[snip]

+/**
+ * dma_async_client_register - allocate and register a &dma_client
+ * @event_callback: callback for notification of channel addition/ 
removal
+ */
+struct dma_client *dma_async_client_register(dma_event_callback  
event_callback)
+{
+	struct dma_client *client;
+
+	client = kzalloc(sizeof(*client), GFP_KERNEL);
+	if (!client)
+		return NULL;
+
+	INIT_LIST_HEAD(&client->channels);
+	spin_lock_init(&client->lock);
+
+	client->chans_desired = 0;
+	client->chan_count = 0;
+	client->event_callback = event_callback;
+
+	spin_lock(&dma_list_lock);
+	list_add_tail(&client->global_node, &dma_client_list);
+	spin_unlock(&dma_list_lock);
+
+	return client;
+}

It would seem that when a client registers (or shortly there after  
when they call dma_async_client_chan_request()) they would expect to  
get the number of channels they need by some given time period.

For example, lets say a client registers but no dma device exists.   
They will never get called to be aware of this condition.

I would think most clients would either spin until they have all the  
channels they need or fall back to a non-async mechanism.

Also, what do you think about adding an operation type (MEMCPY, XOR,  
CRYPTO_AES, etc).  We can than validate if the operation type  
expected is supported by the devices that exist.

+
+/**
+ * dma_async_client_unregister - unregister a client and free the  
&dma_client
+ * @client:
+ *
+ * Force frees any allocated DMA channels, frees the &dma_client  
memory
+ */
+void dma_async_client_unregister(struct dma_client *client)
+{
+	struct dma_chan *chan;
+
+	if (!client)
+		return;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(chan, &client->channels, client_node) {
+		dma_client_chan_free(chan);
+	}
+	rcu_read_unlock();
+
+	spin_lock(&dma_list_lock);
+	list_del(&client->global_node);
+	spin_unlock(&dma_list_lock);
+
+	kfree(client);
+	dma_chans_rebalance();
+}
+
+/**
+ * dma_async_client_chan_request - request DMA channels
+ * @client: &dma_client
+ * @number: count of DMA channels requested
+ *
+ * Clients call dma_async_client_chan_request() to specify how many
+ * DMA channels they need, 0 to free all currently allocated.
+ * The resulting allocations/frees are indicated to the client via  
the
+ * event callback.
+ */
+void dma_async_client_chan_request(struct dma_client *client,
+			unsigned int number)
+{
+	client->chans_desired = number;
+	dma_chans_rebalance();
+}
+

Shouldn't we also have a dma_async_client_chan_free()?

[snip]

+/* --- public DMA engine API --- */
+
+struct dma_client *dma_async_client_register(dma_event_callback  
event_callback);
+void dma_async_client_unregister(struct dma_client *client);
+void dma_async_client_chan_request(struct dma_client *client,
+		unsigned int number);
+
+/**
+ * dma_async_memcpy_buf_to_buf - offloaded copy between virtual  
addresses
+ * @chan: DMA channel to offload copy to
+ * @dest: destination address (virtual)
+ * @src: source address (virtual)
+ * @len: length
+ *
+ * Both @dest and @src must be mappable to a bus address according  
to the
+ * DMA mapping API rules for streaming mappings.
+ * Both @dest and @src must stay memory resident (kernel memory or  
locked
+ * user space pages)
+ */
+static inline dma_cookie_t dma_async_memcpy_buf_to_buf(struct  
dma_chan *chan,
+	void *dest, void *src, size_t len)
+{
+	int cpu = get_cpu();
+	per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
+	per_cpu_ptr(chan->local, cpu)->memcpy_count++;
+	put_cpu();
+
+	return chan->device->device_memcpy_buf_to_buf(chan, dest, src, len);
+}

What about renaming the dma_async_memcpy_* to something like  
dma_async_op_* and have them take an additional operation argument.

