staging: kpc2000: Add DMA driver

Add Daktronics DMA driver.  I've added the SPDX license identifiers, Kconfig
entry, and cleaned up as many of the warnings as I could.

The AIO support code will be removed in a future patch.

Signed-off-by: Matt Sickler <matt.sickler@daktronics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8 files changed, 1181 insertions, 0 deletions

diff --git a/drivers/staging/kpc2000/Kconfig b/drivers/staging/kpc2000/Kconfig
index 926e770d6e0e..fb5922928f47 100644
--- a/drivers/staging/kpc2000/Kconfig
+++ b/drivers/staging/kpc2000/Kconfig
@@ -44,3 +44,14 @@ config KPC2000_I2C
 
 	  If unsure, say N.
 
+config KPC2000_DMA
+	tristate "Daktronics KPC DMA controller"
+	depends on KPC2000
+	help
+	  Say Y here if you wish to support the Daktronics DMA controller.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called kpc2000_dma
+
+	  If unsure, say N.
+
diff --git a/drivers/staging/kpc2000/Makefile b/drivers/staging/kpc2000/Makefile
index 6fcb2ee7b27d..1e48e9df1329 100644
--- a/drivers/staging/kpc2000/Makefile
+++ b/drivers/staging/kpc2000/Makefile
@@ -3,3 +3,4 @@
 obj-$(CONFIG_KPC2000) += kpc2000/
 obj-$(CONFIG_KPC2000_I2C) += kpc_i2c/
 obj-$(CONFIG_KPC2000_SPI) += kpc_spi/
+obj-$(CONFIG_KPC2000_DMA) += kpc_dma/
diff --git a/drivers/staging/kpc2000/kpc_dma/Makefile b/drivers/staging/kpc2000/kpc_dma/Makefile
new file mode 100644
index 000000000000..fe5db532c8c8
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-m := kpc_dma.o
+kpc_dma-objs += dma.o
+kpc_dma-objs += fileops.o
+kpc_dma-objs += kpc_dma_driver.o
diff --git a/drivers/staging/kpc2000/kpc_dma/dma.c b/drivers/staging/kpc2000/kpc_dma/dma.c
new file mode 100644
index 000000000000..6959bac11388
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/dma.c
@@ -0,0 +1,264 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <asm/io.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/fs.h>
+#include <linux/rwsem.h>
+#include "kpc_dma_driver.h"
+
+/**********  IRQ Handlers  **********/
+static
+irqreturn_t  ndd_irq_handler(int irq, void *dev_id)
+{
+	struct kpc_dma_device *ldev = (struct kpc_dma_device*)dev_id;
+	
+	if ((GetEngineControl(ldev) & ENG_CTL_IRQ_ACTIVE) || (ldev->desc_completed->MyDMAAddr != GetEngineCompletePtr(ldev)))
+		schedule_work(&ldev->irq_work);
+	
+	return IRQ_HANDLED;
+}
+
+static
+void  ndd_irq_worker(struct work_struct *ws)
+{
+	struct kpc_dma_descriptor *cur;
+	struct kpc_dma_device *eng = container_of(ws, struct kpc_dma_device, irq_work);
+	lock_engine(eng);
+	
+	if (GetEngineCompletePtr(eng) == 0)
+		goto out;
+	
+	if (eng->desc_completed->MyDMAAddr == GetEngineCompletePtr(eng))
+		goto out;
+	
+	cur = eng->desc_completed;
+	do {
+		cur = cur->Next;
+		dev_dbg(&eng->pldev->dev, "Handling completed descriptor %p (acd = %p)\n", cur, cur->acd);
+		BUG_ON(cur == eng->desc_next); // Ordering failure.
+		
+		if (cur->DescControlFlags & DMA_DESC_CTL_SOP){
+			eng->accumulated_bytes = 0;
+			eng->accumulated_flags = 0;
+		}
+		
+		eng->accumulated_bytes += cur->DescByteCount;
+		if (cur->DescStatusFlags & DMA_DESC_STS_ERROR)
+			eng->accumulated_flags |= ACD_FLAG_ENG_ACCUM_ERROR;
+		
+		if (cur->DescStatusFlags & DMA_DESC_STS_SHORT)
+			eng->accumulated_flags |= ACD_FLAG_ENG_ACCUM_SHORT;
+		
+		if (cur->DescControlFlags & DMA_DESC_CTL_EOP){
+			if (cur->acd)
+				transfer_complete_cb(cur->acd, eng->accumulated_bytes, eng->accumulated_flags | ACD_FLAG_DONE);
+		}
+		
+		eng->desc_completed = cur;
+	} while (cur->MyDMAAddr != GetEngineCompletePtr(eng));
+	
+ out:
+	SetClearEngineControl(eng, ENG_CTL_IRQ_ACTIVE, 0);
+	
+	unlock_engine(eng);
+}
+
+
+/**********  DMA Engine Init/Teardown  **********/
+void  start_dma_engine(struct kpc_dma_device *eng)
+{
+	eng->desc_next       = eng->desc_pool_first;
+	eng->desc_completed  = eng->desc_pool_last;
+	
+	// Setup the engine pointer registers
+	SetEngineNextPtr(eng, eng->desc_pool_first);
+	SetEngineSWPtr(eng, eng->desc_pool_first);
+	ClearEngineCompletePtr(eng);
+	
+	WriteEngineControl(eng, ENG_CTL_DMA_ENABLE | ENG_CTL_IRQ_ENABLE);
+}
+
+int  setup_dma_engine(struct kpc_dma_device *eng, u32 desc_cnt)
+{
+	u32 caps;
+	struct kpc_dma_descriptor * cur;
+	struct kpc_dma_descriptor * next;
+	dma_addr_t next_handle;
+	dma_addr_t head_handle;
+	unsigned int i;
+	int rv;
+	dev_dbg(&eng->pldev->dev, "Setting up DMA engine [%p]\n", eng);
+	
+	caps = GetEngineCapabilities(eng);
+	
+	if (WARN(!(caps & ENG_CAP_PRESENT), "setup_dma_engine() called for DMA Engine at %p which isn't present in hardware!\n", eng))
+		return -ENXIO;
+	
+	if (caps & ENG_CAP_DIRECTION){
+		eng->dir = DMA_FROM_DEVICE;
+	} else {
+		eng->dir = DMA_TO_DEVICE;
+	}
+	
+	eng->desc_pool_cnt = desc_cnt;
