rp2: Add support for RP2350 in RISCV mode.

As part of this change, the RV32I native emitter is enabled on RISCV
board variants.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

ports/rp2/CMakeLists.txt

@@ -93,6 +93,14 @@ include(${MICROPY_DIR}/py/usermod.cmake)
 
 add_executable(${MICROPY_TARGET})
 
+# Provide a C-level definitions of PICO_ARM.
+# (The pico-sdk already defines PICO_RISCV when it's enabled.)
+if(PICO_ARM)
+    target_compile_definitions(pico_platform_headers INTERFACE
+        PICO_ARM=1
+    )
+endif()
+
 set(MICROPY_QSTRDEFS_PORT
     ${MICROPY_PORT_DIR}/qstrdefsport.h
 )
@@ -108,7 +116,6 @@ set(MICROPY_SOURCE_LIB
     ${MICROPY_DIR}/shared/netutils/netutils.c
     ${MICROPY_DIR}/shared/netutils/trace.c
     ${MICROPY_DIR}/shared/readline/readline.c
-    ${MICROPY_DIR}/shared/runtime/gchelper_thumb1.s
     ${MICROPY_DIR}/shared/runtime/gchelper_native.c
     ${MICROPY_DIR}/shared/runtime/interrupt_char.c
     ${MICROPY_DIR}/shared/runtime/mpirq.c
@@ -123,6 +130,16 @@ set(MICROPY_SOURCE_LIB
     ${MICROPY_DIR}/shared/tinyusb/mp_usbd_runtime.c
 )
 
+if(PICO_ARM)
+    list(APPEND MICROPY_SOURCE_LIB
+        ${MICROPY_DIR}/shared/runtime/gchelper_thumb1.s
+    )
+elseif(PICO_RISCV)
+    list(APPEND MICROPY_SOURCE_LIB
+        ${MICROPY_DIR}/shared/runtime/gchelper_rv32i.s
+    )
+endif()
+
 set(MICROPY_SOURCE_DRIVERS
     ${MICROPY_DIR}/drivers/bus/softspi.c
     ${MICROPY_DIR}/drivers/dht/dht.c
@@ -178,7 +195,6 @@ set(MICROPY_SOURCE_QSTR
 )
 
 set(PICO_SDK_COMPONENTS
-    cmsis_core
     hardware_adc
     hardware_base
     hardware_boot_lock
@@ -222,6 +238,17 @@ set(PICO_SDK_COMPONENTS
     tinyusb_device
 )
 
+if(PICO_ARM)
+    list(APPEND PICO_SDK_COMPONENTS
+        cmsis_core
+    )
+elseif(PICO_RISCV)
+    list(APPEND PICO_SDK_COMPONENTS
+        hardware_hazard3
+        hardware_riscv
+    )
+endif()
+
 # Use our custom pico_float_micropython float implementation.  This is needed for two reasons:
 # - to fix inf handling in pico-sdk's __wrap___aeabi_fadd();
 # - so we can use our own libm functions, to fix inaccuracies in the pico-sdk versions.
@@ -243,7 +270,7 @@ if(PICO_RP2040)
         ${PICO_SDK_PATH}/src/rp2_common/pico_float/float_init_rom_rp2040.c
         ${PICO_SDK_PATH}/src/rp2_common/pico_float/float_v1_rom_shim_rp2040.S
     )
-elseif(PICO_RP2350)
+elseif(PICO_RP2350 AND PICO_ARM)
     target_sources(pico_float_micropython INTERFACE
         ${PICO_SDK_PATH}/src/rp2_common/pico_float/float_aeabi_dcp.S
         ${PICO_SDK_PATH}/src/rp2_common/pico_float/float_conv_m33.S
@@ -491,6 +518,12 @@ target_link_options(${MICROPY_TARGET} PRIVATE
     -Wl,--wrap=runtime_init_clocks
 )
 
