![Stefani Seibold](/assets/img/avatar_default.png)
Add DECLARE_KFIFO - macro to declare a kfifo and the associated buffer inside a struct Add INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO Add DEFINE_KFIFO - macro to define and initialize a kfifo as a global or local object Add kfifo_size() - returns the size of the fifo in bytes Add kfifo_is_empty() - returns true if the fifo is empty Add kfifo_is_full() - returns true if the fifo is full Add kfifo_avail() - returns the number of bytes available in the FIFO Do some code cleanup Signed-off-by: Stefani Seibold <stefani@seibold.net> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
235 lines
6.6 KiB
C
235 lines
6.6 KiB
C
/*
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* A generic kernel FIFO implementation.
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*
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* Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
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* Copyright (C) 2004 Stelian Pop <stelian@popies.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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/*
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* Howto porting drivers to the new generic fifo API:
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*
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* - Modify the declaration of the "struct kfifo *" object into a
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* in-place "struct kfifo" object
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* - Init the in-place object with kfifo_alloc() or kfifo_init()
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* Note: The address of the in-place "struct kfifo" object must be
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* passed as the first argument to this functions
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* - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
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* into kfifo_out
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* - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
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* into kfifo_out_locked
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* Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
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* must be passed now to the kfifo_in_locked and kfifo_out_locked
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* as the last parameter.
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* - All formerly name __kfifo_* functions has been renamed into kfifo_*
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*/
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#ifndef _LINUX_KFIFO_H
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#define _LINUX_KFIFO_H
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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struct kfifo {
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unsigned char *buffer; /* the buffer holding the data */
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unsigned int size; /* the size of the allocated buffer */
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unsigned int in; /* data is added at offset (in % size) */
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unsigned int out; /* data is extracted from off. (out % size) */
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};
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/*
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* Macros for declaration and initialization of the kfifo datatype
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*/
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/* helper macro */
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#define __kfifo_initializer(s, b) \
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(struct kfifo) { \
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.size = s, \
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.in = 0, \
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.out = 0, \
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.buffer = b \
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}
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/**
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* DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
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* @name: name of the declared kfifo datatype
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* @size: size of the fifo buffer
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*
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* Note: the macro can be used inside struct or union declaration
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* Note: the macro creates two objects:
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* A kfifo object with the given name and a buffer for the kfifo
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* object named name##kfifo_buffer
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*/
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#define DECLARE_KFIFO(name, size) \
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union { \
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struct kfifo name; \
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unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
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}
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/**
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* INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO
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* @name: name of the declared kfifo datatype
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* @size: size of the fifo buffer
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*/
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#define INIT_KFIFO(name) \
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name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
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sizeof(struct kfifo), name##kfifo_buffer)
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/**
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* DEFINE_KFIFO - macro to define and initialize a kfifo
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* @name: name of the declared kfifo datatype
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* @size: size of the fifo buffer
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*
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* Note: the macro can be used for global and local kfifo data type variables
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* Note: the macro creates two objects:
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* A kfifo object with the given name and a buffer for the kfifo
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* object named name##kfifo_buffer
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*/
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#define DEFINE_KFIFO(name, size) \
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unsigned char name##kfifo_buffer[size]; \
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struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
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#undef __kfifo_initializer
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extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer,
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unsigned int size);
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extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
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gfp_t gfp_mask);
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extern void kfifo_free(struct kfifo *fifo);
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extern unsigned int kfifo_in(struct kfifo *fifo,
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const unsigned char *from, unsigned int len);
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extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
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unsigned char *to, unsigned int len);
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/**
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* kfifo_reset - removes the entire FIFO contents
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* @fifo: the fifo to be emptied.
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*/
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static inline void kfifo_reset(struct kfifo *fifo)
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{
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fifo->in = fifo->out = 0;
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}
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/**
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* kfifo_size - returns the size of the fifo in bytes
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* @fifo: the fifo to be used.
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*/
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static inline __must_check unsigned int kfifo_size(struct kfifo *fifo)
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{
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return fifo->size;
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}
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/**
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* kfifo_len - returns the number of used bytes in the FIFO
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* @fifo: the fifo to be used.
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*/
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static inline unsigned int kfifo_len(struct kfifo *fifo)
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{
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register unsigned int out;
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out = fifo->out;
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smp_rmb();
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return fifo->in - out;
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}
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/**
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* kfifo_is_empty - returns true if the fifo is empty
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* @fifo: the fifo to be used.
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*/
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static inline __must_check int kfifo_is_empty(struct kfifo *fifo)
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{
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return fifo->in == fifo->out;
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}
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/**
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* kfifo_is_full - returns true if the fifo is full
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* @fifo: the fifo to be used.
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*/
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static inline __must_check int kfifo_is_full(struct kfifo *fifo)
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{
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return kfifo_len(fifo) == kfifo_size(fifo);
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}
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/**
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* kfifo_avail - returns the number of bytes available in the FIFO
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* @fifo: the fifo to be used.
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*/
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static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo)
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{
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return kfifo_size(fifo) - kfifo_len(fifo);
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}
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/**
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* kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
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* @fifo: the fifo to be used.
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* @from: the data to be added.
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* @n: the length of the data to be added.
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* @lock: pointer to the spinlock to use for locking.
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*
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* This function copies at most @len bytes from the @from buffer into
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* the FIFO depending on the free space, and returns the number of
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* bytes copied.
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*/
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static inline unsigned int kfifo_in_locked(struct kfifo *fifo,
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const unsigned char *from, unsigned int n, spinlock_t *lock)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(lock, flags);
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ret = kfifo_in(fifo, from, n);
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spin_unlock_irqrestore(lock, flags);
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return ret;
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}
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/**
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* kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
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* @fifo: the fifo to be used.
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* @to: where the data must be copied.
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* @n: the size of the destination buffer.
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* @lock: pointer to the spinlock to use for locking.
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*
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* This function copies at most @len bytes from the FIFO into the
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* @to buffer and returns the number of copied bytes.
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*/
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static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
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unsigned char *to, unsigned int n, spinlock_t *lock)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(lock, flags);
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ret = kfifo_out(fifo, to, n);
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/*
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* optimization: if the FIFO is empty, set the indices to 0
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* so we don't wrap the next time
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*/
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if (kfifo_is_empty(fifo))
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kfifo_reset(fifo);
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spin_unlock_irqrestore(lock, flags);
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return ret;
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}
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#endif
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