->fw_size - priv->bytes, count);
+	if (copy_from_user(priv->vb.vaddr + priv->bytes, buf, count))
+		return -EFAULT;
+
+	priv->bytes += count;
+	return count;
+}
+
+static ssize_t fpga_read(struct file *filp, char __user *buf, size_t count,
+			 loff_t *f_pos)
+{
+	struct fpga_dev *priv = filp->private_data;
+
+	count = min_t(size_t, priv->bytes - *f_pos, count);
+	if (copy_to_user(buf, priv->vb.vaddr + *f_pos, count))
+		return -EFAULT;
+
+	*f_pos += count;
+	return count;
+}
+
+static loff_t fpga_llseek(struct file *filp, loff_t offset, int origin)
+{
+	struct fpga_dev *priv = filp->private_data;
+	loff_t newpos;
+
+	/* only read-only opens are allowed to seek */
+	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
+		return -EINVAL;
+
+	switch (origin) {
+	case SEEK_SET: /* seek relative to the beginning of the file */
+		newpos = offset;
+		break;
+	case SEEK_CUR: /* seek relative to current position in the file */
+		newpos = filp->f_pos + offset;
+		break;
+	case SEEK_END: /* seek relative to the end of the file */
+		newpos = priv->fw_size - offset;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* check for sanity */
+	if (newpos > priv->fw_size)
+		return -EINVAL;
+
+	filp->f_pos = newpos;
+	return newpos;
+}
+
+static const struct file_operations fpga_fops = {
+	.open		= fpga_open,
+	.release	= fpga_release,
+	.write		= fpga_write,
+	.read		= fpga_read,
+	.llseek		= fpga_llseek,
+};
+
+/*
+ * Device Attributes
+ */
+
+static ssize_t pfail_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	u8 val;
+
+	val = ioread8(priv->regs + CTL_PWR_FAIL);
+	return snprintf(buf, PAGE_SIZE, "0x%.2x\n", val);
+}
+
+static ssize_t pgood_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	return snprintf(buf, PAGE_SIZE, "%d\n", fpga_power_good(priv));
+}
+
+static ssize_t penable_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	return snprintf(buf, PAGE_SIZE, "%d\n", fpga_power_enabled(priv));
+}
+
+static ssize_t penable_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	unsigned long val;
+	int ret;
+
+	if (strict_strtoul(buf, 0, &val))
+		return -EINVAL;
+
+	if (val) {
+		ret = fpga_enable_power_supplies(priv);
+		if (ret)
+			return ret;
+	} else {
+		fpga_do_stop(priv);
+		fpga_disable_power_supplies(priv);
+	}
+
+	return count;
+}
+
+static ssize_t program_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	return snprintf(buf, PAGE_SIZE, "%d\n", fpga_running(priv));
+}
+
+static ssize_t program_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct fpga_dev *priv = dev_get_drvdata(dev);
+	unsigned long val;
+	int ret;
+
+	if (strict_strtoul(buf, 0, &val))
+		return -EINVAL;
+
+	/* We can't have an image writer and be programming simultaneously */
+	if (mutex_lock_interruptible(&priv->lock))
+		return -ERESTARTSYS;
+
+	/* Program or Reset the FPGA's */
+	ret = val ? fpga_do_program(priv) : fpga_do_stop(priv);
+	if (ret)
+		goto out_unlock;
+
+	/* Success */
+	ret = count;
+
+out_unlock:
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+
+static DEVICE_ATTR(power_fail, S_IRUGO, pfail_show, NULL);
+static DEVICE_ATTR(power_good, S_IRUGO, pgood_show, NULL);
+static DEVICE_ATTR(power_enable, S_IRUGO | S_IWUSR,
+		   penable_show, penable_store);
+
+static DEVICE_ATTR(program, S_IRUGO | S_IWUSR,
+		   program_show, program_store);
+
+static struct attribute *fpga_attributes[] = {
+	&dev_attr_power_fail.attr,
+	&dev_attr_power_good.attr,
+	&dev_attr_power_enable.attr,
