soc: arm: nordic_nrf: unrevert provide custom busy_wait implementations

This reverts commit bd24b31. While the test case failure described in #14186 is associated with the cycle-based busy-wait implementation, that test is fragile, and fails less frequently once the incongruence between ticks-per-second and the 32 KiHz RTC clock are resolved. It also assumes that the system clock is more stable than the infrastructure underlying the the busy-wait implementation, which is not necessarily true. The gross inaccuracies in the standard busy-wait on Nordic described in issue #11626 justify restoring the custom solution. As this applies to all Nordic devices, move the setting to the top-level Kconfig.defconfig. See: #11626 (comment) Signed-off-by: Peter A. Bigot <pab@pabigot.com>
zephyrproject-rtos · May 7, 2019 · da3f7fe · da3f7fe
1 parent c76dd1e
commit da3f7fe
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Showing 4 changed files with 20 additions and 3 deletions.
diff --git a/soc/arm/nordic_nrf/Kconfig.defconfig b/soc/arm/nordic_nrf/Kconfig.defconfig
@@ -17,6 +17,9 @@ config SYS_CLOCK_TICKS_PER_SEC
 	int
 	default 128
 
+config ARCH_HAS_CUSTOM_BUSY_WAIT
+	default y
+
 config BUILD_OUTPUT_HEX
 	default y
 

diff --git a/soc/arm/nordic_nrf/nrf51/soc.c b/soc/arm/nordic_nrf/nrf51/soc.c
@@ -59,4 +59,16 @@ static int nordicsemi_nrf51_init(struct device *arg)
 	return 0;
 }
 
+#define DELAY_CALL_OVERHEAD_US 2
+
+void z_arch_busy_wait(u32_t time_us)
+{
+	if (time_us <= DELAY_CALL_OVERHEAD_US) {
+		return;
+	}
+
+	time_us -= DELAY_CALL_OVERHEAD_US;
+	nrfx_coredep_delay_us(time_us);
+}
+
 SYS_INIT(nordicsemi_nrf51_init, PRE_KERNEL_1, 0);
diff --git a/soc/arm/nordic_nrf/nrf52/soc.c b/soc/arm/nordic_nrf/nrf52/soc.c
@@ -81,4 +81,9 @@ static int nordicsemi_nrf52_init(struct device *arg)
 	return 0;
 }
 
+void z_arch_busy_wait(u32_t time_us)
+{
+	nrfx_coredep_delay_us(time_us);
+}
+
 SYS_INIT(nordicsemi_nrf52_init, PRE_KERNEL_1, 0);
diff --git a/soc/arm/nordic_nrf/nrf91/Kconfig.defconfig.series b/soc/arm/nordic_nrf/nrf91/Kconfig.defconfig.series
@@ -12,9 +12,6 @@ source "soc/arm/nordic_nrf/nrf91/Kconfig.defconfig.nrf91*"
 config SOC_SERIES
 	default "nrf91"
 
-config ARCH_HAS_CUSTOM_BUSY_WAIT
-	default y
-
 config SYS_POWER_MANAGEMENT
 	default y