// SPDX-License-Identifier: GPL-2.0
/* net/atm/atm_misc.c - Various functions for use by ATM drivers */

/* Written 1995-2000 by Werner Almesberger, EPFL ICA */

#include <linux/module.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/skbuff.h>
#include <linux/sonet.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/atomic.h>

int atm_charge(struct atm_vcc *vcc, int truesize)
{
        atm_force_charge(vcc, truesize);
        if (atomic_read(&sk_atm(vcc)->sk_rmem_alloc) <= sk_atm(vcc)->sk_rcvbuf)
                return 1;
        atm_return(vcc, truesize);
        atomic_inc(&vcc->stats->rx_drop);
        return 0;
}
EXPORT_SYMBOL(atm_charge);

struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc, int pdu_size,
                                 gfp_t gfp_flags)
{
        struct sock *sk = sk_atm(vcc);
        int guess = SKB_TRUESIZE(pdu_size);

        atm_force_charge(vcc, guess);
        if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) {
                struct sk_buff *skb = alloc_skb(pdu_size, gfp_flags);

                if (skb) {
                        atomic_add(skb->truesize-guess,
                                   &sk->sk_rmem_alloc);
                        return skb;
                }
        }
        atm_return(vcc, guess);
        atomic_inc(&vcc->stats->rx_drop);
        return NULL;
}
EXPORT_SYMBOL(atm_alloc_charge);


/*
 * atm_pcr_goal returns the positive PCR if it should be rounded up, the
 * negative PCR if it should be rounded down, and zero if the maximum available
 * bandwidth should be used.
 *
 * The rules are as follows (* = maximum, - = absent (0), x = value "x",
 * (x+ = x or next value above x, x- = x or next value below):
 *
 *      min max pcr     result          min max pcr     result
 *      -   -   -       * (UBR only)    x   -   -       x+
 *      -   -   *       *               x   -   *       *
 *      -   -   z       z-              x   -   z       z-
 *      -   *   -       *               x   *   -       x+
 *      -   *   *       *               x   *   *       *
 *      -   *   z       z-              x   *   z       z-
 *      -   y   -       y-              x   y   -       x+
 *      -   y   *       y-              x   y   *       y-
 *      -   y   z       z-              x   y   z       z-
 *
 * All non-error cases can be converted with the following simple set of rules:
 *
 *   if pcr == z then z-
 *   else if min == x && pcr == - then x+
 *     else if max == y then y-
 *       else *
 */

int atm_pcr_goal(const struct atm_trafprm *tp)
{
        if (tp->pcr && tp->pcr != ATM_MAX_PCR)
                return -tp->pcr;
        if (tp->min_pcr && !tp->pcr)
                return tp->min_pcr;
        if (tp->max_pcr != ATM_MAX_PCR)
                return -tp->max_pcr;
        return 0;
}
EXPORT_SYMBOL(atm_pcr_goal);

void sonet_copy_stats(struct k_sonet_stats *from, struct sonet_stats *to)
{
#define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
        __SONET_ITEMS
#undef __HANDLE_ITEM
}
EXPORT_SYMBOL(sonet_copy_stats);

void sonet_subtract_stats(struct k_sonet_stats *from, struct sonet_stats *to)
{
#define __HANDLE_ITEM(i) atomic_sub(to->i, &from->i)
        __SONET_ITEMS
#undef __HANDLE_ITEM
}
EXPORT_SYMBOL(sonet_subtract_stats);