8000 rp2: Refactor soft timer to use hardware timer alarm. · micropython/micropython@74fb42a · GitHub
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rp2: Refactor soft timer to use hardware timer alarm.
Progress towards removing pico-sdk alarm pool, due to a known issue. This work was funded through GitHub Sponsors. Signed-off-by: Angus Gratton <angus@redyak.com.au>
1 parent 2926001 commit 74fb42a

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6 files changed

+29
-13
lines changed

6 files changed

+29
-13
lines changed

‎ports/rp2/main.c

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -76,6 +76,8 @@ int main(int argc, char **argv) {
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// This is a tickless port, interrupts should always trigger SEV.
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SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
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79+
soft_timer_init();
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#if MICROPY_HW_ENABLE_UART_REPL
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bi_decl(bi_program_feature("UART REPL"))
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setup_default_uart();

‎ports/rp2/mpconfigport.h

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Original file line numberDiff line numberDiff line change
@@ -154,6 +154,10 @@
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#define MICROPY_SSL_MBEDTLS (1)
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#define MICROPY_PY_LWIP_SOCK_RAW (MICROPY_PY_LWIP)
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157+
// Hardware timer alarm index. Available range 0-3.
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// Number 3 is currently used by pico-sdk (PICO_TIME_DEFAULT_ALARM_POOL_HARDWARE_ALARM_NUM)
159+
#define MICROPY_HW_SOFT_TIMER_ALARM_NUM (2)
160+
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// fatfs configuration
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#define MICROPY_FATFS_ENABLE_LFN (1)
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#define MICROPY_FATFS_LFN_CODE_PAGE 437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */

‎ports/rp2/mphalport.c

Lines changed: 16 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,7 @@
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#include "pendsv.h"
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#include "tusb.h"
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#include "uart.h"
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#include "hardware/irq.h"
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#include "hardware/rtc.h"
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#include "pico/unique_id.h"
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@@ -46,8 +47,6 @@
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// microseconds since the Epoch.
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static uint64_t time_us_64_offset_from_epoch;
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49-
static alarm_id_t soft_timer_alarm_id = 0;
50-
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#if MICROPY_HW_ENABLE_UART_REPL || MICROPY_HW_USB_CDC
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#ifndef MICROPY_HW_STDIN_BUFFER_LEN
@@ -273,21 +272,26 @@ uint32_t storage_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_blo
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panic_unsupported();
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}
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276-
static int64_t soft_timer_callback(alarm_id_t id, void *user_data) {
277-
soft_timer_alarm_id = 0;
278-
pendsv_schedule_dispatch(PENDSV_DISPATCH_SOFT_TIMER, soft_timer_handler);
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return 0; // don't reschedule this alarm
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}
281-
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uint32_t soft_timer_get_ms(void) {
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return mp_hal_ticks_ms();
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}
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void soft_timer_schedule_at_ms(uint32_t ticks_ms) {
287-
if (soft_timer_alarm_id != 0) {
288-
cancel_alarm(soft_timer_alarm_id);
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}
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int32_t ms = soft_timer_ticks_diff(ticks_ms, mp_hal_ticks_ms());
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ms = MAX(0, ms);
292-
soft_timer_alarm_id = add_alarm_in_ms(ms, soft_timer_callback, NULL, true);
282+
if (hardware_alarm_set_target(MICROPY_HW_SOFT_TIMER_ALARM_NUM, delayed_by_ms(get_absolute_time(), ms))) {
283+
// "missed" hardware alarm target
284+
hardware_alarm_force_irq(MICROPY_HW_SOFT_TIMER_ALARM_NUM);
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}
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}
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288+
static void soft_timer_hardware_callback(unsigned int alarm_num) {
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// The timer alarm ISR needs to call here and trigger PendSV dispatch via
290+
// a second ISR, as PendSV may be currently suspended by the other CPU.
291+
pendsv_schedule_dispatch(PENDSV_DISPATCH_SOFT_TIMER, soft_timer_handler);
292+
}
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294+
void soft_timer_init(void) {
295+
hardware_alarm_claim(MICROPY_HW_SOFT_TIMER_ALARM_NUM);
296+
hardware_alarm_set_callback(MICROPY_HW_SOFT_TIMER_ALARM_NUM, soft_timer_hardware_callback);
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}

‎ports/rp2/mpnetworkport.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -66,7 +66,7 @@ static void gpio_irq_handler(void) {
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void cyw43_irq_init(void) {
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gpio_add_raw_irq_handler_with_order_priority(CYW43_PIN_WL_HOST_WAKE, gpio_irq_handler, CYW43_SHARED_IRQ_HANDLER_PRIORITY);
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irq_set_enabled(IO_IRQ_BANK0, true);
69-
NVIC_SetPriority(PendSV_IRQn, PICO_LOWEST_IRQ_PRIORITY);
69+
NVIC_SetPriority(PendSV_IRQn, IRQ_PRI_PENDSV);
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}
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void cyw43_post_poll_hook(void) {

‎ports/rp2/pendsv.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -42,6 +42,9 @@ enum {
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#define PENDSV_DISPATCH_NUM_SLOTS PENDSV_DISPATCH_MAX
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45+
// PendSV IRQ priority, to run system-level tasks that preempt the main thread.
46+
#define IRQ_PRI_PENDSV PICO_LOWEST_IRQ_PRIORITY
47+
4548
typedef void (*pendsv_dispatch_t)(void);
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void pendsv_suspend(void);

‎shared/runtime/softtimer.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -81,6 +81,9 @@ static inline void soft_timer_reinsert(soft_timer_entry_t *entry, uint32_t initi
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// pend-SV IRQ level, or equivalent.
8282
uint32_t soft_timer_get_ms(void);
8383
void soft_timer_schedule_at_ms(uint32_t ticks_ms);
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85+
// Optional port-specific initialisation function (provided and called by the port if needed).
86+
void soft_timer_init(void);
8487
#endif
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8689
#endif // MICROPY_INCLUDED_SHARED_RUNTIME_SOFTTIMER_H

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