[PATCH RESEND v2 16/16] usb/gadget: FunctionFS: add configfs support

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Add support for using FunctionFS in configfs-based USB gadgets.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
---
 Documentation/ABI/testing/configfs-usb-gadget-ffs |    9 ++
 drivers/usb/gadget/Kconfig                        |   12 ++
 drivers/usb/gadget/f_fs.c                         |  150 ++++++++++++++++++++-
 drivers/usb/gadget/u_fs.h                         |    5 +
 4 files changed, 175 insertions(+), 1 deletions(-)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-ffs

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-ffs b/Documentation/ABI/testing/configfs-usb-gadget-ffs
new file mode 100644
index 0000000..14343e2
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-ffs
@@ -0,0 +1,9 @@
+What:		/config/usb-gadget/gadget/functions/ffs.name
+Date:		Nov 2013
+KenelVersion:	3.13
+Description:	The purpose of this directory is to create and remove it.
+
+		A corresponding USB function instance is created/removed.
+		There are no attributes here.
+
+		All parameters are set through FunctionFS.
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 2479644..8da2b1d 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -689,6 +689,18 @@ config USB_CONFIGFS_MASS_STORAGE
 	  device (in much the same way as the "loop" device driver),
 	  specified as a module parameter or sysfs option.
 
+config USB_CONFIGFS_F_FS
+	boolean "Function filesystem (FunctionFS)"
+	depends on USB_CONFIGFS
+	select USB_F_FS
+	help
+	  The Function Filesystem (FunctionFS) lets one create USB
+	  composite functions in user space in the same way GadgetFS
+	  lets one create USB gadgets in user space.  This allows creation
+	  of composite gadgets such that some of the functions are
+	  implemented in kernel space (for instance Ethernet, serial or
+	  mass storage) and other are implemented in user space.
+
 config USB_ZERO
 	tristate "Gadget Zero (DEVELOPMENT)"
 	select USB_LIBCOMPOSITE
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index b24d754..f5c9b5c 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -29,6 +29,7 @@
 #include <linux/usb/functionfs.h>
 
 #include "u_fs.h"
+#include "configfs.h"
 
 #define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */
 
@@ -161,6 +162,7 @@ static struct ffs_dev *ffs_alloc_dev(void);
 static void ffs_free_dev(struct ffs_dev *dev);
 
 static struct mutex *ffs_dev_lock;
+static DEFINE_MUTEX(_ffs_dev_lock);
 
 static void *(*ffs_acquire_dev_cb)(const char *name);
 static void (*ffs_release_dev_cb)(struct ffs_data *ffs_data);
@@ -2362,6 +2364,117 @@ void ffs_set_closed_cb(void (*cb)(struct ffs_data *ffs_data))
 EXPORT_SYMBOL(ffs_set_closed_cb);
 
 
+/* Configfs support *********************************************************/
+
+static int ffs_ready_callback(struct ffs_data *ffs)
+{
+	struct ffs_dev *ffs_dev;
+	int ret = 0;
+
+	ENTER();
+	mutex_lock(ffs_dev_lock);
+
+	ffs_dev = ffs->private_data;
+	if (!ffs_dev) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (WARN_ON(ffs_dev->desc_ready)) {
+		ret = -EBUSY;
+		goto done;
+	}
+	ffs_dev->desc_ready = true;
+	ffs_dev->ffs_data = ffs;
+
+done:
+	mutex_unlock(ffs_dev_lock);
+	return ret;
+}
+
+static void ffs_closed_callback(struct ffs_data *ffs)
+{
+	struct ffs_dev *ffs_dev;
+
+	ENTER();
+	mutex_lock(ffs_dev_lock);
+
+	ffs_dev = ffs->private_data;
+	if (!ffs_dev)
+		goto done;
+
+	ffs_dev->desc_ready = false;
+	if (!ffs_dev->opts || !ffs_dev->opts->func_inst.group.cg_item.ci_parent)
+		goto done;
+
+	unregister_gadget_item(ffs_dev->opts->
+			       func_inst.group.cg_item.ci_parent->ci_parent);
+
+done:
+	mutex_unlock(ffs_dev_lock);
+}
+
+static void *ffs_acquire_dev_callback(const char *dev_name)
+{
+	struct ffs_dev *ffs_dev;
+
+	ENTER();
+	mutex_lock(ffs_dev_lock);
+
+	ffs_dev = ffs_find_dev(dev_name);
+	if (!ffs_dev) {
+		ffs_dev = ERR_PTR(-ENODEV);
+		goto done;
+	}
+
+	if (ffs_dev->mounted) {
+		ffs_dev = ERR_PTR(-EBUSY);
+		goto done;
+	}
+	ffs_dev->mounted = true;
+
+done:
+	mutex_unlock(ffs_dev_lock);
+	return ffs_dev;
+}
+
+static inline struct f_fs_opts *to_ffs_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_fs_opts,
+			    func_inst.group);
+}
+
+static void ffs_release_dev_callback(struct ffs_data *ffs_data)
+{
+	struct ffs_dev *ffs_dev;
+
+	ENTER();
+	mutex_lock(ffs_dev_lock);
+
+	ffs_dev = ffs_data->private_data;
+	if (ffs_dev)
+		ffs_dev->mounted = false;
+
+	mutex_unlock(ffs_dev_lock);
+}
+
+static void ffs_attr_release(struct config_item *item)
+{
+	struct f_fs_opts *opts = to_ffs_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations ffs_item_ops = {
+	.release	= ffs_attr_release,
+};
+
+static struct config_item_type ffs_func_type = {
+	.ct_item_ops	= &ffs_item_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+
 /* Function registration interface ******************************************/
 
