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Subject[PATCH v5 1/4] of: remove *phandle properties from expanded device tree
Date
From: Frank Rowand <frank.rowand@sony.com>

Remove "phandle", "linux,phandle", and "ibm,phandle" properties from
the internal device tree. The phandle will still be in the struct
device_node phandle field.

This is to resolve the issue found by Stephen Boyd [1] when he changed
the type of struct property.value from void * to const void *. As
a result of the type change, the overlay code had compile errors
where the resolver updates phandle values.

[1] http://lkml.iu.edu/hypermail/linux/kernel/1702.1/04160.html

- Add sysfs infrastructure to report np->phandle, as if it was a property.
- Do not create "phandle" "ibm,phandle", and "linux,phandle" properties
in the expanded device tree.
- Remove phandle properties in of_attach_node(), for nodes dynamically
attached to the live tree. Add the phandle sysfs entry for these nodes.
- When creating an overlay changeset, duplicate the node phandle in
__of_node_dup().
- Remove no longer needed checks to exclude "phandle" and "linux,phandle"
properties in several locations.
- A side effect of these changes is that the obsolete "linux,phandle" and
"ibm,phandle" properties will no longer appear in /proc/device-tree (they
will appear as "phandle").
- A side effect is that the value of property "ibm,phandle" will no longer
override the value of properties "phandle" and "linux,phandle".

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---
drivers/of/base.c | 48 +++++++++++++++++++++++++++++++++++++++---
drivers/of/dynamic.c | 55 +++++++++++++++++++++++++++++++++++++------------
drivers/of/fdt.c | 43 +++++++++++++++++++-------------------
drivers/of/of_private.h | 1 +
drivers/of/overlay.c | 4 +---
drivers/of/resolver.c | 23 +--------------------
include/linux/of.h | 1 +
7 files changed, 112 insertions(+), 63 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 28d5f53bc631..941c9a03471d 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -116,6 +116,19 @@ static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
}

+static ssize_t of_node_phandle_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ phandle phandle;
+ struct device_node *np;
+
+ np = container_of(bin_attr, struct device_node, attr_phandle);
+ phandle = cpu_to_be32(np->phandle);
+ return memory_read_from_buffer(buf, count, &offset, &phandle,
+ sizeof(phandle));
+}
+
/* always return newly allocated name, caller must free after use */
static const char *safe_name(struct kobject *kobj, const char *orig_name)
{
@@ -164,6 +177,35 @@ int __of_add_property_sysfs(struct device_node *np, struct property *pp)
return rc;
}

+/*
+ * In the imported device tree (fdt), phandle is a property. In the
+ * internal data structure it is instead stored in the struct device_node.
+ * Make phandle visible in sysfs as if it was a property.
+ */
+int __of_add_phandle_sysfs(struct device_node *np)
+{
+ int rc;
+
+ if (!IS_ENABLED(CONFIG_SYSFS))
+ return 0;
+
+ if (!of_kset || !of_node_is_attached(np))
+ return 0;
+
+ if (!np->phandle || np->phandle == 0xffffffff)
+ return 0;
+
+ sysfs_bin_attr_init(&np->attr_phandle);
+ np->attr_phandle.attr.name = "phandle";
+ np->attr_phandle.attr.mode = 0444;
+ np->attr_phandle.size = sizeof(np->phandle);
+ np->attr_phandle.read = of_node_phandle_read;
+
+ rc = sysfs_create_bin_file(&np->kobj, &np->attr_phandle);
+ WARN(rc, "error adding attribute phandle to node %s\n", np->full_name);
+ return rc;
+}
+
int __of_attach_node_sysfs(struct device_node *np)
{
const char *name;
@@ -193,6 +235,8 @@ int __of_attach_node_sysfs(struct device_node *np)
if (rc)
return rc;

+ __of_add_phandle_sysfs(np);
+
for_each_property_of_node(np, pp)
__of_add_property_sysfs(np, pp);

@@ -2128,9 +2172,7 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
int id, len;

