USB charger - tell the phone it can draw more power
The standard USB qualified method for telling a phone that it can fast charge is to short the D+ and D- lines together. (USB calls this out in its documentation)

The non standard way is to place voltages on the data lines. 







simulate this circuit &ndash; Schematic created using CircuitLab

The usual way this is done is using two resistor dividers. What is unfortunate is that these voltages are all different depending on your device. If your chargers is capable of fast charging your phone then measure the voltages on the data pins and set up your own dividers to get those same voltages. 

ePanorama had a great aggregation of the information on fast charging USB ports as it related to Apple devices. 
This APC article discusses the variation in D-/D+ voltages used by various manufacturers.