[GPTQ Modifier UX] Add default scheme

src/compressed_tensors/quantization/quant_scheme.py

@@ -37,3 +37,32 @@ class QuantizationScheme(BaseModel):
     weights: Optional[QuantizationArgs] = None
     input_activations: Optional[QuantizationArgs] = None
     output_activations: Optional[QuantizationArgs] = None
+
+    @classmethod
+    def default_scheme(
+        cls,
+        targets: Optional[List[str]] = None,
+    ):
+
+        if targets is None:
+            # default to quantizing all Linear layers
+            targets = ["Linear"]
+
+        # default to 8 bit integer symmetric quantization
+        # for weights
+        weights = QuantizationArgs(num_bits=8, symmetric=True)
+
+        # default to 8 bit integer asymmetric quantization
+        input_activations = QuantizationArgs(num_bits=8, symmetric=False)
+
+        # Do not quantize the output activations
+        # by default
+        output_activations = None
+
+        return cls(
+            targets=targets,
+            weights=weights,
+            input_activations=input_activations,
+            output_activations=output_activations,)
+
+