+	eng->desc_pool = dma_pool_create("KPC DMA Descriptors", &eng->pldev->dev, sizeof(struct kpc_dma_descriptor), DMA_DESC_ALIGNMENT, 4096);
+	
+	eng->desc_pool_first = dma_pool_alloc(eng->desc_pool, GFP_KERNEL | GFP_DMA, &head_handle);
+	if (!eng->desc_pool_first){
+		dev_err(&eng->pldev->dev, "setup_dma_engine: couldn't allocate desc_pool_first!\n");
+		dma_pool_destroy(eng->desc_pool);
+		return -ENOMEM;
+	}
+	
+	eng->desc_pool_first->MyDMAAddr = head_handle;
+	clear_desc(eng->desc_pool_first);
+	
+	cur = eng->desc_pool_first;
+	for (i = 1 ; i < eng->desc_pool_cnt ; i++){
+		next = dma_pool_alloc(eng->desc_pool, GFP_KERNEL | GFP_DMA, &next_handle);
+		if (next == NULL)
+			goto done_alloc;
+		
+		clear_desc(next);
+		next->MyDMAAddr = next_handle;
+		
+		cur->DescNextDescPtr = next_handle;
+		cur->Next = next;
+		cur = next;
+	}
+	
+ done_alloc:
+	// Link the last descriptor back to the first, so it's a circular linked list
+	cur->Next = eng->desc_pool_first;
+	cur->DescNextDescPtr = eng->desc_pool_first->MyDMAAddr;
+	
+	eng->desc_pool_last = cur;
+	eng->desc_completed = eng->desc_pool_last;
+	
+	// Setup work queue
+	INIT_WORK(&eng->irq_work, ndd_irq_worker);
+	
+	// Grab IRQ line
+	rv = request_irq(eng->irq, ndd_irq_handler, IRQF_SHARED, KP_DRIVER_NAME_DMA_CONTROLLER, eng);
+	if (rv){
+		dev_err(&eng->pldev->dev, "setup_dma_engine: failed to request_irq: %d\n", rv);
+		return rv;
+	}
+	
+	// Turn on the engine!
+	start_dma_engine(eng);
+	unlock_engine(eng);
+	
+	return 0;
+}
+
+void  stop_dma_engine(struct kpc_dma_device *eng)
+{
+	unsigned long timeout;
+	dev_dbg(&eng->pldev->dev, "Destroying DMA engine [%p]\n", eng);
+	
+	// Disable the descriptor engine
+	WriteEngineControl(eng, 0);
+	
+	// Wait for descriptor engine to finish current operaion
+	timeout = jiffies + (HZ / 2);
+	while (GetEngineControl(eng) & ENG_CTL_DMA_RUNNING){
+		if (time_after(jiffies, timeout)){
+			dev_crit(&eng->pldev->dev, "DMA_RUNNING still asserted!\n");
+			break;
+		}
+	}
+	
+	// Request a reset
+	WriteEngineControl(eng, ENG_CTL_DMA_RESET_REQUEST);
+	
+	// Wait for reset request to be processed
+	timeout = jiffies + (HZ / 2);
+	while (GetEngineControl(eng) & (ENG_CTL_DMA_RUNNING | ENG_CTL_DMA_RESET_REQUEST)){
+		if (time_after(jiffies, timeout)){
+			dev_crit(&eng->pldev->dev, "ENG_CTL_DMA_RESET_REQUEST still asserted!\n");
+			break;
+		}
+	}
+	
+	// Request a reset
+	WriteEngineControl(eng, ENG_CTL_DMA_RESET);
+	
+	// And wait for reset to complete
+	timeout = jiffies + (HZ / 2);
+	while (GetEngineControl(eng) & ENG_CTL_DMA_RESET){
+		if (time_after(jiffies, timeout)){
+			dev_crit(&eng->pldev->dev, "DMA_RESET still asserted!\n");
+			break;
+		}
+	}
+	
+	// Clear any persistent bits just to make sure there is no residue from the reset
+	SetClearEngineControl(eng, (ENG_CTL_IRQ_ACTIVE | ENG_CTL_DESC_COMPLETE | ENG_CTL_DESC_ALIGN_ERR | ENG_CTL_DESC_FETCH_ERR | ENG_CTL_SW_ABORT_ERR | ENG_CTL_DESC_CHAIN_END | ENG_CTL_DMA_WAITING_PERSIST), 0);
+	
+	// Reset performance counters
+	
+	// Completely disable the engine
+	WriteEngineControl(eng, 0);
+}
+
+void  destroy_dma_engine(struct kpc_dma_device *eng)
+{
+	struct kpc_dma_descriptor * cur;
+	dma_addr_t cur_handle;
+	unsigned int i;
+	
+	stop_dma_engine(eng);
+	
+	cur = eng->desc_pool_first;
+	cur_handle = eng->desc_pool_first->MyDMAAddr;
+	
+	for (i = 0 ; i < eng->desc_pool_cnt ; i++){
+		struct kpc_dma_descriptor *next = cur->Next;
+		dma_addr_t next_handle = cur->DescNextDescPtr;
+		dma_pool_free(eng->desc_pool, cur, cur_handle);
+		cur_handle = next_handle;
+		cur = next;
+	}
+	
+	dma_pool_destroy(eng->desc_pool);
+	
+	free_irq(eng->irq, eng);
+}
+
+
+
+/**********  Helper Functions  **********/
+int  count_descriptors_available(struct kpc_dma_device *eng)
+{
+	u32 count = 0;
+	struct kpc_dma_descriptor *cur = eng->desc_next;
+	while (cur != eng->desc_completed){
+		BUG_ON(cur == NULL);
+		count++;
+		cur = cur->Next;
+	}
+	return count;
+}
+
+void  clear_desc(struct kpc_dma_descriptor *desc)
+{
+	if (desc == NULL)
+		return;
+	desc->DescByteCount         = 0;
+	desc->DescStatusErrorFlags  = 0;
+	desc->DescStatusFlags       = 0;
+	desc->DescUserControlLS     = 0;
+	desc->DescUserControlMS     = 0;
+	desc->DescCardAddrLS        = 0;
+	desc->DescBufferByteCount   = 0;
+	desc->DescCardAddrMS        = 0;
+	desc->DescControlFlags      = 0;
+	desc->DescSystemAddrLS      = 0;
+	desc->DescSystemAddrMS      = 0;
+	desc->acd = NULL;
+}
diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
new file mode 100644
index 000000000000..5741d2b49a7d
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -0,0 +1,420 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>   /* printk() */
+#include <linux/slab.h>     /* kmalloc() */
