[dpdk-dev] [PATCH v3 14/17] dma/idxd: add burst capacity API

[Kevin Laatz]

Add support for the burst capacity API. This API will provide the calling
application with the remaining capacity of the current burst (limited by
max HW batch size).

Signed-off-by: Kevin Laatz <kevin.laatz at intel.com>
---
 drivers/dma/idxd/idxd_bus.c      |  1 +
 drivers/dma/idxd/idxd_common.c   | 20 ++++++++++++++++++++
 drivers/dma/idxd/idxd_internal.h |  1 +
 drivers/dma/idxd/idxd_pci.c      |  2 ++
 4 files changed, 24 insertions(+)

diff --git a/drivers/dma/idxd/idxd_bus.c b/drivers/dma/idxd/idxd_bus.c
index 8f0fcad87a..e2bcca1c74 100644
--- a/drivers/dma/idxd/idxd_bus.c
+++ b/drivers/dma/idxd/idxd_bus.c
@@ -102,6 +102,7 @@ static const struct rte_dmadev_ops idxd_vdev_ops = {
 		.stats_get = idxd_stats_get,
 		.stats_reset = idxd_stats_reset,
 		.vchan_status = idxd_vchan_status,
+		.burst_capacity = idxd_burst_capacity,
 };
 
 static void *
diff --git a/drivers/dma/idxd/idxd_common.c b/drivers/dma/idxd/idxd_common.c
index e20b41ae54..ced9f81772 100644
--- a/drivers/dma/idxd/idxd_common.c
+++ b/drivers/dma/idxd/idxd_common.c
@@ -470,6 +470,26 @@ idxd_info_get(const struct rte_dmadev *dev, struct rte_dmadev_info *info, uint32
 	return 0;
 }
 
+uint16_t
+idxd_burst_capacity(const struct rte_dmadev *dev, uint16_t vchan __rte_unused)
+{
+	struct idxd_dmadev *idxd = dev->dev_private;
+	uint16_t write_idx = idxd->batch_start + idxd->batch_size;
+	uint16_t used_space;
+
+	/* Check for space in the batch ring */
+	if ((idxd->batch_idx_read == 0 && idxd->batch_idx_write == idxd->max_batches) ||
+			idxd->batch_idx_write + 1 == idxd->batch_idx_read)
+		return 0;
+
+	/* For descriptors, check for wrap-around on write but not read */
+	if (idxd->ids_returned > write_idx)
+		write_idx += idxd->desc_ring_mask + 1;
+	used_space = write_idx - idxd->ids_returned;
+
+	return RTE_MIN((idxd->desc_ring_mask - used_space), idxd->max_batch_size);
+}
+
 int
 idxd_configure(struct rte_dmadev *dev __rte_unused, const struct rte_dmadev_conf *dev_conf,
 		uint32_t conf_sz)
diff --git a/drivers/dma/idxd/idxd_internal.h b/drivers/dma/idxd/idxd_internal.h
index fcc0235a1d..692d27cf72 100644
--- a/drivers/dma/idxd/idxd_internal.h
+++ b/drivers/dma/idxd/idxd_internal.h
@@ -103,5 +103,6 @@ int idxd_stats_get(const struct rte_dmadev *dev, uint16_t vchan,
 int idxd_stats_reset(struct rte_dmadev *dev, uint16_t vchan);
 int idxd_vchan_status(const struct rte_dmadev *dev, uint16_t vchan,
 		enum rte_dmadev_vchan_status *status);
+uint16_t idxd_burst_capacity(const struct rte_dmadev *dev, uint16_t vchan);
 
 #endif /* _IDXD_INTERNAL_H_ */
diff --git a/drivers/dma/idxd/idxd_pci.c b/drivers/dma/idxd/idxd_pci.c
index f3a5d2a970..5da14eb9a2 100644
--- a/drivers/dma/idxd/idxd_pci.c
+++ b/drivers/dma/idxd/idxd_pci.c
@@ -119,6 +119,7 @@ static const struct rte_dmadev_ops idxd_pci_ops = {
 	.dev_start = idxd_pci_dev_start,
 	.dev_stop = idxd_pci_dev_stop,
 	.vchan_status = idxd_vchan_status,
+	.burst_capacity = idxd_burst_capacity,
 };
 
 /* each portal uses 4 x 4k pages */
@@ -232,6 +233,7 @@ init_pci_device(struct rte_pci_device *dev, struct idxd_dmadev *idxd,
 
 	idxd->u.pci = pci;
 	idxd->max_batches = wq_size;
+	idxd->max_batch_size = 1 << lg2_max_batch;
 
 	/* enable the device itself */
 	err_code = idxd_pci_dev_command(idxd, idxd_enable_dev);
-- 
2.30.2