JFFS for WNR3500Lv2

[tomato.git] / release / src-rt / linux / linux-2.6 / drivers / mtd / mtdcore.c

/*
 * $Id: mtdcore.c,v 1.47 2005/11/07 11:14:20 gleixner Exp $
 *
 * Core registration and callback routines for MTD
 * drivers and users.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/mtd/compatmac.h>
#include <linux/proc_fs.h>

#include <linux/mtd/mtd.h>

/* These are exported solely for the purpose of mtd_blkdevs.c. You
   should not use them for _anything_ else */
DEFINE_MUTEX(mtd_table_mutex);
struct mtd_info *mtd_table[MAX_MTD_DEVICES];

EXPORT_SYMBOL_GPL(mtd_table_mutex);
EXPORT_SYMBOL_GPL(mtd_table);

static LIST_HEAD(mtd_notifiers);

/**
 *      add_mtd_device - register an MTD device
 *      @mtd: pointer to new MTD device info structure
 *
 *      Add a device to the list of MTD devices present in the system, and
 *      notify each currently active MTD 'user' of its arrival. Returns
 *      zero on success or 1 on failure, which currently will only happen
 *      if the number of present devices exceeds MAX_MTD_DEVICES (i.e. 16)
 */

int add_mtd_device(struct mtd_info *mtd)
{
        int i;

        BUG_ON(mtd->writesize == 0);
        mutex_lock(&mtd_table_mutex);

        for (i=0; i < MAX_MTD_DEVICES; i++)
                if (!mtd_table[i]) {
                        struct mtd_notifier *not;

                        mtd_table[i] = mtd;
                        mtd->index = i;
                        mtd->usecount = 0;

                        /* Some chips always power up locked. Unlock them now */
                        if ((mtd->flags & MTD_WRITEABLE)
                            && (mtd->flags & MTD_STUPID_LOCK) && mtd->unlock) {
                                if (mtd->unlock(mtd, 0, mtd->size))
                                        printk(KERN_WARNING
                                               "%s: unlock failed, "
                                               "writes may not work\n",
                                               mtd->name);
                        }

                        DEBUG(0, "mtd: Giving out device %d to %s\n",i, mtd->name);
                        /* No need to get a refcount on the module containing
                           the notifier, since we hold the mtd_table_mutex */
                        list_for_each_entry(not, &mtd_notifiers, list)
                                not->add(mtd);

                        mutex_unlock(&mtd_table_mutex);
                        /* We _know_ we aren't being removed, because
                           our caller is still holding us here. So none
                           of this try_ nonsense, and no bitching about it
                           either. :) */
                        __module_get(THIS_MODULE);
                        return 0;
                }

        mutex_unlock(&mtd_table_mutex);
        return 1;
}

/**
 *      del_mtd_device - unregister an MTD device
 *      @mtd: pointer to MTD device info structure
 *
 *      Remove a device from the list of MTD devices present in the system,
 *      and notify each currently active MTD 'user' of its departure.
 *      Returns zero on success or 1 on failure, which currently will happen
 *      if the requested device does not appear to be present in the list.
 */

int del_mtd_device (struct mtd_info *mtd)
{
        int ret;

        mutex_lock(&mtd_table_mutex);

        if (mtd_table[mtd->index] != mtd) {
                ret = -ENODEV;
        } else if (mtd->usecount) {
                printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
                       mtd->index, mtd->name, mtd->usecount);
                ret = -EBUSY;
        } else {
                struct mtd_notifier *not;

                /* No need to get a refcount on the module containing
                   the notifier, since we hold the mtd_table_mutex */
                list_for_each_entry(not, &mtd_notifiers, list)
                        not->remove(mtd);

                mtd_table[mtd->index] = NULL;

                module_put(THIS_MODULE);
                ret = 0;
        }

        mutex_unlock(&mtd_table_mutex);
        return ret;
}

/**
 *      register_mtd_user - register a 'user' of MTD devices.
 *      @new: pointer to notifier info structure
 *
 *      Registers a pair of callbacks function to be called upon addition
 *      or removal of MTD devices. Causes the 'add' callback to be immediately
 *      invoked for each MTD device currently present in the system.
 */

void register_mtd_user (struct mtd_notifier *new)
{
        int i;

        mutex_lock(&mtd_table_mutex);

        list_add(&new->list, &mtd_notifiers);

