Remove extra yields for Zephyr

Instead, delay in a couple spots within Zephyr.

Author: tannewt

ports/zephyr-cp/background.c

@@ -36,10 +36,9 @@ void port_background_tick(void) {
     #endif
 }
 
-// Allow boards to override this.
-MP_WEAK void board_background_task(void) {
-}
-
 void port_background_task(void) {
-    board_background_task();
+    // Make sure time advances in the simulator.
+    #if defined(CONFIG_ARCH_POSIX)
+    k_busy_wait(100);
+    #endif
 }

ports/zephyr-cp/mphalport.h

@@ -13,7 +13,12 @@
 #include "py/mpconfig.h"
 #include "supervisor/shared/tick.h"
 
+#include <zephyr/kernel.h>
+
 #define mp_hal_ticks_ms()       ((mp_uint_t)supervisor_ticks_ms32())
-#define mp_hal_delay_us(us)     NRFX_DELAY_US((uint32_t)(us))
+
+static inline void mp_hal_delay_us(mp_uint_t us) {
+    k_busy_wait((uint32_t)us);
+}
 
 bool mp_hal_stdin_any(void);

ports/zephyr-cp/supervisor/port.c

@@ -67,10 +67,6 @@ void port_wake_main_task_from_isr(void) {
 
 void port_yield(void) {
     k_yield();
-    // Make sure time advances in the simulator.
-    #if defined(CONFIG_ARCH_POSIX)
-    k_busy_wait(100);
-    #endif
 }
 
 void port_boot_info(void) {
@@ -97,6 +93,10 @@ uint32_t port_get_saved_word(void) {
 }
 
 uint64_t port_get_raw_ticks(uint8_t *subticks) {
+    // Make sure time advances in the simulator.
+    #if defined(CONFIG_ARCH_POSIX)
+    k_busy_wait(100);
+    #endif
     int64_t uptime = k_uptime_ticks() * 32768 / CONFIG_SYS_CLOCK_TICKS_PER_SEC;
     if (subticks != NULL) {
         *subticks = uptime % 32;

supervisor/shared/background_callback.c

@@ -61,10 +61,6 @@ static int background_prevention_count;
 void PLACE_IN_ITCM(background_callback_run_all)(void) {
     port_background_task();
     if (!background_callback_pending()) {
-        // TEMPORARY to fix #10822
-        #ifdef __ZEPHYR__
-        port_yield();
-        #endif
         return;
     }
     CALLBACK_CRITICAL_BEGIN;
@@ -91,10 +87,6 @@ void PLACE_IN_ITCM(background_callback_run_all)(void) {
     }
     --background_prevention_count;
     CALLBACK_CRITICAL_END;
-    // TEMPORARY to fix #10822
-    #ifdef __ZEPHYR__
-    port_yield();
-    #endif
 }
 
 void background_callback_prevent(void) {

supervisor/shared/safe_mode.c

@@ -82,10 +82,6 @@ safe_mode_t wait_for_safe_mode_reset(void) {
             boot_in_safe_mode = true;
             break;
         }
-        // TEMPORARY to fix #10822
-        #ifdef __ZEPHYR__
-        port_yield();
-        #endif
         diff = supervisor_ticks_ms64() - start_ticks;
     }
     #if CIRCUITPY_STATUS_LED