/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1995, 96, 97, 98, 99, 2001 by Ralf Baechle
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Copyright (C) 2001 Thiemo Seufer.
 * Copyright (C) 2002 Maciej W. Rozycki
 * Copyright (C) 2014 Imagination Technologies Ltd.
 */
#ifndef _ASM_CHECKSUM_H
#define _ASM_CHECKSUM_H

#ifdef CONFIG_GENERIC_CSUM
#include <asm-generic/checksum.h>
#else

#include <linux/in6.h>

#include <linux/uaccess.h>

/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
__wsum csum_partial(const void *buff, int len, __wsum sum);

__wsum __csum_partial_copy_from_user(const void __user *src, void *dst, int len);
__wsum __csum_partial_copy_to_user(const void *src, void __user *dst, int len);

#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
static inline
__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
{
        might_fault();
        if (!access_ok(src, len))
                return 0;
        return __csum_partial_copy_from_user(src, dst, len);
}

/*
 * Copy and checksum to user
 */
#define HAVE_CSUM_COPY_USER
static inline
__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
{
        might_fault();
        if (!access_ok(dst, len))
                return 0;
        return __csum_partial_copy_to_user(src, dst, len);
}

/*
 * the same as csum_partial, but copies from user space (but on MIPS
 * we have just one address space, so this is identical to the above)
 */
#define _HAVE_ARCH_CSUM_AND_COPY
__wsum __csum_partial_copy_nocheck(const void *src, void *dst, int len);
static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
{
        return __csum_partial_copy_nocheck(src, dst, len);
}

/*
 *      Fold a partial checksum without adding pseudo headers
 */
static inline __sum16 csum_fold(__wsum csum)
{
        u32 sum = (__force u32)csum;

        sum += (sum << 16);
        csum = (__force __wsum)(sum < (__force u32)csum);
        sum >>= 16;
        sum += (__force u32)csum;

        return (__force __sum16)~sum;
}
#define csum_fold csum_fold

/*
 *      This is a version of ip_compute_csum() optimized for IP headers,
 *      which always checksum on 4 octet boundaries.
 *
 *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
 *      Arnt Gulbrandsen.
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
        const unsigned int *word = iph;
        const unsigned int *stop = word + ihl;
        unsigned int csum;
        int carry;

        csum = word[0];
        csum += word[1];
        carry = (csum < word[1]);
        csum += carry;

        csum += word[2];
        carry = (csum < word[2]);
        csum += carry;

        csum += word[3];
        carry = (csum < word[3]);
        csum += carry;

        word += 4;
        do {
                csum += *word;
                carry = (csum < *word);
                csum += carry;
                word++;
        } while (word != stop);

        return csum_fold(csum);
}
#define ip_fast_csum ip_fast_csum

static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                                        __u32 len, __u8 proto,
                                        __wsum isum)
{
        const unsigned int sh32 = IS_ENABLED(CONFIG_64BIT) ? 32 : 0;
        unsigned long sum = (__force unsigned long)daddr;
        unsigned long tmp;
        __u32 osum;

        tmp = (__force unsigned long)saddr;
        sum += tmp;

        if (IS_ENABLED(CONFIG_32BIT))
                sum += sum < tmp;

        /*
         * We know PROTO + LEN has the sign bit clear, so cast to a signed
         * type to avoid an extraneous zero-extension where TMP is 64-bit.
         */
        tmp = (__s32)(proto + len);
        tmp <<= IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? 8 : 0;
        sum += tmp;
        if (IS_ENABLED(CONFIG_32BIT))
                sum += sum < tmp;

        tmp = (__force unsigned long)isum;
        sum += tmp;

        if (IS_ENABLED(CONFIG_32BIT)) {
                sum += sum < tmp;
                osum = sum;
        } else if (IS_ENABLED(CONFIG_64BIT)) {
                tmp = sum << sh32;
                sum += tmp;
                osum = sum < tmp;
                osum += sum >> sh32;
        } else {
                BUILD_BUG();
        }

        return (__force __wsum)osum;
}
#define csum_tcpudp_nofold csum_tcpudp_nofold

/*
 * this routine is used for miscellaneous IP-like checksums, mainly
 * in icmp.c
 */
static inline __sum16 ip_compute_csum(const void *buff, int len)
{
        return csum_fold(csum_partial(buff, len, 0));
}

#define _HAVE_ARCH_IPV6_CSUM
static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
                                          const struct in6_addr *daddr,
                                          __u32 len, __u8 proto,
                                          __wsum sum)
{
        __wsum tmp;

        __asm__(
        "       .set    push            # csum_ipv6_magic\n"
        "       .set    noreorder       \n"
        "       .set    noat            \n"
        "       addu    %0, %5          # proto (long in network byte order)\n"
        "       sltu    $1, %0, %5      \n"
        "       addu    %0, $1          \n"

        "       addu    %0, %6          # csum\n"
        "       sltu    $1, %0, %6      \n"
        "       lw      %1, 0(%2)       # four words source address\n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 4(%2)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 8(%2)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 12(%2)      \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 0(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 4(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 8(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 12(%3)      \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       addu    %0, $1          # Add final carry\n"
        "       .set    pop"
        : "=&r" (sum), "=&r" (tmp)
        : "r" (saddr), "r" (daddr),
          "0" (htonl(len)), "r" (htonl(proto)), "r" (sum)
        : "memory");

        return csum_fold(sum);
}

#include <asm-generic/checksum.h>
#endif /* CONFIG_GENERIC_CSUM */

#endif /* _ASM_CHECKSUM_H */