base, python: Add a Temperature type and associated param

Add a class to represent a temperature. The class stores temperatures
in Kelvin and provides helper methods to convert to/from Celsius. The
corresponding param type automatically converts from Kelvin, Celsius,
and Fahrenheit to the underlying C++ type.

Change-Id: I5783cc4f4fecbea5aba9821dfc71bfa77c3f75a9
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39218
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/python/m5/util/convert.py

@@ -292,3 +292,25 @@ def toCurrent(value):
 
 def toEnergy(value):
     return toMetricFloat(value, 'energy', 'J')
+
+def toTemperature(value):
+    """Convert a string value specified to a temperature in Kelvin"""
+
+    magnitude, unit = toNum(value,
+                            target_type='temperature',
+                            units=('K', 'C', 'F'),
+                            prefixes=metric_prefixes,
+                            converter=float)
+    if unit == 'K':
+        kelvin = magnitude
+    elif unit == 'C':
+        kelvin = magnitude + 273.15
+    elif unit == 'F':
+        kelvin = (magnitude + 459.67) / 1.8
+    else:
+        raise ValueError(f"'{value}' needs a valid temperature unit.")
+
+    if kelvin < 0:
+        raise ValueError(f"{value} is an invalid temperature")
+
+    return kelvin