usb: gadget: FunctionFS: convert to new function interface with backward compatibility

This is required in order to integrate configfs support.
f_fs needs to be a separately compiled module and so it needs to use the new
interface.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -539,6 +539,9 @@ config USB_F_RNDIS
 config USB_F_MASS_STORAGE
 	tristate
 
+config USB_F_FS
+	tristate
+
 choice
 	tristate "USB Gadget Drivers"
 	default USB_ETH

drivers/usb/gadget/Makefile

@@ -61,6 +61,8 @@ usb_f_rndis-y			:= f_rndis.o rndis.o
 obj-$(CONFIG_USB_F_RNDIS)	+= usb_f_rndis.o
 usb_f_mass_storage-y		:= f_mass_storage.o storage_common.o
 obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o
+usb_f_fs-y			:= f_fs.o
+obj-$(CONFIG_USB_F_FS)		+= usb_f_fs.o
 
 #
 # USB gadget drivers

drivers/usb/gadget/g_ffs.c

@@ -54,6 +54,7 @@ static struct usb_function *f_rndis;
 #  endif
 #endif
 
+#define USB_FFS_INCLUDED
 #include "f_fs.c"
 
 #define DRIVER_NAME	"g_ffs"

drivers/usb/gadget/u_fs.h

@@ -20,6 +20,22 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 
+#ifdef VERBOSE_DEBUG
+#ifndef pr_vdebug
+#  define pr_vdebug pr_debug
+#endif /* pr_vdebug */
+#  define ffs_dump_mem(prefix, ptr, len) \
+	print_hex_dump_bytes(pr_fmt(prefix ": "), DUMP_PREFIX_NONE, ptr, len)
+#else
+#ifndef pr_vdebug
+#  define pr_vdebug(...)                 do { } while (0)
+#endif /* pr_vdebug */
+#  define ffs_dump_mem(prefix, ptr, len) do { } while (0)
+#endif /* VERBOSE_DEBUG */
+
+#define ENTER()    pr_vdebug("%s()\n", __func__)
+
+
 struct ffs_dev {
 	const char *name;
 	bool mounted;
@@ -30,6 +46,8 @@ struct ffs_dev {
 
 	int (*ffs_ready_callback)(struct ffs_data *ffs);
 	void (*ffs_closed_callback)(struct ffs_data *ffs);
+	void *(*ffs_acquire_dev_callback)(struct ffs_dev *dev);
+	void (*ffs_release_dev_callback)(struct ffs_dev *dev);
 };
 
 extern struct mutex ffs_lock;
@@ -49,4 +67,200 @@ int ffs_name_dev(struct ffs_dev *dev, const char *name);
 int ffs_single_dev(struct ffs_dev *dev);
 void ffs_free_dev(struct ffs_dev *dev);
 
