[PATCH 10/10] pylibfdt: Support the sequential-write interface

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It is useful to be able to create a device tree from scratch using
software. This is supported in libfdt but not currently available in the
Python bindings.

Add a new FdtSw class to handle this, with various methods corresponding
to the libfdt functions. When the tree is complete, calling AsFdt() will
return the completed device-tree object.

Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx>
---

 pylibfdt/libfdt.i       | 269 ++++++++++++++++++++++++++++++++++++++++
 tests/pylibfdt_tests.py |  91 +++++++++++++-
 2 files changed, 357 insertions(+), 3 deletions(-)

diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
index cf4ed93..36971b6 100644
--- a/pylibfdt/libfdt.i
+++ b/pylibfdt/libfdt.i
@@ -57,6 +57,17 @@
 %{
 #define SWIG_FILE_WITH_INIT
 #include "libfdt.h"
+
+/*
+ * We rename this function here to avoid problems with swig, since we also have
+ * a struct called fdt_property. That struct causes swig to create a class in
+ * libfdt.py called fdt_property(), which confuses things.
+ */
+static int _fdt_property(void *fdt, const char *name, const char *val, int len)
+{
+    return fdt_property(fdt, name, val, len);
+}
+
 %}
 
 %pythoncode %{
@@ -695,6 +706,251 @@ class Property(bytearray):
 
     def as_str(self):
         return self[:-1]
+
+
+class FdtSw(object):
+    """Software interface to create a device tree from scratch
+
+    The methods in this class work by adding to an existing 'partial' device
+    tree buffer of a fixed size created by instantiating this class. When the
+    tree is complete, call finish() to complete the device tree so that it can
+    be used.
+
+    Similarly with nodes, a new node is started with begin_node() and finished
+    with end_node().
+
+    The context manager functions can be used to make this a bit easier:
+
+    # First create the device tree with a node and property:
+    with FdtSw(small_size) as sw:
+        with sw.AddNode('node'):
+            sw.property_u32('reg', 2)
+    fdt = sw.AsFdt()
+
+    # Now we can use it as a real device tree
+    fdt.setprop_u32(0, 'reg', 3)
+    """
+    def __init__(self, size, quiet=()):
+        fdtrw = bytearray(size)
+        err = check_err(fdt_create(fdtrw, size))
+        if err:
+            return err
+        self._fdtrw = fdtrw
+
+    def __enter__(self):
+        """Contact manager to use to create a device tree via software"""
+        return self
+
+    def __exit__(self, type, value, traceback):
+        check_err(fdt_finish(self._fdtrw))
+
+    def AsFdt(self):
+        """Convert a FdtSw into an Fdt so it can be accessed as normal
+
+        Note that finish() must be called before this function will work. If
+        you are using the context manager (see 'with' code in the FdtSw class
+        comment) then this will happen automatically.
+
+        Returns:
+            Fdt object allowing access to the newly created device tree
+        """
+        return Fdt(self._fdtrw)
+
+    def resize(self, size, quiet=()):
+        """Resize the buffer to accommodate a larger tree
+
+        Args:
+            size: New size of tree
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        fdt = bytearray(size)
+        fdt[:len(self._fdtrw)] = self._fdtrw
+        err = check_err(fdt_resize(self._fdtrw, fdt, size), quiet)
+        if err:
+            return err
+        self._fdtrw = fdt
+
+    def add_reservemap_entry(self, addr, size, quiet=()):
+        """Add a new memory reserve map entry
+
+        Once finished adding, you must call finish_reservemap().
+
+        Args:
+            addr: 64-bit start address
+            size: 64-bit size
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_add_reservemap_entry(self._fdtrw, addr, size),
+                         quiet)
+
+    def finish_reservemap(self, quiet=()):
+        """Indicate that there are no more reserve map entries to add
+
+        Args:
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_finish_reservemap(self._fdtrw), quiet)
+
+    def begin_node(self, name, quiet=()):
+        """Begin a new node
+
+        Use this before adding properties to the node. Then call end_node() to
+        finish it. You can also use the context manager as shown in the FdtSw
+        class comment.
+
+        Args:
+            name: Name of node to begin
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_begin_node(self._fdtrw, name), quiet)
+
+    def property_string(self, name, string, quiet=()):
+        """Add a property with a string value
+
+        The string will be nul-terminated when written to the device tree
+
+        Args:
+            name: Name of property to add
+            string: String value of property
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_property_string(self._fdtrw, name, string), quiet)
+
+    def property_u32(self, name, val, quiet=()):
+        """Add a property with a 32-bit value
+
+        Write a single-cell value to the device tree
+
+        Args:
+            name: Name of property to add
+            val: Value of property
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_property_u32(self._fdtrw, name, val), quiet)
+
+    def property_u64(self, name, val, quiet=()):
+        """Add a property with a 64-bit value
+
+        Write a double-cell value to the device tree in big-endian format
+
+        Args:
+            name: Name of property to add
+            val: Value of property
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_property_u64(self._fdtrw, name, val), quiet)
+
+    def property_cell(self, name, val, quiet=()):
+        """Add a property with a single-cell value
+
+        Write a single-cell value to the device tree
+
+        Args:
+            name: Name of property to add
+            val: Value of property
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_property_cell(self._fdtrw, name, val), quiet)
+
+    def property(self, name, val, quiet=()):
+        """Add a property
+
+        Write a new property with the given value to the device tree. The value
+        is taken as is and is not nul-terminated
+
+        Args:
+            name: Name of property to add
+            val: Value of property
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(_fdt_property(self._fdtrw, name, val, len(val)), quiet)
+
+    def end_node(self, quiet=()):
+        """End a node
+
+        Use this after adding properties to a node to close it off. You can also
+        use the context manager as shown in the FdtSw class comment.
+
+        Args:
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_end_node(self._fdtrw), quiet)
+
+    def finish(self, quiet=()):
+        """Finish writing the device tree
+
+        This closes off the device tree ready for use
+
+        Args:
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Raises:
+            FdtException if no node found or other error occurs
+        """
+        return check_err(fdt_finish(self._fdtrw), quiet)
+
+    def AddNode(self, name):
+        """Create a new context for adding a node
+
+        When used in a 'with' clause this starts a new node and finishes it
+        afterward.
+
+        Args:
+            name: Name of node to add
+        """
+        return NodeAdder(self._fdtrw, name)
+
+
+class NodeAdder():
+    """Class to provide a node context
+
+    This allows you to add nodes in a more natural way:
+
+        with fdtsw.AddNode('name'):
+            fdtsw.property_string('test', 'value')
+
+    The node is automatically completed with a call to end_node() when the
+    context exits.
+    """
+    def __init__(self, fdt, name):
+        self._fdt = fdt
+        self._name = name
+
+    def __enter__(self):
+        check_err(fdt_begin_node(self._fdt, self._name))
+
+    def __exit__(self, type, value, traceback):
+        check_err(fdt_end_node(self._fdt))
 %}
 
