ARM: 5648/1: bcmring: add bmcring dma.c
authorLeo Chen <leochen@broadcom.com>
Fri, 7 Aug 2009 19:01:13 +0000 (20:01 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Sat, 15 Aug 2009 15:01:41 +0000 (16:01 +0100)
implement dma support for bcmring

Signed-off-by: Leo Chen <leochen@broadcom.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/mach-bcmring/dma.c [new file with mode: 0644]

diff --git a/arch/arm/mach-bcmring/dma.c b/arch/arm/mach-bcmring/dma.c
new file mode 100644 (file)
index 0000000..7b20fcc
--- /dev/null
@@ -0,0 +1,2321 @@
+/*****************************************************************************
+* Copyright 2004 - 2008 Broadcom Corporation.  All rights reserved.
+*
+* Unless you and Broadcom execute a separate written software license
+* agreement governing use of this software, this software is licensed to you
+* under the terms of the GNU General Public License version 2, available at
+* http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
+*
+* Notwithstanding the above, under no circumstances may you combine this
+* software in any way with any other Broadcom software provided under a
+* license other than the GPL, without Broadcom's express prior written
+* consent.
+*****************************************************************************/
+
+/****************************************************************************/
+/**
+*   @file   dma.c
+*
+*   @brief  Implements the DMA interface.
+*/
+/****************************************************************************/
+
+/* ---- Include Files ---------------------------------------------------- */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/proc_fs.h>
+
+#include <mach/timer.h>
+
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <asm/atomic.h>
+#include <mach/dma.h>
+
+/* I don't quite understand why dc4 fails when this is set to 1 and DMA is enabled */
+/* especially since dc4 doesn't use kmalloc'd memory. */
+
+#define ALLOW_MAP_OF_KMALLOC_MEMORY 0
+
+/* ---- Public Variables ------------------------------------------------- */
+
+/* ---- Private Constants and Types -------------------------------------- */
+
+#define MAKE_HANDLE(controllerIdx, channelIdx)    (((controllerIdx) << 4) | (channelIdx))
+
+#define CONTROLLER_FROM_HANDLE(handle)    (((handle) >> 4) & 0x0f)
+#define CHANNEL_FROM_HANDLE(handle)       ((handle) & 0x0f)
+
+#define DMA_MAP_DEBUG   0
+
+#if DMA_MAP_DEBUG
+#   define  DMA_MAP_PRINT(fmt, args...)   printk("%s: " fmt, __func__,  ## args)
+#else
+#   define  DMA_MAP_PRINT(fmt, args...)
+#endif
+
+/* ---- Private Variables ------------------------------------------------ */
+
+static DMA_Global_t gDMA;
+static struct proc_dir_entry *gDmaDir;
+
+static atomic_t gDmaStatMemTypeKmalloc = ATOMIC_INIT(0);
+static atomic_t gDmaStatMemTypeVmalloc = ATOMIC_INIT(0);
+static atomic_t gDmaStatMemTypeUser = ATOMIC_INIT(0);
+static atomic_t gDmaStatMemTypeCoherent = ATOMIC_INIT(0);
+
+#include "dma_device.c"
+
+/* ---- Private Function Prototypes -------------------------------------- */
+
+/* ---- Functions  ------------------------------------------------------- */
+
+/****************************************************************************/
+/**
+*   Displays information for /proc/dma/mem-type
+*/
+/****************************************************************************/
+
+static int dma_proc_read_mem_type(char *buf, char **start, off_t offset,
+                                 int count, int *eof, void *data)
+{
+       int len = 0;
+
+       len += sprintf(buf + len, "dma_map_mem statistics\n");
+       len +=
+           sprintf(buf + len, "coherent: %d\n",
+                   atomic_read(&gDmaStatMemTypeCoherent));
+       len +=
+           sprintf(buf + len, "kmalloc:  %d\n",
+                   atomic_read(&gDmaStatMemTypeKmalloc));
+       len +=
+           sprintf(buf + len, "vmalloc:  %d\n",
+                   atomic_read(&gDmaStatMemTypeVmalloc));
+       len +=
+           sprintf(buf + len, "user:     %d\n",
+                   atomic_read(&gDmaStatMemTypeUser));
+
+       return len;
+}
+
+/****************************************************************************/
+/**
+*   Displays information for /proc/dma/channels
+*/
+/****************************************************************************/
+
+static int dma_proc_read_channels(char *buf, char **start, off_t offset,
+                                 int count, int *eof, void *data)
+{
+       int controllerIdx;
+       int channelIdx;
+       int limit = count - 200;
+       int len = 0;
+       DMA_Channel_t *channel;
+
+       if (down_interruptible(&gDMA.lock) < 0) {
+               return -ERESTARTSYS;
+       }
+
+       for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
+            controllerIdx++) {
+               for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
+                    channelIdx++) {
+                       if (len >= limit) {
+                               break;
+                       }
+
+                       channel =
+                           &gDMA.controller[controllerIdx].channel[channelIdx];
+
+                       len +=
+                           sprintf(buf + len, "%d:%d ", controllerIdx,
+                                   channelIdx);
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) !=
+                           0) {
+                               len +=
+                                   sprintf(buf + len, "Dedicated for %s ",
+                                           DMA_gDeviceAttribute[channel->
+                                                                devType].name);
+                       } else {
+                               len += sprintf(buf + len, "Shared ");
+                       }
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_NO_ISR) != 0) {
+                               len += sprintf(buf + len, "No ISR ");
+                       }
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_LARGE_FIFO) != 0) {
+                               len += sprintf(buf + len, "Fifo: 128 ");
+                       } else {
+                               len += sprintf(buf + len, "Fifo: 64  ");
+                       }
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_IN_USE) != 0) {
+                               len +=
+                                   sprintf(buf + len, "InUse by %s",
+                                           DMA_gDeviceAttribute[channel->
+                                                                devType].name);
+#if (DMA_DEBUG_TRACK_RESERVATION)
+                               len +=
+                                   sprintf(buf + len, " (%s:%d)",
+                                           channel->fileName,
+                                           channel->lineNum);
+#endif
+                       } else {
+                               len += sprintf(buf + len, "Avail ");
+                       }
+
+                       if (channel->lastDevType != DMA_DEVICE_NONE) {
+                               len +=
+                                   sprintf(buf + len, "Last use: %s ",
+                                           DMA_gDeviceAttribute[channel->
+                                                                lastDevType].
+                                           name);
+                       }
+
+                       len += sprintf(buf + len, "\n");
+               }
+       }
+       up(&gDMA.lock);
+       *eof = 1;
+
+       return len;
+}
+
+/****************************************************************************/
+/**
+*   Displays information for /proc/dma/devices
+*/
+/****************************************************************************/
+
+static int dma_proc_read_devices(char *buf, char **start, off_t offset,
+                                int count, int *eof, void *data)
+{
+       int limit = count - 200;
+       int len = 0;
+       int devIdx;
+
+       if (down_interruptible(&gDMA.lock) < 0) {
+               return -ERESTARTSYS;
+       }
+
+       for (devIdx = 0; devIdx < DMA_NUM_DEVICE_ENTRIES; devIdx++) {
+               DMA_DeviceAttribute_t *devAttr = &DMA_gDeviceAttribute[devIdx];
+
+               if (devAttr->name == NULL) {
+                       continue;
+               }
+
+               if (len >= limit) {
+                       break;
+               }
+
+               len += sprintf(buf + len, "%-12s ", devAttr->name);
+
+               if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
+                       len +=
+                           sprintf(buf + len, "Dedicated %d:%d ",
+                                   devAttr->dedicatedController,
+                                   devAttr->dedicatedChannel);
+               } else {
+                       len += sprintf(buf + len, "Shared DMA:");
+                       if ((devAttr->flags & DMA_DEVICE_FLAG_ON_DMA0) != 0) {
+                               len += sprintf(buf + len, "0");
+                       }
+                       if ((devAttr->flags & DMA_DEVICE_FLAG_ON_DMA1) != 0) {
+                               len += sprintf(buf + len, "1");
+                       }
+                       len += sprintf(buf + len, " ");
+               }
+               if ((devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) != 0) {
+                       len += sprintf(buf + len, "NoISR ");
+               }
+               if ((devAttr->flags & DMA_DEVICE_FLAG_ALLOW_LARGE_FIFO) != 0) {
+                       len += sprintf(buf + len, "Allow-128 ");
+               }
+
+               len +=
+                   sprintf(buf + len,
+                           "Xfer #: %Lu Ticks: %Lu Bytes: %Lu DescLen: %u\n",
+                           devAttr->numTransfers, devAttr->transferTicks,
+                           devAttr->transferBytes,
+                           devAttr->ring.bytesAllocated);
+
+       }
+
+       up(&gDMA.lock);
+       *eof = 1;
+
+       return len;
+}
+
+/****************************************************************************/
+/**
+*   Determines if a DMA_Device_t is "valid".
+*
+*   @return
+*       TRUE        - dma device is valid
+*       FALSE       - dma device isn't valid
+*/
+/****************************************************************************/
+
+static inline int IsDeviceValid(DMA_Device_t device)
+{
+       return (device >= 0) && (device < DMA_NUM_DEVICE_ENTRIES);
+}
+
+/****************************************************************************/
+/**
+*   Translates a DMA handle into a pointer to a channel.
