Summary: Add Initial support to pico2 (Arm Cortex M)

[psiddh]

Test Plan:
1\ Cross Compile Executorch for Arm Cortex M target
cd
rm -rf build; mkdir build; cd build; cmake .. -DCMAKE_TOOLCHAIN_FILE=./backends/raspberry_pi/arm-cortex-m0plus-toolchain.cmake -DEXECUTORCH_BUILD_ARM_BAREMETAL=ON -DCMAKE_BUILD_TYPE=Release -DROOT_OPS=aten::add.out; cmake --build . -j$(nproc);

2\ // Export PICO_SDK_PATH
export PICO_SDK_PATH=

3\ // In executorch/third-party folder
Make sure you downloaded c10 & torch folders

4\ cd examples/raspberry_pi/pico2/
rm -rf build; mkdir build; cd build; cmake .. -DPICO_BOARD=pico2 -DCMAKE_BUILD_TYPE=Debug; cmake --build . -j$(nproc)

5\ Flash the firmware

• Hold BOOTSEL
• Plug in Pico 2
• Mounts as RPI-RP2
• Copy executorch_pico.uf2 to that drive

6\ Check that LED light blinks 10 times , indicating that inference has been successful
(or)
7\ On Mac: check the USB logs as follows -
screen /dev/tty.usbmodem1101 115200

TODO:
1\ Add README.md
2\ Decide the directory structure
3\ Add copyrights to all the files
4\ Add triage / debugging tips for pico2 board

Summary

[PLEASE REMOVE] See CONTRIBUTING.md's Pull Requests for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a Fixes #<issue-id> line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be the upcoming release notes, please add a "Release notes: " label. For a list of available release notes labels, check out CONTRIBUTING.md's Pull Requests.

Test plan

[PLEASE REMOVE] How did you test this PR? Please write down any manual commands you used and note down tests that you have written if applicable.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/12518

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 2 New Failures, 3 Unrelated Failures

As of commit a565eed with merge base 7c70403 ():

NEW FAILURES - The following jobs have failed:

• Lint / lintrunner / linux-job (gh)
• pull / test-eval_llama-mmlu-linux / linux-job (gh)
  RuntimeError: Command docker exec -t f1961e9c4b249fe0f8642b1be9d35994b8322300a982e65fce46252b9750eaef /exec failed with exit code 1

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / test-selective-build-linux / linux-job (gh) (matched linux rule in flaky-rules.json)
  The process '/usr/bin/git' failed with exit code 128

BROKEN TRUNK - The following jobs failed but was present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / linux / linux-job (gh) (trunk failure)
  examples/models/llama/tests/test_ring_attention.py::TestRingAttention::test_sliding_window_attention
• pull / unittest-editable / linux / linux-job (gh) (trunk failure)
  examples/models/llama/tests/test_ring_attention.py::TestRingAttention::test_sliding_window_attention

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.

[larryliu0820]

All files in this repo seem to more fit in https://github.com/pytorch/executorch/tree/main/examples/arm