Update of /cvsroot/linux-vax/kernel-2.4/arch/cris/drivers/examples
In directory usw-pr-cvs1:/tmp/cvs-serv9037/cris/drivers/examples
Added Files:
kiobuftest.c
Log Message:
synch 2.4.15 commit 34
--- NEW FILE ---
/*
* Example showing how to pin down a range of virtual pages from user-space
* to be able to do for example DMA directly into them.
*
* It is necessary because the pages the virtual pointers reference, might
* not exist in memory (could be mapped to the zero-page, filemapped etc)
* and DMA cannot trigger the MMU to force them in (and would have time
* contraints making it impossible to wait for it anyway).
*
* Author: Bjorn Wesen
*
* $Log: kiobuftest.c,v $
* Revision 1.1 2002/04/10 14:15:58 atp
* synch 2.4.15 commit 34
*
* Revision 1.2 2001/02/27 13:52:50 bjornw
* malloc.h -> slab.h
*
* Revision 1.1 2001/01/19 15:57:49 bjornw
* Example of how to do direct HW -> user-mode DMA
*
*
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/iobuf.h>
#define KIOBUFTEST_MAJOR 124 /* in the local range, experimental */
static ssize_t
kiobuf_read(struct file *filp, char *buf, size_t len, loff_t *ppos)
{
struct kiobuf *iobuf;
int res, i;
/* Make a kiobuf that maps the entire length the reader has given
* us
*/
res = alloc_kiovec(1, &iobuf);
if (res)
return res;
if((res = map_user_kiobuf(READ, iobuf, (unsigned long)buf, len))) {
printk("map_user_kiobuf failed, return %d\n", res);
return res;
}
/* At this point, the virtual area buf[0] -> buf[len-1] will
* have corresponding pages mapped in physical memory and locked
* until we unmap the kiobuf. They cannot be swapped out or moved
* around.
*/
printk("nr_pages == %d\noffset == %d\nlength == %d\n",
iobuf->nr_pages, iobuf->offset, iobuf->length);
for(i = 0; i < iobuf->nr_pages; i++) {
printk("page_add(maplist[%d]) == 0x%x\n", i,
page_address(iobuf->maplist[i]));
}
/* This is the place to create the necessary scatter-gather vector
* for the DMA using the iobuf->maplist array and page_address
* (don't forget __pa if the DMA needs the actual physical DRAM address)
* and run it.
*/
/* Release the mapping and exit */
unmap_kiobuf(iobuf); /* The unlock_kiobuf is implicit here */
return len;
}
static struct file_operations kiobuf_fops = {
owner: THIS_MODULE,
read: kiobuf_read
};
static int __init
kiobuftest_init(void)
{
int res;
/* register char device */
res = register_chrdev(KIOBUFTEST_MAJOR, "kiobuftest", &kiobuf_fops);
if(res < 0) {
printk(KERN_ERR "kiobuftest: couldn't get a major number.\n");
return res;
}
printk("Initializing kiobuf-test device\n");
}
module_init(kiobuftest_init);
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