gen_domain: assign conventional Zephyr TTC label

Zephyr's ZynqMP and Versal R5 timer configuration refers to the ttc0
nodelabel, while an SDT domain can retain a differently labeled TTC or
more than one TTC. Normalize the domain-local result instead of making
Zephyr select an arbitrary compatible instance.

Preserve an explicitly mapped ttc0 and otherwise promote the first TTC
retained by domain access. Accept both cdns,ttc and xlnx,ttcps inputs,
update the symbols node, and cover single, multiple, compatible, and
non-R5 cases.

Signed-off-by: Ben Levinsky <ben.levinsky@amd.com>

Author: bentheredonethat

lopper/assists/gen_domain_dts.py

@@ -27,6 +27,39 @@
 from openamp_xlnx import xlnx_openamp_keep_node
 
 
+def _xlnx_zephyr_assign_ttc0(tree, machine):
+    """Give the Zephyr-selected ZynqMP/Versal R5 TTC a stable label.
+
+    Domain access has already removed devices that are not assigned to the
+    target. Preserve an explicit ``ttc0`` selection. If none exists, promote
+    the first TTC retained for this domain so Zephyr has its conventional
+    timer label.
+    """
+    if not ("psu_cortexr5" in machine or "psv_cortexr5" in machine):
+        return
+
+    ttc_compatibles = {"cdns,ttc", "xlnx,ttcps"}
+    ttc_nodes = []
+    for node in tree.nodes('.*'):
+        compatibles = set(node.propval("compatible", list))
+        if compatibles & ttc_compatibles:
+            ttc_nodes.append(node)
+
+    if any(node.label == "ttc0" for node in ttc_nodes):
+        return
+    if not ttc_nodes:
+        return
+
+    ttc = ttc_nodes[0]
+    ttc.label_set("ttc0")
+    try:
+        symbols = tree["/__symbols__"]
+    except KeyError:
+        symbols = LopperNode(-1, "/__symbols__")
+        tree + symbols
+    symbols["ttc0"] = ttc.abs_path
+
+
 def xlnx_zephyr_fixup_rpu_memory_names(tree, machine, memory_nodes):
     """Match R5/R52 Zephyr memory unit addresses to their local reg view."""
     if not ("cortexr5" in machine or "cortexr52" in machine):
@@ -801,6 +834,7 @@ def xlnx_generate_domain_dts(tgt_node, sdt, options):
     if zephyr_dt:
         if "r52" in machine or "a78" in machine or "a72" in machine or "r5" in machine or "a53" in machine:
             xlnx_generate_zephyr_domain_dts_arm(tgt_node, sdt, options, machine)
+            _xlnx_zephyr_assign_ttc0(sdt.tree, machine)
             if "a78" in machine or "a72" in machine:
                 new_dst_node = LopperNode()
                 new_dst_node['compatible'] = "arm,psci-1.1"

tests/test_xlnx_gen_domain.py

@@ -21,6 +21,69 @@
 from lopper.tree import LopperNode, LopperTree
 
 
+def _ttc_tree(*labels, compatible="xlnx,ttcps"):
+    """Create a minimal tree containing TTC nodes with optional labels."""
+    tree = LopperTree()
+    tree + LopperNode(-1, "/__symbols__")
+    nodes = []
+    for index, label in enumerate(labels):
+        node = LopperNode(-1, f"/axi/timer@ff1{index}0000")
+        node["compatible"] = [compatible]
+        if label:
+            node.label = label
+        tree + node
+        nodes.append(node)
+    return tree, nodes
+
+
+def test_zephyr_r5_labels_sole_selected_ttc_as_ttc0():
+    """A sole domain-selected TTC gets Zephyr's stable ttc0 label."""
+    tree, nodes = _ttc_tree("ttc2")
+
+    gen_domain_dts._xlnx_zephyr_assign_ttc0(tree, "psu_cortexr5_0")
+
+    assert nodes[0].label == "ttc0"
+    assert tree["/__symbols__"].propval("ttc0", list) == [nodes[0].abs_path]
+
+
+def test_zephyr_r5_preserves_explicit_ttc0_with_multiple_ttcs():
+    """An explicitly selected ttc0 wins without relying on tree order."""
+    tree, nodes = _ttc_tree("ttc1", "ttc0")
+
+    gen_domain_dts._xlnx_zephyr_assign_ttc0(tree, "psv_cortexr5_0")
+
+    assert [node.label for node in nodes] == ["ttc1", "ttc0"]
+
+
+def test_zephyr_r5_labels_first_domain_ttc_when_no_ttc0_exists():
+    """The first domain-retained TTC becomes ttc0 when none is explicit."""
+    tree, _ = _ttc_tree("ttc1", "ttc2")
+
+    gen_domain_dts._xlnx_zephyr_assign_ttc0(tree, "psu_cortexr5_0")
+
+    assert tree["/axi/timer@ff100000"].label == "ttc0"
+    assert tree["/axi/timer@ff110000"].label == "ttc2"
+
+
+def test_zephyr_r5_accepts_sdt_cdns_ttc_compatible():
+    """ZynqMP's SDT-side cdns,ttc node participates in label selection."""
+    tree, nodes = _ttc_tree("ttc1", compatible="cdns,ttc")
+
+    gen_domain_dts._xlnx_zephyr_assign_ttc0(tree, "psu_cortexr5_0")
+
+    assert nodes[0].label == "ttc0"
+
+
+def test_ttc_label_normalization_is_r5_platform_specific():
+    """Other Zephyr processor families retain their original TTC labels."""
+    tree, nodes = _ttc_tree("ttc2")
+
+    gen_domain_dts._xlnx_zephyr_assign_ttc0(tree, "cortexr52_0")
+
+    assert nodes[0].label == "ttc2"
+    assert tree["/__symbols__"].propval("ttc0") == ['']
+
+
 def test_rpu_memory_rename_refreshes_path_and_phandle_references():
     """RPU local-view renames preserve chosen, symbol, and phandle refs."""
     tree = LopperTree()