rpmsg: glink: Add TX_DATA_CONT command while sending

With current design the transport can send packets of size upto
FIFO_SIZE which is 16k and return failure for all packets above 16k.

Add TX_DATA_CONT command to send packets greater than 16k by splitting
into 8K chunks.

Signed-off-by: Arun Kumar Neelakantam <[email protected]>
Signed-off-by: Deepak Kumar Singh <[email protected]>
Signed-off-by: Bjorn Andersson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Arun Kumar Neelakantam

drivers/rpmsg/qcom_glink_native.c

@@ -1271,6 +1271,8 @@ static int __qcom_glink_send(struct glink_channel *channel,
 	} __packed req;
 	int ret;
 	unsigned long flags;
+	int chunk_size = len;
+	int left_size = 0;
 
 	if (!glink->intentless) {
 		while (!intent) {
@@ -1304,18 +1306,46 @@ static int __qcom_glink_send(struct glink_channel *channel,
 		iid = intent->id;
 	}
 
+	if (wait && chunk_size > SZ_8K) {
+		chunk_size = SZ_8K;
+		left_size = len - chunk_size;
+	}
 	req.msg.cmd = cpu_to_le16(RPM_CMD_TX_DATA);
 	req.msg.param1 = cpu_to_le16(channel->lcid);
 	req.msg.param2 = cpu_to_le32(iid);
-	req.chunk_size = cpu_to_le32(len);
-	req.left_size = cpu_to_le32(0);
+	req.chunk_size = cpu_to_le32(chunk_size);
+	req.left_size = cpu_to_le32(left_size);
 
-	ret = qcom_glink_tx(glink, &req, sizeof(req), data, len, wait);
+	ret = qcom_glink_tx(glink, &req, sizeof(req), data, chunk_size, wait);
 
 	/* Mark intent available if we failed */
-	if (ret && intent)
+	if (ret && intent) {
 		intent->in_use = false;
+		return ret;
+	}
 
+	while (left_size > 0) {
+		data = (void *)((char *)data + chunk_size);
+		chunk_size = left_size;
+		if (chunk_size > SZ_8K)
+			chunk_size = SZ_8K;
+		left_size -= chunk_size;
+
+		req.msg.cmd = cpu_to_le16(RPM_CMD_TX_DATA_CONT);
+		req.msg.param1 = cpu_to_le16(channel->lcid);
+		req.msg.param2 = cpu_to_le32(iid);
+		req.chunk_size = cpu_to_le32(chunk_size);
+		req.left_size = cpu_to_le32(left_size);
+
+		ret = qcom_glink_tx(glink, &req, sizeof(req), data,
+				    chunk_size, wait);
+
+		/* Mark intent available if we failed */
+		if (ret && intent) {
+			intent->in_use = false;
+			break;
+		}
+	}
 	return ret;
 }