drivers/char/ftape/lowlevel/ftape-buffer.c

   1 /*
   2  *      Copyright (C) 1997 Claus-Justus Heine
   3
   4  This program is free software; you can redistribute it and/or modify
   5  it under the terms of the GNU General Public License as published by
   6  the Free Software Foundation; either version 2, or (at your option)
   7  any later version.
   8
   9  This program is distributed in the hope that it will be useful,
  10  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  GNU General Public License for more details.
  13
  14  You should have received a copy of the GNU General Public License
  15  along with this program; see the file COPYING.  If not, write to
  16  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18  *
  19  * $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-buffer.c,v $
  20  * $Revision: 1.3 $
  21  * $Date: 1997/10/16 23:33:11 $
  22  *
  23  *  This file contains the allocator/dealloctor for ftape's dynamic dma
  24  *  buffer.
  25  */
  26
  27 #include <linux/slab.h>
  28 #include <linux/mm.h>
  29 #include <linux/mman.h>
  30 #include <asm/dma.h>
  31
  32 #include <linux/ftape.h>
  33 #include "../lowlevel/ftape-rw.h"
  34 #include "../lowlevel/ftape-read.h"
  35 #include "../lowlevel/ftape-tracing.h"
  36 #include "../lowlevel/ftape-buffer.h"
  37
  38 /*  DMA'able memory allocation stuff.
  39  */
  40
  41 static inline void *dmaalloc(size_t size)
  42 {
  43         unsigned long addr;
  44
  45         if (size == 0) {
  46                 return NULL;
  47         }
  48         addr = __get_dma_pages(GFP_KERNEL, get_order(size));
  49         if (addr) {
  50                 struct page *page;
  51
  52                 for (page = virt_to_page(addr); page < virt_to_page(addr+size); page++)
  53                         SetPageReserved(page);
  54         }
  55         return (void *)addr;
  56 }
  57
  58 static inline void dmafree(void *addr, size_t size)
  59 {
  60         if (size > 0) {
  61                 struct page *page;
  62
  63                 for (page = virt_to_page((unsigned long)addr);
  64                      page < virt_to_page((unsigned long)addr+size); page++)
  65                         ClearPageReserved(page);
  66                 free_pages((unsigned long) addr, get_order(size));
  67         }
  68 }
  69
  70 static int add_one_buffer(void)
  71 {
  72         TRACE_FUN(ft_t_flow);
  73
  74         if (ft_nr_buffers >= FT_MAX_NR_BUFFERS) {
  75                 TRACE_EXIT -ENOMEM;
  76         }
  77         ft_buffer[ft_nr_buffers] = kmalloc(sizeof(buffer_struct), GFP_KERNEL);
  78         if (ft_buffer[ft_nr_buffers] == NULL) {
  79                 TRACE_EXIT -ENOMEM;
  80         }
  81         memset(ft_buffer[ft_nr_buffers], 0, sizeof(buffer_struct));
  82         ft_buffer[ft_nr_buffers]->address = dmaalloc(FT_BUFF_SIZE);
  83         if (ft_buffer[ft_nr_buffers]->address == NULL) {
  84                 kfree(ft_buffer[ft_nr_buffers]);
  85                 ft_buffer[ft_nr_buffers] = NULL;
  86                 TRACE_EXIT -ENOMEM;
  87         }
  88         ft_nr_buffers ++;
  89         TRACE(ft_t_info, "buffer nr #%d @ %p, dma area @ %p",
  90               ft_nr_buffers,
  91               ft_buffer[ft_nr_buffers-1],
  92               ft_buffer[ft_nr_buffers-1]->address);
  93         TRACE_EXIT 0;
  94 }
  95
  96 static void del_one_buffer(void)
  97 {
  98         TRACE_FUN(ft_t_flow);
  99         if (ft_nr_buffers > 0) {
 100                 TRACE(ft_t_info, "releasing buffer nr #%d @ %p, dma area @ %p",
 101                       ft_nr_buffers,
 102                       ft_buffer[ft_nr_buffers-1],
 103                       ft_buffer[ft_nr_buffers-1]->address);
 104                 ft_nr_buffers --;
 105                 dmafree(ft_buffer[ft_nr_buffers]->address, FT_BUFF_SIZE);
 106                 kfree(ft_buffer[ft_nr_buffers]);
 107                 ft_buffer[ft_nr_buffers] = NULL;
 108         }
 109         TRACE_EXIT;
 110 }
 111
 112 int ftape_set_nr_buffers(int cnt)
 113 {
 114         int delta = cnt - ft_nr_buffers;
 115         TRACE_FUN(ft_t_flow);
 116
 117         if (delta > 0) {
 118                 while (delta--) {
 119                         if (add_one_buffer() < 0) {
 120                                 TRACE_EXIT -ENOMEM;
 121                         }
 122                 }
 123         } else if (delta < 0) {
 124                 while (delta++) {
 125                         del_one_buffer();
 126                 }
 127         }
 128         ftape_zap_read_buffers();
 129         TRACE_EXIT 0;
 130 }