From b93a76eaab7e42a0581172f178ed65b0af0148dd Mon Sep 17 00:00:00 2001 From: Simon Arlott Date: Mon, 19 May 2025 19:35:20 +0100 Subject: [PATCH] patches: RP2040 Fix 64-bit uptime being wrapped as a 32-bit value --- ...e-API-to-force-a-timer-event-and-get.patch | 24 +++++ ...icker-don-t-modify-the-system-uptime.patch | 100 ++++++++++++++++++ 2 files changed, 124 insertions(+) create mode 100644 patches/0263-RP2040-us_ticker-use-API-to-force-a-timer-event-and-get.patch create mode 100644 patches/0264-RP2040-us_ticker-don-t-modify-the-system-uptime.patch diff --git a/patches/0263-RP2040-us_ticker-use-API-to-force-a-timer-event-and-get.patch b/patches/0263-RP2040-us_ticker-use-API-to-force-a-timer-event-and-get.patch new file mode 100644 index 000000000..7f06693e6 --- /dev/null +++ b/patches/0263-RP2040-us_ticker-use-API-to-force-a-timer-event-and-get.patch @@ -0,0 +1,24 @@ +From e67b7f8d7a719db34a71cbcd793237ccaf6cf6d5 Mon Sep 17 00:00:00 2001 +From: Simon Arlott +Date: Mon, 19 May 2025 18:46:50 +0100 +Subject: [PATCH 1/2] RP2040: us_ticker: use API to force a timer event and get + an interrupt + +us_ticker_irq_handler() must only be called from interrupt context +--- + targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c b/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c +index b3b8497188c..3a5e1f1686f 100644 +--- a/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c ++++ b/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c +@@ -99,7 +99,7 @@ void us_ticker_set_interrupt(timestamp_t timestamp) + + void us_ticker_fire_interrupt(void) + { +- us_ticker_irq_handler(); ++ hardware_alarm_force_irq(alarm_num); + } + + void us_ticker_disable_interrupt(void) diff --git a/patches/0264-RP2040-us_ticker-don-t-modify-the-system-uptime.patch b/patches/0264-RP2040-us_ticker-don-t-modify-the-system-uptime.patch new file mode 100644 index 000000000..5ae9ab8d9 --- /dev/null +++ b/patches/0264-RP2040-us_ticker-don-t-modify-the-system-uptime.patch @@ -0,0 +1,100 @@ +From 2ec69171e77ebd105064c8c2c9ba4df58bb1a992 Mon Sep 17 00:00:00 2001 +From: Simon Arlott +Date: Mon, 19 May 2025 18:59:40 +0100 +Subject: [PATCH 2/2] RP2040: us_ticker: don't modify the system uptime + +There is only one user of this API, the mbed timer queue. It sets targets +a maximum of (2**32)//16*7 microseconds in the future. Assuming there are +no other timer events to be scheduled, after 3 instances of this at 5637s +uptime the 64-bit uptime gets wrapped. + +Never modify the system uptime because that makes it unusable when the +64-bit uptime that should never wrap, unexpectedly does. With the uptime +proceeding as normal into large 64-bit values the 32-bit timestamp needs +special handling. + +It's ambiguous what the 32-bit timestamp means because time advances while +the ticker functions are being called, so the 64-bit time could wrap +between calculating the next 32-bit timestamp and setting it as the target +time. + +The only way to avoid this is to know for certain what the caller meant by +keeping track of the last 32-bit value that was read. This relies on there +only being caller but other mbed timer implementations already keep track +of the last call to us_ticker_read() to handle ambiguity in timestamp +values. + +Track the last read of the full 64-bit time too, so that we can always +prepare the correct 64-bit time value. Avoid reading the current time +repeatedly because it could change between calls. + +If the timestamp is in the near future it's possible that it has been set +too late and the time has been missed. Force a timer interrupt when this +happens. +--- + .../TARGET_RP2040/us_ticker.c | 39 ++++++++++--------- + 1 file changed, 21 insertions(+), 18 deletions(-) + +diff --git a/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c b/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c +index 3a5e1f1686f..2062ac36118 100644 +--- a/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c ++++ b/targets/TARGET_RASPBERRYPI/TARGET_RP2040/us_ticker.c +@@ -54,6 +54,7 @@ const ticker_info_t* us_ticker_get_info() + } + + static const uint8_t alarm_num = 0; ++static uint64_t last_read_u64 = 0; + + static void us_ticker_irq_handler_internal(uint alarm_src) { + if (alarm_num == alarm_src) { +@@ -69,30 +70,32 @@ void us_ticker_init(void) + + uint32_t us_ticker_read() + { +- return time_us_32(); ++ uint64_t now_u64 = time_us_64(); ++ ++ core_util_critical_section_enter(); ++ last_read_u64 = now_u64; ++ core_util_critical_section_exit(); ++ ++ return now_u64; + } + +-void us_ticker_set_interrupt(timestamp_t timestamp) ++void us_ticker_set_interrupt(timestamp_t timestamp_u32) + { + core_util_critical_section_enter(); + +- uint64_t _timestamp = (uint64_t)timestamp; +- +- if (timestamp < time_us_32()) { +- //32 bit timestamp has been wrapped +- //We need to provide a 64 bit timestamp able to fire the irq for this round +- _timestamp = (((time_us_64() >> 32) + 1) << 32) + timestamp; +- } else { +- //Then, at the next round, wrap the 64 bit timer to follow the 32 bit one +- if ((time_us_64() >> 32) > 0) { +- uint64_t current_time = time_us_64(); +- uint64_t wrapped_time = current_time - 0xFFFFFFFF; +- timer_hw->timelw = (uint32_t)wrapped_time; +- timer_hw->timehw = 0; +- } ++ uint32_t last_read_u32 = (uint32_t)last_read_u64; ++ uint64_t timestamp_u64 = (uint64_t)timestamp_u32 | (last_read_u64 & 0xFFFFFFFF00000000ULL); ++ ++ if (timestamp_u32 < last_read_u32) { ++ timestamp_u64 += 1ULL << 32; ++ } ++ ++ absolute_time_t target = { timestamp_u64 }; ++ bool missed = hardware_alarm_set_target(alarm_num, target); ++ ++ if (missed) { ++ us_ticker_fire_interrupt(); + } +- absolute_time_t target = { _timestamp }; +- hardware_alarm_set_target(alarm_num, target); + + core_util_critical_section_exit(); + } pFad - Phonifier reborn

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