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/*
* A generic kernel FIFO implementation
*
* Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.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.
*
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/log2.h>
#include <linux/uaccess.h>
#include <linux/kfifo.h>
/*
* internal helper to calculate the unused elements in a fifo
*/
static inline unsigned int kfifo_unused(struct __kfifo *fifo)
{
return (fifo->mask + 1) - (fifo->in - fifo->out);
}
int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
size_t esize, gfp_t gfp_mask)
{
/*
* round down to the next power of 2, since our 'let the indices
* wrap' technique works only in this case.
*/
if (!is_power_of_2(size))
size = rounddown_pow_of_two(size);
fifo->in = 0;
fifo->out = 0;
fifo->esize = esize;
if (size < 2) {
fifo->data = NULL;
fifo->mask = 0;
return -EINVAL;
}
fifo->data = kmalloc(size * esize, gfp_mask);
if (!fifo->data) {
fifo->mask = 0;
return -ENOMEM;
}
fifo->mask = size - 1;
return 0;
}
EXPORT_SYMBOL(__kfifo_alloc);
void __kfifo_free(struct __kfifo *fifo)
{
kfree(fifo->data);
fifo->in = 0;
fifo->out = 0;
fifo->esize = 0;
fifo->data = NULL;
fifo->mask = 0;
}
EXPORT_SYMBOL(__kfifo_free);
int __kfifo_init(struct __kfifo *fifo, void *buffer,
unsigned int size, size_t esize)
{
size /= esize;
if (!is_power_of_2(size))
size = rounddown_pow_of_two(size);
fifo->in = 0;
fifo->out = 0;
fifo->esize = esize;
fifo->data = buffer;
if (size < 2) {
fifo->mask = 0;
return -EINVAL;
}
fifo->mask = size - 1;
return 0;
}
EXPORT_SYMBOL(__kfifo_init);
static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
unsigned int len, unsigned int off)
{
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
unsigned int l;
off &= fifo->mask;
if (esize != 1) {
off *= esize;
size *= esize;
len *= esize;
}
l = min(len, size - off);
memcpy(fifo->data + off, src, l);
memcpy(fifo->data, src + l, len - l);
/*
* make sure that the data in the fifo is up to date before
* incrementing the fifo->in index counter
*/
smp_wmb();
}
unsigned int __kfifo_in(struct __kfifo *fifo,
const void *buf, unsigned int len)
{
unsigned int l;
l = kfifo_unused(fifo);
if (len > l)
len = l;
kfifo_copy_in(fifo, buf, len, fifo->in);
fifo->in += len;
return len;
}
EXPORT_SYMBOL(__kfifo_in);
static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
unsigned int len, unsigned int off)
{
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
unsigned int l;
off &= fifo->mask;
if (esize != 1) {
off *= esize;
size *= esize;
len *= esize;
}
l = min(len, size - off);
memcpy(dst, fifo->data + off, l);
memcpy(dst + l, fifo->data, len - l);
/*
* make sure that the data is copied before
* incrementing the fifo->out index counter
*/
smp_wmb();
}
unsigned int __kfifo_out_peek(struct __kfifo *fifo,
void *buf, unsigned int len)
{
unsigned int l;
l = fifo->in - fifo->out;
if (len > l)
len = l;
kfifo_copy_out(fifo, buf, len, fifo->out);
return len;
}
EXPORT_SYMBOL(__kfifo_out_peek);
unsigned int __kfifo_out(struct __kfifo *fifo,
void *buf, unsigned int len)
{
len = __kfifo_out_peek(fifo, buf, len);
fifo->out += len;
return len;
}
EXPORT_SYMBOL(__kfifo_out);
static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
const void __user *from, unsigned int len, unsigned int off,
unsigned int *copied)
{
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
unsigned int l;
unsigned long ret;
off &= fifo->mask;
if (esize != 1) {
off *= esize;
size *= esize;
len *= esize;
}
l = min(len, size - off);
ret = copy_from_user(fifo->data + off, from, l);
if (unlikely(ret))
ret = DIV_ROUND_UP(ret + len - l, esize);
else {
ret = copy_from_user(fifo->data, from + l, len - l);
if (unlikely(ret))
ret = DIV_ROUND_UP(ret, esize);
}
/*
* make sure that the data in the fifo is up to date before
* incrementing the fifo->in index counter
*/
smp_wmb();
*copied = len - ret;
/* return the number of elements which are not copied */
return ret;
}
int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
unsigned long len, unsigned int *copied)
{
unsigned int l;
unsigned long ret;
unsigned int esize = fifo->esize;
int err;
if (esize != 1)
len /= esize;
l = kfifo_unused(fifo);
if (len > l)
len = l;
ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
if (unlikely(ret)) {
len -= ret;
err = -EFAULT;
} else
err = 0;
fifo->in += len;
return err;
}
EXPORT_SYMBOL(__kfifo_from_user);
static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
unsigned int len, unsigned int off, unsigned int *copied)
{
unsigned int l;
unsigned long ret;
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
off &= fifo->mask;
if (esize != 1) {
off *= esize;
size *= esize;
len *= esize;
}
l = min(len, size - off);
ret = copy_to_user(to, fifo->data + off, l);
if (unlikely(ret))
ret = DIV_ROUND_UP(ret + len - l, esize);
else {
ret = copy_to_user(to + l, fifo->data, len - l);
if (unlikely(ret))
ret = DIV_ROUND_UP(ret, esize);
}
/*
* make sure that the data is copied before
* incrementing the fifo->out index counter
*/
smp_wmb();
*copied = len - ret;
/* return the number of elements which are not copied */
return ret;
}
int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
unsigned long len, unsigned int *copied)
{
unsigned int l;
unsigned long ret;
unsigned int esize = fifo->esize;
int err;
if (esize != 1)
len /= esize;
l = fifo->in - fifo->out;
if (len > l)
len = l;
ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
if (unlikely(ret)) {
len -= ret;
err = -EFAULT;
} else
err = 0;
fifo->out += len;
return err;
}
EXPORT_SYMBOL(__kfifo_to_user);
