soc: stm32n6: Add NPU driver

Provide Neural-ART driver for STM32N6.
This driver handles unit initialization (clock, rif).

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

soc/st/stm32/stm32n6x/CMakeLists.txt

@@ -5,6 +5,10 @@ zephyr_sources(
   soc.c
   )
 
+zephyr_sources_ifdef(CONFIG_STM32N6_NPU
+  npu/npu_stm32n6.c
+  )
+
 zephyr_include_directories(.)
 
 set(SOC_LINKER_SCRIPT ${ZEPHYR_BASE}/include/zephyr/arch/arm/cortex_m/scripts/linker.ld CACHE INTERNAL "")

soc/st/stm32/stm32n6x/Kconfig

@@ -23,3 +23,8 @@ config SOC_SERIES_STM32N6X
 
 config STM32N6_BOOT_SERIAL
 	bool "Serial boot target (USB)"
+
+config STM32N6_NPU
+	bool "Neural-ART accelerator (NPU)"
+	select USE_STM32_HAL_RIF
+	select USE_STM32_HAL_CACHEAXI

soc/st/stm32/stm32n6x/npu/npu_stm32n6.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2025 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT st_stm32_npu
+
+#include <errno.h>
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/reset.h>
+#include <zephyr/init.h>
+#include <soc.h>
+
+#include <zephyr/drivers/clock_control/stm32_clock_control.h>
+
+/* Read-only driver configuration */
+struct npu_stm32_cfg {
+	/* Clock configuration. */
+	struct stm32_pclken pclken;
+	/* Reset configuration */
+	const struct reset_dt_spec reset;
+};
+
+static void npu_risaf_config(void)
+{
+	RIMC_MasterConfig_t RIMC_master = {0};
+
+	RIMC_master.MasterCID = RIF_CID_1;
+	RIMC_master.SecPriv = RIF_ATTRIBUTE_SEC | RIF_ATTRIBUTE_PRIV;
+	HAL_RIF_RIMC_ConfigMasterAttributes(RIF_MASTER_INDEX_NPU, &RIMC_master);
+	HAL_RIF_RISC_SetSlaveSecureAttributes(RIF_RISC_PERIPH_INDEX_NPU,
+					      RIF_ATTRIBUTE_SEC | RIF_ATTRIBUTE_PRIV);
+}
+
+static int npu_stm32_init(const struct device *dev)
+{
+	const struct device *const clk = DEVICE_DT_GET(STM32_CLOCK_CONTROL_NODE);
+	const struct npu_stm32_cfg *cfg = dev->config;
+
+	if (!device_is_ready(clk)) {
+		return -ENODEV;
+	}
+
+	if (clock_control_on(clk, (clock_control_subsys_t) &cfg->pclken) != 0) {
+		return -EIO;
+	}
+
+	if (!device_is_ready(cfg->reset.dev)) {
+		return -ENODEV;
+	}
+
+	/* Reset timer to default state using RCC */
+	(void)reset_line_toggle_dt(&cfg->reset);
+
+	npu_risaf_config();
+
+	return 0;
+}
+
+
+static const struct npu_stm32_cfg npu_stm32_cfg = {
+	.pclken = {
+		.enr = DT_CLOCKS_CELL(DT_NODELABEL(npu), bits),
+		.bus = DT_CLOCKS_CELL(DT_NODELABEL(npu), bus),
+	},
+	.reset = RESET_DT_SPEC_GET(DT_NODELABEL(npu)),
+};
+
+DEVICE_DT_DEFINE(DT_NODELABEL(npu), npu_stm32_init, NULL,
+		 NULL, &npu_stm32_cfg, POST_KERNEL,
+		 CONFIG_APPLICATION_INIT_PRIORITY, NULL);