release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/net/wireless/ath/main.c

   1 /*
   2  * Copyright (c) 2009 Atheros Communications Inc.
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19
  20 #include "ath.h"
  21
  22 MODULE_AUTHOR("Atheros Communications");
  23 MODULE_DESCRIPTION("Shared library for Atheros wireless LAN cards.");
  24 MODULE_LICENSE("Dual BSD/GPL");
  25
  26 struct sk_buff *ath_rxbuf_alloc(struct ath_common *common,
  27                                 u32 len,
  28                                 gfp_t gfp_mask)
  29 {
  30         struct sk_buff *skb;
  31         u32 off;
  32
  33         /*
  34          * Cache-line-align.  This is important (for the
  35          * 5210 at least) as not doing so causes bogus data
  36          * in rx'd frames.
  37          */
  38
  39         /* Note: the kernel can allocate a value greater than
  40          * what we ask it to give us. We really only need 4 KB as that
  41          * is this hardware supports and in fact we need at least 3849
  42          * as that is the MAX AMSDU size this hardware supports.
  43          * Unfortunately this means we may get 8 KB here from the
  44          * kernel... and that is actually what is observed on some
  45          * systems :( */
  46         skb = __dev_alloc_skb(len + common->cachelsz - 1, gfp_mask);
  47         if (skb != NULL) {
  48                 off = ((unsigned long) skb->data) % common->cachelsz;
  49                 if (off != 0)
  50                         skb_reserve(skb, common->cachelsz - off);
  51         } else {
  52                 printk(KERN_ERR "skbuff alloc of size %u failed\n", len);
  53                 return NULL;
  54         }
  55
  56         return skb;
  57 }
  58 EXPORT_SYMBOL(ath_rxbuf_alloc);