Merge branch 'feature/xtal_freq_autodetect' into 'master'

XTAL frequency detection, support for selecting XTAL frequency

This MR adds more robust XTAL frequency detection code (which gets run in the bootloader) and an option to set XTAL frequency in Kconfig. By default we still use autodetection, since it is more reliable than the one used in ROM code.

This will help with issues about XTAL frequency detection in high ambient temperature conditions.

Ref TW12008

See merge request !694

components/esp32/Kconfig

@@ -560,6 +560,34 @@ config ESP32_DEEP_SLEEP_WAKEUP_DELAY
         If you are seeing "flash read err, 1000" message printed to the
         console after deep sleep reset, try increasing this value.
 
+choice ESP32_XTAL_FREQ_SEL
+    prompt "Main XTAL frequency"
+    default ESP32_XTAL_FREQ_AUTO
+    help
+        ESP32 currently supports the following XTAL frequencies:
+            - 26 MHz
+            - 40 MHz
+        Startup code can automatically estimate XTAL frequency. This feature
+        uses the internal 8MHz oscillator as a reference. Because the internal
+        oscillator frequency is temperature dependent, it is not recommended
+        to use automatic XTAL frequency detection in applications which need
+        to work at high ambient temperatures and use high-temperature
+        qualified chips and modules.
+config ESP32_XTAL_FREQ_40
+    bool "40 MHz"
+config ESP32_XTAL_FREQ_26
+    bool "26 MHz"
+config ESP32_XTAL_FREQ_AUTO
+    bool "Autodetect"
+endchoice
+
+# Keep these values in sync with rtc_xtal_freq_t enum in soc/rtc.h
+config ESP32_XTAL_FREQ
+    int
+    default 0 if ESP32_XTAL_FREQ_AUTO
+    default 40 if ESP32_XTAL_FREQ_40
+    default 26 if ESP32_XTAL_FREQ_26
+
 endmenu
 
 menuconfig WIFI_ENABLED