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

https://bitbucket.org/evzijst/gittest
C | 129 lines | 89 code | 13 blank | 27 comment | 18 complexity | 73ae48a651a22654efc049a78fff2eb9 MD5 | raw file
  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
 37/*  DMA'able memory allocation stuff.
 38 */
 39
 40static inline void *dmaalloc(size_t size)
 41{
 42	unsigned long addr;
 43
 44	if (size == 0) {
 45		return NULL;
 46	}
 47	addr = __get_dma_pages(GFP_KERNEL, get_order(size));
 48	if (addr) {
 49		struct page *page;
 50
 51		for (page = virt_to_page(addr); page < virt_to_page(addr+size); page++)
 52			SetPageReserved(page);
 53	}
 54	return (void *)addr;
 55}
 56
 57static inline void dmafree(void *addr, size_t size)
 58{
 59	if (size > 0) {
 60		struct page *page;
 61
 62		for (page = virt_to_page((unsigned long)addr);
 63		     page < virt_to_page((unsigned long)addr+size); page++)
 64			ClearPageReserved(page);
 65		free_pages((unsigned long) addr, get_order(size));
 66	}
 67}
 68
 69static int add_one_buffer(void)
 70{
 71	TRACE_FUN(ft_t_flow);
 72	
 73	if (ft_nr_buffers >= FT_MAX_NR_BUFFERS) {
 74		TRACE_EXIT -ENOMEM;
 75	}
 76	ft_buffer[ft_nr_buffers] = kmalloc(sizeof(buffer_struct), GFP_KERNEL);
 77	if (ft_buffer[ft_nr_buffers] == NULL) {
 78		TRACE_EXIT -ENOMEM;
 79	}
 80	memset(ft_buffer[ft_nr_buffers], 0, sizeof(buffer_struct));
 81	ft_buffer[ft_nr_buffers]->address = dmaalloc(FT_BUFF_SIZE);
 82	if (ft_buffer[ft_nr_buffers]->address == NULL) {
 83		kfree(ft_buffer[ft_nr_buffers]);
 84		ft_buffer[ft_nr_buffers] = NULL;
 85		TRACE_EXIT -ENOMEM;
 86	}
 87	ft_nr_buffers ++;
 88	TRACE(ft_t_info, "buffer nr #%d @ %p, dma area @ %p",
 89	      ft_nr_buffers,
 90	      ft_buffer[ft_nr_buffers-1],
 91	      ft_buffer[ft_nr_buffers-1]->address);
 92	TRACE_EXIT 0;
 93}
 94
 95static void del_one_buffer(void)
 96{
 97	TRACE_FUN(ft_t_flow);
 98	if (ft_nr_buffers > 0) {
 99		TRACE(ft_t_info, "releasing buffer nr #%d @ %p, dma area @ %p",
100		      ft_nr_buffers,
101		      ft_buffer[ft_nr_buffers-1],
102		      ft_buffer[ft_nr_buffers-1]->address);
103		ft_nr_buffers --;
104		dmafree(ft_buffer[ft_nr_buffers]->address, FT_BUFF_SIZE);
105		kfree(ft_buffer[ft_nr_buffers]);
106		ft_buffer[ft_nr_buffers] = NULL;
107	}
108	TRACE_EXIT;
109}
110
111int ftape_set_nr_buffers(int cnt)
112{
113	int delta = cnt - ft_nr_buffers;
114	TRACE_FUN(ft_t_flow);
115
116	if (delta > 0) {
117		while (delta--) {
118			if (add_one_buffer() < 0) {
119				TRACE_EXIT -ENOMEM;
120			}
121		}
122	} else if (delta < 0) {
123		while (delta++) {
124			del_one_buffer();
125		}
126	}
127	ftape_zap_read_buffers();
128	TRACE_EXIT 0;
129}