[PATCH 2/3] of: Support hashtable lookups for phandles

[Pantelis Antoniou]

Signed-off-by: Pantelis Antoniou <pantelis.anton...@konsulko.com>
---
 drivers/of/base.c       | 35 ++++++++++++++++++++++++++++++++---
 drivers/of/dynamic.c    |  8 ++++++++
 drivers/of/of_private.h | 31 +++++++++++++++++++++++++++++++
 include/linux/of.h      |  2 ++
 4 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 20bbc2f..770cb95 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -27,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/proc_fs.h>
+#include <linux/rhashtable.h>
 
 #include "of_private.h"
 
@@ -41,6 +42,16 @@ static const char *of_stdout_options;
 
 struct kset *of_kset;
 
+const struct rhashtable_params of_phandle_ht_params = {
+       .key_offset = offsetof(struct device_node, phandle), /* base offset */
+       .key_len = sizeof(phandle),
+       .head_offset = offsetof(struct device_node, ht_node),
+       .automatic_shrinking = true,
+};
+
+struct rhashtable of_phandle_ht;
+bool of_phandle_ht_initialized;
+
 /*
  * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
  * This mutex must be held whenever modifications are being made to the
@@ -162,6 +173,12 @@ int __of_attach_node_post(struct device_node *np)
        struct property *pp;
        int rc;
 
+       if (of_phandle_ht_available()) {
+               rc = of_phandle_ht_insert(np);
+               WARN(rc, "insert to phandle hash fail @%s\n",
+                               of_node_full_name(np));
+       }
+
        if (!IS_ENABLED(CONFIG_SYSFS))
                return 0;
 
@@ -194,6 +211,13 @@ void __init of_core_init(void)
        struct device_node *np;
        int ret;
 
+       ret = rhashtable_init(&of_phandle_ht, &of_phandle_ht_params);
+       if (ret) {
+               pr_warn("devicetree: Failed to initialize hashtable\n");
+               return;
+       }
+       of_phandle_ht_initialized = 1;
+
        /* Create the kset, and register existing nodes */
        mutex_lock(&of_mutex);
        of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
@@ -1073,9 +1097,14 @@ struct device_node *of_find_node_by_phandle(phandle 
handle)
                return NULL;
 
        raw_spin_lock_irqsave(&devtree_lock, flags);
-       for_each_of_allnodes(np)
-               if (np->phandle == handle)
-                       break;
+       /* when we're ready use the hash table */
+       if (of_phandle_ht_available() && !in_interrupt())
+               np = of_phandle_ht_lookup(handle);
+       else { /* fallback */
+               for_each_of_allnodes(np)
+                       if (np->phandle == handle)
+                               break;
+       }
        of_node_get(np);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index eb31a55..bdebdf5 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/proc_fs.h>
+#include <linux/rhashtable.h>
 
 #include "of_private.h"
 
@@ -44,6 +45,13 @@ EXPORT_SYMBOL(of_node_put);
 void __of_detach_node_post(struct device_node *np)
 {
        struct property *pp;
+       int rc;
+
+       if (of_phandle_ht_available()) {
+               rc = of_phandle_ht_remove(np);
+               WARN(rc, "remove from phandle hash fail @%s\n",
+                               of_node_full_name(np));
+       }
 
        if (!IS_ENABLED(CONFIG_SYSFS))
                return;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 10b0342..88b3b8f 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -101,4 +101,35 @@ static inline int of_overlay_init(void)
 }
 #endif
 
+extern const struct rhashtable_params of_phandle_ht_params;
+extern struct rhashtable of_phandle_ht;
+extern bool of_phandle_ht_initialized;
+
+static inline bool of_phandle_ht_available(void)
+{
+       return of_phandle_ht_initialized;
+}
+
+static inline int of_phandle_ht_insert(struct device_node *np)
+{
+       if (!np || !np->phandle)
+               return 0;
+       return rhashtable_insert_fast(&of_phandle_ht,
+               &np->ht_node, of_phandle_ht_params);
+}
+
+static inline int of_phandle_ht_remove(struct device_node *np)
+{
+       if (!np || !np->phandle)
+               return 0;
+       return rhashtable_remove_fast(&of_phandle_ht,
+               &np->ht_node, of_phandle_ht_params);
+}
+
+static inline struct device_node *of_phandle_ht_lookup(phandle handle)
+{
+       return rhashtable_lookup_fast(&of_phandle_ht,
+                       &handle, of_phandle_ht_params);
+}
+
 #endif /* _LINUX_OF_PRIVATE_H */
diff --git a/include/linux/of.h b/include/linux/of.h
index 582bc45..56bb62d 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -25,6 +25,7 @@
 #include <linux/notifier.h>
 #include <linux/property.h>
 #include <linux/list.h>
+#include <linux/rhashtable.h>
 
 #include <asm/byteorder.h>
 #include <asm/errno.h>
@@ -52,6 +53,7 @@ struct device_node {
        phandle phandle;
        const char *full_name;
        struct fwnode_handle fwnode;
+       struct rhash_head ht_node;
 
        struct  property *properties;
        struct  property *deadprops;    /* removed properties */
-- 
1.7.12