+
+/**
+ * dma_async_memcpy_buf_to_pg - offloaded copy
+ * @chan: DMA channel to offload copy to
+ * @page: destination page
+ * @offset: offset in page to copy to
+ * @kdata: source address (virtual)
+ * @len: length
+ *
+ * Both @page/@offset and @kdata must be mappable to a bus address  
according
+ * to the DMA mapping API rules for streaming mappings.
+ * Both @page/@offset and @kdata must stay memory resident (kernel  
memory or
+ * locked user space pages)
+ */
+static inline dma_cookie_t dma_async_memcpy_buf_to_pg(struct  
dma_chan *chan,
+	struct page *page, unsigned int offset, void *kdata, size_t len)
+{
+	int cpu = get_cpu();
+	per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
+	per_cpu_ptr(chan->local, cpu)->memcpy_count++;
+	put_cpu();
+
+	return chan->device->device_memcpy_buf_to_pg(chan, page, offset,
+	                                             kdata, len);
+}
+
+/**
+ * dma_async_memcpy_buf_to_pg - offloaded copy
+ * @chan: DMA channel to offload copy to
+ * @dest_page: destination page
+ * @dest_off: offset in page to copy to
+ * @src_page: source page
+ * @src_off: offset in page to copy from
+ * @len: length
+ *
+ * Both @dest_page/@dest_off and @src_page/@src_off must be  
mappable to a bus
+ * address according to the DMA mapping API rules for streaming  
mappings.
+ * Both @dest_page/@dest_off and @src_page/@src_off must stay  
memory resident
+ * (kernel memory or locked user space pages)
+ */
+static inline dma_cookie_t dma_async_memcpy_pg_to_pg(struct  
dma_chan *chan,
+	struct page *dest_pg, unsigned int dest_off, struct page *src_pg,
+	unsigned int src_off, size_t len)
+{
+	int cpu = get_cpu();
+	per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
+	per_cpu_ptr(chan->local, cpu)->memcpy_count++;
+	put_cpu();
+
+	return chan->device->device_memcpy_pg_to_pg(chan, dest_pg, dest_off,
+	                                            src_pg, src_off, len);
+}
+
+/**
+ * dma_async_memcpy_issue_pending - flush pending copies to HW
+ * @chan:
+ *
+ * This allows drivers to push copies to HW in batches,
+ * reducing MMIO writes where possible.
+ */
+static inline void dma_async_memcpy_issue_pending(struct dma_chan  
*chan)
+{
+	return chan->device->device_memcpy_issue_pending(chan);
+}
+
+/**
+ * dma_async_memcpy_complete - poll for transaction completion
+ * @chan: DMA channel
+ * @cookie: transaction identifier to check status of
+ * @last: returns last completed cookie, can be NULL
+ * @used: returns last issued cookie, can be NULL
+ *
+ * If @last and @used are passed in, upon return they reflect the  
driver
+ * internal state and can be used with dma_async_is_complete() to  
check
+ * the status of multiple cookies without re-checking hardware state.
+ */
+static inline enum dma_status dma_async_memcpy_complete(struct  
dma_chan *chan,
+	dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)
+{
+	return chan->device->device_memcpy_complete(chan, cookie, last,  
used);
+}
+
+/**
+ * dma_async_is_complete - test a cookie against chan state
+ * @cookie: transaction identifier to test status of
+ * @last_complete: last know completed transaction
+ * @last_used: last cookie value handed out
+ *
+ * dma_async_is_complete() is used in dma_async_memcpy_complete()
+ * the test logic is seperated for lightweight testing of multiple  
cookies
+ */
+static inline enum dma_status dma_async_is_complete(dma_cookie_t  
cookie,
+			dma_cookie_t last_complete, dma_cookie_t last_used)
+{
+	if (last_complete <= last_used) {
+		if ((cookie <= last_complete) || (cookie > last_used))
+			return DMA_SUCCESS;
+	} else {
+		if ((cookie <= last_complete) && (cookie > last_used))
+			return DMA_SUCCESS;
+	}
+	return DMA_IN_PROGRESS;
+}
+
+
+/* --- DMA device --- */
+
+int dma_async_device_register(struct dma_device *device);
+void dma_async_device_unregister(struct dma_device *device);
+
+#endif /* CONFIG_DMA_ENGINE */
+#endif /* DMAENGINE_H */

-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html