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NOMMU: Present backing device capabilities for MTD chardevs

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Present backing device capabilities for MTD character device files to allow
NOMMU mmap to do direct mapping where possible.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
David Howells
2009-02-12 10:40:00 +00:00
committed by David Woodhouse
parent 9ce969082e
commit 402d326519
10 changed files with 215 additions and 2 deletions
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63
drivers/mtd/mtdchar.c
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@@ -13,6 +13,7 @@
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/compatmac.h>
@@ -107,12 +108,15 @@ static int mtd_open(struct inode *inode, struct file *file)
goto out;
}
if (MTD_ABSENT == mtd->type) {
if (mtd->type == MTD_ABSENT) {
put_mtd_device(mtd);
ret = -ENODEV;
goto out;
}
if (mtd->backing_dev_info)
file->f_mapping->backing_dev_info = mtd->backing_dev_info;
/* You can't open it RW if it's not a writeable device */
if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
put_mtd_device(mtd);
@@ -781,6 +785,59 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
return ret;
} /* memory_ioctl */
/*
* try to determine where a shared mapping can be made
* - only supported for NOMMU at the moment (MMU can't doesn't copy private
* mappings)
*/
#ifndef CONFIG_MMU
static unsigned long mtd_get_unmapped_area(struct file *file,
unsigned long addr,
unsigned long len,
unsigned long pgoff,
unsigned long flags)
{
struct mtd_file_info *mfi = file->private_data;
struct mtd_info *mtd = mfi->mtd;
if (mtd->get_unmapped_area) {
unsigned long offset;
if (addr != 0)
return (unsigned long) -EINVAL;
if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
return (unsigned long) -EINVAL;
offset = pgoff << PAGE_SHIFT;
if (offset > mtd->size - len)
return (unsigned long) -EINVAL;
return mtd->get_unmapped_area(mtd, len, offset, flags);
}
/* can't map directly */
return (unsigned long) -ENOSYS;
}
#endif
/*
* set up a mapping for shared memory segments
*/
static int mtd_mmap(struct file *file, struct vm_area_struct *vma)
{
#ifdef CONFIG_MMU
struct mtd_file_info *mfi = file->private_data;
struct mtd_info *mtd = mfi->mtd;
if (mtd->type == MTD_RAM || mtd->type == MTD_ROM)
return 0;
return -ENOSYS;
#else
return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;
#endif
}
static const struct file_operations mtd_fops = {
.owner = THIS_MODULE,
.llseek = mtd_lseek,
@@ -789,6 +846,10 @@ static const struct file_operations mtd_fops = {
.ioctl = mtd_ioctl,
.open = mtd_open,
.release = mtd_close,
.mmap = mtd_mmap,
#ifndef CONFIG_MMU
.get_unmapped_area = mtd_get_unmapped_area,
#endif
};
static int __init init_mtdchar(void)