This change adds esp_deep_sleep_get_wakeup_cause, which returns the
source which has caused wakeup from deep sleep.
Similar to esp_deep_sleep_get_ext1_wakeup_status, a function is added
to check touch pad wakeup status: esp_deep_sleep_get_touchpad_wakeup_status.
This function returns the touch pad which has caused wakeup.
ULP and touch FSMs in ESP32 revisions 0 and 1 do not operate correctly
if RTC_PERIPH power domain is force powered on (ESP_PD_OPTION_ON).
Both ULP and touch still work, but clock frequency of the ULP may be
incorrect and touch values may be off by considerable amount. As such,
when these wakeup modes are used, RTC_PERIPH power domain has to be set
to ESP_PD_OPTION_AUTO (or, in the current implementation,
ESP_PD_OPTION_OFF — though this will change in the future when _OFF will
actually *force* the power domain to be powered off).
Because EXT0 wakeup source requires RTC_PERIPH to be powered ON, mark
ULP and touch wakeup sources as incompatible with EXT0. Workaround for
this is to use EXT1 wakeup source instead, which offers similar or
better functions without having to keep RTC_PERIPH powered on.
This change allows setting pin configuration for EXT1 wakeup depending on the state of RTC_PERIPH power domain:
- if peripherals are enabled (due to another wakeup mode, or due to esp_deep_sleep_pd_config call), we can keep internal pullups/pulldowns enabled
- if peripherals are disabled, pullups and pulldowns need to be disabled as well
Also add comments about the purpose of registers being configured.
