Inline ESP::getCycleCount() to make it safe to call from ISRs (#3165)

* Inline ESP::getCycleCount() to make it safe to call from ISRs

* Attribute IRAM_ATTR ISR-safe function in addition to inlining.

cores/esp32/Esp.cpp

@@ -92,13 +92,6 @@ void EspClass::deepSleep(uint32_t time_us)
     esp_deep_sleep(time_us);
 }
 
-uint32_t EspClass::getCycleCount()
-{
-    uint32_t ccount;
-    __asm__ __volatile__("esync; rsr %0,ccount":"=a" (ccount));
-    return ccount;
-}
-
 void EspClass::restart(void)
 {
     esp_restart();

cores/esp32/Esp.h

@@ -76,7 +76,7 @@ public:
 
     uint8_t getChipRevision();
     uint32_t getCpuFreqMHz(){ return getCpuFrequencyMhz(); }
-    uint32_t getCycleCount();
+    inline uint32_t getCycleCount() __attribute__((always_inline));
     const char * getSdkVersion();
 
     void deepSleep(uint32_t time_us);
@@ -101,6 +101,13 @@ public:
 
 };
 
+uint32_t IRAM_ATTR EspClass::getCycleCount()
+{
+    uint32_t ccount;
+    __asm__ __volatile__("esync; rsr %0,ccount":"=a" (ccount));
+    return ccount;
+}
+
 extern EspClass ESP;
 
 #endif //ESP_H