Add support for lopper to generate partial dts

Currently ImageBuilder can compile and merge partial dts obtained from
a repository specified using PASSTHROUGH_DTS_REPO. With the recent
changes done in the lopper, we can use it to generate partial dts
automatically (to some extent as this is still an early support).

Introduce LOPPER_PATH option to specify a path to a lopper.py script,
the main script in the Lopper repository, that if set, will invoke lopper
to generate partial dts for the passthrough devices specified in
DOMU_PASSTHROUGH_PATHS.

Introduce LOPPER_CMD option to specify custom command line arguments
(if needed) for lopper's extract assist.

Example usage:
LOPPER_PATH="/home/user/lopper/lopper.py"
DOMU_PASSTHROUGH_PATHS[0]="/axi/spi@ff0f0000 /axi/serial@ff010000"

Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

3 files changed, 100 insertions, 22 deletions

diff --git a/README.md b/README.md
index da9ba78..f4213d5 100644
--- a/README.md
+++ b/README.md
@@ -128,6 +128,20 @@ Where:
 - DT_OVERLAY[number] specifies the path to the hosts device tree overlays
   to be added at boot time in u-boot
 
+- LOPPER_PATH specifies the path to lopper.py script, the main script in the
+  Lopper repository (https://github.com/devicetree-org/lopper). This is
+  optional. However, if this is specified, then DOMU_PASSTHROUGH_PATHS[number]
+  needs to be specified. uboot-script-gen will invoke lopper to generate the
+  partial device trees for devices which have been listed in
+  DOMU_PASSTHROUGH_PATHS[number]. This option is currently in experimental state
+  as the corresponding lopper changes are still in an early support state.
+
+- LOPPER_CMD specifies the command line arguments for lopper's extract assist.
+  This is optional and only applicable when LOPPER_PATH is specified. Only to be
+  used to specify which nodes to include (using -i <node_name>) and which
+  nodes/properties to exclude (using -x <regex>). If not set at all, the default
+  one is used applicable for ZynqMP MPSoC boards.
+
 - NUM_DOMUS specifies how many Dom0-less DomUs to load
 
 - DOMU_KERNEL[number] specifies the DomU kernel to use.
@@ -140,7 +154,7 @@ Where:
 - DOMU_PASSTHROUGH_PATHS[number] specifies the passthrough devices (
   separated by spaces). It adds "xen,passthrough" to the corresponding
   dtb nodes in xen device tree blob.
-  This option is valid in the following two cases:
+  This option is valid in the following cases:
 
   1. When PASSTHROUGH_DTS_REPO is provided.
   With this option, the partial device trees (corresponding to the
@@ -149,7 +163,12 @@ Where:
   Note it assumes that the names of the partial device trees will match
   to the names of the devices specified here.
 
-  2. When DOMU_NOBOOT[number] is provided. In this case, it will only
+  2. When LOPPER_PATH is provided.
+  With this option, the partial device trees (corresponding to the
+  passthrough devices) are generated by the lopper and then compiled and merged
+  by ImageBuilder to be used as DOMU[number] device tree blob.
+
+  3. When DOMU_NOBOOT[number] is provided. In this case, it will only
   add "xen,passthrough" as mentioned before.
 
 - DOMU_PASSTHROUGH_DTB[number] specifies the passthrough device trees
diff --git a/scripts/common b/scripts/common
index ccad03d..2dd98fb 100644
--- a/scripts/common
+++ b/scripts/common
@@ -9,6 +9,9 @@
 # - NUM_DOMUS
 # - DOMU_PASSTHROUGH_PATHS
 # - DOMU_PASSTHROUGH_DTB
+# - LOPPER_PATH
+# - LOPPER_CMD
+# - DEVICE_TREE
 
 tmp_files=()
 tmp_dirs=()
@@ -99,31 +102,41 @@ function compile_merge_partial_dts()
     local tmp
     local tmpdts
     local file
+    local node
     local i
     local j
 
-    if [[ "$repo" =~ .*@.*:.* ]]
+    if test "$repo"
     then
-        tmp=`mktemp -d`
-        tmp_dirs+=($tmp)
-
-        echo "Cloning git repo \"$git_repo\""
-        git clone "$repo" $tmp
-        if test $? -ne 0
+        # Partial dts will be obtained from PASSTHROUGH_DTS_REPO
+        if [[ "$repo" =~ .*@.*:.* ]]
         then
-            echo "Error occurred while cloning \"$git_repo\""
-            return 1
-        fi
+            tmp=`mktemp -d`
+            tmp_dirs+=($tmp)
 
