[PATCH v3 4/9] firmware: arm_scmi: Add xfer raw helpers

[Cristian Marussi]

Add a few SCMI helpers useful to implement SCMI Raw access support.

Signed-off-by: Cristian Marussi <cristian.marussi at arm.com>
---
v1 --> v2
- added scmi_xfer_raw_channel_get
v2 --> v3
- allow for DT-unknown protocols to get a channel
---
 drivers/firmware/arm_scmi/common.h |   9 +++
 drivers/firmware/arm_scmi/driver.c | 115 +++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)

diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 096b66442d84..6d2a57a696d8 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -212,6 +212,15 @@ struct scmi_desc {
 	const bool atomic_enabled;
 };
 
+void scmi_xfer_raw_put(const struct scmi_handle *handle,
+		       struct scmi_xfer *xfer);
+struct scmi_xfer *scmi_xfer_raw_get(const struct scmi_handle *handle);
+struct scmi_chan_info *
+scmi_xfer_raw_channel_get(const struct scmi_handle *handle, u8 protocol_id);
+
+int scmi_xfer_raw_inflight_register(const struct scmi_handle *handle,
+				    struct scmi_xfer *xfer);
+
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_MAILBOX
 extern const struct scmi_desc scmi_mailbox_desc;
 #endif
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 56b1a917f618..c1292452e41f 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -350,6 +350,53 @@ scmi_xfer_inflight_register_unlocked(struct scmi_xfer *xfer,
 	xfer->pending = true;
 }
 
+/**
+ * scmi_xfer_inflight_register  - Try to register an xfer as in-flight
+ *
+ * @xfer: The xfer to register
+ * @minfo: Pointer to Tx/Rx Message management info based on channel type
+ *
+ * Note that this helper does NOT assume anything about the sequence number
+ * that was baked into the provided xfer, so it checks at first if it can
+ * be mapped to a free slot and fails with an error if another xfer with the
+ * same sequence number is currently still registered as in-flight.
+ *
+ * Return: 0 on Success or -EBUSY if sequence number embedded in the xfer
+ *	   could not rbe mapped to a free slot in the xfer_alloc_table.
+ */
+static int scmi_xfer_inflight_register(struct scmi_xfer *xfer,
+				       struct scmi_xfers_info *minfo)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&minfo->xfer_lock, flags);
+	if (!test_bit(xfer->hdr.seq, minfo->xfer_alloc_table))
+		scmi_xfer_inflight_register_unlocked(xfer, minfo);
+	else
+		ret = -EBUSY;
+	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+
+	return ret;
+}
+
+/**
+ * scmi_xfer_raw_inflight_register  - An helper to register the given xfer as in
+ * flight on the TX channe, if possible.
+ *
+ * @handle: Pointer to SCMI entity handle
+ * @xfer: The xfer to register
+ *
+ * Return: 0 on Success, error otherwise
+ */
+int scmi_xfer_raw_inflight_register(const struct scmi_handle *handle,
+				    struct scmi_xfer *xfer)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	return scmi_xfer_inflight_register(xfer, &info->tx_minfo);
+}
+
 /**
  * scmi_xfer_pending_set  - Pick a proper sequence number and mark the xfer
  * as pending in-flight
@@ -425,6 +472,58 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
 	return xfer;
 }
 
+/**
+ * scmi_xfer_raw_get  - Helper to get a bare free xfer from the TX channel
+ *
+ * @handle: Pointer to SCMI entity handle
+ *
+ * Note that xfer is taken from the TX channel structures.
+ *
+ * Return: A valid xfer on Success, or an error-pointer otherwise
+ */
+struct scmi_xfer *scmi_xfer_raw_get(const struct scmi_handle *handle)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	return scmi_xfer_get(handle, &info->tx_minfo);
+}
+
+/**
+ * scmi_xfer_raw_channel_get  - Helper to get a reference to the proper channel
+ * to use for a specific protocol_id Raw transaction.
+ *
+ * @handle: Pointer to SCMI entity handle
+ * @protocol_id: Identifier of the protocol
+ *
+ * Note that in a regular SCMI stack, usually, a protocol has to be defined in
+ * the DT to have an associated channel and be usable; but in Raw mode any
+ * protocol in range is allowed, resusing the Base channel, so as to enable
+ * fuzzing on any protocol without the need of a fully compiled DT.
+ *
+ * Return: A reference to the channel to use, or an ERR_PTR
+ */
+struct scmi_chan_info *
+scmi_xfer_raw_channel_get(const struct scmi_handle *handle, u8 protocol_id)
+{
+	struct scmi_chan_info *cinfo;
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	cinfo = idr_find(&info->tx_idr, protocol_id);
+	if (!cinfo) {
+		if (protocol_id == SCMI_PROTOCOL_BASE)
+			return ERR_PTR(-EINVAL);
+		/* Use Base channel for protocols not defined for DT */
+		cinfo = idr_find(&info->tx_idr, SCMI_PROTOCOL_BASE);
+		if (!cinfo)
+			return ERR_PTR(-EINVAL);
+		dev_warn_once(handle->dev,
+			      "Using Base channel for protocol 0x%X\n",
+			      protocol_id);
+	}
+
+	return cinfo;
+}
+
 /**
  * __scmi_xfer_put() - Release a message
  *
@@ -453,6 +552,22 @@ __scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer)
 	spin_unlock_irqrestore(&minfo->xfer_lock, flags);
 }
 
+/**
+ * scmi_xfer_raw_put  - Release an xfer that was taken by @scmi_xfer_raw_get
+ *
+ * @handle: Pointer to SCMI entity handle
+ * @xfer: A reference to the xfer to put
+ *
+ * Note that as with other xfer_put() handlers the xfer is really effectively
+ * released only if there are no more users on the system.
+ */
+void scmi_xfer_raw_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	return __scmi_xfer_put(&info->tx_minfo, xfer);
+}
+
 /**
  * scmi_xfer_lookup_unlocked  -  Helper to lookup an xfer_id
  *
-- 
2.32.0