[PATCH v1 3/8] software node: Show properties and their values in sysfs

Andy Shevchenko
2021-03-27T22:21:13Z

It's very convenient to see what properties and their values
are currently being assigned in the registered software nodes.

Show properties and their values in sysfs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/base/swnode.c | 137 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 132 insertions(+), 5 deletions(-)

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index 19aa44bc2628..d7fe1a887d2d 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -10,6 +10,7 @@
#include <linux/kernel.h>
#include <linux/property.h>
#include <linux/slab.h>
+#include <linux/sysfs.h>

struct swnode {
int id;
@@ -17,6 +18,10 @@ struct swnode {
struct fwnode_handle fwnode;
const struct software_node *node;

+ /* properties in sysfs */
+ struct kobj_attribute *property_attrs;
+ struct attribute_group property_group;
+
/* hierarchy */
struct ida child_ids;
struct list_head entry;
@@ -25,6 +30,7 @@ struct swnode {

unsigned int allocated:1;
unsigned int managed:1;
+ unsigned int properties:1;
};

static DEFINE_IDA(swnode_root_ids);
@@ -299,6 +305,18 @@ static int property_entry_copy_data(struct property_entry *dst,
return 0;
}

+static int property_entries_count(const struct property_entry *properties)
+{
+ int n = 0;
+
+ if (properties) {
+ while (properties[n].name)
+ n++;
+ }
+
+ return n;
+}
+
/**
* property_entries_dup - duplicate array of properties
* @properties: array of properties to copy
@@ -310,15 +328,13 @@ struct property_entry *
property_entries_dup(const struct property_entry *properties)
{
struct property_entry *p;
- int i, n = 0;
+ int i, n;
int ret;

- if (!properties)
+ n = property_entries_count(properties);
+ if (n == 0)
return NULL;

- while (properties[n].name)
- n++;
-
p = kcalloc(n + 1, sizeof(*p), GFP_KERNEL);
if (!p)
return ERR_PTR(-ENOMEM);
@@ -746,6 +762,108 @@ static void software_node_free(const struct software_node *node)
kfree(node);
}

+static ssize_t
+swnode_property_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ struct swnode *swnode = kobj_to_swnode(kobj);
+ const struct property_entry *prop;
+ const void *pointer;
+ ssize_t len = 0;
+ int i;
+
+ prop = property_entry_get(swnode->node->properties, attr->attr.name);
+ if (!prop)
+ return -EINVAL;
+
+ /* We can't fail here, because it means boolean property */
+ pointer = property_get_pointer(prop);
+ if (!pointer)
+ return sysfs_emit(buf, "\n");
+
+ switch (prop->type) {
+ case DEV_PROP_U8:
+ for (i = 0; i < prop->length / sizeof(u8); i++)
+ len += sysfs_emit_at(buf, len, "%u,", ((u8 *)pointer)[i]);
+ break;
+ case DEV_PROP_U16:
+ for (i = 0; i < prop->length / sizeof(u16); i++)
+ len += sysfs_emit_at(buf, len, "%u,", ((u16 *)pointer)[i]);
+ break;
+ case DEV_PROP_U32:
+ for (i = 0; i < prop->length / sizeof(u32); i++)
+ len += sysfs_emit_at(buf, len, "%u,", ((u32 *)pointer)[i]);
+ break;
+ case DEV_PROP_U64:
+ for (i = 0; i < prop->length / sizeof(u64); i++)
+ len += sysfs_emit_at(buf, len, "%llu,", ((u64 *)pointer)[i]);
+ break;
+ case DEV_PROP_STRING:
+ for (i = 0; i < prop->length / sizeof(const char **); i++)
+ len += sysfs_emit_at(buf, len, "\"%s\",", ((const char **)pointer)[i]);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ sysfs_emit_at(buf, len ? len - 1 : 0, "\n");
+ return len;
+}
+
+static int swnode_register_properties(struct swnode *swnode)
+{
+ const struct property_entry *props = swnode->node->properties;
+ struct attribute **group_attrs;
+ struct kobj_attribute *attrs;
+ int n;
+ int ret;
+
+ n = property_entries_count(props);
+ if (n == 0)
+ return 0;
+
+ group_attrs = kcalloc(n + 1, sizeof(*group_attrs), GFP_KERNEL);
+ if (!group_attrs)
+ return -ENOMEM;
+
+ attrs = kcalloc(n, sizeof(*attrs), GFP_KERNEL);
+ if (!attrs) {
+ kfree(group_attrs);
+ return -ENOMEM;
+ }
+
+ while (n--) {
+ sysfs_attr_init(&attrs[n]);
+ attrs[n].attr.mode = 0444;
+ attrs[n].attr.name = props[n].name;
+ attrs[n].show = swnode_property_show;
+ group_attrs[n] = &attrs[n].attr;
+ }
+
+ swnode->property_group.name = "properties";
+ swnode->property_group.attrs = group_attrs;
+
+ ret = sysfs_create_group(&swnode->kobj, &swnode->property_group);
+ if (ret) {
+ kfree(attrs);
+ kfree(group_attrs);
+ return ret;
+ }
+
+ swnode->property_attrs = attrs;
+ swnode->properties = true;
+ return 0;
+}
+
+static void swnode_unregister_properties(struct swnode *swnode)
+{
+ /*
+ * Nodes under sysfs are removed by __kobject_del(),
+ * we don't need to call sysfs_remove_group() explicitly.
+ */
+ kfree(swnode->property_group.attrs);
+ kfree(swnode->property_attrs);
+}
+
static void software_node_release(struct kobject *kobj)
{
struct swnode *swnode = kobj_to_swnode(kobj);
@@ -757,6 +875,9 @@ static void software_node_release(struct kobject *kobj)
ida_simple_remove(&swnode_root_ids, swnode->id);
}

+ if (swnode->properties)
+ swnode_unregister_properties(swnode);
+
if (swnode->allocated)
software_node_free(swnode->node);

@@ -810,6 +931,12 @@ swnode_register(const struct software_node *node, struct swnode *parent,
return ERR_PTR(ret);
}

+ ret = swnode_register_properties(swnode);
+ if (ret) {
+ kobject_put(&swnode->kobj);
+ return ERR_PTR(ret);
+ }
+
/*
* Assign the flag only in the successful case, so
* the above kobject_put() won't mess up with properties.
--
2.30.2