+*
+*   @return
+*       non-NULL    - pointer to DMA_Channel_t
+*       NULL        - DMA Handle was invalid
+*/
+/****************************************************************************/
+
+static inline DMA_Channel_t *HandleToChannel(DMA_Handle_t handle)
+{
+       int controllerIdx;
+       int channelIdx;
+
+       controllerIdx = CONTROLLER_FROM_HANDLE(handle);
+       channelIdx = CHANNEL_FROM_HANDLE(handle);
+
+       if ((controllerIdx > DMA_NUM_CONTROLLERS)
+           || (channelIdx > DMA_NUM_CHANNELS)) {
+               return NULL;
+       }
+       return &gDMA.controller[controllerIdx].channel[channelIdx];
+}
+
+/****************************************************************************/
+/**
+*   Interrupt handler which is called to process DMA interrupts.
+*/
+/****************************************************************************/
+
+static irqreturn_t dma_interrupt_handler(int irq, void *dev_id)
+{
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+       int irqStatus;
+
+       channel = (DMA_Channel_t *) dev_id;
+
+       /* Figure out why we were called, and knock down the interrupt */
+
+       irqStatus = dmacHw_getInterruptStatus(channel->dmacHwHandle);
+       dmacHw_clearInterrupt(channel->dmacHwHandle);
+
+       if ((channel->devType < 0)
+           || (channel->devType > DMA_NUM_DEVICE_ENTRIES)) {
+               printk(KERN_ERR "dma_interrupt_handler: Invalid devType: %d\n",
+                      channel->devType);
+               return IRQ_NONE;
+       }
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       /* Update stats */
+
+       if ((irqStatus & dmacHw_INTERRUPT_STATUS_TRANS) != 0) {
+               devAttr->transferTicks +=
+                   (timer_get_tick_count() - devAttr->transferStartTime);
+       }
+
+       if ((irqStatus & dmacHw_INTERRUPT_STATUS_ERROR) != 0) {
+               printk(KERN_ERR
+                      "dma_interrupt_handler: devType :%d DMA error (%s)\n",
+                      channel->devType, devAttr->name);
+       } else {
+               devAttr->numTransfers++;
+               devAttr->transferBytes += devAttr->numBytes;
+       }
+
+       /* Call any installed handler */
+
+       if (devAttr->devHandler != NULL) {
+               devAttr->devHandler(channel->devType, irqStatus,
+                                   devAttr->userData);
+       }
+
+       return IRQ_HANDLED;
+}
+
+/****************************************************************************/
+/**
+*   Allocates memory to hold a descriptor ring. The descriptor ring then
+*   needs to be populated by making one or more calls to
+*   dna_add_descriptors.
+*
+*   The returned descriptor ring will be automatically initialized.
+*
+*   @return
+*       0           Descriptor ring was allocated successfully
+*       -EINVAL     Invalid parameters passed in
+*       -ENOMEM     Unable to allocate memory for the desired number of descriptors.
+*/
+/****************************************************************************/
+
+int dma_alloc_descriptor_ring(DMA_DescriptorRing_t *ring,      /* Descriptor ring to populate */
+                             int numDescriptors        /* Number of descriptors that need to be allocated. */
+    ) {
+       size_t bytesToAlloc = dmacHw_descriptorLen(numDescriptors);
+
+       if ((ring == NULL) || (numDescriptors <= 0)) {
+               return -EINVAL;
+       }
+
+       ring->physAddr = 0;
+       ring->descriptorsAllocated = 0;
+       ring->bytesAllocated = 0;
+
+       ring->virtAddr = dma_alloc_writecombine(NULL,
+                                                    bytesToAlloc,
+                                                    &ring->physAddr,
+                                                    GFP_KERNEL);
+       if (ring->virtAddr == NULL) {
+               return -ENOMEM;
+       }
+
+       ring->bytesAllocated = bytesToAlloc;
+       ring->descriptorsAllocated = numDescriptors;
+
+       return dma_init_descriptor_ring(ring, numDescriptors);
+}
+
+EXPORT_SYMBOL(dma_alloc_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Releases the memory which was previously allocated for a descriptor ring.
+*/
+/****************************************************************************/
+
+void dma_free_descriptor_ring(DMA_DescriptorRing_t *ring       /* Descriptor to release */
+    ) {
+       if (ring->virtAddr != NULL) {
+               dma_free_writecombine(NULL,
+                                     ring->bytesAllocated,
+                                     ring->virtAddr, ring->physAddr);
+       }
+
+       ring->bytesAllocated = 0;
+       ring->descriptorsAllocated = 0;
+       ring->virtAddr = NULL;
+       ring->physAddr = 0;
+}
+
+EXPORT_SYMBOL(dma_free_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Initializes a descriptor ring, so that descriptors can be added to it.
+*   Once a descriptor ring has been allocated, it may be reinitialized for
+*   use with additional/different regions of memory.
+*
+*   Note that if 7 descriptors are allocated, it's perfectly acceptable to
+*   initialize the ring with a smaller number of descriptors. The amount
+*   of memory allocated for the descriptor ring will not be reduced, and
+*   the descriptor ring may be reinitialized later
+*
+*   @return
+*       0           Descriptor ring was initialized successfully
+*       -ENOMEM     The descriptor which was passed in has insufficient space
+*                   to hold the desired number of descriptors.
+*/
+/****************************************************************************/
+
+int dma_init_descriptor_ring(DMA_DescriptorRing_t *ring,       /* Descriptor ring to initialize */
+                            int numDescriptors /* Number of descriptors to initialize. */
+    ) {
+       if (ring->virtAddr == NULL) {
+               return -EINVAL;
+       }
+       if (dmacHw_initDescriptor(ring->virtAddr,
+                                 ring->physAddr,
+                                 ring->bytesAllocated, numDescriptors) < 0) {
+               printk(KERN_ERR
+                      "dma_init_descriptor_ring: dmacHw_initDescriptor failed\n");
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_init_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Determines the number of descriptors which would be required for a
+*   transfer of the indicated memory region.
+*
+*   This function also needs to know which DMA device this transfer will
+*   be destined for, so that the appropriate DMA configuration can be retrieved.
+*   DMA parameters such as transfer width, and whether this is a memory-to-memory
+*   or memory-to-peripheral, etc can all affect the actual number of descriptors
+*   required.
+*
+*   @return
+*       > 0     Returns the number of descriptors required for the indicated transfer
+*       -ENODEV - Device handed in is invalid.
+*       -EINVAL Invalid parameters
+*       -ENOMEM Memory exhausted
+*/
+/****************************************************************************/
+
+int dma_calculate_descriptor_count(DMA_Device_t device,        /* DMA Device that this will be associated with */
+                                  dma_addr_t srcData,  /* Place to get data to write to device */
+                                  dma_addr_t dstData,  /* Pointer to device data address */
+                                  size_t numBytes      /* Number of bytes to transfer to the device */
+    ) {
+       int numDescriptors;
+       DMA_DeviceAttribute_t *devAttr;
+
+       if (!IsDeviceValid(device)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[device];
+
+       numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
+                                                             (void *)srcData,
+                                                             (void *)dstData,
+                                                             numBytes);
+       if (numDescriptors < 0) {
+               printk(KERN_ERR
+                      "dma_calculate_descriptor_count: dmacHw_calculateDescriptorCount failed\n");
+               return -EINVAL;
+       }
+
+       return numDescriptors;
+}
+
+EXPORT_SYMBOL(dma_calculate_descriptor_count);
+
+/****************************************************************************/
+/**
+*   Adds a region of memory to the descriptor ring. Note that it may take
+*   multiple descriptors for each region of memory. It is the callers
+*   responsibility to allocate a sufficiently large descriptor ring.
+*
+*   @return
+*       0       Descriptors were added successfully
+*       -ENODEV Device handed in is invalid.
+*       -EINVAL Invalid parameters
+*       -ENOMEM Memory exhausted
+*/
+/****************************************************************************/
+
+int dma_add_descriptors(DMA_DescriptorRing_t *ring,    /* Descriptor ring to add descriptors to */
+                       DMA_Device_t device,    /* DMA Device that descriptors are for */
+                       dma_addr_t srcData,     /* Place to get data (memory or device) */
+                       dma_addr_t dstData,     /* Place to put data (memory or device) */
+                       size_t numBytes /* Number of bytes to transfer to the device */
+    ) {
+       int rc;
+       DMA_DeviceAttribute_t *devAttr;
+
+       if (!IsDeviceValid(device)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[device];
+
+       rc = dmacHw_setDataDescriptor(&devAttr->config,
+                                     ring->virtAddr,
+                                     (void *)srcData,
+                                     (void *)dstData, numBytes);
+       if (rc < 0) {
+               printk(KERN_ERR
+                      "dma_add_descriptors: dmacHw_setDataDescriptor failed with code: %d\n",
+                      rc);
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_add_descriptors);
+
+/****************************************************************************/
+/**
+*   Sets the descriptor ring associated with a device.
+*
+*   Once set, the descriptor ring will be associated with the device, even
+*   across channel request/free calls. Passing in a NULL descriptor ring
+*   will release any descriptor ring currently associated with the device.
