Re: [PATCH v6 3/4] of: overlay: add per overlay sysfs attributes

* A per overlay can_remove sysfs attribute that reports whether
the overlay can be removed or not due to another overlapping overlay.

* A target sysfs attribute listing the target of each fragment,
in a group named after the name of the fragment.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
 drivers/of/overlay.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 99 insertions(+), 4 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 067404e..2d51d9e2 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c

@@ -25,8 +25,23 @@

 #include "of_private.h"

+/* fwd. decl */
+struct of_overlay;
+struct of_overlay_info;
+
+/* an attribute for each fragment */
+struct fragment_attribute {
+       struct attribute attr;
+       ssize_t (*show)(struct kobject *kobj, struct fragment_attribute *fattr,
+                       char *buf);
+       ssize_t (*store)(struct kobject *kobj, struct fragment_attribute *fattr,
+                        const char *buf, size_t count);
+       struct of_overlay_info *ovinfo;
+};
+
 /**
  * struct of_overlay_info - Holds a single overlay info
+ * @info:      info node that contains the target and overlay
  * @target:    target of the overlay operation
  * @overlay:   pointer to the overlay contents node
  *

@@ -34,8 +49,13 @@
  * records.
  */
 struct of_overlay_info {
+       struct of_overlay *ov;
+       struct device_node *info;
        struct device_node *target;
        struct device_node *overlay;
+       struct attribute_group attr_group;
+       struct attribute *attrs[2];
+       struct fragment_attribute target_attr;
 };

 /**

@@ -52,6 +72,7 @@ struct of_overlay {
        struct list_head node;
        int count;
        struct of_overlay_info *ovinfo_tab;
+       const struct attribute_group **attr_groups;
        struct of_changeset cset;
        struct kobject kobj;
 };

@@ -245,6 +266,8 @@ static int of_fill_overlay_info(struct of_overlay *ov,
        if (ovinfo->target == NULL)
                goto err_fail;

+       ovinfo->info = of_node_get(info_node);
+
        return 0;

 err_fail:

@@ -255,6 +278,17 @@ err_fail:
        return -EINVAL;
 }

+static ssize_t target_show(struct kobject *kobj,
+               struct fragment_attribute *fattr, char *buf)
+{
+       struct of_overlay_info *ovinfo = fattr->ovinfo;
+
+       return snprintf(buf, PAGE_SIZE, "%s\n",
+                       of_node_full_name(ovinfo->target));