[PATCH v2 2/2] pylibfdt: Allow reading integer values from properties

[Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>]

Extend the Properties class with some functions to read a single integer
property. Add a new getprop_obj() function to return a Property object
instead of the raw data.

This suggested approach can be extended to handle other types, as well as
arrays.

Signed-off-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
---

Changes in v2: None

 pylibfdt/libfdt.i       | 35 +++++++++++++++++++++++++++++++++++
 tests/pylibfdt_tests.py | 12 ++++++++++++
 tests/run_tests.sh      |  1 +
 tests/test_props.dts    | 11 +++++++++++
 4 files changed, 59 insertions(+)
 create mode 100644 tests/test_props.dts

diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
index f8e3a2c..4d60f90 100644
--- a/pylibfdt/libfdt.i
+++ b/pylibfdt/libfdt.i
@@ -376,6 +376,26 @@ class Fdt:
             return pdata
         return bytearray(pdata[0])
 
+    def getprop_obj(self, nodeoffset, prop_name, quiet=()):
+        """Get a property from a node as a Property object
+
+        Args:
+            nodeoffset: Node offset containing property to get
+            prop_name: Name of property to get
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Returns:
+            Property object, or None if not found
+
+        Raises:
+            FdtError if any error occurs (e.g. the property is not found)
+        """
+        pdata = check_err_null(fdt_getprop(self._fdt, nodeoffset, prop_name),
+                               quiet)
+        if isinstance(pdata, (int)):
+            return None
+        return Property(prop_name, bytearray(pdata[0]))
+
     def get_phandle(self, nodeoffset):
         """Get the phandle of a node
 
@@ -432,6 +452,21 @@ class Property:
     def __init__(self, name, value):
         self.name = name
         self.value = value
+
+    def to_cell(self, fmt):
+        return struct.unpack('>' + fmt, self.value)[0]
+
+    def to_uint32(self):
+        return self.to_cell('L')
+
+    def to_int32(self):
+        return self.to_cell('l')
+
+    def to_uint64(self):
+        return self.to_cell('Q')
+
+    def to_int64(self):
+        return self.to_cell('q')
 %}
 
 %rename(fdt_property) fdt_property_func;
diff --git a/tests/pylibfdt_tests.py b/tests/pylibfdt_tests.py
index 0ec0f38..fc5210b 100644
--- a/tests/pylibfdt_tests.py
+++ b/tests/pylibfdt_tests.py
@@ -89,6 +89,7 @@ class PyLibfdtTests(unittest.TestCase):
     def setUp(self):
         """Read in the device tree we use for testing"""
         self.fdt = _ReadFdt('test_tree1.dtb')
+        self.fdt2 = _ReadFdt('test_props.dtb')
 
     def GetPropList(self, node_path):
         """Read a list of properties from a node
@@ -330,6 +331,17 @@ class PyLibfdtTests(unittest.TestCase):
         node2 = self.fdt.path_offset('/subnode@2/subsubnode@0')
         self.assertEquals(node2, self.fdt.node_offset_by_phandle(0x2001))
 
+    def get_prop(self, name):
+        return self.fdt2.getprop_obj(0, name)
+
+    def testGetIntProperties(self):
+        """Test that we can access properties as integers"""
+        self.assertEquals(0xdeadbeef, self.get_prop("prop-hex32").to_uint32())
+        self.assertEquals(123, self.get_prop("prop-uint32").to_uint32())
+        self.assertEquals(-2, self.get_prop("prop-int32").to_int32())
+        self.assertEquals(9223372036854775807,
+                          self.get_prop("prop-uint64").to_uint64())
+        self.assertEquals(-2, self.get_prop("prop-int64").to_int64())
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index fa7b2f7..441e773 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -809,6 +809,7 @@ fdtoverlay_tests() {
 }
 
 pylibfdt_tests () {
+    run_dtc_test -I dts -O dtb -o test_props.dtb test_props.dts
     TMP=/tmp/tests.stderr.$$
     python pylibfdt_tests.py -v 2> $TMP
 
diff --git a/tests/test_props.dts b/tests/test_props.dts
new file mode 100644
index 0000000..7e59bd1
--- /dev/null
+++ b/tests/test_props.dts
@@ -0,0 +1,11 @@
+/dts-v1/;
+
+/ {
+	compatible = "test_props";
+	prop-hex32 = <0xdeadbeef>;
+	prop-uint32 = <123>;
+	prop-int32 = <0xfffffffe>;
+	prop-hex64 = /bits/ 64 <0xdeadbeef01abcdef>;
+	prop-uint64 = /bits/ 64 <9223372036854775807>;
+	prop-int64 = /bits/ 64 <0xfffffffffffffffe>;
+};
-- 
2.14.1.581.gf28d330327-goog