drivers: entropy: Add new driver based on nrf54l cracen driver

Add a new entropy driver based on the nrf HAL CRACEN CTR DRBG driver

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

drivers/entropy/CMakeLists.txt

@@ -12,6 +12,7 @@ zephyr_library_sources_ifdef(CONFIG_ENTROPY_MCUX_RNGA          entropy_mcux_rnga
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_MCUX_TRNG          entropy_mcux_trng.c)
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_MCUX_CAAM          entropy_mcux_caam.c)
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_NRF5_RNG           entropy_nrf5.c)
+zephyr_library_sources_ifdef(CONFIG_ENTROPY_NRF_CRACEN_CTR_DRBG entropy_nrf_cracen.c)
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_SAM_RNG            entropy_sam.c)
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_SMARTBOND_TRNG     entropy_smartbond.c)
 zephyr_library_sources_ifdef(CONFIG_ENTROPY_STM32_RNG          entropy_stm32.c)

drivers/entropy/Kconfig

@@ -26,6 +26,7 @@ source "drivers/entropy/Kconfig.mcux"
 source "drivers/entropy/Kconfig.stm32"
 source "drivers/entropy/Kconfig.esp32"
 source "drivers/entropy/Kconfig.nrf5"
+source "drivers/entropy/Kconfig.nrf_cracen"
 source "drivers/entropy/Kconfig.sam"
 source "drivers/entropy/Kconfig.smartbond"
 source "drivers/entropy/Kconfig.native_posix"

drivers/entropy/Kconfig.nrf_cracen

@@ -0,0 +1,17 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config ENTROPY_NRF_CRACEN_CTR_DRBG
+	bool "nRF entropy driver based on the CRACEN CTR_DRBG driver"
+	default y
+	depends on DT_HAS_NORDIC_NRF_CRACEN_CTRDRBG_ENABLED
+	depends on SOC_COMPATIBLE_NRF54LX
+	select ENTROPY_HAS_DRIVER
+	select NRFX_CRACEN
+	help
+	  This option enables the 54L CRACEN based entropy driver, based on the nrfx CRACEN CTR_DRBG
+	  random driver.
+	  Notes: This driver is only compatible with 54L devices, and may only be used from one processor
+	  core. This driver cannot be used in conjunction with the nRF security PSA solution, as both
+	  would attempt to use the CRACEN HW exclusively; When that is enabled, the PSA crypto entropy
+	  driver should be selected instead.

drivers/entropy/entropy_nrf_cracen.c

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <nrfx_cracen.h>
+#include <zephyr/irq.h>
+#include <zephyr/drivers/entropy.h>
+
+#define DT_DRV_COMPAT nordic_nrf_cracen_ctrdrbg
+
+static int nrf_cracen_get_entropy_isr(const struct device *dev, uint8_t *buf, uint16_t len,
+				      uint32_t flags)
+{
+	(void)dev;
+	(void)flags;
+
+	unsigned int key = irq_lock();
+
+	/* This will be done in less than 1 microsecond */
+	int ret = nrfx_cracen_ctr_drbg_random_get(buf, len);
+
+	irq_unlock(key);
+
+	if (likely(ret == NRFX_SUCCESS)) {
+		return len;
+	} else if (ret == NRFX_ERROR_INVALID_PARAM) {
+		return -EINVAL;
+	} else {
+		return -EAGAIN;
+	}
+}
+
+static int nrf_cracen_get_entropy(const struct device *dev, uint8_t *buf, uint16_t len)
+{
+	int ret = nrf_cracen_get_entropy_isr(dev, buf, len, 0);
+
+	if (ret < 0) {
+		return ret;
+	} else {
+		return 0;
+	}
+}
+
+static int nrf_cracen_cracen_init(const struct device *dev)
+{
+	(void)dev;
+
+	int ret = nrfx_cracen_ctr_drbg_init();
+
+	if (ret == NRFX_SUCCESS) {
+		return 0;
+	} else {
+		return -EIO;
+	}
+}
+
+static DEVICE_API(entropy, nrf_cracen_api_funcs) = {
+	.get_entropy = nrf_cracen_get_entropy,
+	.get_entropy_isr = nrf_cracen_get_entropy_isr
+};
+
+DEVICE_DT_INST_DEFINE(0, nrf_cracen_cracen_init, NULL, NULL, NULL, PRE_KERNEL_1,
+		      CONFIG_ENTROPY_INIT_PRIORITY, &nrf_cracen_api_funcs);

dts/bindings/rng/nordic,nrf-cracen-ctrdrbg.yaml

@@ -0,0 +1,14 @@
+# Copyright (c) 2025, Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+    Nordic nRF CRACEN CTR_DRBG based (Random Number Generator)
+
+    This driver is only compatible with 54L devices, and may only be used from one processor
+    core. This driver cannot be used in conjunction with the nRF security PSA solution, as both
+    would attempt to use the CRACEN HW exclusively; When that is enabled, zephyr,psa-crypto-rng
+    should be selected instead.
+
+compatible: "nordic,nrf-cracen-ctrdrbg"
+
+include: base.yaml