+#include <linux/fs.h>       /* everything... */
+#include <linux/errno.h>    /* error codes */
+#include <linux/types.h>    /* size_t */
+#include <linux/cdev.h>
+#include <asm/uaccess.h>    /* copy_*_user */
+#include <linux/aio.h>      /* aio stuff */
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include "kpc_dma_driver.h"
+#include "uapi.h"
+
+/**********  Helper Functions  **********/
+static inline
+unsigned int  count_pages(unsigned long iov_base, size_t iov_len)
+{
+	unsigned long first = (iov_base             & PAGE_MASK) >> PAGE_SHIFT;
+	unsigned long last  = ((iov_base+iov_len-1) & PAGE_MASK) >> PAGE_SHIFT;
+	return last - first + 1;
+}
+
+static inline
+unsigned int  count_parts_for_sge(struct scatterlist *sg)
+{
+	unsigned int sg_length = sg_dma_len(sg);
+	sg_length += (0x80000-1);
+	return (sg_length / 0x80000);
+}
+
+/**********  Transfer Helpers  **********/
+static
+int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned long iov_base, size_t iov_len)
+{
+	unsigned int i = 0;
+	long rv = 0;
+	struct kpc_dma_device *ldev;
+	struct aio_cb_data *acd;
+	DECLARE_COMPLETION_ONSTACK(done);
+	u32 desc_needed = 0;
+	struct scatterlist *sg;
+	u32 num_descrs_avail;
+	struct kpc_dma_descriptor *desc;
+	unsigned int pcnt;
+	unsigned int p;
+	u64 card_addr;
+	u64 dma_addr;
+	u64 user_ctl;
+	
+	BUG_ON(priv == NULL);
+	ldev = priv->ldev;
+	BUG_ON(ldev == NULL);
+	
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_transfer(priv = [%p], kcb = [%p], iov_base = [%p], iov_len = %ld) ldev = [%p]\n", priv, kcb, (void*)iov_base, iov_len, ldev);
+	
+	acd = (struct aio_cb_data *) kzalloc(sizeof(struct aio_cb_data), GFP_KERNEL);
+	if (!acd){
+		dev_err(&priv->ldev->pldev->dev, "Couldn't kmalloc space for for the aio data\n");
+		return -ENOMEM;
+	}
+	memset(acd, 0x66, sizeof(struct aio_cb_data));
+	
+	acd->priv = priv;
+	acd->ldev = priv->ldev;
+	acd->cpl = &done;
+	acd->flags = 0;
+	acd->kcb = kcb;
+	acd->len = iov_len;
+	acd->page_count = count_pages(iov_base, iov_len);
+	
+	// Allocate an array of page pointers
+	acd->user_pages = kzalloc(sizeof(struct page *) * acd->page_count, GFP_KERNEL);
+	if (!acd->user_pages){
+		dev_err(&priv->ldev->pldev->dev, "Couldn't kmalloc space for for the page pointers\n");
+		rv = -ENOMEM;
+		goto err_alloc_userpages;
+	}
+	
+	// Lock the user buffer pages in memory, and hold on to the page pointers (for the sglist)
+	down_read(&current->mm->mmap_sem);      /*  get memory map semaphore */
+	rv = get_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE | FOLL_GET, acd->user_pages, NULL);
+	up_read(&current->mm->mmap_sem);        /*  release the semaphore */
+	if (rv != acd->page_count){
+		dev_err(&priv->ldev->pldev->dev, "Couldn't get_user_pages (%ld)\n", rv);
+		goto err_get_user_pages;
+	}
+	
+	// Allocate and setup the sg_table (scatterlist entries)
+	rv = sg_alloc_table_from_pages(&acd->sgt, acd->user_pages, acd->page_count, iov_base & (PAGE_SIZE-1), iov_len, GFP_KERNEL);
+	if (rv){
+		dev_err(&priv->ldev->pldev->dev, "Couldn't alloc sg_table (%ld)\n", rv);
+		goto err_alloc_sg_table;
+	}
+	
+	// Setup the DMA mapping for all the sg entries
+	acd->mapped_entry_count = dma_map_sg(&ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, ldev->dir);
+	if (acd->mapped_entry_count <= 0){
+		dev_err(&priv->ldev->pldev->dev, "Couldn't dma_map_sg (%d)\n", acd->mapped_entry_count);
+		goto err_dma_map_sg;
+	}
+
+	// Calculate how many descriptors are actually needed for this transfer.
+	for_each_sg(acd->sgt.sgl, sg, acd->mapped_entry_count, i){
+		desc_needed += count_parts_for_sge(sg);
+	}
+	
+	lock_engine(ldev);
+	
+	// Figoure out how many descriptors are available and return an error if there aren't enough
+	num_descrs_avail = count_descriptors_available(ldev);
+	dev_dbg(&priv->ldev->pldev->dev, "    mapped_entry_count = %d    num_descrs_needed = %d    num_descrs_avail = %d\n", acd->mapped_entry_count, desc_needed, num_descrs_avail);
+	if (desc_needed >= ldev->desc_pool_cnt){
+		dev_warn(&priv->ldev->pldev->dev, "    mapped_entry_count = %d    num_descrs_needed = %d    num_descrs_avail = %d    TOO MANY to ever complete!\n", acd->mapped_entry_count, desc_needed, num_descrs_avail);
+		rv = -EAGAIN;
+		unlock_engine(ldev);
+		goto err_descr_too_many;
+	}
+	if (desc_needed > num_descrs_avail){
+		dev_warn(&priv->ldev->pldev->dev, "    mapped_entry_count = %d    num_descrs_needed = %d    num_descrs_avail = %d    Too many to complete right now.\n", acd->mapped_entry_count, desc_needed, num_descrs_avail);
+		rv = -EMSGSIZE;
+		unlock_engine(ldev);
+		goto err_descr_too_many;
+	}
+
+	// Loop through all the sg table entries and fill out a descriptor for each one.
