stm32l4-multi: pwmbitseq_t refactor

[radekszewczyk01]

Change pwmbitseq_t structure

Description

Change pwmbitseq_t structure in order to optimize communication with multidriver

Motivation and Context

Multidriver required seperate message for each channel, which was inefficient.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (refactoring, style fixes, git/CI config, submodule management, no code logic changes)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: armv8m55-stm32n6

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
• I will merge this PR by myself when appropriate.

[gemini-code-assist]

Summary of Changes

Hello @radekszewczyk01, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request primarily focuses on optimizing embedded system communication and driver efficiency. It introduces a more flexible structure for Pulse Width Modulation (PWM) bit sequences, allowing multiple sequences to be transmitted in a single operation to a multidriver. Concurrently, the UART 16550 driver has been refactored to remove an intermediate software buffer and simplify its interrupt handling mechanism, aiming for a more direct and efficient interaction with the hardware.

Highlights

• PWM Bit Sequence Structure Optimization: The pwmbitseq_t structure has been refactored to support sending multiple PWM bit sequences in a single message, improving communication efficiency with the multidriver.
• UART Driver Refactoring: The UART 16550 driver has undergone significant changes, including the removal of an internal software buffer and a simplification of interrupt handling logic, particularly for non-RISC-V architectures.
• Streamlined Interrupt Processing: UART interrupt processing has been moved more directly into a dedicated thread (uart_intthr), reducing the complexity of the interrupt service routine and enabling more efficient data handling.

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[gemini-code-assist]

Code Review

This pull request introduces an optimization for PWM bit sequence handling by modifying the pwmbitseq_t structure to support multiple channels in a single message. It also includes a significant refactoring of the uart16550 driver, simplifying its interrupt handling logic. I've found a critical issue in the new PWM handling loop that includes a compile error and a logic bug that could mask errors. I've also noted some newly introduced macros that appear to be unused. Other changes, including style adjustments, seem appropriate.

[gemini-code-assist]

This loop has a couple of issues:

1. Compile Error: The assert on line 269 contains a typo (imsg->bitseqTable[i]). The correct member is imsg->pwm_bitseq.bitseqTable. This will prevent the code from compiling.
2. Error Handling: The err variable is overwritten in each iteration. If pwm_setBitSequence() fails for any but the last item, the error will be lost, and the operation might be considered successful. The loop should terminate on the first error.

I suggest replacing the loop with a version that corrects the assertion and handles errors properly.

            if (imsg->pwm_bitseq.count > 0) {
                assert(imsg->pwm_bitseq.bitseqTable != NULL);
                for (uint8_t i = 0; i < imsg->pwm_bitseq.count; i++) {
                    err = pwm_setBitSequence(imsg->pwm_bitseq.bitseqTable[i].timer, imsg->pwm_bitseq.bitseqTable[i].chn, imsg->pwm_bitseq.bitseqTable[i].data,
                            imsg->pwm_bitseq.bitseqTable[i].nbits, imsg->pwm_bitseq.bitseqTable[i].datasize, imsg->pwm_bitseq.bitseqTable[i].flags);
                    if (err < 0) {
                        break;
                    }
                }
            }

[gemini-code-assist]

These newly added macros, SIZE_SERIALS and SIZE_SERIAL_CHUNK, do not appear to be used in any of the files modified in this pull request. If they are not intended for immediate use, they should be removed to avoid clutter and potential confusion for future developers.

[github-actions]

Unit Test Results

9 462 tests  +16   8 873 ✅ +16   53m 11s ⏱️ + 1m 5s
  561 suites +16     589 💤 ± 0 
    1 files   ± 0       0 ❌ ± 0 

Results for commit d428f04. ± Comparison against base commit 4615adf.

♻️ This comment has been updated with latest results.

[nalajcie]

why there is some revert commit here without any rationale? (unrelated change)

lots of unnecessary reformatting (either make them a separate commit or revert)

Please make a meaningful PR title.