-        repo=$tmp
-    fi
+            echo "Cloning git repo \"$git_repo\""
+            git clone "$repo" $tmp
+            if test $? -ne 0
+            then
+                echo "Error occurred while cloning \"$git_repo\""
+                return 1
+            fi
 
-    if test -z "$dir"
-    then
-        dir="."
+            repo=$tmp
+        fi
+
+        if test -z "$dir"
+        then
+            dir="."
+        fi
+        partial_dts_dir="$repo"/"$dir"
+    else
+        # Partial dts will be generated by the lopper
+        tmp=`mktemp -d`
+        tmp_dirs+=($tmp)
+        partial_dts_dir="$tmp"
     fi
 
-    partial_dts_dir="$repo"/"$dir"
     i=0
     while test $i -lt $NUM_DOMUS
     do
@@ -133,6 +146,34 @@ function compile_merge_partial_dts()
             return 1
         fi
 
+        if test -z "$repo"
+        then
+            # Generate partial dts using lopper
+            for devpath in ${DOMU_PASSTHROUGH_PATHS[$i]}
+            do
+                node=${devpath##*/}
+                file="$partial_dts_dir"/"$node".dts
+
+                # Execute lopper with the following assists:
+                # - extract: used to take the target node, extract it from the
+                #   system device tree, chase the phandle references and place
+                #   it in a new extracted tree structure,
+                # - extract-xen: used to perform Xen specific modifications
+                #   on the extracted tree structure e.g. adding "xen,path",
+                #   "xen,reg", interrupt-parent properties.
+                # For additional information, please see the lopper's README
+                # file as well as usage of the mentioned assists.
+                $LOPPER_PATH --permissive -f $DEVICE_TREE \
+                -- extract -t $devpath $LOPPER_CMD \
+                -- extract-xen -t $node -o $file
+
+                if test $? -ne 0
+                then
+                    return 1
+                fi
+            done
+        fi
+
         sanity_check_partial_dts "${DOMU_PASSTHROUGH_PATHS[$i]}" "$partial_dts_dir"
         if test $? -ne 0
         then
@@ -146,8 +187,8 @@ function compile_merge_partial_dts()
 
         for devpath in ${DOMU_PASSTHROUGH_PATHS[$i]}
         do
-            file=${devpath##*/}
-            file="$partial_dts_dir"/"$file".dts
+            node=${devpath##*/}
+            file="$partial_dts_dir"/"$node".dts
 
             # All the subsequent dts files should not have dts version mentioned
             if test $j -gt 1
diff --git a/scripts/uboot-script-gen b/scripts/uboot-script-gen
index 02f3309..a5b4972 100755
--- a/scripts/uboot-script-gen
+++ b/scripts/uboot-script-gen
@@ -1135,10 +1135,28 @@ fi
 # tftp or move the files to a partition
 cd "$uboot_dir"
 
-if test "$PASSTHROUGH_DTS_REPO"
+# If both PASSTHROUGH_DTS_REPO and LOPPER_PATH options are specified,
+# the former takes precedence because the partial device trees are already
+# created (probably tested), hence the reliability is higher than using lopper.
+if test "$PASSTHROUGH_DTS_REPO" || test "$LOPPER_PATH"
 then
     output_dir=`mktemp -d "partial-dtbs-XXX"`
-    compile_merge_partial_dts $output_dir "$PASSTHROUGH_DTS_REPO"
+    if test "$PASSTHROUGH_DTS_REPO"
+    then
+        compile_merge_partial_dts $output_dir "$PASSTHROUGH_DTS_REPO"
+    else
+        if test -z "$LOPPER_CMD"
+        then
+            # Default for ZynqMP MPSoC.
+            # The following command instructs lopper's extract assist to always
+            # include zynqmp-firmware node (as it contains e.g. clock-controller
+            # required by most of the devices) in the extracted tree structure
+            # and to drop nodes/properties during the extraction process that
+            # are not needed.
+            LOPPER_CMD="-i zynqmp-firmware -x interrupt-controller -x pinctrl -x power-domains -x resets -x current-speed"
+        fi
+        compile_merge_partial_dts $output_dir
+    fi
     if test $? -ne 0
     then
         # Remove the output dir holding the partial dtbs in case of any error