[dpdk-dev] [PATCH v2] dmadev: introduce DMA device library

[Ananyev, Konstantin]

> +#include "rte_dmadev_core.h"
> +
> +/**
> + *  DMA flags to augment operation preparation.
> + *  Used as the 'flags' parameter of rte_dmadev_copy/copy_sg/fill/fill_sg.
> + */
> +#define RTE_DMA_FLAG_FENCE	(1ull << 0)
> +/**< DMA fence flag
> + * It means the operation with this flag must be processed only after all
> + * previous operations are completed.
> + *
> + * @see rte_dmadev_copy()
> + * @see rte_dmadev_copy_sg()
> + * @see rte_dmadev_fill()
> + * @see rte_dmadev_fill_sg()
> + */
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Enqueue a copy operation onto the virtual DMA channel.
> + *
> + * This queues up a copy operation to be performed by hardware, but does not
> + * trigger hardware to begin that operation.
> + *
> + * @param dev_id
> + *   The identifier of the device.
> + * @param vchan
> + *   The identifier of virtual DMA channel.
> + * @param src
> + *   The address of the source buffer.
> + * @param dst
> + *   The address of the destination buffer.
> + * @param length
> + *   The length of the data to be copied.
> + * @param flags
> + *   An flags for this operation.
> + *
> + * @return
> + *   - 0..UINT16_MAX: index of enqueued copy job.
> + *   - <0: Error code returned by the driver copy function.
> + */
> +__rte_experimental
> +static inline int
> +rte_dmadev_copy(uint16_t dev_id, uint16_t vchan, rte_iova_t src, rte_iova_t dst,
> +		uint32_t length, uint64_t flags)
> +{
> +	struct rte_dmadev *dev = &rte_dmadevices[dev_id];

One question I have - did you guys consider hiding definitions of struct rte_dmadev 
and  rte_dmadevices[] into .c straight from the start?
Probably no point to repeat our famous ABI ethdev/cryptodev/... pitfalls here.  

> +#ifdef RTE_DMADEV_DEBUG
> +	RTE_DMADEV_VALID_DEV_ID_OR_ERR_RET(dev_id, -EINVAL);
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->copy, -ENOTSUP);
> +	if (vchan >= dev->data->dev_conf.max_vchans) {
> +		RTE_DMADEV_LOG(ERR, "Invalid vchan %d\n", vchan);
> +		return -EINVAL;
> +	}
> +#endif
> +	return (*dev->copy)(dev, vchan, src, dst, length, flags);
> +}
> +
> +/**