+	desc = ldev->desc_next;
+	card_addr = acd->priv->card_addr;
+	for_each_sg(acd->sgt.sgl, sg, acd->mapped_entry_count, i){
+		pcnt = count_parts_for_sge(sg);
+		for (p = 0 ; p < pcnt ; p++){
+			// Fill out the descriptor
+			BUG_ON(desc == NULL);
+			clear_desc(desc);
+			if (p != pcnt-1){
+				desc->DescByteCount = 0x80000;
+			} else {
+				desc->DescByteCount = sg_dma_len(sg) - (p * 0x80000);
+			}
+			desc->DescBufferByteCount = desc->DescByteCount;
+			
+			desc->DescControlFlags |= DMA_DESC_CTL_IRQONERR;
+			if (i == 0 && p == 0)
+				desc->DescControlFlags |= DMA_DESC_CTL_SOP;
+			if (i == acd->mapped_entry_count-1 && p == pcnt-1)
+				desc->DescControlFlags |= DMA_DESC_CTL_EOP | DMA_DESC_CTL_IRQONDONE;
+			
+			desc->DescCardAddrLS = (card_addr & 0xFFFFFFFF);
+			desc->DescCardAddrMS = (card_addr >> 32) & 0xF;
+			card_addr += desc->DescByteCount;
+			
+			dma_addr  = sg_dma_address(sg) + (p * 0x80000);
+			desc->DescSystemAddrLS = (dma_addr & 0x00000000FFFFFFFF) >>  0;
+			desc->DescSystemAddrMS = (dma_addr & 0xFFFFFFFF00000000) >> 32;
+			
+			user_ctl = acd->priv->user_ctl;
+			if (i == acd->mapped_entry_count-1 && p == pcnt-1){
+				user_ctl = acd->priv->user_ctl_last;
+			}
+			desc->DescUserControlLS = (user_ctl & 0x00000000FFFFFFFF) >>  0;
+			desc->DescUserControlMS = (user_ctl & 0xFFFFFFFF00000000) >> 32;
+			
+			if (i == acd->mapped_entry_count-1 && p == pcnt-1)
+				desc->acd = acd;
+			
+			dev_dbg(&priv->ldev->pldev->dev, "  Filled descriptor %p (acd = %p)\n", desc, desc->acd);
+			
+			ldev->desc_next = desc->Next;
+			desc = desc->Next;
+		}
+	}
+	
+	// Send the filled descriptors off to the hardware to process!
+	SetEngineSWPtr(ldev, ldev->desc_next);
+	
+	unlock_engine(ldev);
+	
+	// If this is a synchronous kiocb, we need to put the calling process to sleep until the transfer is complete
+	if (kcb == NULL || is_sync_kiocb(kcb)){
+		rv = wait_for_completion_interruptible(&done);
+		// If the user aborted (rv == -ERESTARTSYS), we're no longer responsible for cleaning up the acd
+		if (rv == -ERESTARTSYS){
+			acd->cpl = NULL;
+		}
+		if (rv == 0){
+			rv = acd->len;
+			kfree(acd);
+		}
+		return rv;
+	}
+	
+	return -EIOCBQUEUED;
+
+ err_descr_too_many:
+	unlock_engine(ldev);
+	dma_unmap_sg(&ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, ldev->dir);
+	sg_free_table(&acd->sgt);
+ err_dma_map_sg:
+ err_alloc_sg_table:
+	for (i = 0 ; i < acd->page_count ; i++){
+		put_page(acd->user_pages[i]);
+	}
+ err_get_user_pages:
+	kfree(acd->user_pages);
+ err_alloc_userpages:
+	kfree(acd);
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_transfer returning with error %ld\n", rv);
+	return rv;
+}
+
+void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
+{
+	unsigned int i;
+	
+	BUG_ON(acd == NULL);
+	BUG_ON(acd->user_pages == NULL);
+	BUG_ON(acd->sgt.sgl == NULL);
+	BUG_ON(acd->ldev == NULL);
+	BUG_ON(acd->ldev->pldev == NULL);
+	
+	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
+	
+	for (i = 0 ; i < acd->page_count ; i++){
+		if (!PageReserved(acd->user_pages[i])){
+			set_page_dirty(acd->user_pages[i]);
+		}
+	}
+	
+	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
+	
+	for (i = 0 ; i < acd->page_count ; i++){
+		put_page(acd->user_pages[i]);
+	}
+	
+	sg_free_table(&acd->sgt);
+	
+	kfree(acd->user_pages);
+	
+	acd->flags = flags;
+	
+	if (acd->kcb == NULL || is_sync_kiocb(acd->kcb)){
+		if (acd->cpl){
+			complete(acd->cpl);
+		} else {
+			// There's no completion, so we're responsible for cleaning up the acd
+			kfree(acd);
+		}
+	} else {
+#ifdef CONFIG_KPC_DMA_AIO
+		aio_complete(acd->kcb, acd->len, acd->flags);
+#endif
+		kfree(acd);
+	}
+}
+
+/**********  Fileops  **********/
+static
+int  kpc_dma_open(struct inode *inode, struct file *filp)
+{
+	struct dev_private_data *priv;
+	struct kpc_dma_device *ldev = kpc_dma_lookup_device(iminor(inode));
+	if (ldev == NULL)
+		return -ENODEV;
+	
+	if (! atomic_dec_and_test(&ldev->open_count)){
+		atomic_inc(&ldev->open_count);
+		return -EBUSY; /* already open */
+	}
+	
+	priv = kzalloc(sizeof(struct dev_private_data), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	
+	priv->ldev = ldev;
+	filp->private_data = priv;
+	
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_open(inode = [%p], filp = [%p]) priv = [%p] ldev = [%p]\n", inode, filp, priv, priv->ldev);
+	return 0;
+}
+
+static
+int  kpc_dma_close(struct inode *inode, struct file *filp)
+{
+	struct kpc_dma_descriptor *cur;
+	struct dev_private_data *priv = (struct dev_private_data *)filp->private_data;
+	struct kpc_dma_device *eng = priv->ldev;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_close(inode = [%p], filp = [%p]) priv = [%p], ldev = [%p]\n", inode, filp, priv, priv->ldev);
