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Subject[PATCH 03/12] software node: Add support for references
Date
Introducing functions that can be used for adding and
removing references to other software nodes. The goal is to
support fwnode_property_get_reference_args() also with
software nodes, however, get_reference_args fwnode operation
callback is not yet implemented in this commit for the
software nodes. This commit will only add support for
reference addition/removal.

The next example shows how to add references to GPIOs using the
format described in Documentation/acpi/gpio-properties.txt:

/* Array with two GPIOs */
static struct fwnode_reference_args gpioargs[] __initdata = {
{
.nargs = 3,
.args[0]= 19, /* index */
.args[1]= 0, /* pin */
.args[2]= 0, /* active_low */
},
{
.nargs = 3,
.args[0]= 20, /* index */
.args[1]= 0, /* pin */
.args[2]= 0, /* active_low */
},
{ }
};

static int myinit(void)
{
struct software_node_reference *ref;
struct fwnode_handle *gpio_node;
struct fwnode_handle *my_node;

/* Creating the nodes */
gpio_node = fwnode_create_software_node(gpio_props, NULL);
...
my_node = fwnode_create_software_node(my_props, NULL);
...

/* gpio_node is associated with a GPIO/Pin controller in this example */
...

/* Assigning the actual node references */
gpioargs[0].fwnode = gpio_node;
gpioargs[1].fwnode = gpio_node;

/* my_node will now have a named ("gpios") reference to the two GPIOs */
ref = fwnode_create_software_node_reference(my_node, "gpios", gpioargs);
...
return 0;
}

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
drivers/base/swnode.c | 101 +++++++++++++++++++++++++++++++++++++++
include/linux/property.h | 8 ++++
2 files changed, 109 insertions(+)

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index 8d4485d8d0f8..591f290d25be 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -11,10 +11,19 @@
#include <linux/property.h>
#include <linux/slab.h>

+struct software_node_reference {
+ struct list_head list;
+ const char *name;
+ int nrefs;
+ struct fwnode_reference_args *args;
+};
+
struct software_node {
int id;
struct kobject kobj;
struct fwnode_handle fwnode;
+ struct list_head references;
+ struct mutex lock; /* node lock */

/* hierarchy */
struct ida child_ids;
@@ -606,9 +615,11 @@ fwnode_create_software_node(const struct property_entry *properties,
swnode->kobj.kset = swnode_kset;
swnode->fwnode.ops = &software_node_ops;

+ mutex_init(&swnode->lock);
ida_init(&swnode->child_ids);
INIT_LIST_HEAD(&swnode->entry);
INIT_LIST_HEAD(&swnode->children);
+ INIT_LIST_HEAD(&swnode->references);
swnode->parent = p;

if (p) {
@@ -641,10 +652,100 @@ void fwnode_remove_software_node(struct fwnode_handle *fwnode)
if (!swnode)
return;

+ mutex_lock(&swnode->lock);
+ WARN(!list_empty(&swnode->references),
+ "\"%s\" has still references", kobject_name(&swnode->kobj));
+ mutex_unlock(&swnode->lock);
+
kobject_put(&swnode->kobj);
}
EXPORT_SYMBOL_GPL(fwnode_remove_software_node);

+/**
+ * fwnode_create_software_node_reference - Create named reference description
+ * @fwnode: The software node to have the references
+ * @name: Name given to reference description
+ * @args: Zero terminated array of software node references with arguments
+ *
+ * Associates software nodes listed in @args with @fwnode. The association is
+ * named @name. The reference count is incremented for the nodes in @args.
+ *
+ * Returns pointer to software node reference description on success, or ERR_PTR
+ * on failure.
+ */
+struct software_node_reference *
+fwnode_create_software_node_reference(const struct fwnode_handle *fwnode,
+ const char *name,
+ const struct fwnode_reference_args *args)
+{
+ struct software_node *swnode = to_software_node(fwnode);
+ struct software_node_reference *ref;
+ int n;
+
+ if (!swnode)
+ return ERR_PTR(-EINVAL);
+
+ for (n = 0; args[n].fwnode; n++)
+ if (!is_software_node(args[n].fwnode))
+ return ERR_PTR(-EINVAL);
+
+ ref = kzalloc(sizeof(*ref), GFP_KERNEL);
+ if (!ref)
+ return ERR_PTR(-ENOMEM);
+
+ ref->nrefs = n;
+
+ ref->name = kstrdup(name, GFP_KERNEL);
+ if (!ref->name) {
+ kfree(ref);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ ref->args = kcalloc(ref->nrefs, sizeof(*ref->args), GFP_KERNEL);
+ if (!ref->args) {
+ kfree(ref->name);
+ kfree(ref);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ for (n = 0; n < ref->nrefs; n++) {
+ ref->args[n] = args[n];
+ software_node_get(ref->args[n].fwnode);
+ }
+
+ mutex_lock(&swnode->lock);
+ list_add_tail(&ref->list, &swnode->references);
+ mutex_unlock(&swnode->lock);
+
+ return ref;
+}
+EXPORT_SYMBOL_GPL(fwnode_create_software_node_reference);
+
+/**
+ * fwnode_remove_software_node_reference - Remove named reference description
+ * @ref: Software node reference description
+ *
+ * Remove named reference @ref. Decrements the software node reference count of
+ * each node in @ref, and removes the association that was created in
+ * fwnode_create_software_node_reference().
+ */
+void fwnode_remove_software_node_reference(struct software_node_reference *ref)
+{
+ int n;
+
+ if (IS_ERR_OR_NULL(ref))
+ return;
+
+ for (n = 0; n < ref->nrefs; n++)
+ kobject_put(&to_software_node(ref->args[n].fwnode)->kobj);
+
+ list_del(&ref->list);
+ kfree(ref->args);
+ kfree(ref->name);
+ kfree(ref);
+}
+EXPORT_SYMBOL_GPL(fwnode_remove_software_node_reference);
+
int software_node_notify(struct device *dev, unsigned long action)
{
struct fwnode_handle *fwnode = dev_fwnode(dev);
diff --git a/include/linux/property.h b/include/linux/property.h
index 65d3420dd5d1..40e12ca43556 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -314,6 +314,8 @@ int fwnode_graph_parse_endpoint(const struct fwnode_handle *fwnode,
/* -------------------------------------------------------------------------- */
/* Software fwnode support - when HW description is incomplete or missing */

+struct sofware_node_reference;
+
bool is_software_node(const struct fwnode_handle *fwnode);

int software_node_notify(struct device *dev, unsigned long action);
@@ -323,4 +325,10 @@ fwnode_create_software_node(const struct property_entry *properties,
const struct fwnode_handle *parent);
void fwnode_remove_software_node(struct fwnode_handle *fwnode);

+struct software_node_reference *
+fwnode_create_software_node_reference(const struct fwnode_handle *fwnode,
+ const char *name,
+ const struct fwnode_reference_args *args);
+void fwnode_remove_software_node_reference(struct software_node_reference *ref);
+
#endif /* _LINUX_PROPERTY_H_ */
--
2.20.1
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