+*
+*   Note: If you call dma_transfer, or one of the other dma_alloc_ functions
+*         the descriptor ring may be released and reallocated.
+*
+*   Note: This function will release the descriptor memory for any current
+*         descriptor ring associated with this device.
+*
+*   @return
+*       0       Descriptors were added successfully
+*       -ENODEV Device handed in is invalid.
+*/
+/****************************************************************************/
+
+int dma_set_device_descriptor_ring(DMA_Device_t device,        /* Device to update the descriptor ring for. */
+                                  DMA_DescriptorRing_t *ring   /* Descriptor ring to add descriptors to */
+    ) {
+       DMA_DeviceAttribute_t *devAttr;
+
+       if (!IsDeviceValid(device)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[device];
+
+       /* Free the previously allocated descriptor ring */
+
+       dma_free_descriptor_ring(&devAttr->ring);
+
+       if (ring != NULL) {
+               /* Copy in the new one */
+
+               devAttr->ring = *ring;
+       }
+
+       /* Set things up so that if dma_transfer is called then this descriptor */
+       /* ring will get freed. */
+
+       devAttr->prevSrcData = 0;
+       devAttr->prevDstData = 0;
+       devAttr->prevNumBytes = 0;
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_set_device_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Retrieves the descriptor ring associated with a device.
+*
+*   @return
+*       0       Descriptors were added successfully
+*       -ENODEV Device handed in is invalid.
+*/
+/****************************************************************************/
+
+int dma_get_device_descriptor_ring(DMA_Device_t device,        /* Device to retrieve the descriptor ring for. */
+                                  DMA_DescriptorRing_t *ring   /* Place to store retrieved ring */
+    ) {
+       DMA_DeviceAttribute_t *devAttr;
+
+       memset(ring, 0, sizeof(*ring));
+
+       if (!IsDeviceValid(device)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[device];
+
+       *ring = devAttr->ring;
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_get_device_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Configures a DMA channel.
+*
+*   @return
+*       >= 0    - Initialization was successfull.
+*
+*       -EBUSY  - Device is currently being used.
+*       -ENODEV - Device handed in is invalid.
+*/
+/****************************************************************************/
+
+static int ConfigChannel(DMA_Handle_t handle)
+{
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+       int controllerIdx;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+       controllerIdx = CONTROLLER_FROM_HANDLE(handle);
+
+       if ((devAttr->flags & DMA_DEVICE_FLAG_PORT_PER_DMAC) != 0) {
+               if (devAttr->config.transferType ==
+                   dmacHw_TRANSFER_TYPE_MEM_TO_PERIPHERAL) {
+                       devAttr->config.dstPeripheralPort =
+                           devAttr->dmacPort[controllerIdx];
+               } else if (devAttr->config.transferType ==
+                          dmacHw_TRANSFER_TYPE_PERIPHERAL_TO_MEM) {
+                       devAttr->config.srcPeripheralPort =
+                           devAttr->dmacPort[controllerIdx];
+               }
+       }
+
+       if (dmacHw_configChannel(channel->dmacHwHandle, &devAttr->config) != 0) {
+               printk(KERN_ERR "ConfigChannel: dmacHw_configChannel failed\n");
+               return -EIO;
+       }
+
+       return 0;
+}
+
+/****************************************************************************/
+/**
+*   Intializes all of the data structures associated with the DMA.
+*   @return
+*       >= 0    - Initialization was successfull.
+*
+*       -EBUSY  - Device is currently being used.
+*       -ENODEV - Device handed in is invalid.
+*/
+/****************************************************************************/
+
+int dma_init(void)
+{
+       int rc = 0;
+       int controllerIdx;
+       int channelIdx;
+       DMA_Device_t devIdx;
+       DMA_Channel_t *channel;
+       DMA_Handle_t dedicatedHandle;
+
+       memset(&gDMA, 0, sizeof(gDMA));
+
+       init_MUTEX_LOCKED(&gDMA.lock);
+       init_waitqueue_head(&gDMA.freeChannelQ);
+
+       /* Initialize the Hardware */
+
+       dmacHw_initDma();
+
+       /* Start off by marking all of the DMA channels as shared. */
+
+       for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
+            controllerIdx++) {
+               for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
+                    channelIdx++) {
+                       channel =
+                           &gDMA.controller[controllerIdx].channel[channelIdx];
+
+                       channel->flags = 0;
+                       channel->devType = DMA_DEVICE_NONE;
+                       channel->lastDevType = DMA_DEVICE_NONE;
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+                       channel->fileName = "";
+                       channel->lineNum = 0;
+#endif
+
+                       channel->dmacHwHandle =
+                           dmacHw_getChannelHandle(dmacHw_MAKE_CHANNEL_ID
+                                                   (controllerIdx,
+                                                    channelIdx));
+                       dmacHw_initChannel(channel->dmacHwHandle);
+               }
+       }
+
+       /* Record any special attributes that channels may have */
+
+       gDMA.controller[0].channel[0].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
+       gDMA.controller[0].channel[1].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
+       gDMA.controller[1].channel[0].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
+       gDMA.controller[1].channel[1].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
+
+       /* Now walk through and record the dedicated channels. */
+
+       for (devIdx = 0; devIdx < DMA_NUM_DEVICE_ENTRIES; devIdx++) {
+               DMA_DeviceAttribute_t *devAttr = &DMA_gDeviceAttribute[devIdx];
+
+               if (((devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) != 0)
+                   && ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) == 0)) {
+                       printk(KERN_ERR
+                              "DMA Device: %s Can only request NO_ISR for dedicated devices\n",
+                              devAttr->name);
+                       rc = -EINVAL;
+                       goto out;
+               }
+
+               if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
+                       /* This is a dedicated device. Mark the channel as being reserved. */
+
+                       if (devAttr->dedicatedController >= DMA_NUM_CONTROLLERS) {
+                               printk(KERN_ERR
+                                      "DMA Device: %s DMA Controller %d is out of range\n",
+                                      devAttr->name,
+                                      devAttr->dedicatedController);
+                               rc = -EINVAL;
+                               goto out;
+                       }
+
+                       if (devAttr->dedicatedChannel >= DMA_NUM_CHANNELS) {
+                               printk(KERN_ERR
+                                      "DMA Device: %s DMA Channel %d is out of range\n",
+                                      devAttr->name,
+                                      devAttr->dedicatedChannel);
+                               rc = -EINVAL;
+                               goto out;
+                       }
+
+                       dedicatedHandle =
+                           MAKE_HANDLE(devAttr->dedicatedController,
+                                       devAttr->dedicatedChannel);
+                       channel = HandleToChannel(dedicatedHandle);
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) !=
+                           0) {
+                               printk
+                                   ("DMA Device: %s attempting to use same DMA Controller:Channel (%d:%d) as %s\n",
+                                    devAttr->name,
+                                    devAttr->dedicatedController,
+                                    devAttr->dedicatedChannel,
+                                    DMA_gDeviceAttribute[channel->devType].
+                                    name);
+                               rc = -EBUSY;
+                               goto out;
+                       }
+
+                       channel->flags |= DMA_CHANNEL_FLAG_IS_DEDICATED;
+                       channel->devType = devIdx;
+
+                       if (devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) {
+                               channel->flags |= DMA_CHANNEL_FLAG_NO_ISR;
+                       }
+
+                       /* For dedicated channels, we can go ahead and configure the DMA channel now */
+                       /* as well. */
+
+                       ConfigChannel(dedicatedHandle);
+               }
+       }
+
+       /* Go through and register the interrupt handlers */
+
+       for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
+            controllerIdx++) {
+               for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
+                    channelIdx++) {
+                       channel =
+                           &gDMA.controller[controllerIdx].channel[channelIdx];
+
+                       if ((channel->flags & DMA_CHANNEL_FLAG_NO_ISR) == 0) {
+                               snprintf(channel->name, sizeof(channel->name),
+                                        "dma %d:%d %s", controllerIdx,
+                                        channelIdx,
+                                        channel->devType ==
+                                        DMA_DEVICE_NONE ? "" :
+                                        DMA_gDeviceAttribute[channel->devType].
+                                        name);
+
+                               rc =
+                                    request_irq(IRQ_DMA0C0 +
+                                                (controllerIdx *
+                                                 DMA_NUM_CHANNELS) +
+                                                channelIdx,
+                                                dma_interrupt_handler,
+                                                IRQF_DISABLED, channel->name,
+                                                channel);
+                               if (rc != 0) {
+                                       printk(KERN_ERR
+                                              "request_irq for IRQ_DMA%dC%d failed\n",
+                                              controllerIdx, channelIdx);
+                               }
+                       }
+               }
+       }
+
+       /* Create /proc/dma/channels and /proc/dma/devices */
+
+       gDmaDir = create_proc_entry("dma", S_IFDIR | S_IRUGO | S_IXUGO, NULL);
+
+       if (gDmaDir == NULL) {
+               printk(KERN_ERR "Unable to create /proc/dma\n");
+       } else {
+               create_proc_read_entry("channels", 0, gDmaDir,
+                                      dma_proc_read_channels, NULL);
+               create_proc_read_entry("devices", 0, gDmaDir,
+                                      dma_proc_read_devices, NULL);
+               create_proc_read_entry("mem-type", 0, gDmaDir,
+                                      dma_proc_read_mem_type, NULL);
+       }
+
+out:
+
+       up(&gDMA.lock);
+
+       return rc;
+}
+
+/****************************************************************************/
+/**
+*   Reserves a channel for use with @a dev. If the device is setup to use
+*   a shared channel, then this function will block until a free channel
+*   becomes available.