+	
+	lock_engine(eng);
+	
+	stop_dma_engine(eng);
+	
+	cur = eng->desc_completed->Next;
+	while (cur != eng->desc_next){
+		dev_dbg(&eng->pldev->dev, "Aborting descriptor %p (acd = %p)\n", cur, cur->acd);
+		if (cur->DescControlFlags & DMA_DESC_CTL_EOP){
+			if (cur->acd)
+				transfer_complete_cb(cur->acd, 0, ACD_FLAG_ABORT);
+		}
+		
+		clear_desc(cur);
+		eng->desc_completed = cur;
+		
+		cur = cur->Next;
+	}
+	
+	start_dma_engine(eng);
+	
+	unlock_engine(eng);
+	
+	atomic_inc(&priv->ldev->open_count); /* release the device */
+	kfree(priv);
+	return 0;
+}
+
+#ifdef CONFIG_KPC_DMA_AIO
+static
+int  kpc_dma_aio_cancel(struct kiocb *kcb)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)kcb->ki_filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_aio_cancel(kcb = [%p]) priv = [%p], ldev = [%p]\n", kcb, priv, priv->ldev);
+	return 0;
+}
+
+static
+ssize_t   kpc_dma_aio_read(struct kiocb *kcb, const struct iovec *iov, unsigned long iov_count, loff_t pos)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)kcb->ki_filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_aio_read(kcb = [%p], iov = [%p], iov_count = %ld, pos = %lld) priv = [%p], ldev = [%p]\n", kcb, iov, iov_count, pos, priv, priv->ldev);
+	
+	if (priv->ldev->dir != DMA_FROM_DEVICE)
+		return -EMEDIUMTYPE;
+	
+	if (iov_count != 1){
+		dev_err(&priv->ldev->pldev->dev, "kpc_dma_aio_read() called with iov_count > 1!\n");
+		return -EFAULT;
+	}
+	
+	if (!is_sync_kiocb(kcb))
+		kiocb_set_cancel_fn(kcb, kpc_dma_aio_cancel);
+	return kpc_dma_transfer(priv, kcb, (unsigned long)iov->iov_base, iov->iov_len);
+}
+
+static
+ssize_t  kpc_dma_aio_write(struct kiocb *kcb, const struct iovec *iov, unsigned long iov_count, loff_t pos)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)kcb->ki_filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_aio_write(kcb = [%p], iov = [%p], iov_count = %ld, pos = %lld) priv = [%p], ldev = [%p]\n", kcb, iov, iov_count, pos, priv, priv->ldev);
+	
+	if (priv->ldev->dir != DMA_TO_DEVICE)
+		return -EMEDIUMTYPE;
+	
+	if (iov_count != 1){
+		dev_err(&priv->ldev->pldev->dev, "kpc_dma_aio_write() called with iov_count > 1!\n");
+		return -EFAULT;
+	}
+	
+	if (!is_sync_kiocb(kcb))
+		kiocb_set_cancel_fn(kcb, kpc_dma_aio_cancel);
+	return kpc_dma_transfer(priv, kcb, (unsigned long)iov->iov_base, iov->iov_len);
+}
+#endif
+
+static
+ssize_t  kpc_dma_read( struct file *filp,       char __user *user_buf, size_t count, loff_t *ppos)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_read(filp = [%p], user_buf = [%p], count = %zu, ppos = [%p]) priv = [%p], ldev = [%p]\n", filp, user_buf, count, ppos, priv, priv->ldev);
+	
+	if (priv->ldev->dir != DMA_FROM_DEVICE)
+		return -EMEDIUMTYPE;
+	
+	return kpc_dma_transfer(priv, (struct kiocb *)NULL, (unsigned long)user_buf, count);
+}
+
+static
+ssize_t  kpc_dma_write(struct file *filp, const char __user *user_buf, size_t count, loff_t *ppos)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_write(filp = [%p], user_buf = [%p], count = %zu, ppos = [%p]) priv = [%p], ldev = [%p]\n", filp, user_buf, count, ppos, priv, priv->ldev);
+	
+	if (priv->ldev->dir != DMA_TO_DEVICE)
+		return -EMEDIUMTYPE;
+	
+	return kpc_dma_transfer(priv, (struct kiocb *)NULL, (unsigned long)user_buf, count);
+}
+
+static
+long  kpc_dma_ioctl(struct file *filp, unsigned int ioctl_num, unsigned long ioctl_param)
+{
+	struct dev_private_data *priv = (struct dev_private_data *)filp->private_data;
+	dev_dbg(&priv->ldev->pldev->dev, "kpc_dma_ioctl(filp = [%p], ioctl_num = 0x%x, ioctl_param = 0x%lx) priv = [%p], ldev = [%p]\n", filp, ioctl_num, ioctl_param, priv, priv->ldev);
+	
+	switch (ioctl_num){
+		case KND_IOCTL_SET_CARD_ADDR:           priv->card_addr  = ioctl_param; return priv->card_addr; 
+		case KND_IOCTL_SET_USER_CTL:            priv->user_ctl   = ioctl_param; return priv->user_ctl; 
+		case KND_IOCTL_SET_USER_CTL_LAST:       priv->user_ctl_last = ioctl_param; return priv->user_ctl_last; 
+		case KND_IOCTL_GET_USER_STS:            return priv->user_sts;
+	}
+	
+	return -ENOTTY;
+}
+
+
+struct file_operations  kpc_dma_fops = {
+	.owner      = THIS_MODULE,
+	.open           = kpc_dma_open,
+	.release        = kpc_dma_close,
+	.read           = kpc_dma_read,
+	.write          = kpc_dma_write,
+#ifdef CONFIG_KPC_DMA_AIO
+	.aio_read       = kpc_dma_aio_read,
+	.aio_write      = kpc_dma_aio_write,
+#endif
+	.unlocked_ioctl = kpc_dma_ioctl,
+};
+
diff --git a/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c b/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c
new file mode 100644
