[PATCH v3 0/3] of: overlay: load overlay symbols into live device tree

[PATCH v3 0/3] of: overlay: load overlay symbols into live device tree

[frowand.list-Re5JQEeQqe8AvxtiuMwx3w]

From: Frank Rowand <frank.rowand-7U/KSKJipcs@public.gmane.org>

Symbols in a loaded overlay are not currently available to subsequently
loaded overlays because the properties in the overlay's __symbols__
node are not loaded into the live device tree.

Patch 1 is unittests to test patches 2 and 3.

Patch 2 fixes a problem discovered while developing patch 3.  If
a node name in an overlay has a unit-address then the overlay
code does not correctly match the node name against an existing
node in the live tree.

Patch 3 adds the properties in an overlay's __symbol__ node to
the overlay changeset.

This patch set was created on top of v4.12, with Rob's pull request
for 4.13 added (https://lkml.org/lkml/2017/7/6/691).  Thus this
series should apply on 4.13-rc1 when that becomes available.  I will
re-test on 4.13-rc1.

changes since v2:
  - test on 4.13-rc1
  - remove redundant comments from patch headers of patch 0 and patch 1
  - guard make of overlay .dtb files with CONFIG_OF_OVERLAY
  - guard unittest.c references to overlay .dtb files with
    CONFIG_OF_OVERLAY

changes since v1:
  - patch 2: Use for_each_child_of_node() instead of open coding,
    which allowed removing the new function child_by_full_name().


Frank Rowand (3):
  of: overlay: add overlay unittest data for node names and symbols
  of: overlay: correctly apply overlay node with unit-address
  of: overlay: add overlay symbols to live device tree

 drivers/of/overlay.c                            | 121 ++++++++++++++++++++++--
 drivers/of/unittest-data/Makefile               |  19 +++-
 drivers/of/unittest-data/overlay.dts            |  19 +++-
 drivers/of/unittest-data/overlay_bad_symbol.dts |  22 +++++
 drivers/of/unittest-data/overlay_base.dts       |   7 ++
 drivers/of/unittest.c                           |  10 +-
 6 files changed, 180 insertions(+), 18 deletions(-)
 create mode 100644 drivers/of/unittest-data/overlay_bad_symbol.dts

-- 
Frank Rowand <frank.rowand-7U/KSKJipcs@public.gmane.org>

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[PATCH v3 1/3] of: overlay: add overlay unittest data for node names and symbols

[frowand.list-Re5JQEeQqe8AvxtiuMwx3w]

From: Frank Rowand <frank.rowand-7U/KSKJipcs@public.gmane.org>

Add nodes and properties to overlay_base and overlay dts files to
test for
   - incorrect existing node name detection when overlay node name
     has a unit-address
   - adding overlay __symbols__ properties to live tree when an
     overlay is added to the live tree

The following console messages will appear near the end of unittest
until the code errors are corrected:

   OF: Duplicate name in fairway-1, renamed to "ride@100#1"

   ### dt-test ### FAIL of_unittest_overlay_high_level():2296 Adding overlay 'overlay_bad_symbol' failed

   ### dt-test ### end of unittest - 190 passed, 1 failed

Signed-off-by: Frank Rowand <frank.rowand-7U/KSKJipcs@public.gmane.org>
---
 drivers/of/unittest-data/Makefile               | 19 ++++++++++++++-----
 drivers/of/unittest-data/overlay.dts            | 19 ++++++++++++++++++-
 drivers/of/unittest-data/overlay_bad_symbol.dts | 22 ++++++++++++++++++++++
 drivers/of/unittest-data/overlay_base.dts       |  7 +++++++
 drivers/of/unittest.c                           | 10 ++++++++--
 5 files changed, 69 insertions(+), 8 deletions(-)
 create mode 100644 drivers/of/unittest-data/overlay_bad_symbol.dts

diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 6e00a9c69e58..2d135fba94c1 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -1,18 +1,27 @@
 obj-y += testcases.dtb.o
+
+targets += testcases.dtb testcases.dtb.S
+
+ifdef CONFIG_OF_OVERLAY
+
 obj-y += overlay.dtb.o
 obj-y += overlay_bad_phandle.dtb.o
+obj-y += overlay_bad_symbol.dtb.o
 obj-y += overlay_base.dtb.o
 