+	&dev_attr_program.attr,
+	NULL,
+};
+
+static const struct attribute_group fpga_attr_group = {
+	.attrs = fpga_attributes,
+};
+
+/*
+ * OpenFirmware Device Subsystem
+ */
+
+#define SYS_REG_VERSION		0x00
+#define SYS_REG_GEOGRAPHIC	0x10
+
+static bool dma_filter(struct dma_chan *chan, void *data)
+{
+	/*
+	 * DMA Channel #0 is the only acceptable device
+	 *
+	 * This probably won't survive an unload/load cycle of the Freescale
+	 * DMAEngine driver, but that won't be a problem
+	 */
+	return chan->chan_id == 0 && chan->device->dev_id == 0;
+}
+
+static int fpga_of_remove(struct platform_device *op)
+{
+	struct fpga_dev *priv = dev_get_drvdata(&op->dev);
+	struct device *this_device = priv->miscdev.this_device;
+
+	sysfs_remove_group(&this_device->kobj, &fpga_attr_group);
+	misc_deregister(&priv->miscdev);
+
+	free_irq(priv->irq, priv);
+	irq_dispose_mapping(priv->irq);
+
+	/* make sure the power supplies are off */
+	fpga_disable_power_supplies(priv);
+
+	/* unmap registers */
+	iounmap(priv->immr);
+	iounmap(priv->regs);
+
+	dma_release_channel(priv->chan);
+
+	/* drop our reference to the private data structure */
+	kref_put(&priv->ref, fpga_dev_remove);
+	return 0;
+}
+
+/* CTL-CPLD Version Register */
+#define CTL_CPLD_VERSION	0x2000
+
+static int fpga_of_probe(struct platform_device *op,
+			 const struct of_device_id *match)
+{
+	struct device_node *of_node = op->dev.of_node;
+	struct device *this_device;
+	struct fpga_dev *priv;
+	dma_cap_mask_t mask;
+	u32 ver;
+	int ret;
+
+	/* Allocate private data */
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(&op->dev, "Unable to allocate private data\n");
+		ret = -ENOMEM;
+		goto out_return;
+	}
+
+	/* Setup the miscdevice */
+	priv->miscdev.minor = MISC_DYNAMIC_MINOR;
+	priv->miscdev.name = drv_name;
+	priv->miscdev.fops = &fpga_fops;
+
+	kref_init(&priv->ref);
+
+	dev_set_drvdata(&op->dev, priv);
+	priv->dev = &op->dev;
+	mutex_init(&priv->lock);
+	init_completion(&priv->completion);
+	videobuf_dma_init(&priv->vb);
+
+	dev_set_drvdata(priv->dev, priv);
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_MEMCPY, mask);
+	dma_cap_set(DMA_INTERRUPT, mask);
+	dma_cap_set(DMA_SLAVE, mask);
+	dma_cap_set(DMA_SG, mask);
+
+	/* Get control of DMA channel #0 */
+	priv->chan = dma_request_channel(mask, dma_filter, NULL);
+	if (!priv->chan) {
+		dev_err(&op->dev, "Unable to acquire DMA channel #0\n");
+		ret = -ENODEV;
+		goto out_free_priv;
+	}
+
+	/* Remap 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_dma_release_channel;
+	}
+
+	/* Remap the IMMR for use */
+	priv->immr = ioremap(get_immrbase(), 0x100000);
+	if (!priv->immr) {
+		dev_err(&op->dev, "Unable to ioremap IMMR\n");
+		ret = -ENOMEM;
+		goto out_unmap_regs;
+	}
+
+	/*
+	 * Check that external DMA is configured
+	 *
+	 * U-Boot does this for us, but we should check it and bail out if
+	 * there is a problem. Failing to have this register setup correctly
+	 * will cause the DMA controller to transfer a single cacheline
+	 * worth of data, then wedge itself.
+	 */
+	if ((ioread32be(priv->immr + 0x114) & 0xE00) != 0xE00) {
+		dev_err(&op->dev, "External DMA control not configured\n");
+		ret = -ENODEV;
+		goto out_unmap_immr;
+	}
+
+	/*
+	 * Check the CTL-CPLD version
+	 *
+	 * This driver uses the CTL-CPLD DATA-FPGA power sequencer, and we
+	 * don't want to run on any version of the CTL-CPLD that does not use
+	 * a compatible register layout.
