freertos,esp32: automatic light sleep support

components/esp32/pm_esp32.c

@@ -22,10 +22,12 @@
 #include "esp_pm.h"
 #include "esp_log.h"
 #include "esp_crosscore_int.h"
+#include "esp_clk.h"
 
 #include "soc/rtc.h"
 
 #include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
 #include "freertos/xtensa_timer.h"
 #include "xtensa/core-macros.h"
 
@@ -39,6 +41,16 @@
  */
 #define CCOMPARE_UPDATE_TIMEOUT 1000000
 
+/* When changing CCOMPARE, don't allow changes if the difference is less
+ * than this. This is to prevent setting CCOMPARE below CCOUNT.
+ */
+#define CCOMPARE_MIN_CYCLES_IN_FUTURE 1000
+
+/* When light sleep is used, wake this number of microseconds earlier than
+ * the next tick.
+ */
+#define LIGHT_SLEEP_EARLY_WAKEUP_US 100
+
 #ifdef CONFIG_PM_PROFILING
 #define WITH_PROFILING
 #endif
@@ -107,7 +119,7 @@ static const char* s_freq_names[] __attribute__((unused)) = {
         [RTC_CPU_FREQ_2M] = "2"
 };
 
-/* Whether automatic light sleep is enabled. Currently always false */
+/* Whether automatic light sleep is enabled */
 static bool s_light_sleep_en = false;
 
 /* When configuration is changed, current frequency may not match the
@@ -177,9 +189,11 @@ esp_err_t esp_pm_configure(const void* vconfig)
 #endif
 
     const esp_pm_config_esp32_t* config = (const esp_pm_config_esp32_t*) vconfig;
+#ifndef CONFIG_FREERTOS_USE_TICKLESS_IDLE
     if (config->light_sleep_enable) {
         return ESP_ERR_NOT_SUPPORTED;
     }
+#endif
 
     if (config->min_cpu_freq == RTC_CPU_FREQ_2M) {
         /* Minimal APB frequency to achieve 1MHz REF_TICK frequency is 5 MHz */
@@ -401,10 +415,9 @@ static void IRAM_ATTR do_switch(pm_mode_t new_mode)
  */
 static void IRAM_ATTR update_ccompare()
 {
-    const uint32_t ccompare_min_cycles_in_future = 1000;
     uint32_t ccount = XTHAL_GET_CCOUNT();
     uint32_t ccompare = XTHAL_GET_CCOMPARE(XT_TIMER_INDEX);
-    if ((ccompare - ccompare_min_cycles_in_future) - ccount < UINT32_MAX / 2) {
+    if ((ccompare - CCOMPARE_MIN_CYCLES_IN_FUTURE) - ccount < UINT32_MAX / 2) {
         uint32_t diff = ccompare - ccount;
         uint32_t diff_scaled = (diff * s_ccount_mul + s_ccount_div - 1) / s_ccount_div;
         if (diff_scaled < _xt_tick_divisor) {
@@ -453,6 +466,56 @@ void IRAM_ATTR esp_pm_impl_isr_hook()
     ESP_PM_TRACE_EXIT(ISR_HOOK, core_id);
 }
 
+#if CONFIG_FREERTOS_USE_TICKLESS_IDLE
+
+bool IRAM_ATTR vApplicationSleep( TickType_t xExpectedIdleTime )
+{
+    bool result = false;
+    portENTER_CRITICAL(&s_switch_lock);
+    if (s_mode == PM_MODE_LIGHT_SLEEP && !s_is_switching) {
+        /* Calculate how much we can sleep */
+        int64_t next_esp_timer_alarm = esp_timer_get_next_alarm();
+        int64_t now = esp_timer_get_time();
+        int64_t time_until_next_alarm = next_esp_timer_alarm - now;
+        int64_t wakeup_delay_us = portTICK_PERIOD_MS * 1000LL * xExpectedIdleTime;
+        int64_t sleep_time_us = MIN(wakeup_delay_us, time_until_next_alarm);
+        if (sleep_time_us >= configEXPECTED_IDLE_TIME_BEFORE_SLEEP * portTICK_PERIOD_MS * 1000LL) {
+            esp_sleep_enable_timer_wakeup(sleep_time_us - LIGHT_SLEEP_EARLY_WAKEUP_US);
+#ifdef CONFIG_PM_TRACE
+            /* to force tracing GPIOs to keep state */
+            esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);
+#endif
+            /* Enter sleep */
+            int core_id = xPortGetCoreID();
+            ESP_PM_TRACE_ENTER(SLEEP, core_id);
+            int64_t sleep_start = esp_timer_get_time();
+            esp_light_sleep_start();
+            int64_t slept_us = esp_timer_get_time() - sleep_start;
+            ESP_PM_TRACE_EXIT(SLEEP, core_id);
+
+            uint32_t slept_ticks = slept_us / (portTICK_PERIOD_MS * 1000LL);
+            if (slept_ticks > 0) {
+                /* Adjust RTOS tick count based on the amount of time spent in sleep */
+                vTaskStepTick(slept_ticks);
+
+                /* Trigger tick interrupt, since sleep time was longer
+                 * than portTICK_PERIOD_MS. Note that setting INTSET does not
+                 * work for timer interrupt, and changing CCOMPARE would clear
+                 * the interrupt flag.
+                 */
+                XTHAL_SET_CCOUNT(XTHAL_GET_CCOMPARE(XT_TIMER_INDEX) - 16);
+                while (!(XTHAL_GET_INTERRUPT() & BIT(XT_TIMER_INTNUM))) {
+                    ;
+                }
+            }
+            result = true;
+        }
+    }
+    portEXIT_CRITICAL(&s_switch_lock);
+    return result;
+}
+#endif //CONFIG_FREERTOS_USE_TICKLESS_IDLE
+
 #ifdef WITH_PROFILING
 void esp_pm_impl_dump_stats(FILE* out)
 {