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The RP2350 has two system timer blocks (TIMER0, TIMER1), each a free-running 64-bit counter incremented once per microsecond by the TICKS block (set up in rp23xx_clock.c). They are independent of the ARM SysTick that drives the OS tick, so they are free for application use, but the port had no driver for them. Add rp23xx_timer.c, a NuttX timer lower-half that binds a block to a /dev/timerN device. It uses ALARM0 of the block, which matches the low 32 bits of the microsecond counter, to implement single-shot and periodic timeouts with 1 us resolution and a maximum interval of 2^32 - 1 us (~71.5 minutes). Periodic reloads are scheduled relative to the previous expiry to avoid drift, but never behind the counter (an alarm set in the past would not match until the 32-bit counter wraps). Enable with CONFIG_RP23XX_TIMER (which selects CONFIG_TIMER), then turn on each block independently: CONFIG_RP23XX_TIMER0 registers /dev/timer0 and CONFIG_RP23XX_TIMER1 registers /dev/timer1. A block claimed by the tickless oneshot (CONFIG_RP23XX_SYSTIMER_TICKLESS) is excluded from these choices in Kconfig, so the two features can be enabled together without colliding on the same block or its alarm IRQ. Tested on Pimoroni Pico Plus 2 (RP2350B) hardware with examples/timer and a CMSIS-DAP probe. The device registers as /dev/timer0; the ALARM0 interrupt fires at the programmed period (verified over SWD at the configured 1 s interval, not a busy loop), and the full path -- alarm match, the driver ISR, the timer notification and delivery of the SIGNO to user space -- reaches the example's signal handler and increments its counter. Assisted-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> |
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