        __module_get(THIS_MODULE);

        for (i=0; i< MAX_MTD_DEVICES; i++)
                if (mtd_table[i])
                        new->add(mtd_table[i]);

        mutex_unlock(&mtd_table_mutex);
}

/**
 *      unregister_mtd_user - unregister a 'user' of MTD devices.
 *      @old: pointer to notifier info structure
 *
 *      Removes a callback function pair from the list of 'users' to be
 *      notified upon addition or removal of MTD devices. Causes the
 *      'remove' callback to be immediately invoked for each MTD device
 *      currently present in the system.
 */

int unregister_mtd_user (struct mtd_notifier *old)
{
        int i;

        mutex_lock(&mtd_table_mutex);

        module_put(THIS_MODULE);

        for (i=0; i< MAX_MTD_DEVICES; i++)
                if (mtd_table[i])
                        old->remove(mtd_table[i]);

        list_del(&old->list);
        mutex_unlock(&mtd_table_mutex);
        return 0;
}


/**
 *      get_mtd_device - obtain a validated handle for an MTD device
 *      @mtd: last known address of the required MTD device
 *      @num: internal device number of the required MTD device
 *
 *      Given a number and NULL address, return the num'th entry in the device
 *      table, if any.  Given an address and num == -1, search the device table
 *      for a device with that address and return if it's still present. Given
 *      both, return the num'th driver only if its address matches. Return
 *      error code if not.
 */

struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
{
        struct mtd_info *ret = NULL;
        int i, err = -ENODEV;

        mutex_lock(&mtd_table_mutex);

        if (num == -1) {
                for (i=0; i< MAX_MTD_DEVICES; i++)
                        if (mtd_table[i] == mtd)
                                ret = mtd_table[i];
        } else if (num < MAX_MTD_DEVICES) {
                ret = mtd_table[num];
                if (mtd && mtd != ret)
                        ret = NULL;
        }

        if (!ret)
                goto out_unlock;

        if (!try_module_get(ret->owner))
                goto out_unlock;

        if (ret->get_device) {
                err = ret->get_device(ret);
                if (err)
                        goto out_put;
        }

        ret->usecount++;
        mutex_unlock(&mtd_table_mutex);
        return ret;

out_put:
        module_put(ret->owner);
out_unlock:
        mutex_unlock(&mtd_table_mutex);
        return ERR_PTR(err);
}

/**
 *      get_mtd_device_nm - obtain a validated handle for an MTD device by
 *      device name
 *      @name: MTD device name to open
 *
 *      This function returns MTD device description structure in case of
 *      success and an error code in case of failure.
 */

struct mtd_info *get_mtd_device_nm(const char *name)
{
        int i, err = -ENODEV;
        struct mtd_info *mtd = NULL;

        mutex_lock(&mtd_table_mutex);

        for (i = 0; i < MAX_MTD_DEVICES; i++) {
                if (mtd_table[i] && !strcmp(name, mtd_table[i]->name)) {
                        mtd = mtd_table[i];
                        break;
                }
        }

        if (!mtd)
                goto out_unlock;

        if (!try_module_get(mtd->owner))
                goto out_unlock;

        if (mtd->get_device) {
                err = mtd->get_device(mtd);
                if (err)
                        goto out_put;
        }

        mtd->usecount++;
        mutex_unlock(&mtd_table_mutex);
        return mtd;

out_put:
        module_put(mtd->owner);
out_unlock:
        mutex_unlock(&mtd_table_mutex);
        return ERR_PTR(err);
}

void put_mtd_device(struct mtd_info *mtd)
{
        int c;

        mutex_lock(&mtd_table_mutex);
        c = --mtd->usecount;
        if (mtd->put_device)
                mtd->put_device(mtd);
        mutex_unlock(&mtd_table_mutex);
        BUG_ON(c < 0);

        module_put(mtd->owner);
}

/* default_mtd_writev - default mtd writev method for MTD devices that
 *                      don't implement their own
 */

int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
                       unsigned long count, loff_t to, size_t *retlen)
{
        unsigned long i;
        size_t totlen = 0, thislen;
        int ret = 0;

        if(!mtd->write) {
                ret = -EROFS;
        } else {
                for (i=0; i<count; i++) {
                        if (!vecs[i].iov_len)
                                continue;
                        ret = mtd->write(mtd, to, vecs[i].iov_len, &thislen, vecs[i].iov_base);
                        totlen += thislen;
                        if (ret || thislen != vecs[i].iov_len)
                                break;
                        to += vecs[i].iov_len;
                }
        }
        if (retlen)
                *retlen = totlen;
        return ret;
}

