[Core] Use polled waiting on ChibiOS platforms that support it (#17607)
* Use polled waiting on platforms that support it Due to context switching overhead waiting a very short amount of time on a sleeping thread is often not accurate and in fact not usable for timing critical usage i.e. in a driver. Thus we use polled waiting for ranges in the us range on platforms that support it instead. The fallback is the thread sleeping mechanism. This includes: * ARM platforms with CYCCNT register (ARMv7, ARMv8) this is incremented at CPU clock frequency * GD32VF103 RISC-V port with CSR_MCYCLE register this is incremented at CPU clock frequency * RP2040 ARMv6 port which uses the integrated timer peripheral which is incremented with a fixed 1MHz frequency * Use wait_us() instead of chSysPolledDelayX ...as it is powered by busy waiting now. * Add chibios waiting methods test bench
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14 changed files with 126 additions and 31 deletions
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@ -30,6 +30,11 @@
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#ifdef WAIT_US_TIMER
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void wait_us(uint16_t duration);
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#elif PORT_SUPPORTS_RT == TRUE
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# define wait_us(us) \
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do { \
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chSysPolledDelayX(US2RTC(REALTIME_COUNTER_CLOCK, us)); \
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} while (0)
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#else
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# define wait_us(us) \
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do { \
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@ -43,9 +43,8 @@ void __late_init(void) {
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if (magic_location != magic_token) {
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magic_location = magic_token;
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// ChibiOS is not initialized at this point, so sleeping is only
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// possible via busy waiting. The internal timer peripheral is running
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// at this point with a precision of 1us.
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chSysPolledDelayX(MS2RTC(1 * MHZ, RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT));
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// possible via busy waiting.
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wait_us(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT * 1000U);
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magic_location = 0;
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return;
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}
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@ -21,6 +21,9 @@
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#if defined(MCU_RP)
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# define CPU_CLOCK RP_CORE_CLK
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// ChibiOS uses the RP2040 timer peripheral as its real time counter, this timer
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// is monotonic and running at 1MHz.
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# define REALTIME_COUNTER_CLOCK 1000000
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# define USE_GPIOV1
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# define PAL_OUTPUT_TYPE_OPENDRAIN _Static_assert(0, "RP2040 has no Open Drain GPIO configuration, setting this is not possible");
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@ -102,6 +105,11 @@
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# endif
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#endif
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#if defined(MCU_MIMXRT1062)
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# include "clock_config.h"
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# define CPU_CLOCK BOARD_BOOTCLOCKRUN_CORE_CLOCK
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#endif
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#if defined(HT32)
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# define CPU_CLOCK HT32_CK_SYS_FREQUENCY
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# define PAL_MODE_ALTERNATE PAL_HT32_MODE_AF
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@ -109,3 +117,7 @@
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# define PAL_OUTPUT_TYPE_PUSHPULL PAL_HT32_MODE_DIR
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# define PAL_OUTPUT_SPEED_HIGHEST 0
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#endif
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#if !defined(REALTIME_COUNTER_CLOCK)
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# define REALTIME_COUNTER_CLOCK CPU_CLOCK
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#endif
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@ -20,7 +20,8 @@
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# error "chSysPolledDelayX method not supported on this platform"
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#else
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# undef wait_us
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# define wait_us(x) chSysPolledDelayX(US2RTC(CPU_CLOCK, x))
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// Force usage of polled waiting - in case WAIT_US_TIMER is activated
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# define wait_us(us) chSysPolledDelayX(US2RTC(REALTIME_COUNTER_CLOCK, us))
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#endif
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#ifndef SELECT_SOFT_SERIAL_SPEED
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@ -152,7 +152,7 @@ static inline void enter_rx_state(void) {
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}
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// Wait for ~11 bits, 1 start bit + 8 data bits + 1 stop bit + 1 bit
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// headroom.
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chSysPolledDelayX(US2RTC(1 * MHZ, (1000000U * 11 / SERIAL_USART_SPEED)));
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wait_us(1000000U * 11U / SERIAL_USART_SPEED);
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// Disable tx state machine to not interfere with our tx pin manipulation
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pio_sm_set_enabled(pio, tx_state_machine, false);
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gpio_set_drive_strength(SERIAL_USART_TX_PIN, GPIO_DRIVE_STRENGTH_2MA);
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