[OE-core][PATCH v4 2/3] classes: Add a new bbclass that abstracts the generation of FIT blobs

["Nandor Han" <nandor.han@vaisala.com>]

FIT format is very versatile allowing various combination of booting
sequences. In the same time different U-Boot boot stages can use FIT
blobs to pack various binaries (e.g. SPL supports reading U-Boot from a
FIT blob). Because of the allowed level of customization, the generation
of a FIT blob using a fixed image tree source, becomes challenging and
increase the level of complexity where different configurations and
combinations are needed.

This bbclass will know how to generate a FIT blob, leaving the mechanics
of the process (dependencies, task order...) to be handled by the users
of the bbclass. In the same time will allow to separate the knowledge of
the FIT format leaving the user code cleaner and more readable.

Signed-off-by: Nandor Han <nandor.han@vaisala.com>
---
 meta/classes/fit_image.bbclass | 387 +++++++++++++++++++++++++++++++++
 1 file changed, 387 insertions(+)
 create mode 100644 meta/classes/fit_image.bbclass

diff --git a/meta/classes/fit_image.bbclass b/meta/classes/fit_image.bbclass
new file mode 100644
index 0000000000..2d1451020c
--- /dev/null
+++ b/meta/classes/fit_image.bbclass
@@ -0,0 +1,387 @@
+#
+# The class will facilitate the generation of FIT blobs.
+#
+# Glossary
+#    FIT - Flattened uImage Tree
+#
+# Requirements:
+#
+#    * The user need to specify the image content using the format specified in the "FIT Image API" section.
+#
+# FIT Image API
+#
+# The bbclass is using variable and variable flags to declare the FIT image content.
+#
+#    * Sub-Images and Configuration Nodes
+#
+#       ** A sub-image node content is declared using the format `VAR_NODE[<property-name>] = <value>`.
+#         * VAR_NODE - freely selected name of the variable representing a node.
+#         * <property-name> - a sub-image property (e.g. description, type...).
+#         * <value> - the property value.
+#             Depending of the property the value can support different formats.
+#           ** Property Values Formats
+#
+#            string property
+#            ---------------
+#            format: "<text>" - in case the property expects a text.
+#                (e.g. IMAGE_NODE_KERNEL[type] = "kernel")
+#
+#            address property
+#            ----------------
+#            format: "<address>" - in case the property expects an address.
+#                (e.g. IMAGE_NODE_KERNEL[entry] = "0xABCDABCD")
+#
+#            hash property
+#            -------------
+#            format: "<hash type>" - for hash property the hash type needs to be specified.
+#                (e.g. IMAGE_NODE_KERNEL[hash] = "sha256")
+#
+#            sub-image signature property
+#            ----------------------------
+#            format: "<algo>;<key-name-hint>;" - for image signature node.
+#                Both algorithm and key name needs to be provided.
+#                (e.g. IMAGE_NODE_KERNEL[signature] = "sha256,rsa2048;kernel;"
+#
+#            configuration signature property
+#            --------------------------------
+#            format: "<algo>;<key-name-hint>;<sub-image list>" - for configuration signature properties algorithm,
+#                key name and sub-image nodes needs to be provided.
+#                (e.g. CONF_NODE_CONF1[signature] = "sha256,rsa2048;kernel;"kernel","fdt";")
+#
+#       ** Sub-Image and Configuration Nodes Flags
+#              See the code for supported flags.
+#
+#    * FIT_IMAGES_NODE - contains a list of variables used to declare the sub-images nodes, separated by space.
+#                    (e.g. FIT_IMAGES_NODE = "IMAGE_NODE_KERNEL IMAGE_NODE_FDT")
+#
+#    * FIT_CONFIGURATIONS_NODE - contains a list of variables used to declare the configuration nodes,
+#          separated by space. (e.g. FIT_CONFIGURATIONS_NODE = "CONF_NODE_CONF1")
+#        ** Flags
+#           - "default": used to configure the default configuration node.
