[PATCH 1/2] of: Introduce __of_phandle_update_cache

[Dawei Li <dawei.li@shingroup.cn>]

For system with CONFIG_OF_DYNAMIC=y, device nodes can be inserted/removed
dynamically from device tree. Meanwhile phandle_cache is created for fast
lookup from phandle to device node.

For node detach, phandle cache of removed node is invalidated to maintain
the mapping up to date, but the counterpart operation on node attach is
not implemented yet.

Thus, implement the cache updating operation on node attach.

Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
---
 drivers/of/base.c       | 16 ++++++++++++++++
 drivers/of/of_private.h |  1 +
 2 files changed, 17 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index b0ad8fc06e80..8b7da27835eb 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -163,6 +163,22 @@ void __of_phandle_cache_inv_entry(phandle handle)
 		phandle_cache[handle_hash] = NULL;
 }
 
+void __of_phandle_update_cache(struct device_node *np, bool lock)
+{
+	u32 hash;
+
+	if (lock)
+		lockdep_assert_held(&devtree_lock);
+
+	if (unlikely(!np || !np->phandle))
+		return;
+
+	hash = of_phandle_cache_hash(np->phandle);
+
+	if (!phandle_cache[hash])
+		phandle_cache[hash] = np;
+}
+
 void __init of_core_init(void)
 {
 	struct device_node *np;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index f38397c7b582..89559aad8ccb 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -94,6 +94,7 @@ int of_resolve_phandles(struct device_node *tree);
 #endif
 
 void __of_phandle_cache_inv_entry(phandle handle);
+void __of_phandle_update_cache(struct device_node *np, bool lock);
 
 #if defined(CONFIG_OF_OVERLAY)
 void of_overlay_mutex_lock(void);
-- 
2.27.0