[PATCH v8 05/17] firmware: arm_scmi: Add xfer Raw helpers

Cristian Marussi
2023-01-18T12:19:16Z

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

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
v5 --> v6
- handling is_raw as a bitflag
v4 --> v5
- add handling of xfer->is_raw flag
v3 --> v4
- add scmi_xfer_raw_wait_for_response helper
- fixed typos in comments
v2 --> v3
- allow for DT-unknown protocols to get a channel
v1 --> v2
- added scmi_xfer_raw_channel_get
---
drivers/firmware/arm_scmi/common.h | 12 +++
drivers/firmware/arm_scmi/driver.c | 147 +++++++++++++++++++++++++++++
2 files changed, 159 insertions(+)

diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index f785f0ff2090..e9aa1cfef90d 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -229,6 +229,18 @@ static inline bool is_polling_enabled(struct scmi_chan_info *cinfo,
is_transport_polling_capable(desc);
}

+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);
+
+int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer,
+ unsigned int timeout_ms);
#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 ce204a77c7f3..67072699b029 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -450,6 +450,53 @@ 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 channel, 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
@@ -525,6 +572,63 @@ 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_xfer *xfer;
+ struct scmi_info *info = handle_to_scmi_info(handle);
+
+ xfer = scmi_xfer_get(handle, &info->tx_minfo);
+ if (!IS_ERR(xfer))
+ xfer->flags |= SCMI_XFER_FLAG_IS_RAW;
+
+ return xfer;
+}
+
+/**
+ * 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, re-using 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
*
@@ -553,6 +657,23 @@ __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);
+
+ xfer->flags &= ~SCMI_XFER_FLAG_IS_RAW;
+ return __scmi_xfer_put(&info->tx_minfo, xfer);
+}
+
/**
* scmi_xfer_lookup_unlocked - Helper to lookup an xfer_id
*
@@ -979,6 +1100,32 @@ static int scmi_wait_for_message_response(struct scmi_chan_info *cinfo,
info->desc->max_rx_timeout_ms);
}

+/**
+ * scmi_xfer_raw_wait_for_message_response - An helper to wait for a message
+ * reply to an xfer raw request on a specific channel for the required timeout.
+ *
+ * @cinfo: SCMI channel info
+ * @xfer: Reference to the transfer being waited for.
+ * @timeout_ms: The maximum timeout in milliseconds
+ *
+ * Return: 0 on Success, error otherwise.
+ */
+int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer,
+ unsigned int timeout_ms)
+{
+ int ret;
+ struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+ struct device *dev = info->dev;
+
+ ret = scmi_wait_for_reply(dev, info->desc, cinfo, xfer, timeout_ms);
+ if (ret)
+ dev_dbg(dev, "timed out in RAW response - HDR:%08X\n",
+ pack_scmi_header(&xfer->hdr));
+
+ return ret;
+}
+
/**
* do_xfer() - Do one transfer
*