AlmAck opened a new pull request, #20002:
URL: https://github.com/apache/nuttx/pull/20002
## Summary
The driver presents a single channel space of `GPIOTE_CHANNELS` entries
across the application core's two GPIOTE peripherals, and splits it:
```c
inst = (channel < GPIOTE_PER_CHANNEL) ? 0 : 1;
rchan = (inst == 1) ? channel : (channel - GPIOTE_PER_CHANNEL);
```
`rchan` is the channel index *within* the selected instance, used to
build the per-channel register offsets, so it must be
```c
rchan = channel - GPIOTE_PER_CHANNEL * inst
```
The ternary has the two arms the other way round: a channel on instance
0 gets `rchan = channel - GPIOTE_PER_CHANNEL`, which is negative, and a
channel on instance 1 gets an index still offset by a full instance.
### Corroboration
The interrupt handler in this same file already applies that mapping in
the opposite direction, converting a per-instance channel back to the
global one:
```c
off = i + GPIOTE_PER_CHANNEL * inst; /* nrf53_gpiote.c,
nrf53_gpiote_isr() */
```
The two were inconsistent, and it is the `rchan` sites that disagreed
with the rest of the driver.
Per the nRF5340 Product Specification, *GPIOTE - GPIO tasks and events*,
the application core has two GPIOTE instances:
| instance | base | channels | CONFIG |
|---|---|---|---|
| GPIOTE0 (secure) | `0x5000D000` | 8 | `CONFIG[n]`, n = 0..7 |
| GPIOTE1 (non-secure) | `0x4002F000` | 8 | `CONFIG[n]`, n = 0..7 |
`CONFIG[n]` sits at offset `0x510 + 4n`. That matches
`GPIOTE_PER_CHANNEL == 8` in the driver, the two base addresses in
`hardware/nrf53_memorymap_cpuapp.h`, and `NRF53_GPIOTE_CONFIG_OFFSET()`
in `hardware/nrf53_gpiote.h` - so `rchan` is required to be in 0..7 and
a negative value cannot address a CONFIG register.
Both call sites are corrected.
## Impact
Any nRF5340 board using GPIOTE. For a channel on instance 0 the CONFIG
register write lands at a computed-negative offset and the GPIOTE
interrupt is never enabled, so the event never fires - on nrf5340-dk
this makes the board buttons dead.
## Testing
Suggested reproduction to capture:
1. nrf5340-dk with `CONFIG_ARCH_BUTTONS=y` and `CONFIG_INPUT_BUTTONS`,
registering the board button lower-half as `/dev/buttons`.
2. Before the patch, `poll(POLLIN)` on `/dev/buttons` never returns and
no press is observed - the GPIOTE interrupt is never enabled for
channels on instance 0.
3. After the patch, presses and releases arrive.
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