+*
+*   @return
+*       >= 0    - A valid DMA Handle.
+*       -EBUSY  - Device is currently being used.
+*       -ENODEV - Device handed in is invalid.
+*/
+/****************************************************************************/
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+DMA_Handle_t dma_request_channel_dbg
+    (DMA_Device_t dev, const char *fileName, int lineNum)
+#else
+DMA_Handle_t dma_request_channel(DMA_Device_t dev)
+#endif
+{
+       DMA_Handle_t handle;
+       DMA_DeviceAttribute_t *devAttr;
+       DMA_Channel_t *channel;
+       int controllerIdx;
+       int controllerIdx2;
+       int channelIdx;
+
+       if (down_interruptible(&gDMA.lock) < 0) {
+               return -ERESTARTSYS;
+       }
+
+       if ((dev < 0) || (dev >= DMA_NUM_DEVICE_ENTRIES)) {
+               handle = -ENODEV;
+               goto out;
+       }
+       devAttr = &DMA_gDeviceAttribute[dev];
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+       {
+               char *s;
+
+               s = strrchr(fileName, '/');
+               if (s != NULL) {
+                       fileName = s + 1;
+               }
+       }
+#endif
+       if ((devAttr->flags & DMA_DEVICE_FLAG_IN_USE) != 0) {
+               /* This device has already been requested and not been freed */
+
+               printk(KERN_ERR "%s: device %s is already requested\n",
+                      __func__, devAttr->name);
+               handle = -EBUSY;
+               goto out;
+       }
+
+       if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
+               /* This device has a dedicated channel. */
+
+               channel =
+                   &gDMA.controller[devAttr->dedicatedController].
+                   channel[devAttr->dedicatedChannel];
+               if ((channel->flags & DMA_CHANNEL_FLAG_IN_USE) != 0) {
+                       handle = -EBUSY;
+                       goto out;
+               }
+
+               channel->flags |= DMA_CHANNEL_FLAG_IN_USE;
+               devAttr->flags |= DMA_DEVICE_FLAG_IN_USE;
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+               channel->fileName = fileName;
+               channel->lineNum = lineNum;
+#endif
+               handle =
+                   MAKE_HANDLE(devAttr->dedicatedController,
+                               devAttr->dedicatedChannel);
+               goto out;
+       }
+
+       /* This device needs to use one of the shared channels. */
+
+       handle = DMA_INVALID_HANDLE;
+       while (handle == DMA_INVALID_HANDLE) {
+               /* Scan through the shared channels and see if one is available */
+
+               for (controllerIdx2 = 0; controllerIdx2 < DMA_NUM_CONTROLLERS;
+                    controllerIdx2++) {
+                       /* Check to see if we should try on controller 1 first. */
+
+                       controllerIdx = controllerIdx2;
+                       if ((devAttr->
+                            flags & DMA_DEVICE_FLAG_ALLOC_DMA1_FIRST) != 0) {
+                               controllerIdx = 1 - controllerIdx;
+                       }
+
+                       /* See if the device is available on the controller being tested */
+
+                       if ((devAttr->
+                            flags & (DMA_DEVICE_FLAG_ON_DMA0 << controllerIdx))
+                           != 0) {
+                               for (channelIdx = 0;
+                                    channelIdx < DMA_NUM_CHANNELS;
+                                    channelIdx++) {
+                                       channel =
+                                           &gDMA.controller[controllerIdx].
+                                           channel[channelIdx];
+
+                                       if (((channel->
+                                             flags &
+                                             DMA_CHANNEL_FLAG_IS_DEDICATED) ==
+                                            0)
+                                           &&
+                                           ((channel->
+                                             flags & DMA_CHANNEL_FLAG_IN_USE)
+                                            == 0)) {
+                                               if (((channel->
+                                                     flags &
+                                                     DMA_CHANNEL_FLAG_LARGE_FIFO)
+                                                    != 0)
+                                                   &&
+                                                   ((devAttr->
+                                                     flags &
+                                                     DMA_DEVICE_FLAG_ALLOW_LARGE_FIFO)
+                                                    == 0)) {
+                                                       /* This channel is a large fifo - don't tie it up */
+                                                       /* with devices that we don't want using it. */
+
+                                                       continue;
+                                               }
+
+                                               channel->flags |=
+                                                   DMA_CHANNEL_FLAG_IN_USE;
+                                               channel->devType = dev;
+                                               devAttr->flags |=
+                                                   DMA_DEVICE_FLAG_IN_USE;
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+                                               channel->fileName = fileName;
+                                               channel->lineNum = lineNum;
+#endif
+                                               handle =
+                                                   MAKE_HANDLE(controllerIdx,
+                                                               channelIdx);
+
+                                               /* Now that we've reserved the channel - we can go ahead and configure it */
+
+                                               if (ConfigChannel(handle) != 0) {
+                                                       handle = -EIO;
+                                                       printk(KERN_ERR
+                                                              "dma_request_channel: ConfigChannel failed\n");
+                                               }
+                                               goto out;
+                                       }
+                               }
+                       }
+               }
+
+               /* No channels are currently available. Let's wait for one to free up. */
+
+               {
+                       DEFINE_WAIT(wait);
+
+                       prepare_to_wait(&gDMA.freeChannelQ, &wait,
+                                       TASK_INTERRUPTIBLE);
+                       up(&gDMA.lock);
+                       schedule();
+                       finish_wait(&gDMA.freeChannelQ, &wait);
+
+                       if (signal_pending(current)) {
+                               /* We don't currently hold gDMA.lock, so we return directly */
+
+                               return -ERESTARTSYS;
+                       }
+               }
+
+               if (down_interruptible(&gDMA.lock)) {
+                       return -ERESTARTSYS;
+               }
+       }
+
+out:
+       up(&gDMA.lock);
+
+       return handle;
+}
+
+/* Create both _dbg and non _dbg functions for modules. */
+
+#if (DMA_DEBUG_TRACK_RESERVATION)
+#undef dma_request_channel
+DMA_Handle_t dma_request_channel(DMA_Device_t dev)
+{
+       return dma_request_channel_dbg(dev, __FILE__, __LINE__);
+}
+
+EXPORT_SYMBOL(dma_request_channel_dbg);
+#endif
+EXPORT_SYMBOL(dma_request_channel);
+
+/****************************************************************************/
+/**
+*   Frees a previously allocated DMA Handle.
+*/
+/****************************************************************************/
+
+int dma_free_channel(DMA_Handle_t handle       /* DMA handle. */
+    ) {
+       int rc = 0;
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+
+       if (down_interruptible(&gDMA.lock) < 0) {
+               return -ERESTARTSYS;
+       }
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               rc = -EINVAL;
+               goto out;
+       }
+
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) == 0) {
+               channel->lastDevType = channel->devType;
+               channel->devType = DMA_DEVICE_NONE;
+       }
+       channel->flags &= ~DMA_CHANNEL_FLAG_IN_USE;
+       devAttr->flags &= ~DMA_DEVICE_FLAG_IN_USE;
+
+out:
+       up(&gDMA.lock);
+
+       wake_up_interruptible(&gDMA.freeChannelQ);
+
+       return rc;
+}
+
+EXPORT_SYMBOL(dma_free_channel);
+
+/****************************************************************************/
+/**
+*   Determines if a given device has been configured as using a shared
+*   channel.
+*
+*   @return
+*       0           Device uses a dedicated channel
+*       > zero      Device uses a shared channel
+*       < zero      Error code
+*/
+/****************************************************************************/
+
+int dma_device_is_channel_shared(DMA_Device_t device   /* Device to check. */
+    ) {
+       DMA_DeviceAttribute_t *devAttr;
+
+       if (!IsDeviceValid(device)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[device];
+
+       return ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) == 0);
+}
+
+EXPORT_SYMBOL(dma_device_is_channel_shared);
+
+/****************************************************************************/
+/**
+*   Allocates buffers for the descriptors. This is normally done automatically
+*   but needs to be done explicitly when initiating a dma from interrupt
+*   context.
