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* u_fs.h
* Utility definitions for the FunctionFS
* Copyright (c) 2013 Samsung Electronics Co., Ltd.
* Author: Andrzej Pietrasiewicz <>
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
#ifndef U_FFS_H
#define U_FFS_H
#include <linux/usb/composite.h>
#include <linux/list.h>
#include <linux/mutex.h>
#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)
#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 f_fs_opts;
struct ffs_dev {
const char *name;
bool name_allocated;
bool mounted;
bool desc_ready;
bool single;
struct ffs_data *ffs_data;
struct f_fs_opts *opts;
struct list_head entry;
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;
static inline void ffs_dev_lock(void)
static inline void ffs_dev_unlock(void)
struct ffs_dev *ffs_alloc_dev(void);
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).
* 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.
* 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).
enum ffs_setup_state {
/* There is no setup request pending. */
* User has read events and there was a setup request event
* there. The next read/write on ep0 will handle the
* request.
* 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.
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
enum ffs_setup_state setup_state;
#define FFS_SETUP_STATE(ffs) \
((enum ffs_setup_state)cmpxchg(&(ffs)->setup_state, \
/* 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_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;
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 /* U_FFS_H */