extcon: Add extcon_dev_allocate/free() to control the memory of extcon device

This patch add APIs to control the extcon device on extcon provider driver.
The extcon_dev_allocate() allocates the memory of extcon device and initializes
supported cables. And then extcon_dev_free() decrement the reference of the
device of extcon device and free the memory of the extcon device. This APIs
must need to implement devm_extcon_dev_allocate()/free() APIs.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>

drivers/extcon/extcon-class.c

@@ -565,6 +565,42 @@ static void dummy_sysfs_dev_release(struct device *dev)
 {
 }
 
+/*
+ * extcon_dev_allocate() - Allocate the memory of extcon device.
+ * @supported_cable:	Array of supported cable names ending with NULL.
+ *			If supported_cable is NULL, cable name related APIs
+ *			are disabled.
+ *
+ * This function allocates the memory for extcon device without allocating
+ * memory in each extcon provider driver and initialize default setting for
+ * extcon device.
+ *
+ * Return the pointer of extcon device if success or ERR_PTR(err) if fail
+ */
+struct extcon_dev *extcon_dev_allocate(const char **supported_cable)
+{
+	struct extcon_dev *edev;
+
+	edev = kzalloc(sizeof(*edev), GFP_KERNEL);
+	if (!edev)
+		return ERR_PTR(-ENOMEM);
+
+	edev->max_supported = 0;
+	edev->supported_cable = supported_cable;
+
+	return edev;
+}
+
+/*
+ * extcon_dev_free() - Free the memory of extcon device.
+ * @edev:	the extcon device to free
+ */
+void extcon_dev_free(struct extcon_dev *edev)
+{
+	kfree(edev);
+}
+EXPORT_SYMBOL_GPL(extcon_dev_free);
+
 /**
  * extcon_dev_register() - Register a new extcon device
  * @edev	: the new extcon device (should be allocated before calling)

include/linux/extcon.h

@@ -191,6 +191,12 @@ extern void devm_extcon_dev_unregister(struct device *dev,
 				       struct extcon_dev *edev);
 extern struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name);
 
+/*
+ * Following APIs control the memory of extcon device.
+ */
+extern struct extcon_dev *extcon_dev_allocate(const char **cables);
+extern void extcon_dev_free(struct extcon_dev *edev);
+
 /*
  * get/set/update_state access the 32b encoded state value, which represents
  * states of all possible cables of the multistate port. For example, if one
@@ -267,6 +273,13 @@ static inline int devm_extcon_dev_register(struct device *dev,
 static inline void devm_extcon_dev_unregister(struct device *dev,
 					      struct extcon_dev *edev) { }
 
+static inline struct extcon_dev *extcon_dev_allocate(const char **cables)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline void extcon_dev_free(struct extcon_dev *edev) { }
+
 static inline u32 extcon_get_state(struct extcon_dev *edev)
 {
 	return 0;