+*
+*   @return
+*       0       Descriptors were allocated successfully
+*       -EINVAL Invalid device type for this kind of transfer
+*               (i.e. the device is _MEM_TO_DEV and not _DEV_TO_MEM)
+*       -ENOMEM Memory exhausted
+*/
+/****************************************************************************/
+
+int dma_alloc_descriptors(DMA_Handle_t handle, /* DMA Handle */
+                         dmacHw_TRANSFER_TYPE_e transferType,  /* Type of transfer being performed */
+                         dma_addr_t srcData,   /* Place to get data to write to device */
+                         dma_addr_t dstData,   /* Pointer to device data address */
+                         size_t numBytes       /* Number of bytes to transfer to the device */
+    ) {
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+       int numDescriptors;
+       size_t ringBytesRequired;
+       int rc = 0;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       if (devAttr->config.transferType != transferType) {
+               return -EINVAL;
+       }
+
+       /* Figure out how many descriptors we need. */
+
+       /* printk("srcData: 0x%08x dstData: 0x%08x, numBytes: %d\n", */
+       /*        srcData, dstData, numBytes); */
+
+       numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
+                                                             (void *)srcData,
+                                                             (void *)dstData,
+                                                             numBytes);
+       if (numDescriptors < 0) {
+               printk(KERN_ERR "%s: dmacHw_calculateDescriptorCount failed\n",
+                      __func__);
+               return -EINVAL;
+       }
+
+       /* Check to see if we can reuse the existing descriptor ring, or if we need to allocate */
+       /* a new one. */
+
+       ringBytesRequired = dmacHw_descriptorLen(numDescriptors);
+
+       /* printk("ringBytesRequired: %d\n", ringBytesRequired); */
+
+       if (ringBytesRequired > devAttr->ring.bytesAllocated) {
+               /* Make sure that this code path is never taken from interrupt context. */
+               /* It's OK for an interrupt to initiate a DMA transfer, but the descriptor */
+               /* allocation needs to have already been done. */
+
+               might_sleep();
+
+               /* Free the old descriptor ring and allocate a new one. */
+
+               dma_free_descriptor_ring(&devAttr->ring);
+
+               /* And allocate a new one. */
+
+               rc =
+                    dma_alloc_descriptor_ring(&devAttr->ring,
+                                              numDescriptors);
+               if (rc < 0) {
+                       printk(KERN_ERR
+                              "%s: dma_alloc_descriptor_ring(%d) failed\n",
+                              __func__, numDescriptors);
+                       return rc;
+               }
+               /* Setup the descriptor for this transfer */
+
+               if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
+                                         devAttr->ring.physAddr,
+                                         devAttr->ring.bytesAllocated,
+                                         numDescriptors) < 0) {
+                       printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n",
+                              __func__);
+                       return -EINVAL;
+               }
+       } else {
+               /* We've already got enough ring buffer allocated. All we need to do is reset */
+               /* any control information, just in case the previous DMA was stopped. */
+
+               dmacHw_resetDescriptorControl(devAttr->ring.virtAddr);
+       }
+
+       /* dma_alloc/free both set the prevSrc/DstData to 0. If they happen to be the same */
+       /* as last time, then we don't need to call setDataDescriptor again. */
+
+       if (dmacHw_setDataDescriptor(&devAttr->config,
+                                    devAttr->ring.virtAddr,
+                                    (void *)srcData,
+                                    (void *)dstData, numBytes) < 0) {
+               printk(KERN_ERR "%s: dmacHw_setDataDescriptor failed\n",
+                      __func__);
+               return -EINVAL;
+       }
+
+       /* Remember the critical information for this transfer so that we can eliminate */
+       /* another call to dma_alloc_descriptors if the caller reuses the same buffers */
+
+       devAttr->prevSrcData = srcData;
+       devAttr->prevDstData = dstData;
+       devAttr->prevNumBytes = numBytes;
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_alloc_descriptors);
+
+/****************************************************************************/
+/**
+*   Allocates and sets up descriptors for a double buffered circular buffer.
+*
+*   This is primarily intended to be used for things like the ingress samples
+*   from a microphone.
+*
+*   @return
+*       > 0     Number of descriptors actually allocated.
+*       -EINVAL Invalid device type for this kind of transfer
+*               (i.e. the device is _MEM_TO_DEV and not _DEV_TO_MEM)
+*       -ENOMEM Memory exhausted
+*/
+/****************************************************************************/
+
+int dma_alloc_double_dst_descriptors(DMA_Handle_t handle,      /* DMA Handle */
+                                    dma_addr_t srcData,        /* Physical address of source data */
+                                    dma_addr_t dstData1,       /* Physical address of first destination buffer */
+                                    dma_addr_t dstData2,       /* Physical address of second destination buffer */
+                                    size_t numBytes    /* Number of bytes in each destination buffer */
+    ) {
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+       int numDst1Descriptors;
+       int numDst2Descriptors;
+       int numDescriptors;
+       size_t ringBytesRequired;
+       int rc = 0;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       /* Figure out how many descriptors we need. */
+
+       /* printk("srcData: 0x%08x dstData: 0x%08x, numBytes: %d\n", */
+       /*        srcData, dstData, numBytes); */
+
+       numDst1Descriptors =
+            dmacHw_calculateDescriptorCount(&devAttr->config, (void *)srcData,
+                                            (void *)dstData1, numBytes);
+       if (numDst1Descriptors < 0) {
+               return -EINVAL;
+       }
+       numDst2Descriptors =
+            dmacHw_calculateDescriptorCount(&devAttr->config, (void *)srcData,
+                                            (void *)dstData2, numBytes);
+       if (numDst2Descriptors < 0) {
+               return -EINVAL;
+       }
+       numDescriptors = numDst1Descriptors + numDst2Descriptors;
+       /* printk("numDescriptors: %d\n", numDescriptors); */
+
+       /* Check to see if we can reuse the existing descriptor ring, or if we need to allocate */
+       /* a new one. */
+
+       ringBytesRequired = dmacHw_descriptorLen(numDescriptors);
+
+       /* printk("ringBytesRequired: %d\n", ringBytesRequired); */
+
+       if (ringBytesRequired > devAttr->ring.bytesAllocated) {
+               /* Make sure that this code path is never taken from interrupt context. */
+               /* It's OK for an interrupt to initiate a DMA transfer, but the descriptor */
+               /* allocation needs to have already been done. */
+
+               might_sleep();
+
+               /* Free the old descriptor ring and allocate a new one. */
+
+               dma_free_descriptor_ring(&devAttr->ring);
+
+               /* And allocate a new one. */
+
+               rc =
+                    dma_alloc_descriptor_ring(&devAttr->ring,
+                                              numDescriptors);
+               if (rc < 0) {
+                       printk(KERN_ERR
+                              "%s: dma_alloc_descriptor_ring(%d) failed\n",
+                              __func__, ringBytesRequired);
+                       return rc;
+               }
+       }
+
+       /* Setup the descriptor for this transfer. Since this function is used with */
+       /* CONTINUOUS DMA operations, we need to reinitialize every time, otherwise */
+       /* setDataDescriptor will keep trying to append onto the end. */
+
+       if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
+                                 devAttr->ring.physAddr,
+                                 devAttr->ring.bytesAllocated,
+                                 numDescriptors) < 0) {
+               printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n", __func__);
+               return -EINVAL;
+       }
+
+       /* dma_alloc/free both set the prevSrc/DstData to 0. If they happen to be the same */
+       /* as last time, then we don't need to call setDataDescriptor again. */
+
+       if (dmacHw_setDataDescriptor(&devAttr->config,
+                                    devAttr->ring.virtAddr,
+                                    (void *)srcData,
+                                    (void *)dstData1, numBytes) < 0) {
+               printk(KERN_ERR "%s: dmacHw_setDataDescriptor 1 failed\n",
+                      __func__);
+               return -EINVAL;
+       }
+       if (dmacHw_setDataDescriptor(&devAttr->config,
+                                    devAttr->ring.virtAddr,
+                                    (void *)srcData,
+                                    (void *)dstData2, numBytes) < 0) {
+               printk(KERN_ERR "%s: dmacHw_setDataDescriptor 2 failed\n",
+                      __func__);
+               return -EINVAL;
+       }
+
+       /* You should use dma_start_transfer rather than dma_transfer_xxx so we don't */
+       /* try to make the 'prev' variables right. */
+
+       devAttr->prevSrcData = 0;
+       devAttr->prevDstData = 0;
+       devAttr->prevNumBytes = 0;
+
+       return numDescriptors;
+}
+
+EXPORT_SYMBOL(dma_alloc_double_dst_descriptors);
+
+/****************************************************************************/
+/**
+*   Initiates a transfer when the descriptors have already been setup.
+*
+*   This is a special case, and normally, the dma_transfer_xxx functions should
+*   be used.
+*
+*   @return
+*       0       Transfer was started successfully
+*       -ENODEV Invalid handle
+*/
+/****************************************************************************/
+
+int dma_start_transfer(DMA_Handle_t handle)
+{
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       dmacHw_initiateTransfer(channel->dmacHwHandle, &devAttr->config,
+                               devAttr->ring.virtAddr);
+
+       /* Since we got this far, everything went successfully */
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_start_transfer);
+
+/****************************************************************************/
+/**
+*   Stops a previously started DMA transfer.
+*
+*   @return
+*       0       Transfer was stopped successfully
+*       -ENODEV Invalid handle
+*/
+/****************************************************************************/
+
+int dma_stop_transfer(DMA_Handle_t handle)
+{
+       DMA_Channel_t *channel;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+
+       dmacHw_stopTransfer(channel->dmacHwHandle);
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_stop_transfer);
+
+/****************************************************************************/
+/**
+*   Waits for a DMA to complete by polling. This function is only intended
+*   to be used for testing. Interrupts should be used for most DMA operations.
