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Subject[PATCH 3/3] of: overlay: add overlay symbols to live device tree
Date
From: Frank Rowand <frank.rowand@sony.com>

Add overlay __symbols__ properties to live tree when an overlay
is added to the live tree so that the symbols are available to
subsequent overlays.

Expected test result is new __symbols__ entries for labels from
the overlay after the patch is applied.

Before this patch is applied:

Console error message near end of unittest:
### dt-test ### FAIL of_unittest_overlay_high_level():2296 Adding overlay 'overlay_bad_symbol' failed
### dt-test ### end of unittest - 190 passed, 1 failed

The new unittest "fails" because the expected result of loading the
new overlay is an error instead of success.

$ # node hvac-medium-2 exists because the overlay loaded
$ # since the duplicate symbol was not detected
$ cd /proc/device-tree/testcase-data-2/substation@100/
$ ls
compatible hvac-medium-2 motor-8 reg
hvac-large-1 linux,phandle name status
hvac-medium-1 motor-1 phandle

$ cd /proc/device-tree/__symbols__/
$ ls
electric_1 lights_1 name rides_1 spin_ctrl_2
hvac_1 lights_2 retail_1 spin_ctrl_1

After this patch is applied:

Previous console error message no longer occurs, but expected error
occurs:
OF: overlay: Failed to apply prop @/__symbols__/hvac_1
OF: overlay: apply failed '/__symbols__'
### dt-test ### end of unittest - 191 passed, 0 failed

$ # node hvac-medium-2 does not exist because the overlay
$ # properly failed to load due to the duplicate symbol
$ cd /proc/device-tree/testcase-data-2/substation@100/
$ ls
compatible hvac-medium-1 motor-1 name reg
hvac-large-1 linux,phandle motor-8 phandle status

$ cd /proc/device-tree/__symbols__/
$ ls
electric_1 lights_1 retail_1 ride_200_right spin_ctrl_2
hvac_1 lights_2 ride_200 rides_1
hvac_2 name ride_200_left spin_ctrl_1
$ cat ride_200; echo
/testcase-data-2/fairway-1/ride@200
$ cat ride_200_left ; echo
/testcase-data-2/fairway-1/ride@200/track@1
$ cat ride_200_right ; echo
/testcase-data-2/fairway-1/ride@200/track@2

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---
drivers/of/overlay.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 107 insertions(+), 9 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 30aef51eeee5..c484712d124a 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -35,6 +35,7 @@
struct of_overlay_info {
struct device_node *target;
struct device_node *overlay;
+ bool is_symbols_node;
};

/**
@@ -55,7 +56,8 @@ struct of_overlay {
};

static int of_overlay_apply_one(struct of_overlay *ov,
- struct device_node *target, const struct device_node *overlay);
+ struct device_node *target, const struct device_node *overlay,
+ bool is_symbols_node);

static BLOCKING_NOTIFIER_HEAD(of_overlay_chain);

@@ -92,10 +94,74 @@ static int of_overlay_notify(struct of_overlay *ov,
return 0;
}

+static struct property *dup_and_fixup_symbol_prop(struct of_overlay *ov,
+ const struct property *prop)
+{
+ struct of_overlay_info *ovinfo;
+ struct property *new;
+ const char *overlay_name;
+ char *label_path;
+ char *symbol_path;
+ const char *target_path;
+ int k;
+ int label_path_len;
+ int overlay_name_len;
+ int target_path_len;
+
+ if (!prop->value)
+ return NULL;
+ symbol_path = prop->value;
+
+ new = kzalloc(sizeof(*new), GFP_KERNEL);
+ if (!new)
+ return NULL;
+
+ for (k = 0; k < ov->count; k++) {
+ ovinfo = &ov->ovinfo_tab[k];
+ overlay_name = ovinfo->overlay->full_name;
+ overlay_name_len = strlen(overlay_name);
+ if (!strncasecmp(symbol_path, overlay_name, overlay_name_len))
+ break;
+ }
+
+ if (k >= ov->count)
+ goto err_free;
+
+ target_path = ovinfo->target->full_name;
+ target_path_len = strlen(target_path);
+
+ label_path = symbol_path + overlay_name_len;
+ label_path_len = strlen(label_path);
+
+ new->name = kstrdup(prop->name, GFP_KERNEL);
+ new->length = target_path_len + label_path_len + 1;
+ new->value = kzalloc(new->length, GFP_KERNEL);
+
+ if (!new->name || !new->value)
+ goto err_free;
+
+ strcpy(new->value, target_path);
+ strcpy(new->value + target_path_len, label_path);
+
+ /* mark the property as dynamic */
+ of_property_set_flag(new, OF_DYNAMIC);
+
+ return new;
+
+ err_free:
+ kfree(new->name);
+ kfree(new->value);
+ kfree(new);
+ return NULL;
+
+
+}
+
static int of_overlay_apply_single_property(struct of_overlay *ov,
- struct device_node *target, struct property *prop)
+ struct device_node *target, struct property *prop,
+ bool is_symbols_node)
{
- struct property *propn, *tprop;
+ struct property *propn = NULL, *tprop;