/* Skip those we do not want to proceed */
- if (!strcmp(pp->name, "name") ||
- !strcmp(pp->name, "phandle") ||
- !strcmp(pp->name, "linux,phandle"))
+ if (!strcmp(pp->name, "name"))
continue;

np = of_find_node_by_path(pp->value);
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 888fdbc09992..be320082178f 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -218,19 +218,6 @@ int of_property_notify(int action, struct device_node *np,

void __of_attach_node(struct device_node *np)
{
- const __be32 *phandle;
- int sz;
-
- np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
- np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
-
- phandle = __of_get_property(np, "phandle", &sz);
- if (!phandle)
- phandle = __of_get_property(np, "linux,phandle", &sz);
- if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
- phandle = __of_get_property(np, "ibm,phandle", &sz);
- np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
-
np->child = NULL;
np->sibling = np->parent->child;
np->parent->child = np;
@@ -243,11 +230,48 @@ void __of_attach_node(struct device_node *np)
int of_attach_node(struct device_node *np)
{
struct of_reconfig_data rd;
+ struct property *prev;
+ struct property *prop;
+ struct property *save_next;
unsigned long flags;
+ const __be32 *phandle;
+ int sz;

memset(&rd, 0, sizeof(rd));
rd.dn = np;

+ /* use "<NULL>" to be consistent with populate_node() */
+ np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
+ np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
+
+ phandle = __of_get_property(np, "phandle", &sz);
+ if (!phandle)
+ phandle = __of_get_property(np, "linux,phandle", &sz);
+ if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
+ phandle = __of_get_property(np, "ibm,phandle", &sz);
+ np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
+
+ /* remove phandle properties from node */
+ prev = NULL;
+ for (prop = np->properties; prop != NULL; ) {
+ save_next = prop->next;
+ if (!strcmp(prop->name, "phandle") ||
+ !strcmp(prop->name, "ibm,phandle") ||
+ !strcmp(prop->name, "linux,phandle")) {
+ if (prev)
+ prev->next = prop->next;
+ else
+ np->properties = prop->next;
+ prop->next = np->deadprops;
+ np->deadprops = prop;
+ } else {
+ prev = prop;
+ }
+ prop = save_next;
+ }
+
+ __of_add_phandle_sysfs(np);
+
mutex_lock(&of_mutex);
raw_spin_lock_irqsave(&devtree_lock, flags);
__of_attach_node(np);
@@ -429,6 +453,7 @@ struct device_node *__of_node_dup(const struct device_node *np, const char *fmt,
/* Iterate over and duplicate all properties */
if (np) {
struct property *pp, *new_pp;
+ node->phandle = np->phandle;
for_each_property_of_node(np, pp) {
new_pp = __of_prop_dup(pp, GFP_KERNEL);
if (!new_pp)
@@ -441,6 +466,10 @@ struct device_node *__of_node_dup(const struct device_node *np, const char *fmt,
}
}
}
+
+ node->name = __of_get_property(node, "name", NULL) ? : "<NULL>";
+ node->type = __of_get_property(node, "device_type", NULL) ? : "<NULL>";
+
return node;

err_prop:
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 3080d9dd031d..3e3f67475fd4 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -175,6 +175,7 @@ static void populate_properties(const void *blob,
struct property *pp, **pprev = NULL;
int cur;
bool has_name = false;
+ bool prop_is_phandle = false;

pprev = &np->properties;
for (cur = fdt_first_property_offset(blob, offset);
@@ -198,35 +199,33 @@ static void populate_properties(const void *blob,
if (!strcmp(pname, "name"))
has_name = true;

- pp = unflatten_dt_alloc(mem, sizeof(struct property),
- __alignof__(struct property));
+ if (strcmp(pname, "phandle") &&
+ strcmp(pname, "linux,phandle") &&
+ strcmp(pname, "ibm,phandle"))
+ pp = unflatten_dt_alloc(mem, sizeof(struct property),
+ __alignof__(struct property));
+ else
+ prop_is_phandle = true;
+
if (dryrun)
continue;