+*/
+/****************************************************************************/
+
+int dma_wait_transfer_done(DMA_Handle_t handle)
+{
+       DMA_Channel_t *channel;
+       dmacHw_TRANSFER_STATUS_e status;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+
+       while ((status =
+               dmacHw_transferCompleted(channel->dmacHwHandle)) ==
+              dmacHw_TRANSFER_STATUS_BUSY) {
+               ;
+       }
+
+       if (status == dmacHw_TRANSFER_STATUS_ERROR) {
+               printk(KERN_ERR "%s: DMA transfer failed\n", __func__);
+               return -EIO;
+       }
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_wait_transfer_done);
+
+/****************************************************************************/
+/**
+*   Initiates a DMA, allocating the descriptors as required.
+*
+*   @return
+*       0       Transfer was started successfully
+*       -EINVAL Invalid device type for this kind of transfer
+*               (i.e. the device is _DEV_TO_MEM and not _MEM_TO_DEV)
+*/
+/****************************************************************************/
+
+int dma_transfer(DMA_Handle_t handle,  /* DMA Handle */
+                dmacHw_TRANSFER_TYPE_e transferType,   /* Type of transfer being performed */
+                dma_addr_t srcData,    /* Place to get data to write to device */
+                dma_addr_t dstData,    /* Pointer to device data address */
+                size_t numBytes        /* Number of bytes to transfer to the device */
+    ) {
+       DMA_Channel_t *channel;
+       DMA_DeviceAttribute_t *devAttr;
+       int rc = 0;
+
+       channel = HandleToChannel(handle);
+       if (channel == NULL) {
+               return -ENODEV;
+       }
+
+       devAttr = &DMA_gDeviceAttribute[channel->devType];
+
+       if (devAttr->config.transferType != transferType) {
+               return -EINVAL;
+       }
+
+       /* We keep track of the information about the previous request for this */
+       /* device, and if the attributes match, then we can use the descriptors we setup */
+       /* the last time, and not have to reinitialize everything. */
+
+       {
+               rc =
+                    dma_alloc_descriptors(handle, transferType, srcData,
+                                          dstData, numBytes);
+               if (rc != 0) {
+                       return rc;
+               }
+       }
+
+       /* And kick off the transfer */
+
+       devAttr->numBytes = numBytes;
+       devAttr->transferStartTime = timer_get_tick_count();
+
+       dmacHw_initiateTransfer(channel->dmacHwHandle, &devAttr->config,
+                               devAttr->ring.virtAddr);
+
+       /* Since we got this far, everything went successfully */
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_transfer);
+
+/****************************************************************************/
+/**
+*   Set the callback function which will be called when a transfer completes.
+*   If a NULL callback function is set, then no callback will occur.
+*
+*   @note   @a devHandler will be called from IRQ context.
+*
+*   @return
+*       0       - Success
+*       -ENODEV - Device handed in is invalid.
+*/
+/****************************************************************************/
+
+int dma_set_device_handler(DMA_Device_t dev,   /* Device to set the callback for. */
+                          DMA_DeviceHandler_t devHandler,      /* Function to call when the DMA completes */
+                          void *userData       /* Pointer which will be passed to devHandler. */
+    ) {
+       DMA_DeviceAttribute_t *devAttr;
+       unsigned long flags;
+
+       if (!IsDeviceValid(dev)) {
+               return -ENODEV;
+       }
+       devAttr = &DMA_gDeviceAttribute[dev];
+
+       local_irq_save(flags);
+
+       devAttr->userData = userData;
+       devAttr->devHandler = devHandler;
+
+       local_irq_restore(flags);
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_set_device_handler);
+
+/****************************************************************************/
+/**
+*   Initializes a memory mapping structure
+*/
+/****************************************************************************/
+
+int dma_init_mem_map(DMA_MemMap_t *memMap)
+{
+       memset(memMap, 0, sizeof(*memMap));
+
+       init_MUTEX(&memMap->lock);
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_init_mem_map);
+
+/****************************************************************************/
+/**
+*   Releases any memory currently being held by a memory mapping structure.
+*/
+/****************************************************************************/
+
+int dma_term_mem_map(DMA_MemMap_t *memMap)
+{
+       down(&memMap->lock);    /* Just being paranoid */
+
+       /* Free up any allocated memory */
+
+       up(&memMap->lock);
+       memset(memMap, 0, sizeof(*memMap));
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_term_mem_map);
+
+/****************************************************************************/
+/**
+*   Looks at a memory address and categorizes it.
+*
+*   @return One of the values from the DMA_MemType_t enumeration.
+*/
+/****************************************************************************/
+
+DMA_MemType_t dma_mem_type(void *addr)
+{
+       unsigned long addrVal = (unsigned long)addr;
+
+       if (addrVal >= VMALLOC_END) {
+               /* NOTE: DMA virtual memory space starts at 0xFFxxxxxx */
+
+               /* dma_alloc_xxx pages are physically and virtually contiguous */
+
+               return DMA_MEM_TYPE_DMA;
+       }
+
+       /* Technically, we could add one more classification. Addresses between VMALLOC_END */
+       /* and the beginning of the DMA virtual address could be considered to be I/O space. */
+       /* Right now, nobody cares about this particular classification, so we ignore it. */
+
+       if (is_vmalloc_addr(addr)) {
+               /* Address comes from the vmalloc'd region. Pages are virtually */
+               /* contiguous but NOT physically contiguous */
+
+               return DMA_MEM_TYPE_VMALLOC;
+       }
+
+       if (addrVal >= PAGE_OFFSET) {
+               /* PAGE_OFFSET is typically 0xC0000000 */
+
+               /* kmalloc'd pages are physically contiguous */
+
+               return DMA_MEM_TYPE_KMALLOC;
+       }
+
+       return DMA_MEM_TYPE_USER;
+}
+
+EXPORT_SYMBOL(dma_mem_type);
+
+/****************************************************************************/
+/**
+*   Looks at a memory address and determines if we support DMA'ing to/from
+*   that type of memory.
+*
+*   @return boolean -
+*               return value != 0 means dma supported
+*               return value == 0 means dma not supported
+*/
+/****************************************************************************/
+
+int dma_mem_supports_dma(void *addr)
+{
+       DMA_MemType_t memType = dma_mem_type(addr);
+
+       return (memType == DMA_MEM_TYPE_DMA)
+#if ALLOW_MAP_OF_KMALLOC_MEMORY
+           || (memType == DMA_MEM_TYPE_KMALLOC)
+#endif
+           || (memType == DMA_MEM_TYPE_USER);
+}
+
+EXPORT_SYMBOL(dma_mem_supports_dma);
+
+/****************************************************************************/
+/**
+*   Maps in a memory region such that it can be used for performing a DMA.
+*
+*   @return
+*/
+/****************************************************************************/
+
+int dma_map_start(DMA_MemMap_t *memMap,        /* Stores state information about the map */
+                 enum dma_data_direction dir   /* Direction that the mapping will be going */
+    ) {
+       int rc;
+
+       down(&memMap->lock);
+
+       DMA_MAP_PRINT("memMap: %p\n", memMap);
+
+       if (memMap->inUse) {
+               printk(KERN_ERR "%s: memory map %p is already being used\n",
+                      __func__, memMap);
+               rc = -EBUSY;
+               goto out;
+       }
+
+       memMap->inUse = 1;
+       memMap->dir = dir;
+       memMap->numRegionsUsed = 0;
+
+       rc = 0;
+
+out:
+
+       DMA_MAP_PRINT("returning %d", rc);
+
+       up(&memMap->lock);
+
+       return rc;
+}
+
+EXPORT_SYMBOL(dma_map_start);
+
+/****************************************************************************/
+/**
+*   Adds a segment of memory to a memory map. Each segment is both
+*   physically and virtually contiguous.
+*
+*   @return     0 on success, error code otherwise.
