entropy: rpi_pico: implement entropy driver for RP2350

Use get_rand_64() from Pico SDK for entropy. Signed-off-by: Xudong Zheng <[email protected]>
zephyrproject-rtos · Jan 17, 2025 · 14d6fb1 · 14d6fb1
1 parent 334c6be
commit 14d6fb1
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diff --git a/drivers/entropy/CMakeLists.txt b/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_RPI_PICO_RNG       entropy_rpi_pico.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)

diff --git a/drivers/entropy/Kconfig b/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.rpi_pico"
 source "drivers/entropy/Kconfig.sam"
 source "drivers/entropy/Kconfig.smartbond"
 source "drivers/entropy/Kconfig.native_posix"

diff --git a/drivers/entropy/Kconfig.rpi_pico b/drivers/entropy/Kconfig.rpi_pico
@@ -0,0 +1,12 @@
+# Raspberry Pi Pico entropy generator driver configuration
+
+# Copyright (c) 2024 Xudong Zheng
+# SPDX-License-Identifier: Apache-2.0
+
+config ENTROPY_RPI_PICO_RNG
+	bool "Raspberry Pi Pico entropy number generator driver"
+	default y
+	depends on DT_HAS_RASPBERRYPI_PICO_RNG_ENABLED
+	select ENTROPY_HAS_DRIVER
+	select PICOSDK_USE_CLAIM
+	select PICOSDK_USE_RAND
diff --git a/drivers/entropy/entropy_rpi_pico.c b/drivers/entropy/entropy_rpi_pico.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2024 Xudong Zheng
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <string.h>
+#include <pico/rand.h>
+#include <zephyr/drivers/entropy.h>
+#include <zephyr/spinlock.h>
+
+#define DT_DRV_COMPAT raspberrypi_pico_rng
+
+static struct k_spinlock entropy_lock;
+
+static int entropy_rpi_pico_get_entropy(const struct device *dev, uint8_t *buf, uint16_t len)
+{
+	k_spinlock_key_t key = k_spin_lock(&entropy_lock);
+
+	__ASSERT_NO_MSG(buf != NULL);
+	uint8_t *buf_bytes = buf;
+
+	while (len > 0) {
+		uint64_t value = get_rand_64();
+		uint64_t to_copy = MIN(sizeof(value), len);
+
+		memcpy(buf_bytes, &value, to_copy);
+		buf_bytes += to_copy;
+		len -= to_copy;
+	}
+
+	k_spin_unlock(&entropy_lock, key);
+	return 0;
+}
+
+static DEVICE_API(entropy, entropy_rpi_pico_api_funcs) = {
+	.get_entropy = entropy_rpi_pico_get_entropy
+};
+
+static int entropy_rpi_pico_init(const struct device *dev)
+{
+	return 0;
+}
+
+DEVICE_DT_INST_DEFINE(0,
+		    entropy_rpi_pico_init, NULL, NULL, NULL,
+		    PRE_KERNEL_1, CONFIG_ENTROPY_INIT_PRIORITY,
+		    &entropy_rpi_pico_api_funcs);
diff --git a/dts/arm/raspberrypi/rpi_pico/rp2350.dtsi b/dts/arm/raspberrypi/rpi_pico/rp2350.dtsi
@@ -21,6 +21,10 @@
 		die-temp0 = &die_temp;
 	};
 
+	chosen {
+		zephyr,entropy = &rng;
+	};
+
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
@@ -424,6 +428,11 @@
 			resets = <&reset RPI_PICO_RESETS_RESET_PIO2>;
 			status = "disabled";
 		};
+
+		rng: rng {
+			status = "okay";
+			compatible = "raspberrypi,pico-rng";
+		};
 	};
 
 	pinctrl: pin-controller {

diff --git a/dts/bindings/rng/raspberrypi,pico-rng.yaml b/dts/bindings/rng/raspberrypi,pico-rng.yaml
@@ -0,0 +1,8 @@
+# Copyright (c) 2024 Xudong Zheng
+# SPDX-License-Identifier: Apache-2.0
+
+description: Raspberry Pi Pico RNG/Entropy
+
+compatible: "raspberrypi,pico-rng"
+
+include: base.yaml
diff --git a/modules/hal_rpi_pico/CMakeLists.txt b/modules/hal_rpi_pico/CMakeLists.txt
@@ -151,6 +151,18 @@ if(CONFIG_HAS_RPI_PICO)
   zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_CLAIM
           ${common_dir}/hardware_claim/include)
 
+  zephyr_library_sources_ifdef(CONFIG_PICOSDK_USE_RAND
+    ${rp2_common_dir}/hardware_timer/timer.c
+    ${rp2_common_dir}/pico_rand/rand.c
+  )
+  zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_RAND
+    ${common_dir}/pico_sync/include
+    ${common_dir}/pico_time/include
+    ${rp2_common_dir}/pico_rand/include
+    ${rp2_common_dir}/pico_time_adapter/include
+    ${rp2_common_dir}/pico_unique_id/include
+  )
+
   zephyr_library_sources_ifdef(CONFIG_SOC_SERIES_RP2350
           ${rp2_common_dir}/pico_runtime_init/runtime_init.c)
   zephyr_include_directories_ifdef(CONFIG_SOC_SERIES_RP2350

diff --git a/modules/hal_rpi_pico/Kconfig b/modules/hal_rpi_pico/Kconfig
@@ -54,3 +54,8 @@ config PICOSDK_USE_RTC
 	bool
 	help
 	  Use the RTC driver from pico-sdk
+
+config PICOSDK_USE_RAND
+	bool
+	help
+	  Use the "rand" driver from pico-sdk