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/**
* Simple mtd driver that dynamically allocates/frees memory
*
* $Id: ramtd.c,v 1.7 2006/03/08 17:48:28 joern Exp $
*
* Copyright (c) 2005 Joern Engel <joern@wh.fh-wedel.de>
* Copyright (c) 2006 iSteve <isteve@bofh.cz>
* - Added module parameters, immediate allocation and fixed few leaks.
*/
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/vmalloc.h>
struct ramtd {
struct mtd_info mtd;
struct list_head list;
u32 size;
void *page[];
};
static LIST_HEAD(ramtd_list);
static DECLARE_MUTEX(ramtd_mutex);
static unsigned long ramtd_size = 4*1024*1024;
static int ramtd_now = 0;
module_param(ramtd_size, ulong, 0);
MODULE_PARM_DESC(ramtd_size, "Total device size in bytes");
module_param(ramtd_now, bool, 0);
MODULE_PARM_DESC(ramtd_now, "Allocate all memory when loaded");
static void *get_pool_page(void)
{
void *ret = (void*)__get_free_page(GFP_KERNEL);
return ret;
}
static void free_pool_page(void *page)
{
free_page((unsigned long)page);
}
static void free_all_pages(struct ramtd *this)
{
u32 page;
for (page = 0; page < this->mtd.size / PAGE_SIZE; page++) {
if (this->page[page])
free_pool_page(this->page[page]);
}
}
static int alloc_all_pages(struct ramtd *this)
{
u32 page;
if (!ramtd_now)
return 0;
for (page = 0; page < this->mtd.size / PAGE_SIZE; page++) {
if (this->page[page])
continue;
this->page[page] = get_pool_page();
if (!this->page[page])
return -ENOMEM;
memset(this->page[page], 0xff, PAGE_SIZE);
}
return 0;
}
static int ramtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
struct ramtd *ramtd = container_of(mtd, typeof(*ramtd), mtd);
u32 addr = instr->addr;
u32 len = instr->len;
if (addr + len > mtd->size)
return -EINVAL;
if (addr % PAGE_SIZE)
return -EINVAL;
if (len % PAGE_SIZE)
return -EINVAL;
while (len) {
u32 page = addr / PAGE_SIZE;
down_interruptible(&ramtd_mutex);
free_pool_page(ramtd->page[page]);
ramtd->page[page] = NULL;
up(&ramtd_mutex);
addr += PAGE_SIZE;
len -= PAGE_SIZE;
}
instr->state = MTD_ERASE_DONE;
mtd_erase_callback(instr);
return 0;
}
static int ramtd_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, u_char *buf)
{
struct ramtd *ramtd = container_of(mtd, typeof(*ramtd), mtd);
if (from >= mtd->size)
return -EINVAL;
if (len > mtd->size - from)
len = mtd->size - from;
*retlen = 0;
while (len) {
u32 page = from / PAGE_SIZE;
u32 ofs = from % PAGE_SIZE;
u32 rlen = min_t(u32, len, PAGE_SIZE - ofs);
down_interruptible(&ramtd_mutex);
if (!ramtd->page[page])
memset(buf, 0xff, rlen);
else
memcpy(buf, ramtd->page[page] + ofs, rlen);
up(&ramtd_mutex);
buf += rlen;
from += rlen;
*retlen += rlen;
len -= rlen;
}
return 0;
}
static int ramtd_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
struct ramtd *ramtd = container_of(mtd, typeof(*ramtd), mtd);
if (to >= mtd->size)
return -EINVAL;
if (len > mtd->size - to)
len = mtd->size - to;
*retlen = 0;
while (len) {
u32 page = to / PAGE_SIZE;
u32 ofs = to % PAGE_SIZE;
u32 wlen = min_t(u32, len, PAGE_SIZE - ofs);
down_interruptible(&ramtd_mutex);
if (!ramtd->page[page]) {
ramtd->page[page] = get_pool_page();
memset(ramtd->page[page], 0xff, PAGE_SIZE);
}
if (!ramtd->page[page])
return -EIO;
memcpy(ramtd->page[page] + ofs, buf, wlen);
up(&ramtd_mutex);
buf += wlen;
to += wlen;
*retlen += wlen;
len -= wlen;
}
return 0;
}
static int register_device(const char *name, u32 size)
{
struct ramtd *new;
u32 pages_size;
int err;
size = PAGE_ALIGN(size);
pages_size = size / PAGE_SIZE * sizeof(void*);
new = vmalloc(sizeof(*new) + pages_size);
if (!new)
return -ENOMEM;
memset(new, 0, sizeof(*new) + pages_size);
new->mtd.name = (char*)name;
new->mtd.size = size;
new->mtd.flags = MTD_CAP_RAM | MTD_ERASEABLE | MTD_VOLATILE;
new->mtd.owner = THIS_MODULE;
new->mtd.type = MTD_RAM;
new->mtd.erasesize = PAGE_SIZE;
new->mtd.write = ramtd_write;
new->mtd.read = ramtd_read;
new->mtd.erase = ramtd_erase;
if (add_mtd_device(&new->mtd)) {
free_pool_page(new);
return -EAGAIN;
}
err = alloc_all_pages(new);
if (err) {
free_all_pages(new);
vfree(new);
return err;
}
down_interruptible(&ramtd_mutex);
list_add(&new->list, &ramtd_list);
up(&ramtd_mutex);
return 0;
}
static int __init ramtd_init(void)
{
return register_device("ramtd", ramtd_size); /* FIXME */
}
static void __exit ramtd_exit(void)
{
struct ramtd *this, *next;
down_interruptible(&ramtd_mutex);
list_for_each_entry_safe(this, next, &ramtd_list, list) {
free_all_pages(this);
del_mtd_device(&this->mtd);
vfree(this);
}
up(&ramtd_mutex);
}
module_init(ramtd_init);
module_exit(ramtd_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
MODULE_AUTHOR("iSteve <isteve@bofh.cz>");
MODULE_DESCRIPTION("MTD using dynamic memory allocation");
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