mei: dma ring: implement rx circular buffer logic

Implement circular buffer protocol over receive dma
buffer. Add extension to the mei message header that holds
length of the buffer on the dma 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, 29 insertions, 12 deletions

diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 5a661cbdf2ae..055c2d89b310 100644
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -75,6 +75,8 @@ static inline int mei_cl_hbm_equal(struct mei_cl *cl,
  */
 static void mei_irq_discard_msg(struct mei_device *dev, struct mei_msg_hdr *hdr)
 {
+	if (hdr->dma_ring)
+		mei_dma_ring_read(dev, NULL, hdr->extension[0]);
 	/*
 	 * no need to check for size as it is guarantied
 	 * that length fits into rd_msg_buf
@@ -100,6 +102,7 @@ static int mei_cl_irq_read_msg(struct mei_cl *cl,
 	struct mei_device *dev = cl->dev;
 	struct mei_cl_cb *cb;
 	size_t buf_sz;
+	u32 length;
 
 	cb = list_first_entry_or_null(&cl->rd_pending, struct mei_cl_cb, list);
 	if (!cb) {
@@ -119,25 +122,31 @@ static int mei_cl_irq_read_msg(struct mei_cl *cl,
 		goto discard;
 	}
 
-	buf_sz = mei_hdr->length + cb->buf_idx;
+	length = mei_hdr->dma_ring ? mei_hdr->extension[0] : mei_hdr->length;
+
+	buf_sz = length + cb->buf_idx;
 	/* catch for integer overflow */
 	if (buf_sz < cb->buf_idx) {
 		cl_err(dev, cl, "message is too big len %d idx %zu\n",
-		       mei_hdr->length, cb->buf_idx);
+		       length, cb->buf_idx);
 		cb->status = -EMSGSIZE;
 		goto discard;
 	}
 
 	if (cb->buf.size < buf_sz) {
 		cl_dbg(dev, cl, "message overflow. size %zu len %d idx %zu\n",
-			cb->buf.size, mei_hdr->length, cb->buf_idx);
+			cb->buf.size, length, cb->buf_idx);
 		cb->status = -EMSGSIZE;
 		goto discard;
 	}
 
+	if (mei_hdr->dma_ring)
+		mei_dma_ring_read(dev, cb->buf.data + cb->buf_idx, length);
+
+	/*  for DMA read 0 length to generate an interrupt to the device */
 	mei_read_slots(dev, cb->buf.data + cb->buf_idx, mei_hdr->length);
 
-	cb->buf_idx += mei_hdr->length;
+	cb->buf_idx += length;
 
 	if (mei_hdr->msg_complete) {
 		cl_dbg(dev, cl, "completed read length = %zu\n", cb->buf_idx);
@@ -247,6 +256,9 @@ static inline int hdr_is_valid(u32 msg_hdr)
 	if (!msg_hdr || mei_hdr->reserved)
 		return -EBADMSG;
 
+	if (mei_hdr->dma_ring && mei_hdr->length != MEI_SLOT_SIZE)
+		return -EBADMSG;
+
 	return 0;
 }
 
@@ -267,20 +279,20 @@ int mei_irq_read_handler(struct mei_device *dev,
 	struct mei_cl *cl;
 	int ret;
 
-	if (!dev->rd_msg_hdr) {
-		dev->rd_msg_hdr = mei_read_hdr(dev);
+	if (!dev->rd_msg_hdr[0]) {
+		dev->rd_msg_hdr[0] = mei_read_hdr(dev);
 		(*slots)--;
 		dev_dbg(dev->dev, "slots =%08x.\n", *slots);
 
-		ret = hdr_is_valid(dev->rd_msg_hdr);
+		ret = hdr_is_valid(dev->rd_msg_hdr[0]);
 		if (ret) {
 			dev_err(dev->dev, "corrupted message header 0x%08X\n",
-				dev->rd_msg_hdr);
+				dev->rd_msg_hdr[0]);
 			goto end;
 		}
 	}
 
-	mei_hdr = (struct mei_msg_hdr *)&dev->rd_msg_hdr;
+	mei_hdr = (struct mei_msg_hdr *)dev->rd_msg_hdr;
 	dev_dbg(dev->dev, MEI_HDR_FMT, MEI_HDR_PRM(mei_hdr));
 
 	if (mei_slots2data(*slots) < mei_hdr->length) {
@@ -291,6 +303,12 @@ int mei_irq_read_handler(struct mei_device *dev,
 		goto end;
 	}
 
+	if (mei_hdr->dma_ring) {
+		dev->rd_msg_hdr[1] = mei_read_hdr(dev);
+		(*slots)--;
+		mei_hdr->length = 0;
+	}
+
 	/*  HBM message */
 	if (hdr_is_hbm(mei_hdr)) {
 		ret = mei_hbm_dispatch(dev, mei_hdr);
@@ -324,7 +342,7 @@ int mei_irq_read_handler(struct mei_device *dev,
 			goto reset_slots;
 		}
 		dev_err(dev->dev, "no destination client found 0x%08X\n",
-				dev->rd_msg_hdr);
+				dev->rd_msg_hdr[0]);
 		ret = -EBADMSG;
 		goto end;
 	}
@@ -334,9 +352,8 @@ int mei_irq_read_handler(struct mei_device *dev,
 
 reset_slots:
 	/* reset the number of slots and header */
+	memset(dev->rd_msg_hdr, 0, sizeof(dev->rd_msg_hdr));
 	*slots = mei_count_full_read_slots(dev);
-	dev->rd_msg_hdr = 0;
-
 	if (*slots == -EOVERFLOW) {
 		/* overflow - reset */
 		dev_err(dev->dev, "resetting due to slots overflow.\n");