 %rename(fdt_property) fdt_property_func;
@@ -755,6 +1011,11 @@ typedef int fdt32_t;
     $1 = PyString_AsString($input);   /* char *str */
 }
 
+/* typemap used for fdt_add_reservemap_entry() */
+%typemap(in) uint64_t {
+   $1 = PyLong_AsUnsignedLong($input);
+}
+
 /* typemaps used for fdt_next_node() */
 %typemap(in, numinputs=1) int *depth (int depth) {
    depth = (int) PyInt_AsLong($input);
@@ -797,5 +1058,13 @@ int fdt_last_comp_version(const void *fdt);
 int fdt_boot_cpuid_phys(const void *fdt);
 int fdt_size_dt_strings(const void *fdt);
 int fdt_size_dt_struct(const void *fdt);
+int fdt_property_string(void *fdt, const char *name, const char *val);
+int fdt_property_cell(void *fdt, const char *name, uint32_t val);
+
+/*
+ * This function has a stub since the name fdt_property is used for both a
+  * function and a struct, which confuses SWIG.
+ */
+int _fdt_property(void *fdt, const char *name, const char *val, int len);
 
 %include <../libfdt/libfdt.h>
diff --git a/tests/pylibfdt_tests.py b/tests/pylibfdt_tests.py
index 57eedcb..61f064f 100644
--- a/tests/pylibfdt_tests.py
+++ b/tests/pylibfdt_tests.py
@@ -56,17 +56,34 @@ import unittest
 
 sys.path.insert(0, '../pylibfdt')
 import libfdt
-from libfdt import Fdt, FdtException, QUIET_NOTFOUND, QUIET_ALL
+from libfdt import Fdt, FdtSw, FdtException, QUIET_NOTFOUND, QUIET_ALL
 
 small_size = 160
 full_size = 1024
+TEST_ADDR_1H = 0xdeadbeef
+TEST_ADDR_1L = 0x00000000
+TEST_ADDR_1 = (TEST_ADDR_1H << 32) | TEST_ADDR_1L
+TEST_ADDR_1 = 0x8000000000000000
+TEST_SIZE_1H = 0x00000000
+TEST_SIZE_1L = 0x00100000
+TEST_SIZE_1 = (TEST_SIZE_1H << 32) | TEST_SIZE_1L
+TEST_ADDR_2H = 0
+TEST_ADDR_2L = 123456789
+TEST_ADDR_2 = (TEST_ADDR_2H << 32) | TEST_ADDR_2L
+TEST_SIZE_2H = 0
+TEST_SIZE_2L = 010000
+TEST_SIZE_2 = (TEST_SIZE_2H << 32) | TEST_SIZE_2L
 
