by suing below javascript codes we can convert input text value to Upper,lower or Capitalize.
same thing we can achieve using Content Style property, text-transform:uppercase;.

function toUpperValue(event) {

       var inputComponent = event.getCurrentTarget();

       var componentId = event.getSource().getClientId();

       var value = inputComponent.getSubmittedValue();

       if (value != null && value != '') {

              document.getElementById(componentId + '::content').value = value

                           .toUpperCase();

       }

}

function toLowerValue(event) {

       var inputComponent = event.getCurrentTarget();

       inputComponent.setValue(inputComponent.getSubmittedValue().toLowerCase());

}

function toInitCap(event) {

       var inputComponent = event.getCurrentTarget();

       var componentId = event.getSource().getClientId();

       var value = inputComponent.getSubmittedValue();

       if (value != null && value != '') {

              document.getElementById(componentId + '::content').value = value

                            .charAt(0).toUpperCase()

                           + value.substr(1).toLowerCase();

       }

}