+if(PICO_RP2350)
+    target_link_options(${MICROPY_TARGET} PRIVATE
+        -Wl,--defsym=__micropy_extra_stack__=4096
+    )
+endif()
+
 # Apply optimisations to performance-critical source code.
 set_source_files_properties(
     ${MICROPY_PY_DIR}/map.c
@@ -563,7 +596,7 @@ endif()
 
 pico_add_extra_outputs(${MICROPY_TARGET})
 
-pico_find_compiler(PICO_COMPILER_SIZE ${PICO_GCC_TRIPLE}-size)
+pico_find_compiler_with_triples(PICO_COMPILER_SIZE "${PICO_GCC_TRIPLE}" size)
 
 add_custom_command(TARGET ${MICROPY_TARGET}
     POST_BUILD

ports/rp2/main.c

@@ -60,10 +60,8 @@
 #endif
 #if PICO_RP2040
 #include "RP2040.h" // cmsis, for PendSV_IRQn and SCB/SCB_SCR_SEVONPEND_Msk
-#elif PICO_RP2350
+#elif PICO_RP2350 && PICO_ARM
 #include "RP2350.h" // cmsis, for PendSV_IRQn and SCB/SCB_SCR_SEVONPEND_Msk
-#else
-#error Unknown processor
 #endif
 #include "pico/aon_timer.h"
 #include "shared/timeutils/timeutils.h"
@@ -82,7 +80,9 @@ bi_decl(bi_program_feature_group_with_flags(BINARY_INFO_TAG_MICROPYTHON,
 
 int main(int argc, char **argv) {
     // This is a tickless port, interrupts should always trigger SEV.
+    #if PICO_ARM
     SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
+    #endif
 
     pendsv_init();
     soft_timer_init();

ports/rp2/mpconfigport.h

@@ -78,10 +78,16 @@
 
 // MicroPython emitters
 #define MICROPY_PERSISTENT_CODE_LOAD            (1)
+#if PICO_ARM
 #define MICROPY_EMIT_THUMB                      (1)
-#define MICROPY_EMIT_THUMB_ARMV7M               (0)
 #define MICROPY_EMIT_INLINE_THUMB               (1)
+#if PICO_RP2040
+#define MICROPY_EMIT_THUMB_ARMV7M               (0)
 #define MICROPY_EMIT_INLINE_THUMB_FLOAT         (0)
+#endif
+#elif PICO_RISCV
+#define MICROPY_EMIT_RV32                       (1)
+#endif
 
 // Optimisations
 #define MICROPY_OPT_COMPUTED_GOTO               (1)

ports/rp2/pendsv.c

@@ -31,10 +31,10 @@
 
 #if PICO_RP2040
 #include "RP2040.h"
-#elif PICO_RP2350
+#elif PICO_RP2350 && PICO_ARM
 #include "RP2350.h"
-#else
-#error Unknown chip
+#elif PICO_RISCV
+#include "pico/aon_timer.h"
 #endif
 
 #if MICROPY_PY_NETWORK_CYW43
@@ -43,6 +43,8 @@
 
 static pendsv_dispatch_t pendsv_dispatch_table[PENDSV_DISPATCH_NUM_SLOTS];
 
+void PendSV_Handler(void);
+
 // Using the nowait variant here as softtimer updates PendSV from the loop of mp_wfe_or_timeout(),
 // where we don't want the CPU event bit to be set.
 static recursive_mutex_nowait_t pendsv_mutex;
@@ -75,10 +77,16 @@ void pendsv_resume(void) {
 void pendsv_schedule_dispatch(size_t slot, pendsv_dispatch_t f) {
     pendsv_dispatch_table[slot] = f;
     if (pendsv_mutex.mutex.enter_count == 0) {
+        #if PICO_ARM
         // There is a race here where other core calls pendsv_suspend() before
         // ISR can execute, but dispatch will happen later when other core
         // calls pendsv_resume().
         SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
+        #elif PICO_RISCV
+        struct timespec ts;
+        aon_timer_get_time(&ts);
+        aon_timer_enable_alarm(&ts, PendSV_Handler, false);
+        #endif
     } else {
         #if MICROPY_PY_NETWORK_CYW43
         CYW43_STAT_INC(PENDSV_DISABLED_COUNT);