index 000000000000..aeae58d9bc18
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c
@@ -0,0 +1,248 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <asm/io.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/fs.h>
+#include <linux/rwsem.h>
+#include "kpc_dma_driver.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Matt.Sickler@daktronics.com");
+
+#define KPC_DMA_CHAR_MAJOR    UNNAMED_MAJOR
+#define KPC_DMA_NUM_MINORS    1 << MINORBITS
+static DEFINE_MUTEX(kpc_dma_mtx);
+static int assigned_major_num;
+static LIST_HEAD(kpc_dma_list);
+
+
+/**********  kpc_dma_list list management  **********/
+struct kpc_dma_device *  kpc_dma_lookup_device(int minor)
+{
+	struct kpc_dma_device *c;
+	mutex_lock(&kpc_dma_mtx);
+	list_for_each_entry(c, &kpc_dma_list, list) {
+		if (c->pldev->id == minor) {
+			goto out;
+		}
+	}
+	c = NULL; // not-found case
+  out:
+	mutex_unlock(&kpc_dma_mtx);
+	return c;
+}
+
+void  kpc_dma_add_device(struct kpc_dma_device * ldev)
+{
+	mutex_lock(&kpc_dma_mtx);
+	list_add(&ldev->list, &kpc_dma_list);
+	mutex_unlock(&kpc_dma_mtx);
+}
+
+void kpc_dma_del_device(struct kpc_dma_device * ldev)
+{
+	mutex_lock(&kpc_dma_mtx);
+	list_del(&ldev->list);
+	mutex_unlock(&kpc_dma_mtx);
+}
+
+/**********  SysFS Attributes **********/
+static ssize_t  show_engine_regs(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct kpc_dma_device *ldev;
+	struct platform_device *pldev = to_platform_device(dev);
+	if (!pldev) return 0;
+	ldev = platform_get_drvdata(pldev);
+	if (!ldev) return 0;
+	
+	return scnprintf(buf, PAGE_SIZE, 
+		"EngineControlStatus      = 0x%08x\n"
+		"RegNextDescPtr           = 0x%08x\n"
+		"RegSWDescPtr             = 0x%08x\n"
+		"RegCompletedDescPtr      = 0x%08x\n"
+		"desc_pool_first          = %p\n"
+		"desc_pool_last           = %p\n"
+		"desc_next                = %p\n"
+		"desc_completed           = %p\n",
+		readl(ldev->eng_regs + 1),
+		readl(ldev->eng_regs + 2),
+		readl(ldev->eng_regs + 3),
+		readl(ldev->eng_regs + 4),
+		ldev->desc_pool_first,
+		ldev->desc_pool_last,
+		ldev->desc_next,
+		ldev->desc_completed
+	);
+}
+DEVICE_ATTR(engine_regs, 0444, show_engine_regs, NULL);
+
+static const struct attribute *  ndd_attr_list[] = {
+	&dev_attr_engine_regs.attr,
+	NULL,
+};
+
+struct class *kpc_dma_class;
+
+
+/**********  Platform Driver Functions  **********/
+static
+int  kpc_dma_probe(struct platform_device *pldev)
+{
+	struct resource *r = NULL;
+	int rv = 0;
+	dev_t dev;
+	
+	struct kpc_dma_device *ldev = kzalloc(sizeof(struct kpc_dma_device), GFP_KERNEL);
+	if (!ldev){
+		dev_err(&pldev->dev, "kpc_dma_probe: unable to kzalloc space for kpc_dma_device\n");
+		rv = -ENOMEM;
+		goto err_rv;
+	}
+	
+	dev_dbg(&pldev->dev, "kpc_dma_probe(pldev = [%p]) ldev = [%p]\n", pldev, ldev);
+	
+	INIT_LIST_HEAD(&ldev->list);
+	
+	ldev->pldev = pldev;
+	platform_set_drvdata(pldev, ldev);
+	atomic_set(&ldev->open_count, 1);
+	
+	mutex_init(&ldev->sem);
+	lock_engine(ldev);
+	
+	// Get Engine regs resource
+	r = platform_get_resource(pldev, IORESOURCE_MEM, 0);
+	if (!r){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: didn't get the engine regs resource!\n");
+		rv = -ENXIO;
+		goto err_kfree;
+	}
+	ldev->eng_regs = ioremap_nocache(r->start, resource_size(r));
+	if (!ldev->eng_regs){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: failed to ioremap engine regs!\n");
+		rv = -ENXIO;
+		goto err_kfree;
+	}
+	
+	r = platform_get_resource(pldev, IORESOURCE_IRQ, 0);
+	if (!r){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: didn't get the IRQ resource!\n");
+		rv = -ENXIO;
+		goto err_kfree;
+	}
+	ldev->irq = r->start;
+	
+	// Setup miscdev struct
+	dev = MKDEV(assigned_major_num, pldev->id);
+	ldev->kpc_dma_dev = device_create(kpc_dma_class, &pldev->dev, dev, ldev, "kpc_dma%d", pldev->id);
+	if (IS_ERR(ldev->kpc_dma_dev)){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: device_create failed: %d\n", rv);
+		goto err_kfree;
+	}
+	
+	// Setup the DMA engine
+	rv = setup_dma_engine(ldev, 30);
+	if (rv){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: failed to setup_dma_engine: %d\n", rv);
+		goto err_misc_dereg;
+	}
+	
+	// Setup the sysfs files
+	rv = sysfs_create_files(&(ldev->pldev->dev.kobj), ndd_attr_list);
+	if (rv){
+		dev_err(&ldev->pldev->dev, "kpc_dma_probe: Failed to add sysfs files: %d\n", rv);
+		goto err_destroy_eng;
+	}
+	
+	kpc_dma_add_device(ldev);
+	
+	return 0;
+	
+ err_destroy_eng:
+	destroy_dma_engine(ldev);
+ err_misc_dereg:
+	device_destroy(kpc_dma_class, dev);
+ err_kfree:
+	kfree(ldev);
+ err_rv:
+	return rv;
+}
+
+static
+int  kpc_dma_remove(struct platform_device *pldev)
+{
+	struct kpc_dma_device *ldev = platform_get_drvdata(pldev);
