/*
* A generic kernel FIFO implementation.
*
* Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
* Copyright (C) 2004 Stelian Pop <stelian@popies.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
/*
* Howto porting drivers to the new generic fifo API:
*
* - Modify the declaration of the "struct kfifo *" object into a
* in-place "struct kfifo" object
* - Init the in-place object with kfifo_alloc() or kfifo_init()
* Note: The address of the in-place "struct kfifo" object must be
* passed as the first argument to this functions
* - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
* into kfifo_out
* - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
* into kfifo_out_locked
* Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
* must be passed now to the kfifo_in_locked and kfifo_out_locked
* as the last parameter.
* - All formerly name __kfifo_* functions has been renamed into kfifo_*
*/
#ifndef _LINUX_KFIFO_H
#define _LINUX_KFIFO_H
#include <linux/kernel.h>
#include <linux/spinlock.h>
struct kfifo {
unsigned char *buffer; /* the buffer holding the data */
unsigned int size; /* the size of the allocated buffer */
unsigned int in; /* data is added at offset (in % size) */
unsigned int out; /* data is extracted from off. (out % size) */
};
/*
* Macros for declaration and initialization of the kfifo datatype
*/
/* helper macro */
#define __kfifo_initializer(s, b) \
(struct kfifo) { \
.size = s, \
.in = 0, \
.out = 0, \
.buffer = b \
}
/**
* DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
* @name: name of the declared kfifo datatype
* @size: size of the fifo buffer
*
* Note: the macro can be used inside struct or union declaration
* Note: the macro creates two objects:
* A kfifo object with the given name and a buffer for the kfifo
* object named name##kfifo_buffer
*/
#define DECLARE_KFIFO(name, size) \
union { \
struct kfifo name; \
unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
}
/**
* INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO
* @name: name of the declared kfifo datatype
* @size: size of the fifo buffer
*/
#define INIT_KFIFO(name) \
name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
sizeof(struct kfifo), name##kfifo_buffer)
/**
* DEFINE_KFIFO - macro to define and initialize a kfifo
* @name: name of the declared kfifo datatype
* @size: size of the fifo buffer
*
* Note: the macro can be used for global and local kfifo data type variables
* Note: the macro creates two objects:
* A kfifo object with the given name and a buffer for the kfifo
* object named name##kfifo_buffer
*/
#define DEFINE_KFIFO(name, size) \
unsigned char name##kfifo_buffer[size]; \
struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
#undef __kfifo_initializer
extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer,
unsigned int size);
extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
gfp_t gfp_mask);
extern void kfifo_free(struct kfifo *fifo);
extern unsigned int kfifo_in(struct kfifo *fifo,
const unsigned char *from, unsigned int len);
extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
unsigned char *to, unsigned int len);
/**
* kfifo_reset - removes the entire FIFO contents
* @fifo: the fifo to be emptied.
*/
static inline void kfifo_reset(struct kfifo *fifo)
{
fifo->in = fifo->out = 0;
}
/**
* kfifo_reset_out - skip FIFO contents
* @fifo: the fifo to be emptied.
*/
static inline void kfifo_reset_out(struct kfifo *fifo)
{
smp_mb();
fifo->out = fifo->in;
}
/**
* kfifo_size - returns the size of the fifo in bytes
* @fifo: the fifo to be used.
*/
static inline __must_check unsigned int kfifo_size(struct kfifo *fifo)
{
return fifo->size;
}
/**
* kfifo_len - returns the number of used bytes in the FIFO
* @fifo: the fifo to be used.
*/
static inline unsigned int kfifo_len(struct kfifo *fifo)
{
register unsigned int out;
out = fifo->out;
smp_rmb();
return fifo->in - out;
}
/**
* kfifo_is_empty - returns true if the fifo is empty
* @fifo: the fifo to be used.
*/
static inline __must_check int kfifo_is_empty(struct kfifo *fifo)
{
return fifo->in == fifo->out;
}
/**
* kfifo_is_full - returns true if the fifo is full
* @fifo: the fifo to be used.
*/
static inline __must_check int kfifo_is_full(struct kfifo *fifo)
{
return kfifo_len(fifo) == kfifo_size(fifo);
}
/**
* kfifo_avail - returns the number of bytes available in the FIFO
* @fifo: the fifo to be used.
*/
static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo)
{
return kfifo_size(fifo) - kfifo_len(fifo);
}
/**
* kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
* @fifo: the fifo to be used.
* @from: the data to be added.
* @n: the length of the data to be added.
* @lock: pointer to the spinlock to use for locking.
*
* This function copies at most @len bytes from the @from buffer into
* the FIFO depending on the free space, and returns the number of
* bytes copied.