 TEST_VALUE_1 = 0xdeadbeef
+TEST_VALUE_2 = 123456789
 
 TEST_VALUE64_1H = 0xdeadbeef
 TEST_VALUE64_1L = 0x01abcdef
 TEST_VALUE64_1 = (TEST_VALUE64_1H << 32) | TEST_VALUE64_1L
 
+PHANDLE_1 = 0x2000
+PHANDLE_2 = 0x2001
+
 TEST_STRING_1 = 'hello world'
 TEST_STRING_2 = 'hi world'
 
@@ -93,8 +110,8 @@ def _ReadFdt(fname):
     """
     return libfdt.Fdt(open(fname).read())
 
-class PyLibfdtTests(unittest.TestCase):
-    """Test class for pylibfdt
+class PyLibfdtBasicTests(unittest.TestCase):
+    """Test class for basic pylibfdt access functions
 
     Properties:
         fdt: Device tree file used for testing
@@ -458,5 +475,73 @@ class PyLibfdtTests(unittest.TestCase):
         self.assertEquals('test', self.fdt.get_name(node))
 
 
+class PyLibfdtSwTests(unittest.TestCase):
+    """Test class for pylibfdt sequential-write DT creation
+    """
+    def assertOk(self, err_code):
+        self.assertEquals(0, err_code)
+
+    def testCreate(self):
+        # First check the minimum size and also the Fdt() constructor
+        with self.assertRaisesRegexp(FdtException, get_err(libfdt.NOSPACE)):
+            self.assertEquals(-libfdt.NOSPACE, FdtSw(3))
+        _= FdtSw(small_size)
+
+        # Now use the context-manager version
+        with FdtSw(small_size) as sw:
+            sw.add_reservemap_entry(TEST_ADDR_1, TEST_SIZE_1)
+            sw.add_reservemap_entry(TEST_ADDR_2, TEST_SIZE_2)
+            sw.finish_reservemap()
+
+            sw.begin_node('')
+            sw.property_string('compatible', 'test_tree1')
+            with self.assertRaisesRegexp(FdtException, get_err(libfdt.NOSPACE)):
+                sw.property_u32('prop-int', TEST_VALUE_1)
+
+            # Check we can resize to its current size. Then make it bigger.
+            sw.resize(small_size)
+            sw.resize(full_size)
+            sw.property_u32('prop-int', TEST_VALUE_1)
+            sw.property_u64('prop-int64', TEST_VALUE64_1)
+            sw.property_string('prop-str', TEST_STRING_1)
+            sw.property_u32('#address-cells', 1)
+            sw.property_u32('#size-cells', 0)
+
+            # Now that it is bigger we can't shrink it back
+            with self.assertRaisesRegexp(FdtException, get_err(libfdt.NOSPACE)):
+                sw.resize(small_size)
+
+            sw.begin_node('subnode@1')
+            sw.property_string('compatible', 'subnode1')
+            sw.property_u32('reg', 1)
+            sw.property_cell('prop-int', TEST_VALUE_1)
+            sw.begin_node('subsubnode')
+            sw.property('compatible', 'subsubnode1\0subsubnode')
+            sw.property_cell('prop-int', TEST_VALUE_1)
+            sw.end_node()
+            sw.begin_node('ss1')
+            sw.end_node()
+            sw.end_node()
+
+            with sw.AddNode('subnode@2'):
+                sw.property_u32('reg', 2)
+                sw.property_cell('linux,phandle', PHANDLE_1)
+                sw.property_cell('prop-int', TEST_VALUE_2)
+                sw.property_u32('#address-cells', 1)
+                sw.property_u32('#size-cells', 0)
+                with sw.AddNode('subsubnode@0'):
+                    sw.property_u32('reg', 0)
+                    sw.property_cell('phandle', PHANDLE_2)
+                    sw.property('compatible', 'subsubnode2\0subsubnode')
+                    sw.property_cell('prop-int', TEST_VALUE_2)
+                with sw.AddNode('ss2'):
+                    pass
+            sw.end_node()
+
+        fdt = sw.AsFdt()
+        self.assertEqual(2, fdt.num_mem_rsv())
+        self.assertEqual([TEST_ADDR_1, TEST_SIZE_1], fdt.get_mem_rsv(0))
+
+
 if __name__ == "__main__":
     unittest.main()
-- 
2.17.0.441.gb46fe60e1d-goog

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