This patch adds a dummy PTP clock driver implementation that provides
a software-based PTP clock for testing and development purposes.
Key changes include:
1. Dummy PTP clock driver implementation:
- Added drivers/timers/ptp_clock_dummy.c
- Provides software-based PTP clock using system monotonic clock
- Implements all required lower-half driver operations
2. Lower-half driver operations:
- adjfine: Frequency adjustment (stores adjustment value)
- adjtime: Time offset adjustment (applies delta to base time)
- gettime: Returns current PTP clock time
- settime: Sets PTP clock time
- getcaps: Reports clock capabilities (1 billion PPB max adjustment)
- getcrosststamp: Provides system/device cross-timestamp
3. Driver initialization:
- Added ptp_clock_dummy_init() in drivers/drivers_initialize.c
- Auto-registration under CONFIG_PTP_CLOCK_DUMMY configuration
- Creates /dev/ptp0 character device node
4. Build system integration:
- Added CONFIG_PTP_CLOCK_DUMMY Kconfig option (depends on PTP_CLOCK)
- Updated CMakeLists.txt and Make.defs
- Added include/nuttx/timers/ptp_clock_dummy.h header
5. Implementation details:
- Uses clock_gettime(CLOCK_MONOTONIC) as time base
- Tracks time offset and frequency adjustment internally
- Suitable for testing PTP clock applications without hardware
This dummy driver enables development and testing of PTP clock applications
on platforms without dedicated PTP hardware support.
Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
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