Initial support for Raspberry Pico

Also slightly modify SMP code to handle the specific case of the Pico.

Code relies on condition variables implementation proposed in this upstream PR:
raspberrypi/pico-sdk#1101

Signed-off-by: Paul Guyot <pguyot@kallisys.net>

.github/workflows/pico-build.yaml

@@ -0,0 +1,29 @@
+#
+#  Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+#
+#  SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+#
+
+name: Pico Build
+
+on: [push, pull_request]
+
+jobs:
+  pico:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@v3
+
+    - name: "Install deps"
+      run: sudo apt install -y cmake gperf ninja-build gcc-arm-none-eabi libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib
+
+    - name: Build
+      shell: bash
+      working-directory: ./src/platforms/rp2040/
+      run: |
+        set -euo pipefail
+        mkdir build
+        cd build
+        cmake .. -G Ninja
+        ninja

CMakeLists.txt

@@ -43,6 +43,8 @@ endif()
 
 add_subdirectory(tests)
 add_subdirectory(tools/packbeam)
+add_subdirectory(tools/uf2tool)
+
 if (NOT "${CMAKE_GENERATOR}" MATCHES "Xcode")
     add_subdirectory(libs)
     add_subdirectory(examples)

CMakeModules/BuildErlang.cmake

@@ -83,6 +83,14 @@ macro(pack_lib avm_name)
         add_dependencies(${avm_name} ${avm_name}_main)
     endif()
 
+    add_custom_target(
+        ${avm_name}.uf2 ALL
+        COMMAND ${CMAKE_BINARY_DIR}/tools/uf2tool/uf2tool create -o ${avm_name}.uf2 -s 0x10080000 ${avm_name}.avm
+        COMMENT "Creating UF2 file ${avm_name}.uf2"
+        VERBATIM
+    )
+    add_dependencies(${avm_name}.uf2 ${avm_name})
+
 endmacro()
 
 
@@ -153,3 +161,45 @@ macro(pack_test test_avm_name)
     add_dependencies(${test_avm_name} ${ARCHIVE_TARGETS} PackBEAM)
 
 endmacro()
+
+macro(pack_uf2 avm_name main)
+
+    add_custom_command(
+        OUTPUT ${main}.beam
+        COMMAND erlc -I ${CMAKE_SOURCE_DIR}/libs/include ${CMAKE_CURRENT_SOURCE_DIR}/${main}.erl
+        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/${main}.erl
+        COMMENT "Compiling ${main}.erl"
+        VERBATIM
+    )
+
+    add_custom_target(
+        ${avm_name}_main
+        DEPENDS ${main}.beam
+    )
+
+    foreach(archive_name ${ARGN})
+        if(NOT ${archive_name} STREQUAL "exavmlib")
+            set(ARCHIVES ${ARCHIVES} ${CMAKE_BINARY_DIR}/libs/${archive_name}/src/${archive_name}.avm)
+        else()
+            set(ARCHIVES ${ARCHIVES} ${CMAKE_BINARY_DIR}/libs/${archive_name}/lib/${archive_name}.avm)
+        endif()
+        set(ARCHIVE_TARGETS ${ARCHIVE_TARGETS} ${archive_name})
+    endforeach()
+
+    add_custom_target(
+        ${avm_name}.avm ALL
+        COMMAND ${CMAKE_BINARY_DIR}/tools/packbeam/PackBEAM ${avm_name}.avm ${main}.beam ${ARCHIVES}
+        COMMENT "Packing runnable ${avm_name}.avm"
+        VERBATIM
+    )
+    add_dependencies(${avm_name}.avm ${avm_name}_main ${ARCHIVE_TARGETS} PackBEAM)
+
+    add_custom_target(
+        ${avm_name}.uf2 ALL
+        COMMAND ${CMAKE_BINARY_DIR}/tools/uf2tool/uf2tool create -o ${avm_name}.uf2 -s 0x100A0000 ${avm_name}.avm
+        COMMENT "Creating UF2 file ${avm_name}.uf2"
+        VERBATIM
+    )
+    add_dependencies(${avm_name}.uf2 ${avm_name}.avm uf2tool)
+
+endmacro()

README.Md

@@ -18,6 +18,7 @@ Supported Platforms
 * Linux, macOS, FreeBSD ([generic unix](src/platforms/generic_unix))
 * ESP32 SoC (with IDF/FreeRTOS, see [README.ESP32.Md](README.ESP32.Md))
 * STM32 MCUs (with LibOpenCM3, see [README.STM32.Md](README.STM32.Md))
+* Raspberry Pi Pico (see [README.PICO.Md](README.PICO.Md))
 
 AtomVM aims to be easily portable to new platforms with a minimum effort, so additional platforms
 might be supported in a near future.