-targets += testcases.dtb testcases.dtb.S
 targets += overlay.dtb overlay.dtb.S
 targets += overlay_bad_phandle.dtb overlay_bad_phandle.dtb.S
+targets += overlay_bad_symbol.dtb overlay_bad_symbol.dtb.S
 targets += overlay_base.dtb overlay_base.dtb.S
 
-.PRECIOUS: \
-	$(obj)/%.dtb.S \
-	$(obj)/%.dtb
-
 # enable creation of __symbols__ node
 DTC_FLAGS_overlay := -@
 DTC_FLAGS_overlay_bad_phandle := -@
+DTC_FLAGS_overlay_bad_symbol := -@
 DTC_FLAGS_overlay_base := -@
+
+endif
+
+.PRECIOUS: \
+	$(obj)/%.dtb.S \
+	$(obj)/%.dtb
diff --git a/drivers/of/unittest-data/overlay.dts b/drivers/of/unittest-data/overlay.dts
index 6cd7e6a0c13e..81140adbe770 100644
--- a/drivers/of/unittest-data/overlay.dts
+++ b/drivers/of/unittest-data/overlay.dts
@@ -25,7 +25,18 @@
 			#size-cells = <1>;
 			status = "ok";
 
-			ride@200 {
+			ride@100 {
+
+				track@3 {
+					incline_up = < 48 32 16 >;
+				};
+
+				track@4 {
+					incline_up = < 47 31 15 >;
+				};
+			};
+
+			ride_200: ride@200 {
 				compatible = "ot,ferris-wheel";
 				reg = < 0x00000200 0x100 >;
 				hvac-provider = < &hvac_2 >;
@@ -36,6 +47,12 @@
 				spin-rph = < 30 >;
 				gondolas = < 16 >;
 				gondola-capacity = < 6 >;
+
+				ride_200_left: track@1 {
+				};
+
+				ride_200_right: track@2 {
+				};
 			};
 		};
 	};
diff --git a/drivers/of/unittest-data/overlay_bad_symbol.dts b/drivers/of/unittest-data/overlay_bad_symbol.dts
new file mode 100644
index 000000000000..09261cb9a67e
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_bad_symbol.dts
@@ -0,0 +1,22 @@
+/dts-v1/;
+/plugin/;
+
+/ {
+
+	fragment@0 {
+		target = <&electric_1>;
+
+		__overlay__ {
+
+			// This label should cause an error when the overlay
+			// is applied.  There is already a symbol hvac_1
+			// in the base tree
+			hvac_1: hvac-medium-2 {
+				compatible = "ot,hvac-medium";
+				heat-range = < 50 75 >;
+				cool-range = < 60 80 >;
+			};
+
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_base.dts b/drivers/of/unittest-data/overlay_base.dts
index 5566b27fb61a..997d807259e6 100644
--- a/drivers/of/unittest-data/overlay_base.dts
+++ b/drivers/of/unittest-data/overlay_base.dts
@@ -53,6 +53,13 @@
 				spin-controller = < &spin_ctrl_2 5 &spin_ctrl_2 7 >;
 				spin-controller-names = "track_1", "track_2";
 				queues = < 2 >;
+
+				track@3 {
+				};
+
+				track@4 {
+				};
+
 			};
 		};
 
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 0107fc680335..12d08419b736 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1983,6 +1983,8 @@ static void __init of_unittest_overlay(void)
 static inline void __init of_unittest_overlay(void) { }
 #endif
 