- /* We accept flattened tree phandles either in
- * ePAPR-style "phandle" properties, or the
- * legacy "linux,phandle" properties. If both
- * appear and have different values, things
- * will get weird. Don't do that.
+ /* We accept flattened tree phandles in ePAPR-style "phandle"
+ * property, the legacy "linux,phandle" property, or the
+ * "ibm,phandle" property used in pSeries dynamic device tree.
+ * If more than one of them appear and have different values,
+ * things will get weird. Don't do that.
*/
- if (!strcmp(pname, "phandle") ||
- !strcmp(pname, "linux,phandle")) {
+ if (prop_is_phandle) {
if (!np->phandle)
np->phandle = be32_to_cpup(val);
+ } else {
+ pp->name = (char *)pname;
+ pp->length = sz;
+ pp->value = (__be32 *)val;
+ *pprev = pp;
+ pprev = &pp->next;
}
-
- /* And we process the "ibm,phandle" property
- * used in pSeries dynamic device tree
- * stuff
- */
- if (!strcmp(pname, "ibm,phandle"))
- np->phandle = be32_to_cpup(val);
-
- pp->name = (char *)pname;
- pp->length = sz;
- pp->value = (__be32 *)val;
- *pprev = pp;
- pprev = &pp->next;
}

/* With version 0x10 we may not have the name property,
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 4ebb0149d118..1a041411b219 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -47,6 +47,7 @@ extern int of_property_notify(int action, struct device_node *np,
extern void of_node_release(struct kobject *kobj);
extern int __of_changeset_apply(struct of_changeset *ocs);
extern int __of_changeset_revert(struct of_changeset *ocs);
+extern int __of_add_phandle_sysfs(struct device_node *np);
#else /* CONFIG_OF_DYNAMIC */
static inline int of_property_notify(int action, struct device_node *np,
struct property *prop, struct property *old_prop)
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 7827786718d8..ca0b85f5deb1 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -101,9 +101,7 @@ static int of_overlay_apply_single_property(struct of_overlay *ov,
tprop = of_find_property(target, prop->name, NULL);

/* special properties are not meant to be updated (silent NOP) */
- if (of_prop_cmp(prop->name, "name") == 0 ||
- of_prop_cmp(prop->name, "phandle") == 0 ||
- of_prop_cmp(prop->name, "linux,phandle") == 0)
+ if (!of_prop_cmp(prop->name, "name"))
return 0;

propn = __of_prop_dup(prop, GFP_KERNEL);
diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
index 771f4844c781..624cbaeae0a4 100644
--- a/drivers/of/resolver.c
+++ b/drivers/of/resolver.c
@@ -71,30 +71,11 @@ static void adjust_overlay_phandles(struct device_node *overlay,
int phandle_delta)
{
struct device_node *child;
- struct property *prop;
- phandle phandle;

/* adjust node's phandle in node */
if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
overlay->phandle += phandle_delta;

- /* copy adjusted phandle into *phandle properties */
- for_each_property_of_node(overlay, prop) {
-
- if (of_prop_cmp(prop->name, "phandle") &&
- of_prop_cmp(prop->name, "linux,phandle"))
- continue;
-
- if (prop->length < 4)
- continue;
-
- phandle = be32_to_cpup(prop->value);
- if (phandle == OF_PHANDLE_ILLEGAL)
- continue;
-
- *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
- }
-
for_each_child_of_node(overlay, child)
adjust_overlay_phandles(child, phandle_delta);
}
@@ -197,9 +178,7 @@ static int adjust_local_phandle_references(struct device_node *local_fixups,
for_each_property_of_node(local_fixups, prop_fix) {

/* skip properties added automatically */
- if (!of_prop_cmp(prop_fix->name, "name") ||
- !of_prop_cmp(prop_fix->name, "phandle") ||
- !of_prop_cmp(prop_fix->name, "linux,phandle"))
+ if (!of_prop_cmp(prop_fix->name, "name"))
continue;

if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
diff --git a/include/linux/of.h b/include/linux/of.h
index 50fcdb54087f..4e483782d124 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -61,6 +61,7 @@ struct device_node {
struct kobject kobj;
unsigned long _flags;
void *data;
+ struct bin_attribute attr_phandle;
#if defined(CONFIG_SPARC)
const char *path_component_name;
unsigned int unique_id;
--
Frank Rowand <frank.rowand@sony.com>
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