pylibfdt: Support boolean properties

Boolean properties are unusual in that their presense or absence
indicates the value of the property. This makes them a little painful to
support using the existing getprop() support.

Add new methods to deal with booleans specifically.

Signed-off-by: Simon Glass <sjg@chromium.org>
Message-ID: <20230912182716.248253-1-sjg@chromium.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

pylibfdt/libfdt.i

@@ -419,6 +419,35 @@ class FdtRo(object):
             return pdata
         return Property(prop_name, bytearray(pdata[0]))
 
+    def hasprop(self, nodeoffset, prop_name, quiet=()):
+        """Check if a node has a property
+
+        This can be used to check boolean properties
+
+        Args:
+            nodeoffset: Node offset containing property to check
+            prop_name: Name of property to check
+            quiet: Errors to ignore (empty to raise on all errors). Note that
+                NOTFOUND is added internally by this function so need not be
+                provided
+
+        Returns:
+            True if the property exists in the node, else False. If an error
+                other than -NOTFOUND is returned by fdt_getprop() then the error
+                is return (-ve integer)
+
+        Raises:
+            FdtError if any error occurs other than NOTFOUND (e.g. the
+                nodeoffset is invalid)
+        """
+        pdata = check_err_null(fdt_getprop(self._fdt, nodeoffset, prop_name),
+                               quiet + (NOTFOUND,))
+        if isinstance(pdata, (int)):
+            if pdata == -NOTFOUND:
+                return False
+            return pdata
+        return True
+
     def get_phandle(self, nodeoffset):
         """Get the phandle of a node
 
@@ -605,6 +634,32 @@ class Fdt(FdtRo):
         return check_err(fdt_setprop(self._fdt, nodeoffset, prop_name, val,
                                      len(val)), quiet)
 
+    def setprop_bool(self, nodeoffset, prop_name, val, quiet=()):
+        """Set the boolean value of a property
+
+        Either:
+            adds the property if not already present; or
+            deletes the property if present
+
+        Args:
+            nodeoffset: Node offset containing the property to create/delete
+            prop_name: Name of property
+            val: Boolean value to write (i.e. True or False)
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Returns:
+            Error code, or 0 if OK
+
+        Raises:
+            FdtException if no parent found or other error occurs
+        """
+        exists = self.hasprop(nodeoffset, prop_name, quiet)
+        if val != exists:
+            if val:
+                return self.setprop(nodeoffset, prop_name, b'', quiet=quiet)
+            else:
+                return self.delprop(nodeoffset, prop_name, quiet=quiet)
+
     def setprop_u32(self, nodeoffset, prop_name, val, quiet=()):
         """Set the value of a property