README.PICO.Md

@@ -0,0 +1,79 @@
+<!--
+ Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+
+ SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+-->
+
+Building AtomVM for Raspberry Pico
+==================================
+
+* build:
+
+```
+cd src/platforms/rp2040/
+mkdir build
+cd build
+cmake .. -G Ninja
+ninja
+```
+
+> Note: requires cmake and ninja
+
+You may want to build with option `AVM_REBOOT_ON_NOT_OK` so Pico restarts on
+error.
+
+Installing AtomVM on Raspberry Pico
+===================================
+
+VM binary is file `src/platforms/rp2040/build/src/AtomVM.uf2`. Simply copy it
+to the pico. The VM will crash because there is no application.
+
+Installing atomvm library to Raspberry Pico
+===========================================
+
+AtomVM library must be installed as well.
+
+Building it
+-----------
+
+Build of standard libraries is part of the generic unix build.
+
+From the root of the project:
+
+```
+mkdir build
+cd build
+cmake .. -G Ninja
+ninja
+```
+
+> Note: requires cmake, ninja, Erlang/OTP and Elixir for elixir libs
+
+The library to install is `build/libs/atomvmlib.uf2`
+The VM currently expects the library to be loaded at address 0x10080000.
+
+Running BEAM code on Raspberry Pico
+===================================
+
+* BEAM module must be stripped before using PackBEAM:
+
+```
+./PackBEAM packed.avm module.beam
+```
+
+Then the BEAM file must be converted to UF2.
+The VM currently expects the application to be loaded at address 0x100A0000.
+
+```sh
+./uf2tool create -o packed.uf2 -s 0x10080000 packed.avm
+```
+
+Copy this UF2 to the Pico. You probably also need atomvmlib.uf2 first.
+
+Running Hello Pico
+==================
+
+This example will print a Hello Pico message repeatedly.
+
+It is built into `build/examples/erlang/rp2040/hello_pico.uf2`.
+

examples/erlang/CMakeLists.txt

@@ -23,6 +23,7 @@ project(examples_erlang)
 include(BuildErlang)
 
 add_subdirectory(esp32)
+add_subdirectory(rp2040)
 
 pack_runnable(hello_world hello_world eavmlib)
 pack_runnable(udp_server udp_server estdlib eavmlib)

examples/erlang/rp2040/CMakeLists.txt

@@ -0,0 +1,26 @@
+#
+# This file is part of AtomVM.
+#
+# Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+#
+
+project(examples_erlang_rp2040)
+
+include(BuildErlang)
+
+pack_uf2(hello_pico hello_pico eavmlib estdlib)
+pack_uf2(pico_rtc pico_rtc eavmlib estdlib)

examples/erlang/rp2040/hello_pico.erl

@@ -0,0 +1,35 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+-module(hello_pico).
+-export([start/0]).
+
+start() ->
+    % Pico's serial may be too fast to use hello_world example, so this
+    % version loops.
+    hello_pico_loop().
+
+hello_pico_loop() ->
+    console:puts("Hello Pico\n"),
+    receive
+        ok -> ok
+    after 3000 -> ok
+    end,
+    hello_pico_loop().

examples/erlang/rp2040/pico_rtc.erl

@@ -0,0 +1,68 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+% This example demonstrates the usage of the Pico's hardware RTC.
+
+-module(pico_rtc).
+-export([start/0]).
+
+-define(START_DATE, {{2022, 11, 16}, {22, 09, 00}}).
+
+start() ->
+    case atomvm:platform() of
+        pico ->
+            pico_rtc_loop();
+        Other ->
+            erlang:display({unexpected, Other})
+    end.
+
+pico_rtc_loop() ->
+    Date = erlang:universaltime(),
+    print_date(Date),
+    receive
+        ok -> ok
+    after 5000 -> ok
+    end,
+    if
+        Date < ?START_DATE ->
+            pico:rtc_set_datetime(?START_DATE);
+        true ->
+            ok
+    end,
+    pico_rtc_loop().
+
+print_date({{Year, Month, Day}, {Hour, Min, Sec}}) ->
+    % Only ~p and ~s seem to exist for now.
+    YearStr = integer_to_list(Year),
+    MonthStr = format_2_digits(Month),
+    DayStr = format_2_digits(Day),
+    HourStr = format_2_digits(Hour),
+    MinStr = format_2_digits(Min),
+    SecStr = format_2_digits(Sec),
+    console:puts(
+        lists:flatten([
+            YearStr, "-", MonthStr, "-", DayStr, "T", HourStr, ":", MinStr, ":", SecStr, "\n"
+        ])
+    ).
+
+format_2_digits(Num) when Num < 10 ->
+    ["0", integer_to_list(Num)];
+format_2_digits(Num) ->
+    integer_to_list(Num).

libs/eavmlib/src/CMakeLists.txt

@@ -34,6 +34,7 @@ set(ERLANG_MODULES
     logger
     network
     network_fsm
+    pico
     port
     spi
     timer_manager

libs/eavmlib/src/pico.erl

@@ -0,0 +1,40 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+%%-----------------------------------------------------------------------------
+%% @doc PICO-specific APIs
+%%
+%% This module contains functions that are specific to the PICO platform.
+%% @end
+%%-----------------------------------------------------------------------------
+-module(pico).
+
+-export([
+    rtc_set_datetime/1
+]).
+
+%%-----------------------------------------------------------------------------
+%% @doc     Set the datetime on the RTC.
+%%          The datetime can be obtained through bif erlang:localtime()
+%% @end
+%%-----------------------------------------------------------------------------
+-spec rtc_set_datetime(calendar:datetime()) -> ok.
+rtc_set_datetime(_Datetime) ->
+    throw(nif_error).

src/platforms/rp2040/.gitignore

@@ -0,0 +1,20 @@
+#
+# This file is part of AtomVM.
+#
+# Copyright 2022 Paul Guyot <pguyot@kallisys.net>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+#
+build