board/xilinx/common/xdma_channel.h

/******************************************************************************
*
*     Author: Xilinx, Inc.
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*
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*
*     (c) Copyright 2002-2004 Xilinx Inc.
*     All rights reserved.
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*
*     You should have received a copy of the GNU General Public License along
*     with this program; if not, write to the Free Software Foundation, Inc.,
*     675 Mass Ave, Cambridge, MA 02139, USA.
*
* FILENAME:
*
* xdma_channel.h
*
* DESCRIPTION:
*
* This file contains the DMA channel component implementation. This component
* supports a distributed DMA design in which each device can have it's own
* dedicated DMA channel, as opposed to a centralized DMA design.
* A device which uses DMA typically contains two DMA channels, one for
* sending data and the other for receiving data.
*
* This component is designed to be used as a basic building block for
* designing a device driver. It provides registers accesses such that all
* DMA processing can be maintained easier, but the device driver designer
* must still understand all the details of the DMA channel.
*
* The DMA channel allows a CPU to minimize the CPU interaction required to move
* data between a memory and a device.  The CPU requests the DMA channel to
* perform a DMA operation and typically continues performing other processing
* until the DMA operation completes.  DMA could be considered a primitive form
* of multiprocessing such that caching and address translation can be an issue.
*
* Scatter Gather Operations
*
* The DMA channel may support scatter gather operations. A scatter gather
* operation automates the DMA channel such that multiple buffers can be
* sent or received with minimal software interaction with the hardware.  Buffer
* descriptors, contained in the XBufDescriptor component, are used by the
* scatter gather operations of the DMA channel to describe the buffers to be
* processed.
*
* Scatter Gather List Operations
*
* A scatter gather list may be supported by each DMA channel.  The scatter
* gather list allows buffer descriptors to be put into the list by a device
* driver which requires scatter gather.  The hardware processes the buffer
* descriptors which are contained in the list and modifies the buffer
* descriptors to reflect the status of the DMA operations.  The device driver
* is notified by interrupt that specific DMA events occur including scatter
* gather events.  The device driver removes the completed buffer descriptors
* from the scatter gather list to evaluate the status of each DMA operation.
*
* The scatter gather list is created and buffer descriptors are inserted into
* the list.  Buffer descriptors are never removed from the list after it's
* creation such that a put operation copies from a temporary buffer descriptor
* to a buffer descriptor in the list.  Get operations don't copy from the list
* to a temporary, but return a pointer to the buffer descriptor in the list.
* A buffer descriptor in the list may be locked to prevent it from being
* overwritten by a put operation.  This allows the device driver to get a
* descriptor from a scatter gather list and prevent it from being overwritten
* until the buffer associated with the buffer descriptor has been processed.
*
* Typical Scatter Gather Processing
*
* The following steps illustrate the typical processing to use the
* scatter gather features of a DMA channel.
*
* 1. Create a scatter gather list for the DMA channel which puts empty buffer
*    descriptors into the list.
* 2. Create buffer descriptors which describe the buffers to be filled with
* 	 receive data or the buffers which contain data to be sent.
* 3. Put buffer descriptors into the DMA channel scatter list such that scatter
*    gather operations are requested.
* 4. Commit the buffer descriptors in the list such that they are ready to be
*    used by the DMA channel hardware.
* 5. Start the scatter gather operations of the DMA channel.
* 6. Process any interrupts which occur as a result of the scatter gather
*    operations or poll the DMA channel to determine the status.
*
* Interrupts
*
* Each DMA channel has the ability to generate an interrupt.  This component
* does not perform processing for the interrupt as this processing is typically
* tightly coupled with the device which is using the DMA channel.  It is the
* responsibility of the caller of DMA functions to manage the interrupt
* including connecting to the interrupt and enabling/disabling the interrupt.
*
* Critical Sections
*
* It is the responsibility of the device driver designer to use critical
* sections as necessary when calling functions of the DMA channel.  This
* component does not use critical sections and it does access registers using
* read-modify-write operations.  Calls to DMA functions from a main thread
* and from an interrupt context could produce unpredictable behavior such that
* the caller must provide the appropriate critical sections.
*
* Address Translation
*
* All addresses of data structures which are passed to DMA functions must
* be physical (real) addresses as opposed to logical (virtual) addresses.
*
* Caching
*
* The memory which is passed to the function which creates the scatter gather
* list must not be cached such that buffer descriptors are non-cached.  This
* is necessary because the buffer descriptors are kept in a ring buffer and
* not directly accessible to the caller of DMA functions.
*
* The caller of DMA functions is responsible for ensuring that any data
* buffers which are passed to the DMA channel are cache-line aligned if
* necessary.
*
* The caller of DMA functions is responsible for ensuring that any data
* buffers which are passed to the DMA channel have been flushed from the cache.
*
* The caller of DMA functions is responsible for ensuring that the cache is
* invalidated prior to using any data buffers which are the result of a DMA
* operation.
*
* Memory Alignment
*
* The addresses of data buffers which are passed to DMA functions must be
* 32 bit word aligned since the DMA hardware performs 32 bit word transfers.
*
* Mutual Exclusion
*
* The functions of the DMA channel are not thread safe such that the caller
* of all DMA functions is responsible for ensuring mutual exclusion for a
* DMA channel.  Mutual exclusion across multiple DMA channels is not
* necessary.
*
* NOTES:
*
* Many of the provided functions which are register accessors don't provide
* a lot of error detection. The caller is expected to understand the impact
* of a function call based upon the current state of the DMA channel.  This
* is done to minimize the overhead in this component.
*
******************************************************************************/

#ifndef XDMA_CHANNEL_H		/* prevent circular inclusions */
#define XDMA_CHANNEL_H		/* by using protection macros */

/***************************** Include Files *********************************/

#include "xdma_channel_i.h"	/* constants shared with buffer descriptor */
#include "xbasic_types.h"
#include "xstatus.h"
#include "xversion.h"
#include "xbuf_descriptor.h"

/************************** Constant Definitions *****************************/

/* the following constants provide access to the bit fields of the DMA control
 * register (DMACR)
 */
#define XDC_DMACR_SOURCE_INCR_MASK	0x80000000UL	/* increment source address */
#define XDC_DMACR_DEST_INCR_MASK	0x40000000UL	/* increment dest address */
#define XDC_DMACR_SOURCE_LOCAL_MASK 0x20000000UL	/* local source address */
#define XDC_DMACR_DEST_LOCAL_MASK	0x10000000UL	/* local dest address */
#define XDC_DMACR_SG_DISABLE_MASK	0x08000000UL	/* scatter gather disable */
#define XDC_DMACR_GEN_BD_INTR_MASK	0x04000000UL	/* descriptor interrupt */
#define XDC_DMACR_LAST_BD_MASK		XDC_CONTROL_LAST_BD_MASK	/* last buffer */
															 /*     descriptor  */

/* the following constants provide access to the bit fields of the DMA status
 * register (DMASR)
 */
#define XDC_DMASR_BUSY_MASK			0x80000000UL	/* channel is busy */
#define XDC_DMASR_BUS_ERROR_MASK	0x40000000UL	/* bus error occurred */
#define XDC_DMASR_BUS_TIMEOUT_MASK	0x20000000UL	/* bus timeout occurred */
#define XDC_DMASR_LAST_BD_MASK		XDC_STATUS_LAST_BD_MASK	/* last buffer */
														    /* descriptor  */
#define XDC_DMASR_SG_BUSY_MASK		0x08000000UL	/* scatter gather is busy */

/* the following constants provide access to the bit fields of the interrupt
 * status register (ISR) and the interrupt enable register (IER), bit masks
 * match for both registers such that they are named IXR
 */
#define XDC_IXR_DMA_DONE_MASK		0x1UL	/* dma operation done */
#define XDC_IXR_DMA_ERROR_MASK	    0x2UL	/* dma operation error */
#define XDC_IXR_PKT_DONE_MASK	    0x4UL	/* packet done */
#define XDC_IXR_PKT_THRESHOLD_MASK 	0x8UL	/* packet count threshold */
#define XDC_IXR_PKT_WAIT_BOUND_MASK 0x10UL	/* packet wait bound reached */
#define XDC_IXR_SG_DISABLE_ACK_MASK 0x20UL	/* scatter gather disable
						   acknowledge occurred */
#define XDC_IXR_SG_END_MASK			0x40UL	/* last buffer descriptor
							   disabled scatter gather */
#define XDC_IXR_BD_MASK				0x80UL	/* buffer descriptor done */

/**************************** Type Definitions *******************************/

/*
 * the following structure contains data which is on a per instance basis
 * for the XDmaChannel component
 */
typedef struct XDmaChannelTag {
	XVersion Version;	/* version of the driver */
	u32 RegBaseAddress;	/* base address of registers */
	u32 IsReady;		/* device is initialized and ready */

	XBufDescriptor *PutPtr;	/* keep track of where to put into list */
	XBufDescriptor *GetPtr;	/* keep track of where to get from list */
	XBufDescriptor *CommitPtr;	/* keep track of where to commit in list */
	XBufDescriptor *LastPtr;	/* keep track of the last put in the list */
	u32 TotalDescriptorCount;	/* total # of descriptors in the list */
	u32 ActiveDescriptorCount;	/* # of descriptors pointing to buffers
					   * in the buffer descriptor list */
} XDmaChannel;

/***************** Macros (Inline Functions) Definitions *********************/

/************************** Function Prototypes ******************************/

XStatus XDmaChannel_Initialize(XDmaChannel * InstancePtr, u32 BaseAddress);
u32 XDmaChannel_IsReady(XDmaChannel * InstancePtr);
XVersion *XDmaChannel_GetVersion(XDmaChannel * InstancePtr);
XStatus XDmaChannel_SelfTest(XDmaChannel * InstancePtr);
void XDmaChannel_Reset(XDmaChannel * InstancePtr);

/* Control functions */

u32 XDmaChannel_GetControl(XDmaChannel * InstancePtr);
void XDmaChannel_SetControl(XDmaChannel * InstancePtr, u32 Control);

/* Status functions */

u32 XDmaChannel_GetStatus(XDmaChannel * InstancePtr);
void XDmaChannel_SetIntrStatus(XDmaChannel * InstancePtr, u32 Status);
u32 XDmaChannel_GetIntrStatus(XDmaChannel * InstancePtr);
void XDmaChannel_SetIntrEnable(XDmaChannel * InstancePtr, u32 Enable);
u32 XDmaChannel_GetIntrEnable(XDmaChannel * InstancePtr);

/* DMA without scatter gather functions */

void XDmaChannel_Transfer(XDmaChannel * InstancePtr,
			  u32 * SourcePtr, u32 * DestinationPtr, u32 ByteCount);

/* Scatter gather functions */

XStatus XDmaChannel_SgStart(XDmaChannel * InstancePtr);
XStatus XDmaChannel_SgStop(XDmaChannel * InstancePtr,
			   XBufDescriptor ** BufDescriptorPtr);
XStatus XDmaChannel_CreateSgList(XDmaChannel * InstancePtr,
				 u32 * MemoryPtr, u32 ByteCount);
u32 XDmaChannel_IsSgListEmpty(XDmaChannel * InstancePtr);

XStatus XDmaChannel_PutDescriptor(XDmaChannel * InstancePtr,
				  XBufDescriptor * BufDescriptorPtr);
XStatus XDmaChannel_CommitPuts(XDmaChannel * InstancePtr);
XStatus XDmaChannel_GetDescriptor(XDmaChannel * InstancePtr,
				  XBufDescriptor ** BufDescriptorPtr);

/* Packet functions for interrupt collescing */

u32 XDmaChannel_GetPktCount(XDmaChannel * InstancePtr);
void XDmaChannel_DecrementPktCount(XDmaChannel * InstancePtr);
XStatus XDmaChannel_SetPktThreshold(XDmaChannel * InstancePtr, u8 Threshold);
u8 XDmaChannel_GetPktThreshold(XDmaChannel * InstancePtr);
void XDmaChannel_SetPktWaitBound(XDmaChannel * InstancePtr, u32 WaitBound);
u32 XDmaChannel_GetPktWaitBound(XDmaChannel * InstancePtr);

#endif				/* end of protection macro */