*/
static inline unsigned int kfifo_in_locked(struct kfifo *fifo,
const unsigned char *from, unsigned int n, spinlock_t *lock)
{
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(lock, flags);
ret = kfifo_in(fifo, from, n);
spin_unlock_irqrestore(lock, flags);
return ret;
}
/**
* kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
* @fifo: the fifo to be used.
* @to: where the data must be copied.
* @n: the size of the destination buffer.
* @lock: pointer to the spinlock to use for locking.
*
* This function copies at most @len bytes from the FIFO into the
* @to buffer and returns the number of copied bytes.
*/
static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
unsigned char *to, unsigned int n, spinlock_t *lock)
{
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(lock, flags);
ret = kfifo_out(fifo, to, n);
/*
* optimization: if the FIFO is empty, set the indices to 0
* so we don't wrap the next time
*/
if (kfifo_is_empty(fifo))
kfifo_reset(fifo);
spin_unlock_irqrestore(lock, flags);
return ret;
}
extern void kfifo_skip(struct kfifo *fifo, unsigned int len);
extern __must_check unsigned int kfifo_from_user(struct kfifo *fifo,
const void __user *from, unsigned int n);
extern __must_check unsigned int kfifo_to_user(struct kfifo *fifo,
void __user *to, unsigned int n);
/**
* __kfifo_add_out internal helper function for updating the out offset
*/
static inline void __kfifo_add_out(struct kfifo *fifo,
unsigned int off)
{
smp_mb();
fifo->out += off;
}
/**
* __kfifo_add_in internal helper function for updating the in offset
*/
static inline void __kfifo_add_in(struct kfifo *fifo,
unsigned int off)
{
smp_wmb();
fifo->in += off;
}
/**
* __kfifo_off internal helper function for calculating the index of a
* given offeset
*/
static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
{
return off & (fifo->size - 1);
}
/**
* __kfifo_peek_n internal helper function for determinate the length of
* the next record in the fifo
*/
static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
unsigned int recsize)
{
#define __KFIFO_GET(fifo, off, shift) \
((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
unsigned int l;
l = __KFIFO_GET(fifo, 0, 0);
if (--recsize)
l |= __KFIFO_GET(fifo, 1, 8);
return l;
#undef __KFIFO_GET
}
/**
* __kfifo_poke_n internal helper function for storing the length of
* the next record into the fifo
*/
static inline void __kfifo_poke_n(struct kfifo *fifo,
unsigned int recsize, unsigned int n)
{
#define __KFIFO_PUT(fifo, off, val, shift) \
( \
(fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
(unsigned char)((val) >> (shift)) \
)
__KFIFO_PUT(fifo, 0, n, 0);
if (--recsize)
__KFIFO_PUT(fifo, 1, n, 8);
#undef __KFIFO_PUT
}
/**
* __kfifo_in_... internal functions for put date into the fifo
* do not call it directly, use kfifo_in_rec() instead
*/
extern unsigned int __kfifo_in_n(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize);
extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize);
static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize)
{
unsigned int ret;
ret = __kfifo_in_n(fifo, from, n, recsize);
if (likely(ret == 0)) {
if (recsize)
__kfifo_poke_n(fifo, recsize, n);
__kfifo_add_in(fifo, n + recsize);
}
return ret;
}
/**
* kfifo_in_rec - puts some record data into the FIFO
* @fifo: the fifo to be used.
* @from: the data to be added.
* @n: the length of the data to be added.
* @recsize: size of record field
*
* This function copies @n bytes from the @from into the FIFO and returns
* the number of bytes which cannot be copied.
* A returned value greater than the @n value means that the record doesn't
* fit into the buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
void *from, unsigned int n, unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_in_generic(fifo, from, n, recsize);
return __kfifo_in_rec(fifo, from, n, recsize);
}
/**
* __kfifo_out_... internal functions for get date from the fifo
* do not call it directly, use kfifo_out_rec() instead
*/
extern unsigned int __kfifo_out_n(struct kfifo *fifo,
void *to, unsigned int reclen, unsigned int recsize);
extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
void *to, unsigned int n,
unsigned int recsize, unsigned int *total);
static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
void *to, unsigned int n, unsigned int recsize,
unsigned int *total)
{
unsigned int l;
if (!recsize) {
l = n;
if (total)
*total = l;
} else {
l = __kfifo_peek_n(fifo, recsize);
if (total)
*total = l;
if (n < l)
return l;
}
return __kfifo_out_n(fifo, to, l, recsize);
}
/**
* kfifo_out_rec - gets some record data from the FIFO
* @fifo: the fifo to be used.
* @to: where the data must be copied.
* @n: the size of the destination buffer.