+*/
+/****************************************************************************/
+
+static int dma_map_add_segment(DMA_MemMap_t *memMap,   /* Stores state information about the map */
+                              DMA_Region_t *region,    /* Region that the segment belongs to */
+                              void *virtAddr,  /* Virtual address of the segment being added */
+                              dma_addr_t physAddr,     /* Physical address of the segment being added */
+                              size_t numBytes  /* Number of bytes of the segment being added */
+    ) {
+       DMA_Segment_t *segment;
+
+       DMA_MAP_PRINT("memMap:%p va:%p pa:0x%x #:%d\n", memMap, virtAddr,
+                     physAddr, numBytes);
+
+       /* Sanity check */
+
+       if (((unsigned long)virtAddr < (unsigned long)region->virtAddr)
+           || (((unsigned long)virtAddr + numBytes)) >
+           ((unsigned long)region->virtAddr + region->numBytes)) {
+               printk(KERN_ERR
+                      "%s: virtAddr %p is outside region @ %p len: %d\n",
+                      __func__, virtAddr, region->virtAddr, region->numBytes);
+               return -EINVAL;
+       }
+
+       if (region->numSegmentsUsed > 0) {
+               /* Check to see if this segment is physically contiguous with the previous one */
+
+               segment = &region->segment[region->numSegmentsUsed - 1];
+
+               if ((segment->physAddr + segment->numBytes) == physAddr) {
+                       /* It is - just add on to the end */
+
+                       DMA_MAP_PRINT("appending %d bytes to last segment\n",
+                                     numBytes);
+
+                       segment->numBytes += numBytes;
+
+                       return 0;
+               }
+       }
+
+       /* Reallocate to hold more segments, if required. */
+
+       if (region->numSegmentsUsed >= region->numSegmentsAllocated) {
+               DMA_Segment_t *newSegment;
+               size_t oldSize =
+                   region->numSegmentsAllocated * sizeof(*newSegment);
+               int newAlloc = region->numSegmentsAllocated + 4;
+               size_t newSize = newAlloc * sizeof(*newSegment);
+
+               newSegment = kmalloc(newSize, GFP_KERNEL);
+               if (newSegment == NULL) {
+                       return -ENOMEM;
+               }
+               memcpy(newSegment, region->segment, oldSize);
+               memset(&((uint8_t *) newSegment)[oldSize], 0,
+                      newSize - oldSize);
+               kfree(region->segment);
+
+               region->numSegmentsAllocated = newAlloc;
+               region->segment = newSegment;
+       }
+
+       segment = &region->segment[region->numSegmentsUsed];
+       region->numSegmentsUsed++;
+
+       segment->virtAddr = virtAddr;
+       segment->physAddr = physAddr;
+       segment->numBytes = numBytes;
+
+       DMA_MAP_PRINT("returning success\n");
+
+       return 0;
+}
+
+/****************************************************************************/
+/**
+*   Adds a region of memory to a memory map. Each region is virtually
+*   contiguous, but not necessarily physically contiguous.
+*
+*   @return     0 on success, error code otherwise.
+*/
+/****************************************************************************/
+
+int dma_map_add_region(DMA_MemMap_t *memMap,   /* Stores state information about the map */
+                      void *mem,       /* Virtual address that we want to get a map of */
+                      size_t numBytes  /* Number of bytes being mapped */
+    ) {
+       unsigned long addr = (unsigned long)mem;
+       unsigned int offset;
+       int rc = 0;
+       DMA_Region_t *region;
+       dma_addr_t physAddr;
+
+       down(&memMap->lock);
+
+       DMA_MAP_PRINT("memMap:%p va:%p #:%d\n", memMap, mem, numBytes);
+
+       if (!memMap->inUse) {
+               printk(KERN_ERR "%s: Make sure you call dma_map_start first\n",
+                      __func__);
+               rc = -EINVAL;
+               goto out;
+       }
+
+       /* Reallocate to hold more regions. */
+
+       if (memMap->numRegionsUsed >= memMap->numRegionsAllocated) {
+               DMA_Region_t *newRegion;
+               size_t oldSize =
+                   memMap->numRegionsAllocated * sizeof(*newRegion);
+               int newAlloc = memMap->numRegionsAllocated + 4;
+               size_t newSize = newAlloc * sizeof(*newRegion);
+
+               newRegion = kmalloc(newSize, GFP_KERNEL);
+               if (newRegion == NULL) {
+                       rc = -ENOMEM;
+                       goto out;
+               }
+               memcpy(newRegion, memMap->region, oldSize);
+               memset(&((uint8_t *) newRegion)[oldSize], 0, newSize - oldSize);
+
+               kfree(memMap->region);
+
+               memMap->numRegionsAllocated = newAlloc;
+               memMap->region = newRegion;
+       }
+
+       region = &memMap->region[memMap->numRegionsUsed];
+       memMap->numRegionsUsed++;
+
+       offset = addr & ~PAGE_MASK;
+
+       region->memType = dma_mem_type(mem);
+       region->virtAddr = mem;
+       region->numBytes = numBytes;
+       region->numSegmentsUsed = 0;
+       region->numLockedPages = 0;
+       region->lockedPages = NULL;
+
+       switch (region->memType) {
+       case DMA_MEM_TYPE_VMALLOC:
+               {
+                       atomic_inc(&gDmaStatMemTypeVmalloc);
+
+                       /* printk(KERN_ERR "%s: vmalloc'd pages are not supported\n", __func__); */
+
+                       /* vmalloc'd pages are not physically contiguous */
+
+                       rc = -EINVAL;
+                       break;
+               }
+
+       case DMA_MEM_TYPE_KMALLOC:
+               {
+                       atomic_inc(&gDmaStatMemTypeKmalloc);
+
+                       /* kmalloc'd pages are physically contiguous, so they'll have exactly */
+                       /* one segment */
+
+#if ALLOW_MAP_OF_KMALLOC_MEMORY
+                       physAddr =
+                           dma_map_single(NULL, mem, numBytes, memMap->dir);
+                       rc = dma_map_add_segment(memMap, region, mem, physAddr,
+                                                numBytes);
+#else
+                       rc = -EINVAL;
+#endif
+                       break;
+               }
+
+       case DMA_MEM_TYPE_DMA:
+               {
+                       /* dma_alloc_xxx pages are physically contiguous */
+
+                       atomic_inc(&gDmaStatMemTypeCoherent);
+
+                       physAddr = (vmalloc_to_pfn(mem) << PAGE_SHIFT) + offset;
+
+                       dma_sync_single_for_cpu(NULL, physAddr, numBytes,
+                                               memMap->dir);
+                       rc = dma_map_add_segment(memMap, region, mem, physAddr,
+                                                numBytes);
+                       break;
+               }
+
+       case DMA_MEM_TYPE_USER:
+               {
+                       size_t firstPageOffset;
+                       size_t firstPageSize;
+                       struct page **pages;
+                       struct task_struct *userTask;
+
+                       atomic_inc(&gDmaStatMemTypeUser);
+
+#if 1
+                       /* If the pages are user pages, then the dma_mem_map_set_user_task function */
+                       /* must have been previously called. */
+
+                       if (memMap->userTask == NULL) {
+                               printk(KERN_ERR
+                                      "%s: must call dma_mem_map_set_user_task when using user-mode memory\n",
+                                      __func__);
+                               return -EINVAL;
+                       }
+
+                       /* User pages need to be locked. */
+
+                       firstPageOffset =
+                           (unsigned long)region->virtAddr & (PAGE_SIZE - 1);
+                       firstPageSize = PAGE_SIZE - firstPageOffset;
+
+                       region->numLockedPages = (firstPageOffset
+                                                 + region->numBytes +
+                                                 PAGE_SIZE - 1) / PAGE_SIZE;
+                       pages =
+                           kmalloc(region->numLockedPages *
+                                   sizeof(struct page *), GFP_KERNEL);
+
+                       if (pages == NULL) {
+                               region->numLockedPages = 0;
+                               return -ENOMEM;
+                       }
+
+                       userTask = memMap->userTask;
+
+                       down_read(&userTask->mm->mmap_sem);
+                       rc = get_user_pages(userTask,   /* task */
+                                           userTask->mm,       /* mm */
+                                           (unsigned long)region->virtAddr,    /* start */
+                                           region->numLockedPages,     /* len */
+                                           memMap->dir == DMA_FROM_DEVICE,     /* write */
+                                           0,  /* force */
+                                           pages,      /* pages (array of pointers to page) */
+                                           NULL);      /* vmas */
+                       up_read(&userTask->mm->mmap_sem);
+
+                       if (rc != region->numLockedPages) {
+                               kfree(pages);
+                               region->numLockedPages = 0;
+
+                               if (rc >= 0) {
+                                       rc = -EINVAL;
+                               }
+                       } else {
+                               uint8_t *virtAddr = region->virtAddr;
+                               size_t bytesRemaining;
+                               int pageIdx;
+
+                               rc = 0; /* Since get_user_pages returns +ve number */
+
+                               region->lockedPages = pages;
+
+                               /* We've locked the user pages. Now we need to walk them and figure */
+                               /* out the physical addresses. */
+
+                               /* The first page may be partial */
+
+                               dma_map_add_segment(memMap,
+                                                   region,
+                                                   virtAddr,
+                                                   PFN_PHYS(page_to_pfn
+                                                            (pages[0])) +
+                                                   firstPageOffset,
+                                                   firstPageSize);
+
+                               virtAddr += firstPageSize;
+                               bytesRemaining =
+                                   region->numBytes - firstPageSize;
+
+                               for (pageIdx = 1;
+                                    pageIdx < region->numLockedPages;
+                                    pageIdx++) {
+                                       size_t bytesThisPage =
+                                           (bytesRemaining >
+                                            PAGE_SIZE ? PAGE_SIZE :
+                                            bytesRemaining);
+
+                                       DMA_MAP_PRINT
+                                           ("pageIdx:%d pages[pageIdx]=%p pfn=%u phys=%u\n",
+                                            pageIdx, pages[pageIdx],
+                                            page_to_pfn(pages[pageIdx]),
+                                            PFN_PHYS(page_to_pfn
+                                                     (pages[pageIdx])));
+
+                                       dma_map_add_segment(memMap,
+                                                           region,
+                                                           virtAddr,
+                                                           PFN_PHYS(page_to_pfn
+                                                                    (pages
+                                                                     [pageIdx])),
+                                                           bytesThisPage);
+
+                                       virtAddr += bytesThisPage;
+                                       bytesRemaining -= bytesThisPage;
+                               }
+                       }
+#else
+                       printk(KERN_ERR
+                              "%s: User mode pages are not yet supported\n",
+                              __func__);
+
+                       /* user pages are not physically contiguous */
+
+                       rc = -EINVAL;
+#endif
+                       break;
+               }
+
+       default:
+               {
+                       printk(KERN_ERR "%s: Unsupported memory type: %d\n",
+                              __func__, region->memType);
+
+                       rc = -EINVAL;
+                       break;
+               }
+       }
+
+       if (rc != 0) {
+               memMap->numRegionsUsed--;
+       }
+
+out:
+
+       DMA_MAP_PRINT("returning %d\n", rc);
+
+       up(&memMap->lock);
+
+       return rc;
+}
+
+EXPORT_SYMBOL(dma_map_add_segment);
+
+/****************************************************************************/
+/**
+*   Maps in a memory region such that it can be used for performing a DMA.