 static void do_cleanup(struct kref *ref)
@@ -2384,6 +2497,31 @@ static void ffs_free_inst(struct usb_function_instance *f)
 	mutex_unlock(&auto_init_lock);
 }
 
+#define MAX_INST_NAME_LEN	40
+
+static int ffs_set_inst_name(struct usb_function_instance *fi, const char *name)
+{
+	struct f_fs_opts *opts;
+	char *ptr;
+	int name_len;
+
+	name_len = strlen(name) + 1;
+	if (name_len > MAX_INST_NAME_LEN)
+		return -ENAMETOOLONG;
+
+	ptr = kstrndup(name, name_len, GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	opts = to_f_fs_opts(fi);
+	if (opts->dev->name_allocated)
+		kfree(opts->dev->name);
+	opts->dev->name = ptr;
+	opts->dev->name_allocated = true;
+
+	return 0;
+}
+
 static struct usb_function_instance *ffs_alloc_inst(void)
 {
 	struct f_fs_opts *opts;
@@ -2394,6 +2532,7 @@ static struct usb_function_instance *ffs_alloc_inst(void)
 	if (!opts)
 		return ERR_PTR(-ENOMEM);
 
+	opts->func_inst.set_inst_name = ffs_set_inst_name;
 	opts->func_inst.free_func_inst = ffs_free_inst;
 	dev = ffs_alloc_dev();
 	if (IS_ERR(dev)) {
@@ -2401,10 +2540,16 @@ static struct usb_function_instance *ffs_alloc_inst(void)
 		goto error;
 	}
 	opts->dev = dev;
+	dev->opts = opts;
 
 	mutex_lock(&auto_init_lock);
 	if (auto_init_active && do_auto_init) {
 		kref_init(&auto_init_ref);
+		ffs_set_acquire_dev_cb(ffs_acquire_dev_callback);
+		ffs_set_release_dev_cb(ffs_release_dev_callback);
+		ffs_set_ready_cb(ffs_ready_callback);
+		ffs_set_closed_cb(ffs_closed_callback);
+		ffs_dev_lock = &_ffs_dev_lock;
 		ret = functionfs_init(NULL);
 		if (!ret)
 			do_init_kref = do_auto_init = false;
@@ -2418,8 +2563,11 @@ static struct usb_function_instance *ffs_alloc_inst(void)
 	}
 	mutex_unlock(&auto_init_lock);
 
-	if (!ret)
+	if (!ret) {
+		config_group_init_type_name(&opts->func_inst.group, "",
+					    &ffs_func_type);
 		return &opts->func_inst;
+	}
 error:
 	ffs_free_dev(opts->dev);
 	kfree(opts);
diff --git a/drivers/usb/gadget/u_fs.h b/drivers/usb/gadget/u_fs.h
index e5eca6c..8d1d4db 100644
--- a/drivers/usb/gadget/u_fs.h
+++ b/drivers/usb/gadget/u_fs.h
@@ -19,6 +19,8 @@
 #include <linux/usb/composite.h>
 #include <linux/list.h>
 
+#define VERBOSE_DEBUG
+
 #ifdef VERBOSE_DEBUG
 #ifndef pr_vdebug
 #  define pr_vdebug pr_debug
@@ -34,12 +36,15 @@
 
 #define ENTER()    pr_vdebug("%s()\n", __func__)
 
+struct f_fs_opts;
 
 struct ffs_dev {
 	const char *name;
+	bool name_allocated;
 	bool mounted;
 	bool desc_ready;
 	struct ffs_data *ffs_data;
+	struct f_fs_opts *opts;
 	struct list_head entry;
 };
 
-- 
1.7.0.4

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