The worker kthread and ATN ISR both modify the DATA line by changing GPIO2's
direction (open-drain emulation). On quad-core Pi they run simultaneously on
different CPUs, causing their read-modify-write operations on the shared GPFSEL0
register to clobber each other. The ISR's ATN presence-acknowledge could be
erased by the worker's ready-for-data release, causing the C64 to see "device
not present" and drop LISTEN/UNLISTEN command bytes.
Add iec_data_lock spinlock and two synchronized wrappers:
- iec_data_assert_sync(): serializes DATA assert
- iec_data_release_sync(): serializes DATA release and refuses to release while
ATN is asserted, preventing the acknowledge from being undone
Convert all worker and ISR DATA accesses to use the _sync() wrappers. Keep raw
unconditional helpers for init/exit/self-test (exit must free the bus
unconditionally; self-test probes directly).
Generated by Clanker 🤖
Added a 'Frontend output modes' section explaining plain text (default),
--debug (annotated trace), and --raw (hex), with launch.sh examples for
each.
Generated by Clanker
Adopt the confirmed-working reference's pin assignment so the module runs
on that proven wiring: DATA=BCM2 (pin 3), CLK=BCM3 (pin 5), ATN=BCM4
(pin 7). RESET is kept and relocated to BCM17 (pin 11), the pin freed by
moving CLK. All five GPIOs stay in bank 0, so the direct-register hot
path and ATN IRQ are unchanged -- only the IEC_GPIO_* defines, the
device-tree overlay, and the docs/self-test move.
DATA/CLK now sit on the ARM I2C pins (GPIO2/3) with the SoC's fixed
~1.8k pull-ups; keep dtparam=i2c_arm off. The bare-board self-test
expectation changes from 0x15 to 0x0b accordingly.
Generated by Clanker
The IEC bit loop sampled GPIO with a single register read, so a glitch
on a level-shifted 5V<->3.3V bus could corrupt a bit with no chance to
retry (the loop runs with IRQs off). Add a stable-read filter that only
believes a level change after it holds IEC_DEBOUNCE_US (now 5 us); the
fast path is a single read so tight CLK polls stay cheap. Used across
the receive hot path; the ATN ISR and self-test keep raw reads.
Generated by Clanker
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Document the process for setting up and running the Python frontend on
a Raspberry Pi using release packages. Include details on wiring
self-tests, module selection, and using `launch.sh` for streamlined
execution. Update kernel README to cross-reference top-level changes.
Improve error handling in module discovery by identifying unreadable
`.ko` files and providing detailed error messages. Suggest actions like
unzip or rebuild to resolve issues.
Enhance module selection process by validating vermagic against the running kernel. Add detailed error messages with suggestions for manual path overrides or rebuilding for the current kernel. Ensure robust fallback behavior and improve user guidance.
Expand documentation on selftest.sh behavior, module matching, and kernel compatibility. Clarify the auto-selection process based on `vermagic` and provide examples to guide users through fallback handling and manual overrides.
wait_clk() aborted on any asserted ATN, but ATN is held low for the
entire command phase by design. Reception therefore aborted on the
first poll before clocking a single bit, so the listener never decoded
the LISTEN command and always fell through to "not addressed -> IDLE".
Make the ATN abort phase-relative via IEC_RX_ATN meaning "ATN changed":
in the data phase abort when ATN asserts (C64 interrupts with a new
command); in the command phase abort when ATN releases (command
sequence finished). The check collapses to
`iec_atn_asserted() == data_phase`.
Closes#2
Generated by Clanker
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Introduce a conditional `trusted=yes` setting for the Raspberry Pi
repository in the Dockerfile when `DEBIAN_SUITE=trixie`. This bypasses
SHA1 signature rejection by trixie's apt system using Sequoia. Ensure
that bookworm maintains full signature verification. Updated
documentation to explain the trixie-specific caveat.
Introduce `DEBIAN_SUITE` as a configurable argument in the Dockerfile, build
script, and CI workflow to align kernel builds with the target Raspberry Pi
OS release. Updated documentation to clarify the relationship between
suite versions and kernel compatibility.
Log the current working directory in `build-in-docker.sh` to improve the
debugging process during kernel module compilation. This update helps
track the build context path passed to the Docker container.
Replace legacy gpio_to_desc() with GPIO descriptor resolution by chip label
and hardware number, ensuring compatibility with kernels using non-zero
gpiochip bases. Added `selftest.sh` for non-persistent module testing, which
performs a hardware self-test and verifies wiring before connecting the real
bus. Included a detailed README.md documenting the self-test process.