+#                 (e.g. FIT_CONFIGURATIONS_NODE[default] = "conf@0")
+#
+# Example:
+# This is part of a linux_%.bbappend recipe.
+#
+# KERNEL_IMAGE_NODE[name] = "kernel"
+# KERNEL_IMAGE_NODE[description] = "${PF}"
+# KERNEL_IMAGE_NODE[data] = '/incbin/("./arch/${ARCH}/boot/zImage")'
+# KERNEL_IMAGE_NODE[type] = "kernel"
+# KERNEL_IMAGE_NODE[arch] = "${ARCH}"
+# KERNEL_IMAGE_NODE[os] = "linux"
+# KERNEL_IMAGE_NODE[compression] = "none"
+# KERNEL_IMAGE_NODE[load] = "${UBOOT_LOADADDRESS}"
+# KERNEL_IMAGE_NODE[entry] = "${UBOOT_ENTRYPOINT}"
+# KERNEL_IMAGE_NODE[hash] = "sha256"
+#
+# FDT_IMAGE_NODE[name] = "fdt"
+# FDT_IMAGE_NODE[description] = "FDT blob"
+# FDT_IMAGE_NODE[data] = '/incbin/("./arch/${ARCH}/boot/dts/am335x-bone.dtb")'
+# FDT_IMAGE_NODE[type] = "flat_dt"
+# FDT_IMAGE_NODE[arch] = "${ARCH}"
+# FDT_IMAGE_NODE[compression] = "none"
+# FDT_IMAGE_NODE[hash] = "sha256"
+#
+# CONF1_CONF_NODE[name] = "conf"
+# CONF1_CONF_NODE[description] = "Linux kernel and FDT blob"
+# CONF1_CONF_NODE[kernel] = "kernel"
+# CONF1_CONF_NODE[fdt] = "fdt"
+#
+# FIT_IMAGES_NODE = "KERNEL_IMAGE_NODE FDT_IMAGE_NODE"
+# FIT_CONFIGURATIONS_NODE = "CONF1_CONF_NODE"
+# FIT_CONFIGURATIONS_NODE[default] = "${@d.getVarFlag('CONF1_CONF_NODE', 'name') or ""}"
+#
+
+DEPENDS += "\
+    dtc-native \
+    u-boot-mkimage-native \
+"
+
+FIT_IMAGE_DESCRIPTION ??= "Generic FIT image"
+FIT_IMAGE_FILENAME ??= "image-fit"
+FIT_IMAGE_UBOOT_MKIMAGE_OPTS ??= ""
+
+def get_subimage_node_rules():
+    """
+    Defines the properties format and validation for sub-image nodes.
+
+    :return: Return a dictionary with the format rules.
+    """
+
+    #
+    # Rules Format: [Mandatory, Template String, Dictionary keys]
+    # Mandatory: True, False - used to verify if this property is mandatory for generating the image.
+    #            Note: Doesn't take in consideration the conditionally mandatory property.
+    #                  (see: U-Boot/doc/uImage.FIT/source_file_format.txt)
+    # Template String: Property content format. Used to generate the parameter content.
+    # Dictionary Keys: Keys used to be replaced in the Template String.
+    #
+    from collections import OrderedDict
+
+    rules = OrderedDict()
+
+    rules['description'] = [True, '= "$value"', ["value"]]
+    rules['data'] = [True, '= $value', ["value"]]
+    rules['type'] = [True, '= "$value"', ["value"]]
+    rules['arch'] = [False, '= "$value"', ["value"]]
+    rules['os'] = [False, '= "$value"', ["value"]]
+    rules['compression'] = [True, '= "$value"', ["value"]]
+    rules['load'] = [False, '= <$value>', ["value"]]
+    rules['entry'] = [False, '= <$value>', ["value"]]
+    rules['hash'] = [False, '{ algo = "$algo"; }', ['algo']]
+    rules['signature'] = [False, '{ algo = "$algo"; key-name-hint = "$key"; }', ['algo', 'key']]
+
+    return rules
+
+
+def get_conf_node_rules():
+    """
+    Defines the properties format and validation for configuration nodes.
