esp32: initialize PM at startup, add Kconfig options

components/esp32/Kconfig

@@ -945,3 +945,55 @@ config ESP32_PHY_MAX_TX_POWER
 	default ESP32_PHY_MAX_WIFI_TX_POWER
 
 endmenu  # PHY
+
+
+menu "Power Management"
+
+config PM_ENABLE
+	bool "Support for power management"
+	default n
+	help
+		If enabled, application is compiled with support for power management.
+		This option has run-time overhead (increased interrupt latency,
+		longer time to enter idle state), and it also reduces accuracy of
+		RTOS ticks and timers used for timekeeping.
+		Enable this option if application uses power management APIs. 
+
+config PM_DFS_INIT_AUTO
+	bool "Enable dynamic frequency scaling (DFS) at startup"
+	depends on PM_ENABLE
+	default n
+	help
+		If enabled, startup code configures dynamic frequency scaling.
+		Max CPU frequency is set to CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ setting,
+		min frequency is set to XTAL frequency.
+		If disabled, DFS will not be active until the application
+		configures it using esp_pm_configure function.
+
+config PM_PROFILING
+	bool "Enable profiling counters for PM locks"
+	depends on PM_ENABLE
+	default n
+	help
+		If enabled, esp_pm_* functions will keep track of the amount of time
+		each of the power management locks has been held, and esp_pm_dump_locks
+		function will print this information.
+		This feature can be used to analyze which locks are preventing the chip
+		from going into a lower power state, and see what time the chip spends
+		in each power saving mode. This feature does incur some run-time
+		overhead, so should typically be disabled in production builds. 
+
+config PM_TRACE
+	bool "Enable debug tracing of PM using GPIOs"
+	depends on PM_ENABLE
+	default n
+	help
+		If enabled, some GPIOs will be used to signal events such as RTOS ticks,
+		frequency switching, entry/exit from idle state. Refer to pm_trace.c
+		file for the list of GPIOs.
+		This feature is intended to be used when analyzing/debugging behavior
+		of power management implementation, and should be kept disabled in
+		applications.
+	
+
+endmenu # "Power Management"

components/esp32/cpu_start.c

@@ -66,6 +66,8 @@
 #include "esp_spiram.h"
 #include "esp_clk_internal.h"
 #include "esp_timer.h"
+#include "esp_pm.h"
+#include "pm_impl.h"
 #include "trax.h"
 
 #define STRINGIFY(s) STRINGIFY2(s)
@@ -337,6 +339,18 @@ void start_cpu0_default(void)
     spi_flash_init();
     /* init default OS-aware flash access critical section */
     spi_flash_guard_set(&g_flash_guard_default_ops);
+#ifdef CONFIG_PM_ENABLE
+    esp_pm_impl_init();
+#ifdef CONFIG_PM_DFS_INIT_AUTO
+    rtc_cpu_freq_t max_freq;
+    rtc_clk_cpu_freq_from_mhz(CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ, &max_freq);
+    esp_pm_config_esp32_t cfg = {
+            .max_cpu_freq = max_freq,
+            .min_cpu_freq = RTC_CPU_FREQ_XTAL
+    };
+    esp_pm_configure(&cfg);
+#endif //CONFIG_PM_DFS_INIT_AUTO
+#endif //CONFIG_PM_ENABLE
 
 #if CONFIG_ESP32_ENABLE_COREDUMP
     esp_core_dump_init();