/* NOTE: Multiple changes of single properties not supported */
tprop = of_find_property(target, prop->name, NULL);
@@ -106,7 +172,15 @@ static int of_overlay_apply_single_property(struct of_overlay *ov,
of_prop_cmp(prop->name, "linux,phandle") == 0)
return 0;

- propn = __of_prop_dup(prop, GFP_KERNEL);
+ if (is_symbols_node) {
+ /* changing a property in __symbols__ node not allowed */
+ if (tprop)
+ return -EINVAL;
+ propn = dup_and_fixup_symbol_prop(ov, prop);
+ } else {
+ propn = __of_prop_dup(prop, GFP_KERNEL);
+ }
+
if (propn == NULL)
return -ENOMEM;

@@ -155,7 +229,7 @@ static int of_overlay_apply_single_device_node(struct of_overlay *ov,
return -EINVAL;

/* apply overlay recursively */
- ret = of_overlay_apply_one(ov, tchild, child);
+ ret = of_overlay_apply_one(ov, tchild, child, 0);
of_node_put(tchild);
} else {
/* create empty tree as a target */
@@ -170,7 +244,7 @@ static int of_overlay_apply_single_device_node(struct of_overlay *ov,
if (ret)
return ret;

- ret = of_overlay_apply_one(ov, tchild, child);
+ ret = of_overlay_apply_one(ov, tchild, child, 0);
if (ret)
return ret;
}
@@ -186,14 +260,16 @@ static int of_overlay_apply_single_device_node(struct of_overlay *ov,
* by using the changeset.
*/
static int of_overlay_apply_one(struct of_overlay *ov,
- struct device_node *target, const struct device_node *overlay)
+ struct device_node *target, const struct device_node *overlay,
+ bool is_symbols_node)
{
struct device_node *child;
struct property *prop;
int ret;

for_each_property_of_node(overlay, prop) {
- ret = of_overlay_apply_single_property(ov, target, prop);
+ ret = of_overlay_apply_single_property(ov, target, prop,
+ is_symbols_node);
if (ret) {
pr_err("Failed to apply prop @%s/%s\n",
target->full_name, prop->name);
@@ -201,6 +277,10 @@ static int of_overlay_apply_one(struct of_overlay *ov,
}
}

+ /* do not allow symbols node to have any children */
+ if (is_symbols_node)
+ return 0;
+
for_each_child_of_node(overlay, child) {
ret = of_overlay_apply_single_device_node(ov, target, child);
if (ret != 0) {
@@ -231,7 +311,8 @@ static int of_overlay_apply(struct of_overlay *ov)
for (i = 0; i < ov->count; i++) {
struct of_overlay_info *ovinfo = &ov->ovinfo_tab[i];

- err = of_overlay_apply_one(ov, ovinfo->target, ovinfo->overlay);
+ err = of_overlay_apply_one(ov, ovinfo->target, ovinfo->overlay,
+ ovinfo->is_symbols_node);
if (err != 0) {
pr_err("apply failed '%s'\n", ovinfo->target->full_name);
return err;
@@ -329,6 +410,9 @@ static int of_build_overlay_info(struct of_overlay *ov,
for_each_child_of_node(tree, node)
cnt++;

+ if (of_get_child_by_name(tree, "__symbols__"))
+ cnt++;
+
ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
if (ovinfo == NULL)
return -ENOMEM;
@@ -340,6 +424,20 @@ static int of_build_overlay_info(struct of_overlay *ov,
cnt++;
}

+ node = of_get_child_by_name(tree, "__symbols__");
+ if (node) {
+ ovinfo[cnt].overlay = node;
+ ovinfo[cnt].target = of_find_node_by_path("/__symbols__");
+ ovinfo[cnt].is_symbols_node = 1;
+
+ if (!ovinfo[cnt].target) {
+ pr_err("no symbols in root of device tree.\n");
+ return -EINVAL;
+ }
+
+ cnt++;
+ }
+
/* if nothing filled, return error */
if (cnt == 0) {
kfree(ovinfo);
--
Frank Rowand <frank.rowand@sony.com>
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