Add support for Raspberry Pi Pico

This adds improved support for the Raspberry Pi Pico range of
microcontrollers.

Benchmark now compiles, and added support for the RNG functions of the
Pico SDK. This gives a ~2x RNG performance improvement on the RP2040 and
over 3x improvement on the RP2350.

The accelerated SHA256 in the RP2350 unfortunately cannot be used with
wolfSSL.

wolfcrypt/benchmark/benchmark.c

@@ -14498,7 +14498,15 @@ void bench_sphincsKeySign(byte level, byte optim)
 
         return (double) ticks/TICKS_PER_SECOND;
     }
+#elif defined(WOLFSSL_RPIPICO)
+    #include "pico/stdlib.h"
 
+    double current_time(int reset)
+    {
+        (void)reset;
+
+        return (double) time_us_64() / 1000000;
+    }
 #elif defined(THREADX)
     #include "tx_api.h"
     double current_time(int reset)

wolfcrypt/src/include.am

@@ -147,7 +147,9 @@ EXTRA_DIST += wolfcrypt/src/port/ti/ti-aes.c \
               wolfcrypt/src/port/cypress/psoc6_crypto.c \
               wolfcrypt/src/port/liboqs/liboqs.c \
               wolfcrypt/src/port/maxim/max3266x.c \
-              wolfcrypt/src/ASN_TEMPLATE.md
+              wolfcrypt/src/ASN_TEMPLATE.md \
+              wolfcrypt/src/port/rpi_pico/pico.c \
+              wolfcrypt/src/port/rpi_pico/README.md
 
 $(ASYNC_FILES):
 	$(AM_V_at)touch $(srcdir)/$@

wolfcrypt/src/port/rpi_pico/README.md

@@ -0,0 +1,72 @@
+# wolfSSL Raspberry Pi Pico Acceleration
+
+wolfSSL supports RNG acceleration on the Raspberry Pi RP2040 and RP2350
+microcontrollers. Everything here assumes you are using the standard [Raspberry
+Pi Pico SDK](https://github.com/raspberrypi/pico-sdk).
+
+It has only been tested with the ARM cores of the RP2350, not the RISC-V cores.
+
+## RNG Acceleration
+
+The Pico SDK has RNG functions for both the RP2040 and RP2350. In the RP2040
+this is an optimised PRNG method, in the RP2350 it uses a built-in TRNG. The
+same API is used for both.
+
+## Comiling wolfSSL
+
+In your `user_settings.h`, you should set the following to add support in
+wolfSSL:
+
+```c
+#define WOLFSSL_RPIPICO
+```
+
+Then for an RP2040, enable the ARM Thumb instructions:
+
+```c
+#define WOLFSSL_SP_ARM_THUMB_ASM
+```
+
+or for an RP2350, the Cortex-M instructions should be used:
+
+```c
+#define WOLFSSL_SP_ARM_CORTEX_M_ASM
+```
+
+To enable the RNG acceleration add the following:
+
+```c
+#define WC_NO_HASHDRBG
+#define CUSTOM_RAND_GENERATE_BLOCK wc_pico_rng_gen_block
+```
+
+In CMake you should add the following linking to both wolfSSL and the end
+application:
+
+```cmake
+target_link_libraries(wolfssl
+    pico_stdlib
+    pico_rand
+)
+```
+
+A full example can be found in the
+[`RPi-Pico`](https://github.com/wolfSSL/wolfssl-examples/tree/master/RPi-Pico)
+directory of the
+[`wolfssl-examples`](https://github.com/wolfSSL/wolfssl-examples) GitHub
+repository.
+
+## Note on RP2350 SHA256
+
+Although RP2350 has SHA256 acceleration, we cannot use this. It is because
+we need to get an intermediate result using `wc_Sha256GetHash()`. The hardware
+will only deal with 64byte packets of data, so to get a result we need to do
+SHA padding. Once the SHA padding is done, it is not in a state to add more
+data.
+The only real workaround would be to cache everything being sent into the
+hardware and replay it as a new instance when trying to get an intermediate
+result. This would not very efficient for an embedded device.
+
+## Support
+
+For questions please email [email protected]