* @recsize: size of record field
* @total: pointer where the total number of to copied bytes should stored
*
* This function copies at most @n bytes from the FIFO to @to and returns the
* number of bytes which cannot be copied.
* A returned value greater than the @n value means that the record doesn't
* fit into the @to buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
void *to, unsigned int n, unsigned int recsize,
unsigned int *total)
{
if (!__builtin_constant_p(recsize))
return __kfifo_out_generic(fifo, to, n, recsize, total);
return __kfifo_out_rec(fifo, to, n, recsize, total);
}
/**
* __kfifo_from_user_... internal functions for transfer from user space into
* the fifo. do not call it directly, use kfifo_from_user_rec() instead
*/
extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize);
extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize);
static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize)
{
unsigned int ret;
ret = __kfifo_from_user_n(fifo, from, n, recsize);
if (likely(ret == 0)) {
if (recsize)
__kfifo_poke_n(fifo, recsize, n);
__kfifo_add_in(fifo, n + recsize);
}
return ret;
}
/**
* kfifo_from_user_rec - puts some data from user space into the FIFO
* @fifo: the fifo to be used.
* @from: pointer to the data to be added.
* @n: the length of the data to be added.
* @recsize: size of record field
*
* This function copies @n bytes from the @from into the
* FIFO and returns the number of bytes which cannot be copied.
*
* If the returned value is equal or less the @n value, the copy_from_user()
* functions has failed. Otherwise the record doesn't fit into the buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_from_user_generic(fifo, from, n, recsize);
return __kfifo_from_user_rec(fifo, from, n, recsize);
}
/**
* __kfifo_to_user_... internal functions for transfer fifo data into user space
* do not call it directly, use kfifo_to_user_rec() instead
*/
extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int reclen,
unsigned int recsize);
extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int recsize,
unsigned int *total);
static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
void __user *to, unsigned int n,
unsigned int recsize, unsigned int *total)
{
unsigned int l;
if (!recsize) {
l = n;
if (total)
*total = l;
} else {
l = __kfifo_peek_n(fifo, recsize);
if (total)
*total = l;
if (n < l)
return l;
}
return __kfifo_to_user_n(fifo, to, n, l, recsize);
}
/**
* kfifo_to_user_rec - gets data from the FIFO and write it to user space
* @fifo: the fifo to be used.
* @to: where the data must be copied.
* @n: the size of the destination buffer.
* @recsize: size of record field
* @total: pointer where the total number of to copied bytes should stored
*
* This function copies at most @n bytes from the FIFO to the @to.
* In case of an error, the function returns the number of bytes which cannot
* be copied.
* If the returned value is equal or less the @n value, the copy_to_user()
* functions has failed. Otherwise the record doesn't fit into the @to buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int recsize,
unsigned int *total)
{
if (!__builtin_constant_p(recsize))
return __kfifo_to_user_generic(fifo, to, n, recsize, total);
return __kfifo_to_user_rec(fifo, to, n, recsize, total);
}
/**
* __kfifo_peek_... internal functions for peek into the next fifo record
* do not call it directly, use kfifo_peek_rec() instead
*/
extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
unsigned int recsize);
/**
* kfifo_peek_rec - gets the size of the next FIFO record data
* @fifo: the fifo to be used.
* @recsize: size of record field
*
* This function returns the size of the next FIFO record in number of bytes
*/
static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_peek_generic(fifo, recsize);
if (!recsize)
return kfifo_len(fifo);
return __kfifo_peek_n(fifo, recsize);
}
/**
* __kfifo_skip_... internal functions for skip the next fifo record
* do not call it directly, use kfifo_skip_rec() instead
*/
extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);
static inline void __kfifo_skip_rec(struct kfifo *fifo,
unsigned int recsize)
{
unsigned int l;
if (recsize) {
l = __kfifo_peek_n(fifo, recsize);
if (l + recsize <= kfifo_len(fifo)) {
__kfifo_add_out(fifo, l + recsize);
return;
}
}
kfifo_reset_out(fifo);
}
/**
* kfifo_skip_rec - skip the next fifo out record
* @fifo: the fifo to be used.
* @recsize: size of record field
*
* This function skips the next FIFO record
*/
static inline void kfifo_skip_rec(struct kfifo *fifo,
unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
__kfifo_skip_generic(fifo, recsize);
else
__kfifo_skip_rec(fifo, recsize);
}
/**
* kfifo_avail_rec - returns the number of bytes available in a record FIFO
* @fifo: the fifo to be used.
* @recsize: size of record field
*/
static inline __must_check unsigned int kfifo_avail_rec(struct kfifo *fifo,
unsigned int recsize)
{
unsigned int l = kfifo_size(fifo) - kfifo_len(fifo);
return (l > recsize) ? l - recsize : 0;
}
#endif