+struct ffs_epfile;
+struct ffs_function;
+
+enum ffs_state {
+	/*
+	 * Waiting for descriptors and strings.
+	 *
+	 * In this state no open(2), read(2) or write(2) on epfiles
+	 * may succeed (which should not be the problem as there
+	 * should be no such files opened in the first place).
+	 */
+	FFS_READ_DESCRIPTORS,
+	FFS_READ_STRINGS,
+
+	/*
+	 * We've got descriptors and strings.  We are or have called
+	 * functionfs_ready_callback().  functionfs_bind() may have
+	 * been called but we don't know.
+	 *
+	 * This is the only state in which operations on epfiles may
+	 * succeed.
+	 */
+	FFS_ACTIVE,
+
+	/*
+	 * All endpoints have been closed.  This state is also set if
+	 * we encounter an unrecoverable error.  The only
+	 * unrecoverable error is situation when after reading strings
+	 * from user space we fail to initialise epfiles or
+	 * functionfs_ready_callback() returns with error (<0).
+	 *
+	 * In this state no open(2), read(2) or write(2) (both on ep0
+	 * as well as epfile) may succeed (at this point epfiles are
+	 * unlinked and all closed so this is not a problem; ep0 is
+	 * also closed but ep0 file exists and so open(2) on ep0 must
+	 * fail).
+	 */
+	FFS_CLOSING
+};
+
+enum ffs_setup_state {
+	/* There is no setup request pending. */
+	FFS_NO_SETUP,
+	/*
+	 * User has read events and there was a setup request event
+	 * there.  The next read/write on ep0 will handle the
+	 * request.
+	 */
+	FFS_SETUP_PENDING,
+	/*
+	 * There was event pending but before user space handled it
+	 * some other event was introduced which canceled existing
+	 * setup.  If this state is set read/write on ep0 return
+	 * -EIDRM.  This state is only set when adding event.
+	 */
+	FFS_SETUP_CANCELED
+};
+
+struct ffs_data {
+	struct usb_gadget		*gadget;
+
+	/*
+	 * Protect access read/write operations, only one read/write
+	 * at a time.  As a consequence protects ep0req and company.
+	 * While setup request is being processed (queued) this is
+	 * held.
+	 */
+	struct mutex			mutex;
+
+	/*
+	 * Protect access to endpoint related structures (basically
+	 * usb_ep_queue(), usb_ep_dequeue(), etc. calls) except for
+	 * endpoint zero.
+	 */
+	spinlock_t			eps_lock;
+
+	/*
+	 * XXX REVISIT do we need our own request? Since we are not
+	 * handling setup requests immediately user space may be so
+	 * slow that another setup will be sent to the gadget but this
+	 * time not to us but another function and then there could be
+	 * a race.  Is that the case? Or maybe we can use cdev->req
+	 * after all, maybe we just need some spinlock for that?
+	 */
+	struct usb_request		*ep0req;		/* P: mutex */
+	struct completion		ep0req_completion;	/* P: mutex */
+	int				ep0req_status;		/* P: mutex */
+
+	/* reference counter */
+	atomic_t			ref;
+	/* how many files are opened (EP0 and others) */
+	atomic_t			opened;
+
+	/* EP0 state */
+	enum ffs_state			state;
+
+	/*
+	 * Possible transitions:
+	 * + FFS_NO_SETUP       -> FFS_SETUP_PENDING  -- P: ev.waitq.lock
+	 *               happens only in ep0 read which is P: mutex
+	 * + FFS_SETUP_PENDING  -> FFS_NO_SETUP       -- P: ev.waitq.lock
+	 *               happens only in ep0 i/o  which is P: mutex
+	 * + FFS_SETUP_PENDING  -> FFS_SETUP_CANCELED -- P: ev.waitq.lock
+	 * + FFS_SETUP_CANCELED -> FFS_NO_SETUP       -- cmpxchg
+	 */
+	enum ffs_setup_state		setup_state;
+
+#define FFS_SETUP_STATE(ffs)					\
+	((enum ffs_setup_state)cmpxchg(&(ffs)->setup_state,	\
+				       FFS_SETUP_CANCELED, FFS_NO_SETUP))
+
+	/* Events & such. */
+	struct {
+		u8				types[4];
+		unsigned short			count;
+		/* XXX REVISIT need to update it in some places, or do we? */
+		unsigned short			can_stall;
+		struct usb_ctrlrequest		setup;
+
+		wait_queue_head_t		waitq;
+	} ev; /* the whole structure, P: ev.waitq.lock */
+
+	/* Flags */
+	unsigned long			flags;
+#define FFS_FL_CALL_CLOSED_CALLBACK 0
+#define FFS_FL_BOUND                1
+
+	/* Active function */
+	struct ffs_function		*func;
+
+	/*
+	 * Device name, write once when file system is mounted.
+	 * Intended for user to read if she wants.
+	 */
+	const char			*dev_name;
+	/* Private data for our user (ie. gadget).  Managed by user. */
+	void				*private_data;
+
+	/* filled by __ffs_data_got_descs() */
+	/*
+	 * Real descriptors are 16 bytes after raw_descs (so you need
+	 * to skip 16 bytes (ie. ffs->raw_descs + 16) to get to the
+	 * first full speed descriptor).  raw_descs_length and
+	 * raw_fs_descs_length do not have those 16 bytes added.
+	 */
+	const void			*raw_descs;
+	unsigned			raw_descs_length;
+	unsigned			raw_fs_descs_length;
+	unsigned			fs_descs_count;
+	unsigned			hs_descs_count;
+
+	unsigned short			strings_count;
+	unsigned short			interfaces_count;
+	unsigned short			eps_count;
+	unsigned short			_pad1;
+
+	/* filled by __ffs_data_got_strings() */
+	/* ids in stringtabs are set in functionfs_bind() */
+	const void			*raw_strings;
+	struct usb_gadget_strings	**stringtabs;
+
+	/*
+	 * File system's super block, write once when file system is
+	 * mounted.
+	 */
+	struct super_block		*sb;
+
+	/* File permissions, written once when fs is mounted */
+	struct ffs_file_perms {
+		umode_t				mode;
+		kuid_t				uid;
+		kgid_t				gid;
+	}				file_perms;
+
+	/*
+	 * The endpoint files, filled by ffs_epfiles_create(),
+	 * destroyed by ffs_epfiles_destroy().
+	 */
+	struct ffs_epfile		*epfiles;
+};
+
+
+#ifndef USB_FFS_INCLUDED
+struct f_fs_opts {
+	struct usb_function_instance	func_inst;
+	struct ffs_dev			*dev;
+	unsigned			refcnt;
+	bool				no_configfs;
+};
+
+static inline struct f_fs_opts *to_f_fs_opts(struct usb_function_instance *fi)
+{
+	return container_of(fi, struct f_fs_opts, func_inst);
+}
+#endif
+
 #endif /* U_FFS_H */

include/linux/usb/functionfs.h

@@ -3,6 +3,7 @@
 
 #include <uapi/linux/usb/functionfs.h>
 
+#ifdef USB_FFS_INCLUDED
 
 struct ffs_data;
 struct usb_composite_dev;
@@ -20,3 +21,4 @@ static int functionfs_bind_config(struct usb_composite_dev *cdev,
 
 
 #endif
+#endif