+	 *
+	 * v2: changed register layout, added power sequencer
+	 * v3: added glitch filter on the i2c overcurrent/overtemp outputs
+	 */
+	ver = ioread8(priv->regs + CTL_CPLD_VERSION);
+	if (ver != 0x02 && ver != 0x03) {
+		dev_err(&op->dev, "CTL-CPLD is not version 0x02 or 0x03!\n");
+		ret = -ENODEV;
+		goto out_unmap_immr;
+	}
+
+	/* Set the exact size that the firmware image should be */
+	ver = ioread32be(priv->regs + SYS_REG_VERSION);
+	priv->fw_size = (ver & (1 << 18)) ? FW_SIZE_EP2S130 : FW_SIZE_EP2S90;
+
+	/* 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_unmap_immr;
+	}
+
+	/* Request the IRQ */
+	ret = request_irq(priv->irq, fpga_irq, IRQF_SHARED, drv_name, priv);
+	if (ret) {
+		dev_err(&op->dev, "Unable to request IRQ %d\n", priv->irq);
+		ret = -ENODEV;
+		goto out_irq_dispose_mapping;
+	}
+
+	/* Reset and stop the FPGA's, just in case */
+	fpga_do_stop(priv);
+
+	/* Register the miscdevice */
+	ret = misc_register(&priv->miscdev);
+	if (ret) {
+		dev_err(&op->dev, "Unable to register miscdevice\n");
+		goto out_free_irq;
+	}
+
+	/* Create the sysfs files */
+	this_device = priv->miscdev.this_device;
+	dev_set_drvdata(this_device, priv);
+	ret = sysfs_create_group(&this_device->kobj, &fpga_attr_group);
+	if (ret) {
+		dev_err(&op->dev, "Unable to create sysfs files\n");
+		goto out_misc_deregister;
+	}
+
+	dev_info(priv->dev, "CARMA FPGA Programmer: %s rev%s with %s FPGAs\n",
+			(ver & (1 << 17)) ? "Correlator" : "Digitizer",
+			(ver & (1 << 16)) ? "B" : "A",
+			(ver & (1 << 18)) ? "EP2S130" : "EP2S90");
+
+	return 0;
+
+out_misc_deregister:
+	misc_deregister(&priv->miscdev);
+out_free_irq:
+	free_irq(priv->irq, priv);
+out_irq_dispose_mapping:
+	irq_dispose_mapping(priv->irq);
+out_unmap_immr:
+	iounmap(priv->immr);
+out_unmap_regs:
+	iounmap(priv->regs);
+out_dma_release_channel:
+	dma_release_channel(priv->chan);
+out_free_priv:
+	kref_put(&priv->ref, fpga_dev_remove);
+out_return:
+	return ret;
+}
+
+static struct of_device_id fpga_of_match[] = {
+	{ .compatible = "carma,fpga-programmer", },
+	{},
+};
+
+static struct of_platform_driver fpga_of_driver = {
+	.probe		= fpga_of_probe,
+	.remove		= fpga_of_remove,
+	.driver		= {
+		.name		= drv_name,
+		.of_match_table	= fpga_of_match,
+		.owner		= THIS_MODULE,
+	},
+};
+
+/*
+ * Module Init / Exit
+ */
+
+static int __init fpga_init(void)
+{
+	led_trigger_register_simple("fpga", &ledtrig_fpga);
+	return of_register_platform_driver(&fpga_of_driver);
+}
+
+static void __exit fpga_exit(void)
+{
+	of_unregister_platform_driver(&fpga_of_driver);
+	led_trigger_unregister_simple(ledtrig_fpga);
+}
+
+MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
+MODULE_DESCRIPTION("CARMA Board DATA-FPGA Programmer");
+MODULE_LICENSE("GPL");
+
+module_init(fpga_init);
+module_exit(fpga_exit);