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Subject[PATCH v4 7/9] dmaengine: idxd: add descriptor manipulation routines
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Date
This commit adds helper functions for DSA descriptor allocation,
submission, and free operations.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
drivers/dma/idxd/Makefile | 2 -
drivers/dma/idxd/idxd.h | 10 +++++
drivers/dma/idxd/submit.c | 93 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 104 insertions(+), 1 deletion(-)
create mode 100644 drivers/dma/idxd/submit.c

diff --git a/drivers/dma/idxd/Makefile b/drivers/dma/idxd/Makefile
index a552560a03dc..50eca12015e2 100644
--- a/drivers/dma/idxd/Makefile
+++ b/drivers/dma/idxd/Makefile
@@ -1,2 +1,2 @@
obj-$(CONFIG_INTEL_IDXD) += idxd.o
-idxd-y := init.o irq.o device.o sysfs.o
+idxd-y := init.o irq.o device.o sysfs.o submit.o
diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 909926aefd3e..d369b75468e3 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -68,6 +68,11 @@ enum idxd_wq_type {
#define WQ_NAME_SIZE 1024
#define WQ_TYPE_SIZE 10

+enum idxd_op_type {
+ IDXD_OP_BLOCK = 0,
+ IDXD_OP_NONBLOCK = 1,
+};
+
struct idxd_wq {
void __iomem *dportal;
struct device conf_dev;
@@ -246,4 +251,9 @@ int idxd_wq_disable(struct idxd_wq *wq);
int idxd_wq_map_portal(struct idxd_wq *wq);
void idxd_wq_unmap_portal(struct idxd_wq *wq);

+/* submission */
+int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc);
+struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype);
+void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc);
+
#endif
diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c
new file mode 100644
index 000000000000..20c683870046
--- /dev/null
+++ b/drivers/dma/idxd/submit.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/dmaengine.h>
+#include <uapi/linux/idxd.h>
+#include "../dmaengine.h"
+#include "idxd.h"
+#include "registers.h"
+
+struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype)
+{
+ struct idxd_desc *desc;
+ int idx;
+ struct idxd_device *idxd = wq->idxd;
+
+ if (idxd->state != IDXD_DEV_ENABLED)
+ return ERR_PTR(-EIO);
+
+ if (optype == IDXD_OP_BLOCK)
+ percpu_down_read(&wq->submit_lock);
+ else if (!percpu_down_read_trylock(&wq->submit_lock))
+ return ERR_PTR(-EBUSY);
+
+ if (!atomic_add_unless(&wq->dq_count, 1, wq->size)) {
+ int rc;
+
+ if (optype == IDXD_OP_NONBLOCK) {
+ percpu_up_read(&wq->submit_lock);
+ return ERR_PTR(-EAGAIN);
+ }
+
+ percpu_up_read(&wq->submit_lock);
+ percpu_down_write(&wq->submit_lock);
+ rc = wait_event_interruptible(wq->submit_waitq,
+ atomic_add_unless(&wq->dq_count,
+ 1, wq->size) ||
+ idxd->state != IDXD_DEV_ENABLED);
+ percpu_up_write(&wq->submit_lock);
+ if (rc < 0)
+ return ERR_PTR(-EINTR);
+ if (idxd->state != IDXD_DEV_ENABLED)
+ return ERR_PTR(-EIO);
+ } else {
+ percpu_up_read(&wq->submit_lock);
+ }
+
+ idx = sbitmap_get(&wq->sbmap, 0, false);
+ if (idx < 0) {
+ atomic_dec(&wq->dq_count);
+ return ERR_PTR(-EAGAIN);
+ }
+
+ desc = wq->descs[idx];
+ memset(desc->hw, 0, sizeof(struct dsa_hw_desc));
+ memset(desc->completion, 0, sizeof(struct dsa_completion_record));
+ return desc;
+}
+
+void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc)
+{
+ atomic_dec(&wq->dq_count);
+
+ sbitmap_clear_bit(&wq->sbmap, desc->id);
+ wake_up(&wq->submit_waitq);
+}
+
+int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
+{
+ struct idxd_device *idxd = wq->idxd;
+ int vec = desc->hw->int_handle;
+
+ if (idxd->state != IDXD_DEV_ENABLED)
+ return -EIO;
+
+ /*
+ * The wmb() flushes writes to coherent DMA data before possibly
+ * triggering a DMA read. The wmb() is necessary even on UP because
+ * the recipient is a device.
+ */
+ wmb();
+ iosubmit_cmds512(wq->dportal, desc->hw, 1);
+
+ /*
+ * Pending the descriptor to the lockless list for the irq_entry
+ * that we designated the descriptor to.
+ */
+ llist_add(&desc->llnode, &idxd->irq_entries[vec].pending_llist);
+
+ return 0;
+}
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