linux-kernel - [RFC v5 2/5] drivers: firmware: scmi: Introduce scmi_get_max_msg

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Date:   Fri, 27 Oct 2023 06:28:09 +0000
From:   Oleksii Moisieiev <Oleksii_Moisieiev@...m.com>
To:     "sudeep.holla@....com" <sudeep.holla@....com>
CC:     Oleksii Moisieiev <Oleksii_Moisieiev@...m.com>,
        Cristian Marussi <cristian.marussi@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: [RFC v5 2/5] drivers: firmware: scmi: Introduce scmi_get_max_msg_size
 function

Current SCMI implementation supports only receiving arrays from the
SCMI server and provides helpers to process received data. It uses
msg_max_size value to determine maximum message size that can be
transmitted via selected protocol. When sending arrays to SCMI server
this value should be checked by the Client driver to prevent
overflowing protocol buffers.
That's why scmi_get_max_msg_size call was introduced.

Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@...m.com>
---
 drivers/firmware/arm_scmi/common.h |  3 +++
 drivers/firmware/arm_scmi/driver.c | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index c46dc5215af7..3db97f59bc59 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -286,6 +286,9 @@ int scmi_xfer_raw_inflight_register(const struct scmi_handle *handle,
 int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
 					    struct scmi_xfer *xfer,
 					    unsigned int timeout_ms);
+
+int scmi_get_max_msg_size(const struct scmi_protocol_handle *ph);
+
 #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 729201d8f935..f15e9b2b21f3 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1152,6 +1152,22 @@ int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
 	return ret;
 }
 
+/**
+ * scmi_get_max_msg_size  - An helper to get currently configured
+ * maximum message size.
+ *
+ * @ph: SCMI protocol handle
+ *
+ * Return: Maximum message size for the current protocol.
+ */
+int scmi_get_max_msg_size(const struct scmi_protocol_handle *ph)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+	struct scmi_info *info = handle_to_scmi_info(pi->handle);
+
+	return info->desc->max_msg_size;
+}
+
 /**
  * do_xfer() - Do one transfer
  *
-- 
2.25.1