+	if (!ldev)
+		return -ENXIO;
+	
+	dev_dbg(&ldev->pldev->dev, "kpc_dma_remove(pldev = [%p]) ldev = [%p]\n", pldev, ldev);
+	
+	lock_engine(ldev);
+	sysfs_remove_files(&(ldev->pldev->dev.kobj), ndd_attr_list);
+	destroy_dma_engine(ldev);
+	kpc_dma_del_device(ldev);
+	device_destroy(kpc_dma_class, MKDEV(assigned_major_num, ldev->pldev->id));
+	kfree(ldev);
+	
+	return 0;
+}
+
+
+/**********  Driver Functions  **********/
+struct platform_driver kpc_dma_plat_driver_i = {
+	.probe        = kpc_dma_probe,
+	.remove       = kpc_dma_remove,
+	.driver = {
+		.name   = KP_DRIVER_NAME_DMA_CONTROLLER,
+		.owner  = THIS_MODULE,
+	},
+};
+
+static
+int __init  kpc_dma_driver_init(void)
+{
+	int err;
+	
+	err = __register_chrdev(KPC_DMA_CHAR_MAJOR, 0, KPC_DMA_NUM_MINORS, "kpc_dma", &kpc_dma_fops);
+	if (err < 0){
+		pr_err("Can't allocate a major number (%d) for kpc_dma (err = %d)\n", KPC_DMA_CHAR_MAJOR, err);
+		goto fail_chrdev_register;
+	}
+	assigned_major_num = err;
+	
+	kpc_dma_class = class_create(THIS_MODULE, "kpc_dma");
+	err = PTR_ERR(kpc_dma_class);
+	if (IS_ERR(kpc_dma_class)){
+		pr_err("Can't create class kpc_dma (err = %d)\n", err);
+		goto fail_class_create;
+	}
+	
+	err = platform_driver_register(&kpc_dma_plat_driver_i);
+	if (err){
+		pr_err("Can't register platform driver for kpc_dma (err = %d)\n", err);
+		goto fail_platdriver_register;
+	}
+	
+	return err;
+	
+  fail_platdriver_register:
+	class_destroy(kpc_dma_class);
+  fail_class_create:
+	__unregister_chrdev(KPC_DMA_CHAR_MAJOR, 0, KPC_DMA_NUM_MINORS, "kpc_dma");
+  fail_chrdev_register:
+	return err;
+}
+module_init(kpc_dma_driver_init);
+
+static
+void __exit  kpc_dma_driver_exit(void)
+{
+	platform_driver_unregister(&kpc_dma_plat_driver_i);
+	class_destroy(kpc_dma_class);
+	__unregister_chrdev(KPC_DMA_CHAR_MAJOR, 0, KPC_DMA_NUM_MINORS, "kpc_dma");
+}
+module_exit(kpc_dma_driver_exit);
diff --git a/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.h b/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.h
new file mode 100644
index 000000000000..ef913b7496e6
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.h
@@ -0,0 +1,220 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef KPC_DMA_DRIVER_H
+#define KPC_DMA_DRIVER_H
+#include <linux/platform_device.h>
+#include <linux/cdev.h>
+#include <linux/kfifo.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+#include <linux/miscdevice.h>
+#include <linux/rwsem.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/aio.h>
+#include <linux/bitops.h>
+#include "../kpc.h"
+
+
+struct kp2000_device;
+struct kpc_dma_device {
+	struct list_head            list;
+	struct platform_device     *pldev;
+	u32 __iomem                *eng_regs;
+	struct device              *kpc_dma_dev;
+	struct kobject              kobj;
+	char                        name[16];
+	
+	int                         dir; // DMA_FROM_DEVICE || DMA_TO_DEVICE
+	struct mutex                sem;
+	unsigned int                irq;
+	struct work_struct          irq_work;
+	
+	atomic_t                    open_count;
+	
+	size_t                      accumulated_bytes;
+	u32                         accumulated_flags;
+	
+	// Descriptor "Pool" housekeeping
+	u32                         desc_pool_cnt;
+	struct dma_pool            *desc_pool;
+	struct kpc_dma_descriptor  *desc_pool_first;
+	struct kpc_dma_descriptor  *desc_pool_last;
+	
+	struct kpc_dma_descriptor  *desc_next;
+	struct kpc_dma_descriptor  *desc_completed;
+};
+
+struct dev_private_data {
+	struct kpc_dma_device      *ldev;
+	u64                         card_addr;
+	u64                         user_ctl;
+	u64                         user_ctl_last;
+	u64                         user_sts;
+};
+
+struct kpc_dma_device *  kpc_dma_lookup_device(int minor);
+
+extern struct file_operations  kpc_dma_fops;
+
+#define ENG_CAP_PRESENT                 0x00000001
+#define ENG_CAP_DIRECTION               0x00000002
+#define ENG_CAP_TYPE_MASK               0x000000F0
+#define ENG_CAP_NUMBER_MASK             0x0000FF00
+#define ENG_CAP_CARD_ADDR_SIZE_MASK     0x007F0000
+#define ENG_CAP_DESC_MAX_BYTE_CNT_MASK  0x3F000000
+#define ENG_CAP_PERF_SCALE_MASK         0xC0000000
+
+#define ENG_CTL_IRQ_ENABLE              BIT(0)
+#define ENG_CTL_IRQ_ACTIVE              BIT(1)
+#define ENG_CTL_DESC_COMPLETE           BIT(2)
+#define ENG_CTL_DESC_ALIGN_ERR          BIT(3)
+#define ENG_CTL_DESC_FETCH_ERR          BIT(4)
+#define ENG_CTL_SW_ABORT_ERR            BIT(5)
+#define ENG_CTL_DESC_CHAIN_END          BIT(7)
+#define ENG_CTL_DMA_ENABLE              BIT(8)
+#define ENG_CTL_DMA_RUNNING             BIT(10)
+#define ENG_CTL_DMA_WAITING             BIT(11)