+#ifdef CONFIG_OF_OVERLAY
+
 /*
  * __dtb_ot_begin[] and __dtb_ot_end[] are created by cmd_dt_S_dtb
  * in scripts/Makefile.lib
@@ -2010,14 +2012,14 @@ struct overlay_info {
 OVERLAY_INFO_EXTERN(overlay_base);
 OVERLAY_INFO_EXTERN(overlay);
 OVERLAY_INFO_EXTERN(overlay_bad_phandle);
-
-#ifdef CONFIG_OF_OVERLAY
+OVERLAY_INFO_EXTERN(overlay_bad_symbol);
 
 /* order of entries is hard-coded into users of overlays[] */
 static struct overlay_info overlays[] = {
 	OVERLAY_INFO(overlay_base, -9999),
 	OVERLAY_INFO(overlay, 0),
 	OVERLAY_INFO(overlay_bad_phandle, -EINVAL),
+	OVERLAY_INFO(overlay_bad_symbol, -EINVAL),
 	{}
 };
 
@@ -2289,6 +2291,10 @@ static __init void of_unittest_overlay_high_level(void)
 
 	unittest(overlay_data_add(2),
 		 "Adding overlay 'overlay_bad_phandle' failed\n");
+
+	unittest(overlay_data_add(3),
+		 "Adding overlay 'overlay_bad_symbol' failed\n");
+
 	return;
 
 err_unlock:
-- 
Frank Rowand <frank.rowand-7U/KSKJipcs@public.gmane.org>

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Re: [PATCH v3 1/3] of: overlay: add overlay unittest data for node names and symbols

[Rob Herring]

On Tue, Jul 18, 2017 at 10:52 PM,  <frowand.list@gmail.com> wrote:
> From: Frank Rowand <frank.rowand@sony.com>
>
> Add nodes and properties to overlay_base and overlay dts files to
> test for
>    - incorrect existing node name detection when overlay node name
>      has a unit-address
>    - adding overlay __symbols__ properties to live tree when an
>      overlay is added to the live tree
>
> The following console messages will appear near the end of unittest
> until the code errors are corrected:
>
>    OF: Duplicate name in fairway-1, renamed to "ride@100#1"
>
>    ### dt-test ### FAIL of_unittest_overlay_high_level():2296 Adding overlay 'overlay_bad_symbol' failed
>
>    ### dt-test ### end of unittest - 190 passed, 1 failed
>
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---

> diff --git a/drivers/of/unittest-data/overlay.dts b/drivers/of/unittest-data/overlay.dts
> index 6cd7e6a0c13e..81140adbe770 100644
> --- a/drivers/of/unittest-data/overlay.dts
> +++ b/drivers/of/unittest-data/overlay.dts
> @@ -25,7 +25,18 @@
>                         #size-cells = <1>;
>                         status = "ok";
>
> -                       ride@200 {
> +                       ride@100 {
> +
> +                               track@3 {

These need a reg property.

> +                                       incline_up = < 48 32 16 >;

Don't use '_'.

Build with W=2 to check dtc warnings.

Rob

Re: [PATCH v3 1/3] of: overlay: add overlay unittest data for node names and symbols

[Frank Rowand]

On 07/19/17 06:39, Rob Herring wrote:
> On Tue, Jul 18, 2017 at 10:52 PM,  <frowand.list@gmail.com> wrote:
>> From: Frank Rowand <frank.rowand@sony.com>
>>
>> Add nodes and properties to overlay_base and overlay dts files to
>> test for
>>    - incorrect existing node name detection when overlay node name
>>      has a unit-address
>>    - adding overlay __symbols__ properties to live tree when an
>>      overlay is added to the live tree
>>
>> The following console messages will appear near the end of unittest
>> until the code errors are corrected:
>>
>>    OF: Duplicate name in fairway-1, renamed to "ride@100#1"
>>
>>    ### dt-test ### FAIL of_unittest_overlay_high_level():2296 Adding overlay 'overlay_bad_symbol' failed
>>
>>    ### dt-test ### end of unittest - 190 passed, 1 failed
>>
>> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
>> ---
> 
>> diff --git a/drivers/of/unittest-data/overlay.dts b/drivers/of/unittest-data/overlay.dts
>> index 6cd7e6a0c13e..81140adbe770 100644
>> --- a/drivers/of/unittest-data/overlay.dts
>> +++ b/drivers/of/unittest-data/overlay.dts
>> @@ -25,7 +25,18 @@
>>                         #size-cells = <1>;
>>                         status = "ok";
>>
>> -                       ride@200 {
>> +                       ride@100 {
>> +
>> +                               track@3 {
> 
> These need a reg property.

