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Subject[PATCH RFC v3 06/14] dmaengine: add dma request submit and completion path support
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There are several issues with the existing dmaengine submission APIs.
1. A new function pointer is introduced every time a new operation is
added.
2. The whole submission path requires locking and requires multiple API
calls with prep+submit+start engine.

A new DMA register function for request based DMA devices is added,
dma_async_request_device_register(). This allows the checking of parts for
dma requests that are setup.

A new submission API call that can start an I/O immediately in a single
call and will be lockless is being introduced. A helper function that
submits and wait is also added for consumers such as dmatest that will wait
on the completion of the I/O. And a helper function is added that completes
the I/O by either calling complete() or envoking the callback depending on
the setup for submission.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
drivers/dma/dmaengine.c | 59 ++++++++++++++++++++++++++++++++++++++++
include/linux/dmaengine.h | 67 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 3c74402f1c34..5b053624f9e3 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1050,6 +1050,37 @@ static int __dma_async_device_register(struct dma_device *device)
return 0;
}

+/**
+ * dma_async_request_device_register - registers DMA devices found that
+ * support DMA requests.
+ * @device: &dma_device
+ */
+int dma_async_request_device_register(struct dma_device *device)
+{
+ int rc;
+
+ if (!device)
+ return -ENODEV;
+
+ /* validate device routines */
+ if (!device->dev) {
+ pr_err("DMA device must have dev\n");
+ return -EIO;
+ }
+
+ if (!device->device_submit_request) {
+ dev_err(device->dev, "Device has no op defined\n");
+ return -EIO;
+ }
+
+ rc = __dma_async_device_register(device);
+ if (rc != 0)
+ return rc;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dma_async_request_device_register);
+
/**
* dma_async_device_register - registers DMA devices found
* @device: &dma_device
@@ -1232,6 +1263,34 @@ int dmaenginem_async_device_register(struct dma_device *device)
}
EXPORT_SYMBOL(dmaenginem_async_device_register);

+/**
+ * dmaenginem_async_request_device_register - registers DMA devices
+ * support DMA requests found
+ * @device: &dma_device
+ *
+ * The operation is managed and will be undone on driver detach.
+ */
+int dmaenginem_async_request_device_register(struct dma_device *device)
+{
+ void *p;
+ int ret;
+
+ p = devres_alloc(dmam_device_release, sizeof(void *), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ ret = dma_async_request_device_register(device);
+ if (!ret) {
+ *(struct dma_device **)p = device;
+ devres_add(device->dev, p);
+ } else {
+ devres_free(p);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(dmaenginem_async_request_device_register);
+
struct dmaengine_unmap_pool {
struct kmem_cache *cache;
const char *name;
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 7bc8c3f8283f..220d241d71ed 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -461,6 +461,7 @@ enum dmaengine_tx_result {
DMA_TRANS_NOERROR = 0, /* SUCCESS */
DMA_TRANS_READ_FAILED, /* Source DMA read failed */
DMA_TRANS_WRITE_FAILED, /* Destination DMA write failed */
+ DMA_TRANS_ERROR, /* General error not rd/wr */
DMA_TRANS_ABORTED, /* Op never submitted / aborted */
};

@@ -831,6 +832,10 @@ struct dma_device {
dma_cookie_t cookie,
struct dma_tx_state *txstate);
void (*device_issue_pending)(struct dma_chan *chan);
+
+ /* function calls for request API */
+ int (*device_submit_request)(struct dma_chan *chan,
+ struct dma_request *req);
};

static inline int dmaengine_slave_config(struct dma_chan *chan,
@@ -1390,6 +1395,66 @@ static inline int dma_get_slave_caps(struct dma_chan *chan,
}
#endif

+/* dmaengine_submit_request - helper routine for caller to submit
+ * a DMA request.
+ * @chan: dma channel context
+ * @req: dma request context
+ */
+static inline int dmaengine_submit_request(struct dma_chan *chan,
+ struct dma_request *req)
+{
+ struct dma_device *ddev;
+
+ if (!chan)
+ return -EINVAL;
+
+ ddev = chan->device;
+ if (!ddev->device_submit_request)
+ return -EINVAL;
+
+ return ddev->device_submit_request(chan, req);
+}
+
+/* dmaengine_submit_request_and_wait - helper routine for caller to submit
+ * a DMA request and wait until
+ * completion or timeout.
+ * @chan: dma channel context
+ * @req: dma request context
+ * @timeout: time in jiffies to wait for completion timeout. A timeout of 0
+ * equals to wait indefinitely.
+ */
+static inline int dmaengine_submit_request_and_wait(struct dma_chan *chan,
+ struct dma_request *req,
+ int timeout)
+{
+ int rc;
+ DECLARE_COMPLETION_ONSTACK(done);
+
+ req->rq_private = &done;
+ rc = dmaengine_submit_request(chan, req);
+ if (rc < 0)
+ return rc;
+
+ if (timeout)
+ return wait_for_completion_timeout(&done, timeout);
+
+ wait_for_completion(&done);
+ return 0;
+}
+
+/* dmaengine_request_complete - helper function to complete dma request.
+ * If callback exists will envoke callback.
+ *
+ * @req - dma request context
+ */
+static inline void dmaengine_request_complete(struct dma_request *req)
+{
+ if (req->rq_private)
+ complete(req->rq_private);
+ else if (req->callback)
+ req->callback(req->callback_param, &req->result);
+}
+
#ifdef CONFIG_DMA_ENGINE_REQUEST
struct dma_request *dma_chan_alloc_request(struct dma_chan *chan);
void dma_chan_free_request(struct dma_chan *chan, struct dma_request *rq);
@@ -1454,7 +1519,9 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
/* --- DMA device --- */

int dma_async_device_register(struct dma_device *device);
+int dma_async_request_device_register(struct dma_device *device);
int dmaenginem_async_device_register(struct dma_device *device);
+int dmaenginem_async_request_device_register(struct dma_device *device);
void dma_async_device_unregister(struct dma_device *device);
int dma_async_device_channel_register(struct dma_device *device,
struct dma_chan *chan);
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