static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
int nents, unsigned int len)
{
int n;
unsigned int l;
unsigned int off;
struct page *page;
if (!nents)
return 0;
if (!len)
return 0;
n = 0;
page = virt_to_page(buf);
off = offset_in_page(buf);
l = 0;
while (len >= l + PAGE_SIZE - off) {
struct page *npage;
l += PAGE_SIZE;
buf += PAGE_SIZE;
npage = virt_to_page(buf);
if (page_to_phys(page) != page_to_phys(npage) - l) {
sg_set_page(sgl, page, l - off, off);
sgl = sg_next(sgl);
if (++n == nents || sgl == NULL)
return n;
page = npage;
len -= l - off;
l = off = 0;
}
}
sg_set_page(sgl, page, len, off);
return n + 1;
}
static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
int nents, unsigned int len, unsigned int off)
{
unsigned int size = fifo->mask + 1;
unsigned int esize = fifo->esize;
unsigned int l;
unsigned int n;
off &= fifo->mask;
if (esize != 1) {
off *= esize;
size *= esize;
len *= esize;
}
l = min(len, size - off);
n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
return n;
}
unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len)
{
unsigned int l;
l = kfifo_unused(fifo);
if (len > l)
len = l;
return setup_sgl(fifo, sgl, nents, len, fifo->in);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare);
unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len)
{
unsigned int l;
l = fifo->in - fifo->out;
if (len > l)
len = l;
return setup_sgl(fifo, sgl, nents, len, fifo->out);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare);
unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
{
unsigned int max = (1 << (recsize << 3)) - 1;
if (len > max)
return max;
return len;
}
#define __KFIFO_PEEK(data, out, mask) \
((data)[(out) & (mask)])
/*
* __kfifo_peek_n internal helper function for determinate the length of
* the next record in the fifo
*/
static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
{
unsigned int l;
unsigned int mask = fifo->mask;
unsigned char *data = fifo->data;
l = __KFIFO_PEEK(data, fifo->out, mask);
if (--recsize)
l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
return l;
}
#define __KFIFO_POKE(data, in, mask, val) \
( \
(data)[(in) & (mask)] = (unsigned char)(val) \
)
/*
* __kfifo_poke_n internal helper function for storeing the length of
* the record into the fifo
*/
static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
{
unsigned int mask = fifo->mask;
unsigned char *data = fifo->data;
__KFIFO_POKE(data, fifo->in, mask, n);
if (recsize > 1)
__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
}
unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
{
return __kfifo_peek_n(fifo, recsize);
}
EXPORT_SYMBOL(__kfifo_len_r);
unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
unsigned int len, size_t recsize)
{
if (len + recsize > kfifo_unused(fifo))
return 0;
__kfifo_poke_n(fifo, len, recsize);
kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
fifo->in += len + recsize;
return len;
}
EXPORT_SYMBOL(__kfifo_in_r);
static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
void *buf, unsigned int len, size_t recsize, unsigned int *n)
{
*n = __kfifo_peek_n(fifo, recsize);
if (len > *n)
len = *n;
kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
return len;
}
unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
unsigned int len, size_t recsize)
{
unsigned int n;
if (fifo->in == fifo->out)
return 0;
return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
}
EXPORT_SYMBOL(__kfifo_out_peek_r);
unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
unsigned int len, size_t recsize)
{
unsigned int n;
if (fifo->in == fifo->out)
return 0;
len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
fifo->out += n + recsize;
return len;
}
EXPORT_SYMBOL(__kfifo_out_r);
void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
{
unsigned int n;
n = __kfifo_peek_n(fifo, recsize);
fifo->out += n + recsize;
}
EXPORT_SYMBOL(__kfifo_skip_r);
int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
unsigned long len, unsigned int *copied, size_t recsize)
{
unsigned long ret;
len = __kfifo_max_r(len, recsize);
if (len + recsize > kfifo_unused(fifo)) {
*copied = 0;
return 0;
}
__kfifo_poke_n(fifo, len, recsize);
ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
if (unlikely(ret)) {
*copied = 0;
return -EFAULT;
}
fifo->in += len + recsize;
return 0;
}
EXPORT_SYMBOL(__kfifo_from_user_r);
int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
unsigned long len, unsigned int *copied, size_t recsize)
{
unsigned long ret;
unsigned int n;
if (fifo->in == fifo->out) {
*copied = 0;
return 0;
}
n = __kfifo_peek_n(fifo, recsize);
if (len > n)
len = n;
ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
if (unlikely(ret)) {
*copied = 0;
return -EFAULT;
}
fifo->out += n + recsize;
return 0;
}
EXPORT_SYMBOL(__kfifo_to_user_r);
unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
{
if (!nents)
BUG();
len = __kfifo_max_r(len, recsize);
if (len + recsize > kfifo_unused(fifo))
return 0;
return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
unsigned int len, size_t recsize)
{
len = __kfifo_max_r(len, recsize);
__kfifo_poke_n(fifo, len, recsize);
fifo->in += len + recsize;
}
EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
{
if (!nents)
BUG();
len = __kfifo_max_r(len, recsize);
if (len + recsize > fifo->in - fifo->out)
return 0;
return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
{
unsigned int len;
len = __kfifo_peek_n(fifo, recsize);
fifo->out += len + recsize;
}
EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
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