+
+    :return: Return a dictionary with the format rules.
+    """
+    #
+    # Rules Format: [Mandatory, Template String, Dictionary keys]
+    # Mandatory: True, False - used to verify if this property is mandatory for generating the image.
+    #            Note: Doesn't take in consideration the conditionally mandatory property.
+    #                  (see: U-Boot/doc/uImage.FIT/source_file_format.txt)
+    # Template String: Property content format. Used to generate the parameter content.
+    # Dictionary Keys: Keys used to be replaced in the Template String.
+    #
+    from collections import OrderedDict
+
+    rules = OrderedDict()
+
+    rules['description'] = [True, '= "$value"', ["value"]]
+    rules['kernel'] = [False, '= "$value"', ["value"]]
+    rules['ramdisk'] = [False, '= "$value"', ["value"]]
+    rules['firmware'] = [False, '= "$value"', ["value"]]
+    rules['standalone'] = [False, '= "$value"', ["value"]]
+    rules['fdt'] = [False, '= "$value"', ["value"]]
+    rules['loadables'] = [False, '= "$value"', ["value"]]
+    rules['signature'] = [False, '{ algo = "$algo"; key-name-hint = "$key"; sign-images = $images; }',
+                          ['algo', 'key', 'images']]
+
+    return rules
+
+
+def generate_node(name, params, rules):
+    """
+    Generates a node.
+
+    :param name: Node name.
+    :param params: A dictionary containing the properties values.
+    :param rules: A dictionary containing the properties values validation and format.
+
+    :return: A string containing the node, including the new line characters.
+    """
+    from string import Template
+
+    content = []
+
+    for rule in rules.keys():
+        if rule in params.keys():
+            content.append('{param} {value}; '.format(
+                param=rule,
+                value=Template(rules[rule][1]).substitute(
+                    dict(zip(rules[rule][2], params[rule].split(';'))))))
+        elif rules[rule][0]:
+            bb.fatal('Missing mandatory parameter "{param}" from "{section}" section'.format(param=rule, section=name))
+
+    content = """
+                     """.join(content)
+    node = """   {name} {{
+                     {content}
+              }};
+           """.format(name=name, content=content)
+
+    return node
+
+
+def get_section_configuration(var, d):
+    """
+    Generates a string build from variable's flags.
+
+    :param var: variable to extract the flags.
+    :param d: bitbake environment.
+
+    :return: A string with the format '<flag1> = <value1>; <flag2> = <value2>;...'.
+    """
+    flags = d.getVarFlags(var)
+    if flags is not None:
+        flags = dict((flag, d.expand(value))
+                     for flag, value in list(flags.items()))
+    else:
+        flags = {}
+
+    configuration = ''.join((
+              """{name} = "{value}";
+              """.format(name=name, value=value) for name, value in flags.items()))
+
+    return configuration
+
+
+def get_section_properties(var, d):
+    """
+    Extract the nodes and parameters for a section.
+
+    :param var: variable containing the variable names of the nodes that are part of this section.
+    :param d: bitbake environment.
+
+    :return: a list containing dictionaries with section nodes parameters.
+    """
+    nodes = []
+    parameters = {}
+
+    for node in d.getVar(var).split():
+        parameters = d.getVarFlags(node)
+        if parameters is not None:
+            parameters = dict((parameter, d.expand(value))
+                              for parameter, value in list(parameters.items()))
+            nodes.append(parameters)
+
+    return nodes
+
+
+def generate_section(var, rules, d):
+    """
+    Generates a section node (configuration or sub-image).
+
+    :param var: Variable to extract the node names.
+    :param rules: Rules to use for generating this section.
+    :param d: bitbake environment.
+
+    :return: A string containing the section, including the new line characters.
+    """
+
+    section = get_section_configuration(var, d)
+
+    nodes_parameters = get_section_properties(var, d)
+    for parameters in nodes_parameters:
+        try:
+            name = parameters.pop('name')
+            node = generate_node(name, parameters, rules)
+            section += node
+        except KeyError:
+            bb.fatal("Missing name property for node: {node}".format(node=var))
+
+    return section
+
+
+def get_fit_image_template():
+    """
+    Get the FIT format.