+*
+*   @return     0 on success, error code otherwise.
+*/
+/****************************************************************************/
+
+int dma_map_mem(DMA_MemMap_t *memMap,  /* Stores state information about the map */
+               void *mem,      /* Virtual address that we want to get a map of */
+               size_t numBytes,        /* Number of bytes being mapped */
+               enum dma_data_direction dir     /* Direction that the mapping will be going */
+    ) {
+       int rc;
+
+       rc = dma_map_start(memMap, dir);
+       if (rc == 0) {
+               rc = dma_map_add_region(memMap, mem, numBytes);
+               if (rc < 0) {
+                       /* Since the add fails, this function will fail, and the caller won't */
+                       /* call unmap, so we need to do it here. */
+
+                       dma_unmap(memMap, 0);
+               }
+       }
+
+       return rc;
+}
+
+EXPORT_SYMBOL(dma_map_mem);
+
+/****************************************************************************/
+/**
+*   Setup a descriptor ring for a given memory map.
+*
+*   It is assumed that the descriptor ring has already been initialized, and
+*   this routine will only reallocate a new descriptor ring if the existing
+*   one is too small.
+*
+*   @return     0 on success, error code otherwise.
+*/
+/****************************************************************************/
+
+int dma_map_create_descriptor_ring(DMA_Device_t dev,   /* DMA device (where the ring is stored) */
+                                  DMA_MemMap_t *memMap,        /* Memory map that will be used */
+                                  dma_addr_t devPhysAddr       /* Physical address of device */
+    ) {
+       int rc;
+       int numDescriptors;
+       DMA_DeviceAttribute_t *devAttr;
+       DMA_Region_t *region;
+       DMA_Segment_t *segment;
+       dma_addr_t srcPhysAddr;
+       dma_addr_t dstPhysAddr;
+       int regionIdx;
+       int segmentIdx;
+
+       devAttr = &DMA_gDeviceAttribute[dev];
+
+       down(&memMap->lock);
+
+       /* Figure out how many descriptors we need */
+
+       numDescriptors = 0;
+       for (regionIdx = 0; regionIdx < memMap->numRegionsUsed; regionIdx++) {
+               region = &memMap->region[regionIdx];
+
+               for (segmentIdx = 0; segmentIdx < region->numSegmentsUsed;
+                    segmentIdx++) {
+                       segment = &region->segment[segmentIdx];
+
+                       if (memMap->dir == DMA_TO_DEVICE) {
+                               srcPhysAddr = segment->physAddr;
+                               dstPhysAddr = devPhysAddr;
+                       } else {
+                               srcPhysAddr = devPhysAddr;
+                               dstPhysAddr = segment->physAddr;
+                       }
+
+                       rc =
+                            dma_calculate_descriptor_count(dev, srcPhysAddr,
+                                                           dstPhysAddr,
+                                                           segment->
+                                                           numBytes);
+                       if (rc < 0) {
+                               printk(KERN_ERR
+                                      "%s: dma_calculate_descriptor_count failed: %d\n",
+                                      __func__, rc);
+                               goto out;
+                       }
+                       numDescriptors += rc;
+               }
+       }
+
+       /* Adjust the size of the ring, if it isn't big enough */
+
+       if (numDescriptors > devAttr->ring.descriptorsAllocated) {
+               dma_free_descriptor_ring(&devAttr->ring);
+               rc =
+                    dma_alloc_descriptor_ring(&devAttr->ring,
+                                              numDescriptors);
+               if (rc < 0) {
+                       printk(KERN_ERR
+                              "%s: dma_alloc_descriptor_ring failed: %d\n",
+                              __func__, rc);
+                       goto out;
+               }
+       } else {
+               rc =
+                    dma_init_descriptor_ring(&devAttr->ring,
+                                             numDescriptors);
+               if (rc < 0) {
+                       printk(KERN_ERR
+                              "%s: dma_init_descriptor_ring failed: %d\n",
+                              __func__, rc);
+                       goto out;
+               }
+       }
+
+       /* Populate the descriptors */
+
+       for (regionIdx = 0; regionIdx < memMap->numRegionsUsed; regionIdx++) {
+               region = &memMap->region[regionIdx];
+
+               for (segmentIdx = 0; segmentIdx < region->numSegmentsUsed;
+                    segmentIdx++) {
+                       segment = &region->segment[segmentIdx];
+
+                       if (memMap->dir == DMA_TO_DEVICE) {
+                               srcPhysAddr = segment->physAddr;
+                               dstPhysAddr = devPhysAddr;
+                       } else {
+                               srcPhysAddr = devPhysAddr;
+                               dstPhysAddr = segment->physAddr;
+                       }
+
+                       rc =
+                            dma_add_descriptors(&devAttr->ring, dev,
+                                                srcPhysAddr, dstPhysAddr,
+                                                segment->numBytes);
+                       if (rc < 0) {
+                               printk(KERN_ERR
+                                      "%s: dma_add_descriptors failed: %d\n",
+                                      __func__, rc);
+                               goto out;
+                       }
+               }
+       }
+
+       rc = 0;
+
+out:
+
+       up(&memMap->lock);
+       return rc;
+}
+
+EXPORT_SYMBOL(dma_map_create_descriptor_ring);
+
+/****************************************************************************/
+/**
+*   Maps in a memory region such that it can be used for performing a DMA.
+*
+*   @return
+*/
+/****************************************************************************/
+
+int dma_unmap(DMA_MemMap_t *memMap,    /* Stores state information about the map */
+             int dirtied       /* non-zero if any of the pages were modified */
+    ) {
+       int regionIdx;
+       int segmentIdx;
+       DMA_Region_t *region;
+       DMA_Segment_t *segment;
+
+       for (regionIdx = 0; regionIdx < memMap->numRegionsUsed; regionIdx++) {
+               region = &memMap->region[regionIdx];
+
+               for (segmentIdx = 0; segmentIdx < region->numSegmentsUsed;
+                    segmentIdx++) {
+                       segment = &region->segment[segmentIdx];
+
+                       switch (region->memType) {
+                       case DMA_MEM_TYPE_VMALLOC:
+                               {
+                                       printk(KERN_ERR
+                                              "%s: vmalloc'd pages are not yet supported\n",
+                                              __func__);
+                                       return -EINVAL;
+                               }
+
+                       case DMA_MEM_TYPE_KMALLOC:
+                               {
+#if ALLOW_MAP_OF_KMALLOC_MEMORY
+                                       dma_unmap_single(NULL,
+                                                        segment->physAddr,
+                                                        segment->numBytes,
+                                                        memMap->dir);
+#endif
+                                       break;
+                               }
+
+                       case DMA_MEM_TYPE_DMA:
+                               {
+                                       dma_sync_single_for_cpu(NULL,
+                                                               segment->
+                                                               physAddr,
+                                                               segment->
+                                                               numBytes,
+                                                               memMap->dir);
+                                       break;
+                               }
+
+                       case DMA_MEM_TYPE_USER:
+                               {
+                                       /* Nothing to do here. */
+
+                                       break;
+                               }
+
+                       default:
+                               {
+                                       printk(KERN_ERR
+                                              "%s: Unsupported memory type: %d\n",
+                                              __func__, region->memType);
+                                       return -EINVAL;
+                               }
+                       }
+
+                       segment->virtAddr = NULL;
+                       segment->physAddr = 0;
+                       segment->numBytes = 0;
+               }
+
+               if (region->numLockedPages > 0) {
+                       int pageIdx;
+
+                       /* Some user pages were locked. We need to go and unlock them now. */
+
+                       for (pageIdx = 0; pageIdx < region->numLockedPages;
+                            pageIdx++) {
+                               struct page *page =
+                                   region->lockedPages[pageIdx];
+
+                               if (memMap->dir == DMA_FROM_DEVICE) {
+                                       SetPageDirty(page);
+                               }
+                               page_cache_release(page);
+                       }
+                       kfree(region->lockedPages);
+                       region->numLockedPages = 0;
+                       region->lockedPages = NULL;
+               }
+
+               region->memType = DMA_MEM_TYPE_NONE;
+               region->virtAddr = NULL;
+               region->numBytes = 0;
+               region->numSegmentsUsed = 0;
+       }
+       memMap->userTask = NULL;
+       memMap->numRegionsUsed = 0;
+       memMap->inUse = 0;
+
+       up(&memMap->lock);
+
+       return 0;
+}
+
+EXPORT_SYMBOL(dma_unmap);