drivers: firmware: scmi: add nxp specific processing

An option is added to allow vendor specific processing at
scmi_shmem_write_message() and scmi_shmem_read_message().
Additionally code has been added specific to NXP which has
some extended validation features.

Signed-off-by: Andre Heinemans <andre.heinemans@nxp.com>

boards/nxp/imx95_evk/imx95_evk_mimx9596_m7_ddr_defconfig

@@ -17,6 +17,7 @@ CONFIG_CONSOLE=y
 CONFIG_MBOX=y
 CONFIG_MBOX_INIT_PRIORITY=0
 CONFIG_ARM_SCMI=y
+CONFIG_ARM_SCMI_NXP_VENDOR_EXTENSIONS=y
 
 # kernel-related configurations
 CONFIG_XIP=n

boards/nxp/imx95_evk/imx95_evk_mimx9596_m7_defconfig

@@ -13,3 +13,4 @@ CONFIG_XIP=y
 CONFIG_MBOX=y
 CONFIG_MBOX_INIT_PRIORITY=0
 CONFIG_ARM_SCMI=y
+CONFIG_ARM_SCMI_NXP_VENDOR_EXTENSIONS=y

drivers/firmware/scmi/CMakeLists.txt

@@ -11,3 +11,5 @@ zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_SHMEM shmem.c)
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_CLK_HELPERS clk.c)
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_PINCTRL_HELPERS pinctrl.c)
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_POWER_DOMAIN_HELPERS power.c)
+
+add_subdirectory_ifdef(CONFIG_ARM_SCMI nxp)

drivers/firmware/scmi/Kconfig

@@ -64,4 +64,6 @@ config ARM_SCMI_TRANSPORT_INIT_PRIORITY
 	help
 	  SCMI transport driver device initialization priority.
 
+source "drivers/firmware/scmi/nxp/Kconfig"
+
 endif # ARM_SCMI

drivers/firmware/scmi/nxp/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_NXP_VENDOR_EXTENSIONS shmem.c)

drivers/firmware/scmi/nxp/Kconfig

@@ -0,0 +1,8 @@
+# Copyright 2025 NXP
+# SPDX-License-Identifier: Apache-2.0
+
+config ARM_SCMI_NXP_VENDOR_EXTENSIONS
+	bool "Allow NXP specific SCMI features"
+	select CRC
+	help
+	  When enabled, additional SCMI features specific to NXP will be available

drivers/firmware/scmi/nxp/shmem.c

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2025 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/drivers/firmware/scmi/shmem.h>
+#include <zephyr/sys/crc.h>
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(arm_scmi_shmem_nxp);
+
+#define SMT_CRC_NONE  0U
+#define SMT_CRC_XOR   1U /* Unsupported */
+#define SMT_CRC_J1850 2U /* Unsupported */
+#define SMT_CRC_CRC32 3U
+
+int scmi_shmem_vendor_read_message(const struct scmi_shmem_layout *layout)
+{
+	uint32_t validation_type = layout->res1[0];
+
+	if (validation_type == SMT_CRC_CRC32) {
+		if (layout->res1[1] != crc32_ieee((const uint8_t *)&layout->msg_hdr, layout->len)) {
+			LOG_ERR("bad message crc");
+			return -EBADMSG;
+		}
+	} else if (validation_type == SMT_CRC_NONE) {
+		/* do nothing */
+	} else {
+		LOG_ERR("invalid validation type 0x%x", validation_type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int scmi_shmem_vendor_write_message(struct scmi_shmem_layout *layout)
+{
+	uint32_t validation_type = layout->res1[0];
+
+	if (validation_type == SMT_CRC_CRC32) {
+		layout->res1[1] = crc32_ieee((const uint8_t *)&layout->msg_hdr, layout->len);
+	} else if (validation_type == SMT_CRC_NONE) {
+		/* do nothing */
+	} else {
+		LOG_ERR("invalid validation type 0x%x", validation_type);
+		return -EINVAL;
+	}
+
+	return 0;
+}

drivers/firmware/scmi/shmem.c

@@ -26,15 +26,6 @@ struct scmi_shmem_data {
 	mm_reg_t regmap;
 };
 
-struct scmi_shmem_layout {
-	volatile uint32_t res0;
-	volatile uint32_t chan_status;
-	volatile uint32_t res1[2];
-	volatile uint32_t chan_flags;
-	volatile uint32_t len;
-	volatile uint32_t msg_hdr;
-};
-
 int scmi_shmem_get_channel_status(const struct device *dev, uint32_t *status)
 {
 	struct scmi_shmem_data *data;
@@ -57,6 +48,16 @@ static void scmi_shmem_memcpy(mm_reg_t dst, mm_reg_t src, uint32_t bytes)
 	}
 }
 
+__weak int scmi_shmem_vendor_read_message(const struct scmi_shmem_layout *layout)
+{
+	return 0;
+}
+
+__weak int scmi_shmem_vendor_write_message(struct scmi_shmem_layout *layout)
+{
+	return 0;
+}
+
 int scmi_shmem_read_message(const struct device *shmem, struct scmi_message *msg)
 {
 	struct scmi_shmem_layout *layout;
@@ -96,6 +97,11 @@ int scmi_shmem_read_message(const struct device *shmem, struct scmi_message *msg
 		return -EINVAL;
 	}
 
+	if (scmi_shmem_vendor_read_message(layout) < 0) {
+		LOG_ERR("vendor specific validation failed");
+		return -EINVAL;
+	}
+
 	if (msg->content) {
 		scmi_shmem_memcpy(POINTER_TO_UINT(msg->content),
 				  data->regmap + sizeof(*layout), msg->len);
@@ -139,6 +145,10 @@ int scmi_shmem_write_message(const struct device *shmem, struct scmi_message *ms
 				  POINTER_TO_UINT(msg->content), msg->len);
 	}
 
+	if (scmi_shmem_vendor_write_message(layout) < 0) {
+		return -EINVAL;
+	}
+
 	/* done, mark channel as busy and proceed */
 	layout->chan_status &= ~SCMI_SHMEM_CHAN_STATUS_BUSY_BIT;
 

include/zephyr/drivers/firmware/scmi/shmem.h

@@ -19,6 +19,15 @@
 #define SCMI_SHMEM_CHAN_STATUS_BUSY_BIT BIT(0)
 #define SCMI_SHMEM_CHAN_FLAG_IRQ_BIT BIT(0)
 
+struct scmi_shmem_layout {
+	volatile uint32_t res0;
+	volatile uint32_t chan_status;
+	volatile uint32_t res1[2];
+	volatile uint32_t chan_flags;
+	volatile uint32_t len;
+	volatile uint32_t msg_hdr;
+};
+
 struct scmi_message;
 
 /**
@@ -64,4 +73,24 @@ void scmi_shmem_update_flags(const struct device *shmem,
  */
 uint32_t scmi_shmem_channel_status(const struct device *shmem);
 
+/**
+ * @brief Process vendor specific features when writing message
+ *
+ * @param layout layout of the message
+ *
+ * @retval 0 if successful
+ * @retval negative errno if failure
+ */
+int scmi_shmem_vendor_write_message(struct scmi_shmem_layout *layout);
+
+/**
+ * @brief Process vendor specific features when reading message
+ *
+ * @param layout layout of the message
+ *
+ * @retval 0 if successful
+ * @retval negative errno if failure
+ */
+int scmi_shmem_vendor_read_message(const struct scmi_shmem_layout *layout);
+
 #endif /* _INCLUDE_ZEPHYR_DRIVERS_FIRMWARE_SCMI_SHMEM_H_ */