[nrf fromlist] soc: nrf53: Add implementation of workaround for anomaly 168

Use the already available in the tree mechanism of adding assembly
instructions right after WFI/WFE to implement the workaround for
nRF5340 anomaly 168 (replace the 4 NOP solution used on the network
core as it turned out to be insufficient) and provide two related
Kconfig options so that users are able to adjust the workaround to
their actual needs (disable it entirely or use it in the extended
version).

Signed-off-by: Andrzej Głąbek <[email protected]>

Upstream PR: zephyrproject-rtos/zephyr#66159

Author: anangl

soc/arm/nordic_nrf/nrf53/Kconfig.soc

@@ -12,13 +12,14 @@ config SOC_NRF5340_CPUAPP
 	select HAS_POWEROFF
 	select SOC_COMPATIBLE_NRF5340_CPUAPP
 	imply SOC_NRF53_RTC_PRETICK
+	imply SOC_NRF53_ANOMALY_168_WORKAROUND
 
 config SOC_NRF5340_CPUNET
 	bool
-	select ARM_ON_EXIT_CPU_IDLE
 	select SOC_COMPATIBLE_NRF5340_CPUNET
 	imply SOC_NRF53_ANOMALY_160_WORKAROUND_NEEDED
 	imply SOC_NRF53_RTC_PRETICK if !WDT_NRFX
+	imply SOC_NRF53_ANOMALY_168_WORKAROUND
 
 choice
 	prompt "nRF53x MCU Selection"
@@ -79,6 +80,25 @@ config SOC_NRF53_RTC_PRETICK_IPC_CH_TO_NET
 
 endif
 
+config SOC_NRF53_ANOMALY_168_WORKAROUND
+	bool "Workaround for nRF5340 anomaly 168"
+	select ARM_ON_EXIT_CPU_IDLE
+	help
+	  Indicates that the workaround for the anomaly 168 that affects
+	  the nRF5340 SoC should be applied.
+	  The workaround involves execution of 8 NOP instructions when the CPU
+	  exist its idle state (when the WFI/WFE instruction returns) and it is
+	  enabled by default for both the application and network core.
+
+config SOC_NRF53_ANOMALY_168_WORKAROUND_FOR_EXECUTION_FROM_RAM
+	bool "Extend the workaround to execution at 128 MHz from RAM"
+	depends on SOC_NRF53_ANOMALY_168_WORKAROUND && SOC_NRF5340_CPUAPP
+	help
+	  Indicates that the anomaly 168 workaround is to be extended to cover
+	  also a specific case when the WFI/WFE instruction is executed at 128
+	  MHz from RAM. Then, 26 instead of 8 NOP instructions needs to be
+	  executed after WFI/WFE. This extension is not enabled by default.
+
 if SOC_NRF5340_CPUAPP
 
 config SOC_DCDC_NRF53X_APP

soc/arm/nordic_nrf/nrf53/soc_cpu_idle.h

@@ -11,10 +11,16 @@
 
 #if defined(_ASMLANGUAGE)
 
+#if defined(CONFIG_SOC_NRF53_ANOMALY_168_WORKAROUND_FOR_EXECUTION_FROM_RAM)
 #define SOC_ON_EXIT_CPU_IDLE \
+	.rept 26 \
 	nop; \
+	.endr
+#elif defined(CONFIG_SOC_NRF53_ANOMALY_168_WORKAROUND)
+#define SOC_ON_EXIT_CPU_IDLE \
+	.rept 8 \
 	nop; \
-	nop; \
-	nop;
+	.endr
+#endif
 
 #endif /* _ASMLANGUAGE */