// 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);