wolfcrypt/src/port/rpi_pico/pico.c

@@ -0,0 +1,59 @@
+/* pico.c
+ *
+ * Copyright (C) 2024 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+
+
+
+#include <inttypes.h>
+#include <string.h>
+#include <wolfssl/wolfcrypt/settings.h>
+#include <wolfssl/wolfcrypt/types.h>
+
+#if defined(WOLFSSL_RPIPICO)
+#include "pico/rand.h"
+
+
+/* On RP2040 this uses an optimized PRNG, on RP2350 this uses a hardware TRNG.
+ * There is a 128bit function, but internally this is just 2x 64bit calls.
+ * Likewise the 32bit call is just a truncated 64bit call, so just stick with
+ * the 64bit calls.
+ */
+
+int wc_pico_rng_gen_block(unsigned char *output, unsigned int sz)
+{
+    uint32_t i = 0;
+
+    while (i < sz)
+    {
+        uint64_t rnd = get_rand_64();
+        if (i + 8 < sz)
+        {
+            XMEMCPY(output + i, &rnd, 8);
+            i += 8;
+        } else {
+            XMEMCPY(output + i, &rnd, sz - i);
+            i = sz;
+        }
+    }
+
+    return 0;
+}
+#endif

wolfcrypt/src/random.c

@@ -111,6 +111,8 @@ This library contains implementation for the random number generator.
     #include <random.h>
 #elif defined(WOLFSSL_XILINX_CRYPT_VERSAL)
     #include "wolfssl/wolfcrypt/port/xilinx/xil-versal-trng.h"
+#elif defined(WOLFSSL_RPIPICO)
+    #include "wolfssl/wolfcrypt/port/rpi_pico/pico.h"
 #elif defined(NO_DEV_RANDOM)
 #elif defined(CUSTOM_RAND_GENERATE)
 #elif defined(CUSTOM_RAND_GENERATE_BLOCK)
@@ -2968,7 +2970,6 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
         }
         return RAN_BLOCK_E;
     }
-
 #elif !defined(WOLFSSL_CAAM) && \
     (defined(FREESCALE_MQX) || defined(FREESCALE_KSDK_MQX) || \
      defined(FREESCALE_KSDK_BM) || defined(FREESCALE_FREE_RTOS))

wolfssl/wolfcrypt/include.am

@@ -119,7 +119,8 @@ noinst_HEADERS+= \
                          wolfssl/wolfcrypt/port/Renesas/renesas_tsip_types.h \
                          wolfssl/wolfcrypt/port/cypress/psoc6_crypto.h \
                          wolfssl/wolfcrypt/port/maxim/max3266x.h \
-                         wolfssl/wolfcrypt/port/maxim/max3266x-cryptocb.h
+                         wolfssl/wolfcrypt/port/maxim/max3266x-cryptocb.h \
+                         wolfssl/wolfcrypt/port/rpi_pico/pico.h
 
 if BUILD_CRYPTOAUTHLIB
 nobase_include_HEADERS+= wolfssl/wolfcrypt/port/atmel/atmel.h

wolfssl/wolfcrypt/port/rpi_pico/pico.h

@@ -0,0 +1,29 @@
+/* pico.h
+ *
+ * Copyright (C) 2024 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+#ifndef _WOLFPORT_RPIPICO_H_
+#define _WOLFPORT_RPIPICO_H_
+#if defined(WOLFSSL_RPIPICO)
+
+WOLFSSL_LOCAL int wc_pico_rng_gen_block(unsigned char* output, unsigned int sz);
+
+#endif /* WOLFSSL_RPPICO */
+#endif /* _WOLFPORT_RPIPICO_H_ */

wolfssl/wolfcrypt/settings.h

@@ -264,6 +264,9 @@
 /* Uncomment next line if using MAXQ108x */
 /* #define WOLFSSL_MAXQ108X */
 
+/* Uncomment next line if using Raspberry Pi RP2040 or RP2350 */
+/* #define WOLFSSL_RPIPICO */
+
 /* Check PLATFORMIO first, as it may define other known environments. */
 #ifdef PLATFORMIO
     #ifdef ESP_PLATFORM