linux-kernel - [RFC PATCH 03/11] firmware: arm_scmi: Add support for notifications message processing

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Message-Id: <20200120122333.46217-4-cristian.marussi@arm.com>
Date:   Mon, 20 Jan 2020 12:23:25 +0000
From:   Cristian Marussi <cristian.marussi@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     sudeep.holla@....com, lukasz.luba@....com,
        james.quinlan@...adcom.com, cristian.marussi@....com
Subject: [RFC PATCH 03/11] firmware: arm_scmi: Add support for notifications message processing

From: Sudeep Holla <sudeep.holla@....com>

Add the mechanisms to distinguish notifications from delayed responses and
to properly fetch notification messages upon reception: notifications
processing does not continue further after the fetch phase.

Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Cristian Marussi <cristian.marussi@....com>
---
 drivers/firmware/arm_scmi/driver.c | 92 +++++++++++++++++++++---------
 1 file changed, 65 insertions(+), 27 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 9611e8037d77..28ed1f0cb417 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -212,6 +212,15 @@ static void scmi_fetch_response(struct scmi_xfer *xfer,
 	memcpy_fromio(xfer->rx.buf, mem->msg_payload + 4, xfer->rx.len);
 }
 
+static void scmi_fetch_notification(struct scmi_xfer *xfer, size_t max_len,
+				    struct scmi_shared_mem __iomem *mem)
+{
+	/* Skip only length of header in payload area i.e 4 bytes */
+	xfer->rx.len = min_t(size_t, max_len, ioread32(&mem->length) - 4);
+
+	memcpy_fromio(xfer->rx.buf, mem->msg_payload, xfer->rx.len);
+}
+
 /**
  * pack_scmi_header() - packs and returns 32-bit header
  *
@@ -339,6 +348,58 @@ __scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer)
 	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
 }
 
+static void scmi_handle_notification(struct scmi_chan_info *cinfo, u32 msg_hdr)
+{
+	struct scmi_xfer *xfer;
+	struct device *dev = cinfo->dev;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct scmi_xfers_info *minfo = &info->rx_minfo;
+	struct scmi_shared_mem __iomem *mem = cinfo->payload;
+
+	xfer = scmi_xfer_get(cinfo->handle, minfo);
+	if (IS_ERR(xfer)) {
+		dev_err(dev, "failed to get free message slot (%ld)\n",
+			PTR_ERR(xfer));
+		iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE,
+			  &mem->channel_status);
+		return;
+	}
+
+	unpack_scmi_header(msg_hdr, &xfer->hdr);
+	scmi_dump_header_dbg(dev, &xfer->hdr);
+	scmi_fetch_notification(xfer, info->desc->max_msg_size, mem);
+	__scmi_xfer_put(minfo, xfer);
+
+	iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE, &mem->channel_status);
+}
+
+static void scmi_handle_xfer_delayed_resp(struct scmi_chan_info *cinfo,
+					  u16 xfer_id, bool delayed_resp)
+{
+	struct scmi_xfer *xfer;
+	struct device *dev = cinfo->dev;
+	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+	struct scmi_xfers_info *minfo = &info->tx_minfo;
+	struct scmi_shared_mem __iomem *mem = cinfo->payload;
+
+	/* Are we even expecting this? */
+	if (!test_bit(xfer_id, minfo->xfer_alloc_table)) {
+		dev_err(dev, "message for %d is not expected!\n", xfer_id);
+		return;
+	}
+
+	xfer = &minfo->xfer_block[xfer_id];
+
+	scmi_dump_header_dbg(dev, &xfer->hdr);
+
+	scmi_fetch_response(xfer, mem);
+
+	if (delayed_resp)
+		complete(xfer->async_done);
+	else
+		complete(&xfer->done);
+}
+
 /**
  * scmi_rx_callback() - mailbox client callback for receive messages
  *
@@ -355,41 +416,18 @@ static void scmi_rx_callback(struct mbox_client *cl, void *m)
 {
 	u8 msg_type;
 	u32 msg_hdr;
-	u16 xfer_id;
-	struct scmi_xfer *xfer;
 	struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
-	struct device *dev = cinfo->dev;
-	struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
-	struct scmi_xfers_info *minfo = &info->tx_minfo;
 	struct scmi_shared_mem __iomem *mem = cinfo->payload;
 
 	msg_hdr = ioread32(&mem->msg_header);
 	msg_type = MSG_XTRACT_TYPE(msg_hdr);
-	xfer_id = MSG_XTRACT_TOKEN(msg_hdr);
 
 	if (msg_type == MSG_TYPE_NOTIFICATION)
-		return; /* Notifications not yet supported */
-
-	/* Are we even expecting this? */
-	if (!test_bit(xfer_id, minfo->xfer_alloc_table)) {
-		dev_err(dev, "message for %d is not expected!\n", xfer_id);
-		return;
-	}
-
-	xfer = &minfo->xfer_block[xfer_id];
-
-	scmi_dump_header_dbg(dev, &xfer->hdr);
-
-	scmi_fetch_response(xfer, mem);
-
-	trace_scmi_rx_done(xfer->transfer_id, xfer->hdr.id,
-			   xfer->hdr.protocol_id, xfer->hdr.seq,
-			   msg_type);
-
-	if (msg_type == MSG_TYPE_DELAYED_RESP)
-		complete(xfer->async_done);
+		scmi_handle_notification(cinfo, msg_hdr);
 	else
-		complete(&xfer->done);
+		scmi_handle_xfer_delayed_resp(cinfo, MSG_XTRACT_TOKEN(msg_hdr),
+					      msg_type);
+
 }
 
 /**
-- 
2.17.1