+
+    :return: A Template string containing the FIT image format.
+    """
+    from string import Template
+
+    template = Template("""/dts-v1/;
+        /{
+             description = "$description";
+             #address-cells = <1>;
+             images {
+                 $images_section
+             };
+             configurations {
+                 $configurations_section
+             };
+        };""")
+    return template
+
+
+def generate_image_tree_source(d):
+    """
+    Generates a string containing the image tree source.
+
+    :return: A string representing the image tree.
+    """
+    from string import Template
+
+    values = {}
+    values['description'] = d.getVar('FIT_IMAGE_DESCRIPTION')
+
+    image_rules = get_subimage_node_rules()
+    if d.getVar('FIT_IMAGES_NODE', False) is None:
+       bb.fatal("Please add the FIT image nodes to FIT_IMAGES_NODE variable.")
+    values['images_section'] = generate_section('FIT_IMAGES_NODE', image_rules, d)
+
+    conf_rules = get_conf_node_rules()
+    if d.getVar('FIT_CONFIGURATIONS_NODE', False) is None:
+       bb.fatal("Please add the FIT configuration nodes to FIT_CONFIGURATIONS_NODE variable.")
+    values['configurations_section'] = generate_section('FIT_CONFIGURATIONS_NODE', conf_rules, d)
+
+    image_tree_source = get_fit_image_template().substitute(values)
+
+    return image_tree_source
+
+
+def generate_image_blob(file_name, image, d):
+    """
+    Generates a FIT blob.
+
+    :param file_name: FIT blob file name.
+    :param image: String containing the image tree source.
+    :param d: Bitbake environment.
+    """
+    import tempfile
+    import subprocess
+
+    bb.debug(1, "Generated FIT source is:\n {image}".format(image=image))
+
+    builddir = d.getVar('B')
+    blob_file_name = file_name + '.itb'
+
+    try:
+        fd, faux = tempfile.mkstemp(dir=builddir, prefix=file_name, suffix=".its")
+        with os.fdopen(fd, "w") as f:
+            f.write(image)
+
+        mkimage_opts = d.getVar('FIT_IMAGE_UBOOT_MKIMAGE_OPTS').split() or ""
+        cmd = ['mkimage', '-f', faux]
+        cmd.extend(mkimage_opts)
+        cmd.append('{output_name}'.format(output_name=blob_file_name))
+
+        ret = subprocess.run(
+            cmd,
+            check=True,
+            universal_newlines=True,
+            cwd=builddir,
+            stderr=subprocess.STDOUT,
+            stdout=subprocess.PIPE)
+
+        bb.debug(1, "Command for generating the FIT blob is:\n {cmd}".format(cmd=" ".join(ret.args)))
+
+    except subprocess.CalledProcessError as e:
+        bb.fatal('Failed to generate the FIT blob: {message}: {output}'.format(
+            message=str(e), output=e.stdout))
+    finally:
+        os.remove(faux)
+
+
+def generate_fit_image(file_name, d):
+    """
+    Create and generate FIT blob.
+
+    :param file_name: FIT blob file name.
+    :param d: Bitbake environment.
+    """
+    image = generate_image_tree_source(d)
+    generate_image_blob(file_name, image, d)
+
+
+python fit_image_do_generate_fit_image() {
+    generate_fit_image(d.getVar('FIT_IMAGE_FILENAME'), d)
+}
+
+do_generate_fit_image[vardeps] += " \
+    ${FIT_CONFIGURATIONS_NODE} \
+    ${FIT_IMAGES_NODE} \
+    FIT_CONFIGURATIONS_NODE \
+    FIT_IMAGES_NODE \
+    FIT_IMAGE_FILENAME \
+"
+
+addtask do_generate_fit_image after do_compile before do_deploy
+
+EXPORT_FUNCTIONS do_generate_fit_image
-- 
2.24.1