// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * A generic kernel FIFO implementation
 *
 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
 */

#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/kfifo.h>
#include <linux/log2.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/uaccess.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_node(struct __kfifo *fifo, unsigned int size,
                size_t esize, gfp_t gfp_mask, int node)
{
        /*
         * round up to the next power of 2, since our 'let the indices
         * wrap' technique works only in this case.
         */
        size = roundup_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_array_node(size, esize, gfp_mask, node);

        if (!fifo->data) {
                fifo->mask = 0;
                return -ENOMEM;
        }
        fifo->mask = size - 1;

        return 0;
}
EXPORT_SYMBOL(__kfifo_alloc_node);

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_linear(struct __kfifo *fifo,
                unsigned int *tail, unsigned int n)
{
        unsigned int size = fifo->mask + 1;
        unsigned int off = fifo->out & fifo->mask;

        if (tail)
                *tail = off;

        return min3(n, fifo->in - fifo->out, size - off);
}
EXPORT_SYMBOL(__kfifo_out_linear);

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 * esize;
        /* 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 * esize;
        /* 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 unsigned int setup_sgl_buf(struct __kfifo *fifo, struct scatterlist *sgl,
                                  unsigned int data_offset, int nents,
                                  unsigned int len, dma_addr_t dma)
{
        const void *buf = fifo->data + data_offset;

        if (!nents || !len)
                return 0;

        sg_set_buf(sgl, buf, len);

        if (dma != DMA_MAPPING_ERROR) {
                sg_dma_address(sgl) = dma + data_offset;
                sg_dma_len(sgl) = len;
        }

        return 1;
}

static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
                int nents, unsigned int len, unsigned int off, dma_addr_t dma)
{
        unsigned int size = fifo->mask + 1;
        unsigned int esize = fifo->esize;
        unsigned int len_to_end;
        unsigned int n;

        off &= fifo->mask;
        if (esize != 1) {
                off *= esize;
                size *= esize;
                len *= esize;
        }
        len_to_end = min(len, size - off);

        n = setup_sgl_buf(fifo, sgl, off, nents, len_to_end, dma);
        n += setup_sgl_buf(fifo, sgl + n, 0, nents - n, len - len_to_end, dma);

        return n;
}

unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
                struct scatterlist *sgl, int nents, unsigned int len,
                dma_addr_t dma)
{
        unsigned int l;

        l = kfifo_unused(fifo);
        if (len > l)
                len = l;

        return setup_sgl(fifo, sgl, nents, len, fifo->in, dma);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare);

unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
                struct scatterlist *sgl, int nents, unsigned int len,
                dma_addr_t dma)
{
        unsigned int l;

        l = fifo->in - fifo->out;
        if (len > l)
                len = l;

        return setup_sgl(fifo, sgl, nents, len, fifo->out, dma);
}
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;
}
EXPORT_SYMBOL(__kfifo_max_r);

#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 storing 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_linear_r(struct __kfifo *fifo,
                unsigned int *tail, unsigned int n, size_t recsize)
{
        if (fifo->in == fifo->out)
                return 0;

        if (tail)
                *tail = fifo->out + recsize;

        return min(n, __kfifo_peek_n(fifo, recsize));
}
EXPORT_SYMBOL(__kfifo_out_linear_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,
        dma_addr_t dma)
{
        BUG_ON(!nents);

        len = __kfifo_max_r(len, recsize);

        if (len + recsize > kfifo_unused(fifo))
                return 0;

        return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize, dma);
}
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,
        dma_addr_t dma)
{
        BUG_ON(!nents);

        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, dma);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);