jihonen opened a new pull request, #18870:
URL: https://github.com/apache/nuttx/pull/18870
• Add support for the i.MX9 SAR ADC block.
The driver provides initialization, deinitialization, channel-mask
validation, and one-shot reads for the supported ADC channels. It also handles
ADC clock bring-up, power-up, calibration, and raw 12-bit result extraction
from the per-channel data registers.
## Summary
Add a basic helper driver for the i.MX9 SAR ADC block in
`arch/arm64/src/imx9`.
This change is needed to support board-level analog sampling on i.MX9
systems without duplicating ADC register sequencing in each board bring-up
file. The driver encapsulates the hardware initialization sequence, validates
the enabled channel mask, and exposes a simple one-shot read path for the
supported channels.
The driver:
- enables and disables the ADC clock tree through the i.MX9 CCM helpers
- powers up the ADC block
- runs the calibration sequence during initialization
- clears stale status before the first conversion
- starts one-shot conversions on a requested channel
- reads the raw 12-bit result from the per-channel data register
- reports initialization state for board code
## Impact
This change adds new runtime support in `arch/arm64/src/imx9` only.
Impact areas:
- Build: `imx9_sar_adc.c` is compiled when `CONFIG_IMX9_SAR_ADC` is enabled
- Runtime: adds ADC initialization, de-initialization, and read support
for the i.MX9 SAR ADC block
- API: adds the internal helper interface in `imx9_sar_adc.h` for
board/arch bring-up code
- Compatibility: no existing user-space API is changed
- Documentation: no documentation updates were included in this change
- Security: no security-sensitive behavior is introduced
## Testing
Testing performed:
- Built and ran on NXP93 hardware
- Verified ADC reporting with `listener adc_report`
Observed output:
```text
TOPIC: adc_report
adc_report
timestamp: 11804674 (0.001465 seconds ago)
device_id: 9371904 (Type: 0x8F, UNKNOWN:0 (0x01))
raw_data: [2024, 2032, 1355, 6, 0, 0, 0, 0, 0, 0, 0, 0]
resolution: 4096
v_ref: 1.80000
channel_id: [0, 1, 2, 3, -1, -1, -1, -1, -1, -1, -1, -1]
References:
- nuttx: arch/arm64/src/imx9/imx9_sar_adc.c
- nuttx: arch/arm64/src/imx9/imx9_sar_adc.h
Dependencies:
- none
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