OK.

I changed track@3 to track@30, and track@4 to track@40.
Then I added the reg property to .../ride@100/track@30/ and
.../ride@100/track@40/ in the base dts since those nodes
exist in the base dts.  As a result, W=2 will still warn
about a missing reg property for these two nodes in
the overlay.

> 
>> +                                       incline_up = < 48 32 16 >;
> 
> Don't use '_'.

OK.

> 
> Build with W=2 to check dtc warnings.

OK.

> 
> Rob
> 

[PATCH v3 2/3] of: overlay: correctly apply overlay node with unit-address

[frowand.list]

From: Frank Rowand <frank.rowand@sony.com>

Correct existing node name detection when overlay node name has
a unit-address.

Expected test result is overlay will update the nodes and properties
for /testcase-data-2/fairway-1/ride@100/ after this commit.

Before this commit:

   Console error message near end of unittest:
      OF: Duplicate name in fairway-1, renamed to "ride@100#1"

   $ cd /proc/device-tree/testcase-data-2/fairway-1/
   $ # extra node: ride@100#1
   $ ls
   #address-cells  linux,phandle   phandle         ride@200
   #size-cells     name            ride@100        status
   compatible      orientation     ride@100#1
   $ cd /proc/device-tree/testcase-data-2/fairway-1/ride@100/
   $ ls track@3/incline_up
   ls: track@3/incline_up: No such file or directory
   $ ls track@4/incline_up
   ls: track@4/incline_up: No such file or directory

After this commit:

   Console error message no longer occurs

   $ cd /proc/device-tree/testcase-data-2/fairway-1/
   $ # no extra node: ride@100#1
   $ ls
   #address-cells  compatible      name            phandle         ride@200
   #size-cells     linux,phandle   orientation     ride@100        status
   $ cd /proc/device-tree/testcase-data-2/fairway-1/ride@100/
   $ ls track@3/incline_up
   track@3/incline_up
   $ ls track@4/incline_up
   track@4/incline_up

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---
 drivers/of/overlay.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index c0e4ee1cd1ba..bd3c32f2d411 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -130,7 +130,10 @@ static int of_overlay_apply_single_device_node(struct of_overlay *ov,
 		return -ENOMEM;
 
 	/* NOTE: Multiple mods of created nodes not supported */
-	tchild = of_get_child_by_name(target, cname);
+	for_each_child_of_node(target, tchild)
+		if (!of_node_cmp(cname, kbasename(tchild->full_name)))
+			break;
+
 	if (tchild != NULL) {
 		/* new overlay phandle value conflicts with existing value */
 		if (child->phandle)
-- 
Frank Rowand <frank.rowand@sony.com>

[PATCH v3 3/3] of: overlay: add overlay symbols to live device tree

[frowand.list]

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 this commit.

Before this commit:

   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 commit:

   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 bd3c32f2d411..b7fe9817b644 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;
 
@@ -140,7 +214,7 @@ 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 */
@@ -155,7 +229,7 @@ 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;
 	}
@@ -171,14 +245,16 @@ 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);
@@ -186,6 +262,10 @@ 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) {
@@ -216,7 +296,8 @@ 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;
@@ -314,6 +395,9 @@ 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;
@@ -325,6 +409,20 @@ 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>