/**
 * mtd_kmalloc_up_to - allocate a contiguous buffer up to the specified size
 * @size: A pointer to the ideal or maximum size of the allocation. Points
 *        to the actual allocation size on success.
 *
 * This routine attempts to allocate a contiguous kernel buffer up to
 * the specified size, backing off the size of the request exponentially
 * until the request succeeds or until the allocation size falls below
 * the system page size. This attempts to make sure it does not adversely
 * impact system performance, so when allocating more than one page, we
 * ask the memory allocator to avoid re-trying, swapping, writing back
 * or performing I/O.
 *
 * Note, this function also makes sure that the allocated buffer is aligned to
 * the MTD device's min. I/O unit, i.e. the "mtd->writesize" value.
 *
 * This is called, for example by mtd_{read,write} and jffs2_scan_medium,
 * to handle smaller (i.e. degraded) buffer allocations under low- or
 * fragmented-memory situations where such reduced allocations, from a
 * requested ideal, are allowed.
 *
 * Returns a pointer to the allocated buffer on success; otherwise, NULL.
 */
void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size)
{
        gfp_t flags = __GFP_NOWARN | __GFP_WAIT |
                       __GFP_NORETRY;
        size_t min_alloc = max_t(size_t, mtd->writesize, PAGE_SIZE);
        void *kbuf;

        *size = min_t(size_t, *size, KMALLOC_MAX_SIZE);

        while (*size > min_alloc) {
                kbuf = kmalloc(*size, flags);
                if (kbuf)
                        return kbuf;

                *size >>= 1;
                *size = ALIGN(*size, mtd->writesize);
        }

        /*
         * For the last resort allocation allow 'kmalloc()' to do all sorts of
         * things (write-back, dropping caches, etc) by using GFP_KERNEL.
         */
        return kmalloc(*size, GFP_KERNEL);
}

EXPORT_SYMBOL_GPL(add_mtd_device);
EXPORT_SYMBOL_GPL(del_mtd_device);
EXPORT_SYMBOL_GPL(get_mtd_device);
EXPORT_SYMBOL_GPL(get_mtd_device_nm);
EXPORT_SYMBOL_GPL(put_mtd_device);
EXPORT_SYMBOL_GPL(register_mtd_user);
EXPORT_SYMBOL_GPL(unregister_mtd_user);
EXPORT_SYMBOL_GPL(default_mtd_writev);
EXPORT_SYMBOL_GPL(mtd_kmalloc_up_to);

#ifdef CONFIG_PROC_FS

/*====================================================================*/
/* Support for /proc/mtd */

static struct proc_dir_entry *proc_mtd;

static inline int mtd_proc_info (char *buf, int i)
{
        struct mtd_info *this = mtd_table[i];

        if (!this)
                return 0;

        return sprintf(buf, "mtd%d: %8.8x %8.8x \"%s\"\n", i, this->size,
                       this->erasesize, this->name);
}

static int mtd_read_proc (char *page, char **start, off_t off, int count,
                          int *eof, void *data_unused)
{
        int len, l, i;
        off_t   begin = 0;

        mutex_lock(&mtd_table_mutex);

        len = sprintf(page, "dev:    size   erasesize  name\n");
        for (i=0; i< MAX_MTD_DEVICES; i++) {

                l = mtd_proc_info(page + len, i);
                len += l;
                if (len+begin > off+count)
                        goto done;
                if (len+begin < off) {
                        begin += len;
                        len = 0;
                }
        }

        *eof = 1;

done:
        mutex_unlock(&mtd_table_mutex);
        if (off >= len+begin)
                return 0;
        *start = page + (off-begin);
        return ((count < begin+len-off) ? count : begin+len-off);
}

/*====================================================================*/
/* