Spdk/include/spdk/ioat.h

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/** \file
 * I/OAT DMA engine driver public interface
 */

#ifndef SPDK_IOAT_H
#define SPDK_IOAT_H

#include "spdk/stdinc.h"

#ifdef __cplusplus
extern "C" {
#endif

#include "spdk/env.h"

/**
 * Opaque handle for a single I/OAT channel returned by \ref spdk_ioat_probe().
 */
struct spdk_ioat_chan;

/**
 * Signature for callback function invoked when a request is completed.
 *
 * \param arg User-specified opaque value corresponding to cb_arg from the
 * request submission.
 */
typedef void (*spdk_ioat_req_cb)(void *arg);

/**
 * Callback for spdk_ioat_probe() enumeration.
 *
 * \param cb_ctx User-specified opaque value corresponding to cb_ctx from spdk_ioat_probe().
 * \param pci_dev PCI device that is being probed.
 *
 * \return true to attach to this device.
 */
typedef bool (*spdk_ioat_probe_cb)(void *cb_ctx, struct spdk_pci_device *pci_dev);

/**
 * Callback for spdk_ioat_probe() to report a device that has been attached to
 * the userspace I/OAT driver.
 *
 * \param cb_ctx User-specified opaque value corresponding to cb_ctx from spdk_ioat_probe().
 * \param pci_dev PCI device that was attached to the driver.
 * \param ioat I/OAT channel that was attached to the driver.
 */
typedef void (*spdk_ioat_attach_cb)(void *cb_ctx, struct spdk_pci_device *pci_dev,
				    struct spdk_ioat_chan *ioat);

/**
 * Enumerate the I/OAT devices attached to the system and attach the userspace
 * I/OAT driver to them if desired.
 *
 * If called more than once, only devices that are not already attached to the
 * SPDK I/OAT driver will be reported.
 *
 * To stop using the controller and release its associated resources, call
 * spdk_ioat_detach() with the ioat_channel instance returned by this function.
 *
 * \param cb_ctx Opaque value which will be passed back in cb_ctx parameter of
 * the callbacks.
 * \param probe_cb will be called once per I/OAT device found in the system.
 * \param attach_cb will be called for devices for which probe_cb returned true
 * once the I/OAT controller has been attached to the userspace driver.
 *
 * \return 0 on success, -1 on failure.
 */
int spdk_ioat_probe(void *cb_ctx, spdk_ioat_probe_cb probe_cb, spdk_ioat_attach_cb attach_cb);

/**
 * Detach specified device returned by spdk_ioat_probe() from the I/OAT driver.
 *
 * \param ioat I/OAT channel to detach from the driver.
  */
void spdk_ioat_detach(struct spdk_ioat_chan *ioat);

/**
 * Build a DMA engine memory copy request.
 *
 * This function will build the descriptor in the channel's ring.  The
 * caller must also explicitly call spdk_ioat_flush to submit the
 * descriptor, possibly after building additional descriptors.
 *
 * \param chan I/OAT channel to build request.
 * \param cb_arg Opaque value which will be passed back as the arg parameter in
 * the completion callback.
 * \param cb_fn Callback function which will be called when the request is complete.
 * \param dst Destination virtual address.
 * \param src Source virtual address.
 * \param nbytes Number of bytes to copy.
 *
 * \return 0 on success, negative errno on failure.
 */
int spdk_ioat_build_copy(struct spdk_ioat_chan *chan,
			 void *cb_arg, spdk_ioat_req_cb cb_fn,
			 void *dst, const void *src, uint64_t nbytes);

/**
 * Build and submit a DMA engine memory copy request.
 *
 * This function will build the descriptor in the channel's ring and then
 * immediately submit it by writing the channel's doorbell.  Calling this
 * function does not require a subsequent call to spdk_ioat_flush.
 *
 * \param chan I/OAT channel to submit request.
 * \param cb_arg Opaque value which will be passed back as the arg parameter in
 * the completion callback.
 * \param cb_fn Callback function which will be called when the request is complete.
 * \param dst Destination virtual address.
 * \param src Source virtual address.
 * \param nbytes Number of bytes to copy.
 *
 * \return 0 on success, negative errno on failure.
 */
int spdk_ioat_submit_copy(struct spdk_ioat_chan *chan,
			  void *cb_arg, spdk_ioat_req_cb cb_fn,
			  void *dst, const void *src, uint64_t nbytes);

/**
 * Build a DMA engine memory fill request.
 *
 * This function will build the descriptor in the channel's ring.  The
 * caller must also explicitly call spdk_ioat_flush to submit the
 * descriptor, possibly after building additional descriptors.
 *
 * \param chan I/OAT channel to build request.
 * \param cb_arg Opaque value which will be passed back as the cb_arg parameter
 * in the completion callback.
 * \param cb_fn Callback function which will be called when the request is complete.
 * \param dst Destination virtual address.
 * \param fill_pattern Repeating eight-byte pattern to use for memory fill.
 * \param nbytes Number of bytes to fill.
 *
 * \return 0 on success, negative errno on failure.
 */
int spdk_ioat_build_fill(struct spdk_ioat_chan *chan,
			 void *cb_arg, spdk_ioat_req_cb cb_fn,
			 void *dst, uint64_t fill_pattern, uint64_t nbytes);

/**
 * Build and submit a DMA engine memory fill request.
 *
 * This function will build the descriptor in the channel's ring and then
 * immediately submit it by writing the channel's doorbell.  Calling this
 * function does not require a subsequent call to spdk_ioat_flush.
 *
 * \param chan I/OAT channel to submit request.
 * \param cb_arg Opaque value which will be passed back as the cb_arg parameter
 * in the completion callback.
 * \param cb_fn Callback function which will be called when the request is complete.
 * \param dst Destination virtual address.
 * \param fill_pattern Repeating eight-byte pattern to use for memory fill.
 * \param nbytes Number of bytes to fill.
 *
 * \return 0 on success, negative errno on failure.
 */
int spdk_ioat_submit_fill(struct spdk_ioat_chan *chan,
			  void *cb_arg, spdk_ioat_req_cb cb_fn,
			  void *dst, uint64_t fill_pattern, uint64_t nbytes);

/**
 * Flush previously built descriptors.
 *
 * Descriptors are flushed by writing the channel's dmacount doorbell
 * register.  This function enables batching multiple descriptors followed by
 * a single doorbell write.
 *
 * \param chan I/OAT channel to flush.
 */
void spdk_ioat_flush(struct spdk_ioat_chan *chan);

/**
 * Check for completed requests on an I/OAT channel.
 *
 * \param chan I/OAT channel to check for completions.
 *
 * \return number of events handled on success, negative errno on failure.
 */
int spdk_ioat_process_events(struct spdk_ioat_chan *chan);

/**
 * DMA engine capability flags
 */
enum spdk_ioat_dma_capability_flags {
	SPDK_IOAT_ENGINE_COPY_SUPPORTED	= 0x1, /**< The memory copy is supported */
	SPDK_IOAT_ENGINE_FILL_SUPPORTED	= 0x2, /**< The memory fill is supported */
};

/**
 * Get the DMA engine capabilities.
 *
 * \param chan I/OAT channel to query.
 *
 * \return a combination of flags from spdk_ioat_dma_capability_flags().
 */
uint32_t spdk_ioat_get_dma_capabilities(struct spdk_ioat_chan *chan);

#ifdef __cplusplus
}
#endif

#endif