+#define ENG_CTL_DMA_WAITING_PERSIST     BIT(12)
+#define ENG_CTL_DMA_RESET_REQUEST       BIT(14)
+#define ENG_CTL_DMA_RESET               BIT(15)
+#define ENG_CTL_DESC_FETCH_ERR_CLASS_MASK   0x700000
+
+struct aio_cb_data {
+	struct dev_private_data    *priv;
+	struct kpc_dma_device      *ldev;
+	struct completion  *cpl;
+	unsigned char       flags;
+	struct kiocb       *kcb;
+	size_t              len;
+	
+	unsigned int        page_count;
+	struct page       **user_pages;
+	struct sg_table     sgt;
+	int                 mapped_entry_count;
+};
+
+#define ACD_FLAG_DONE               0
+#define ACD_FLAG_ABORT              1
+#define ACD_FLAG_ENG_ACCUM_ERROR    4
+#define ACD_FLAG_ENG_ACCUM_SHORT    5
+
+struct kpc_dma_descriptor {
+	struct {
+		volatile u32  DescByteCount              :20;
+		volatile u32  DescStatusErrorFlags       :4;
+		volatile u32  DescStatusFlags            :8;
+	};
+		volatile u32  DescUserControlLS;
+		volatile u32  DescUserControlMS;
+		volatile u32  DescCardAddrLS;
+	struct {
+		volatile u32  DescBufferByteCount        :20;
+		volatile u32  DescCardAddrMS             :4;
+		volatile u32  DescControlFlags           :8;
+	};
+		volatile u32  DescSystemAddrLS;
+		volatile u32  DescSystemAddrMS;
+		volatile u32  DescNextDescPtr;
+		
+		dma_addr_t    MyDMAAddr;
+		struct kpc_dma_descriptor   *Next;
+		
+		struct aio_cb_data  *acd;
+} __attribute__((packed));
+// DescControlFlags:
+#define DMA_DESC_CTL_SOP            BIT(7)
+#define DMA_DESC_CTL_EOP            BIT(6)
+#define DMA_DESC_CTL_AFIFO          BIT(2)
+#define DMA_DESC_CTL_IRQONERR       BIT(1)
+#define DMA_DESC_CTL_IRQONDONE      BIT(0)
+// DescStatusFlags:
+#define DMA_DESC_STS_SOP            BIT(7)
+#define DMA_DESC_STS_EOP            BIT(6)
+#define DMA_DESC_STS_ERROR          BIT(4)
+#define DMA_DESC_STS_USMSZ          BIT(3)
+#define DMA_DESC_STS_USLSZ          BIT(2)
+#define DMA_DESC_STS_SHORT          BIT(1)
+#define DMA_DESC_STS_COMPLETE       BIT(0)
+// DescStatusErrorFlags:
+#define DMA_DESC_ESTS_ECRC          BIT(2)
+#define DMA_DESC_ESTS_POISON        BIT(1)
+#define DMA_DESC_ESTS_UNSUCCESSFUL  BIT(0)
+
+#define DMA_DESC_ALIGNMENT          0x20
+
+static inline
+u32  GetEngineCapabilities(struct kpc_dma_device *eng)
+{
+	return readl(eng->eng_regs + 0);
+}
+
+static inline
+void  WriteEngineControl(struct kpc_dma_device *eng, u32 value)
+{
+	writel(value, eng->eng_regs + 1);
+}
+static inline
+u32  GetEngineControl(struct kpc_dma_device *eng)
+{
+	return readl(eng->eng_regs + 1);
+}
+static inline
+void  SetClearEngineControl(struct kpc_dma_device *eng, u32 set_bits, u32 clear_bits)
+{
+	u32 val = GetEngineControl(eng);
+	val |= set_bits;
+	val &= ~clear_bits;
+	WriteEngineControl(eng, val);
+}
+
+static inline
+void  SetEngineNextPtr(struct kpc_dma_device *eng, struct kpc_dma_descriptor * desc)
+{
+	writel(desc->MyDMAAddr, eng->eng_regs + 2);
+}
+static inline
+void  SetEngineSWPtr(struct kpc_dma_device *eng, struct kpc_dma_descriptor * desc)
+{
+	writel(desc->MyDMAAddr, eng->eng_regs + 3);
+}
+static inline
+void  ClearEngineCompletePtr(struct kpc_dma_device *eng)
+{
+	writel(0, eng->eng_regs + 4);
+}
+static inline
+u32  GetEngineCompletePtr(struct kpc_dma_device *eng)
+{
+	return readl(eng->eng_regs + 4);
+}
+
+static inline
+void  lock_engine(struct kpc_dma_device *eng)
+{
+	BUG_ON(eng == NULL);
+	mutex_lock(&eng->sem);
+}
+
+static inline
+void  unlock_engine(struct kpc_dma_device *eng)
+{
+	BUG_ON(eng == NULL);
+	mutex_unlock(&eng->sem);
+}
+
+
+/// Shared Functions
+void  start_dma_engine(struct kpc_dma_device *eng);
+int   setup_dma_engine(struct kpc_dma_device *eng, u32 desc_cnt);
+void  stop_dma_engine(struct kpc_dma_device *eng);
+void  destroy_dma_engine(struct kpc_dma_device *eng);
+void  clear_desc(struct kpc_dma_descriptor *desc);
+int   count_descriptors_available(struct kpc_dma_device *eng);
+void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags);
+
+#endif /* KPC_DMA_DRIVER_H */
+
diff --git a/drivers/staging/kpc2000/kpc_dma/uapi.h b/drivers/staging/kpc2000/kpc_dma/uapi.h
new file mode 100644
index 000000000000..5ff6a1a36ff9
--- /dev/null
+++ b/drivers/staging/kpc2000/kpc_dma/uapi.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef KPC_DMA_DRIVER_UAPI_H_
+#define KPC_DMA_DRIVER_UAPI_H_
+#include <linux/ioctl.h>
+
+#define KND_IOCTL_SET_CARD_ADDR                     _IOW('k', 1, __u32)
+#define KND_IOCTL_SET_USER_CTL                      _IOW('k', 2, __u64)
+#define KND_IOCTL_SET_USER_CTL_LAST                 _IOW('k', 4, __u64)
+#define KND_IOCTL_GET_USER_STS                      _IOR('k', 3, __u64)
+
+#endif /* KPC_DMA_DRIVER_UAPI_H_ */