mei: dma ring: implement transmit flow

Implement a circular buffer on allocated system memory. Read and write
indices are stored on the control block which is also shared between the
device and the host.
Two new functions are exported from the DMA module: mei_dma_ring_write,
and mei_dma_ring_empty_slots. The former simply copy a packet on the TX
DMA circular buffer and later, returns the number of empty slots on the
TX DMA circular buffer.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 51 insertions, 13 deletions

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index 5d15501af313..1fc8ea0f519b 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -1558,10 +1558,13 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 	struct mei_msg_hdr mei_hdr;
 	size_t hdr_len = sizeof(mei_hdr);
 	size_t len;
-	size_t hbuf_len;
+	size_t hbuf_len, dr_len;
 	int hbuf_slots;
+	u32 dr_slots;
+	u32 dma_len;
 	int rets;
 	bool first_chunk;
+	const void *data;
 
 	if (WARN_ON(!cl || !cl->dev))
 		return -ENODEV;
@@ -1582,6 +1585,7 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 	}
 
 	len = buf->size - cb->buf_idx;
+	data = buf->data + cb->buf_idx;
 	hbuf_slots = mei_hbuf_empty_slots(dev);
 	if (hbuf_slots < 0) {
 		rets = -EOVERFLOW;
@@ -1589,6 +1593,8 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 	}
 
 	hbuf_len = mei_slots2data(hbuf_slots);
+	dr_slots = mei_dma_ring_empty_slots(dev);
+	dr_len = mei_slots2data(dr_slots);
 
 	mei_msg_hdr_init(&mei_hdr, cb);
 
@@ -1599,23 +1605,33 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 	if (len + hdr_len <= hbuf_len) {
 		mei_hdr.length = len;
 		mei_hdr.msg_complete = 1;
+	} else if (dr_slots && hbuf_len >= hdr_len + sizeof(dma_len)) {
+		mei_hdr.dma_ring = 1;
+		if (len > dr_len)
+			len = dr_len;
+		else
+			mei_hdr.msg_complete = 1;
+
+		mei_hdr.length = sizeof(dma_len);
+		dma_len = len;
+		data = &dma_len;
 	} else if ((u32)hbuf_slots == mei_hbuf_depth(dev)) {
-		mei_hdr.length = hbuf_len - hdr_len;
+		len = hbuf_len - hdr_len;
+		mei_hdr.length = len;
 	} else {
 		return 0;
 	}
 
-	cl_dbg(dev, cl, "buf: size = %zu idx = %zu\n",
-			cb->buf.size, cb->buf_idx);
+	if (mei_hdr.dma_ring)
+		mei_dma_ring_write(dev, buf->data + cb->buf_idx, len);
 
-	rets = mei_write_message(dev, &mei_hdr, hdr_len,
-				 buf->data + cb->buf_idx, mei_hdr.length);
+	rets = mei_write_message(dev, &mei_hdr, hdr_len, data, mei_hdr.length);
 	if (rets)
 		goto err;
 
 	cl->status = 0;
 	cl->writing_state = MEI_WRITING;
-	cb->buf_idx += mei_hdr.length;
+	cb->buf_idx += len;
 
 	if (first_chunk) {
 		if (mei_cl_tx_flow_ctrl_creds_reduce(cl)) {
@@ -1650,11 +1666,13 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 	struct mei_msg_data *buf;
 	struct mei_msg_hdr mei_hdr;
 	size_t hdr_len = sizeof(mei_hdr);
-	size_t len;
-	size_t hbuf_len;
+	size_t len, hbuf_len, dr_len;
 	int hbuf_slots;
+	u32 dr_slots;
+	u32 dma_len;
 	ssize_t rets;
 	bool blocking;
+	const void *data;
 
 	if (WARN_ON(!cl || !cl->dev))
 		return -ENODEV;
@@ -1666,10 +1684,12 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 
 	buf = &cb->buf;
 	len = buf->size;
-	blocking = cb->blocking;
 
 	cl_dbg(dev, cl, "len=%zd\n", len);
 
+	blocking = cb->blocking;
+	data = buf->data;
+
 	rets = pm_runtime_get(dev->dev);
 	if (rets < 0 && rets != -EINPROGRESS) {
 		pm_runtime_put_noidle(dev->dev);
@@ -1706,16 +1726,32 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 	}
 
 	hbuf_len = mei_slots2data(hbuf_slots);
+	dr_slots = mei_dma_ring_empty_slots(dev);
+	dr_len =  mei_slots2data(dr_slots);
 
 	if (len + hdr_len <= hbuf_len) {
 		mei_hdr.length = len;
 		mei_hdr.msg_complete = 1;
+	} else if (dr_slots && hbuf_len >= hdr_len + sizeof(dma_len)) {
+		mei_hdr.dma_ring = 1;
+		if (len > dr_len)
+			len = dr_len;
+		else
+			mei_hdr.msg_complete = 1;
+
+		mei_hdr.length = sizeof(dma_len);
+		dma_len = len;
+		data = &dma_len;
 	} else {
-		mei_hdr.length = hbuf_len - hdr_len;
+		len = hbuf_len - hdr_len;
+		mei_hdr.length = len;
 	}
 
+	if (mei_hdr.dma_ring)
+		mei_dma_ring_write(dev, buf->data, len);
+
 	rets = mei_write_message(dev, &mei_hdr, hdr_len,
-				 buf->data, mei_hdr.length);
+				 data, mei_hdr.length);
 	if (rets)
 		goto err;
 
@@ -1724,7 +1760,9 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 		goto err;
 
 	cl->writing_state = MEI_WRITING;
-	cb->buf_idx = mei_hdr.length;
+	cb->buf_idx = len;
+	/* restore return value */
+	len = buf->size;
 
 out:
 	if (mei_hdr.msg_complete)