Answer

The charge detection is compatible to the USB BC1.2 specification, so it can handle chargers compliant to that standard and provide the interrupt response based on the charger configuration as it passes through the stages of detection.

For chargers that may not be compliant and set their own proprietary voltages on the D+/D- pins, you can use the ADC to monitor those voltages. D+/D- inputs are brought to the ADC input mux internally for this purpose (ADC0.28 and ADC0.29 on EFM8UB1). The voltage reference for the ADC is flexible as well so you can accommodate different ADC input voltage ranges up to VDD of 3.3V. 

The charge detect sequencing is controlled via the firmware. For example, once you perform the initial data contact detect, the firmware can enable the next phase or primary detection, and so on. The firmware controls the peripheral settings (enable/disable) and can decouple each scenario. For the chargers that would require the ADC, you can measure D+/D- after VBUS detection before going through the data contact detection sequence.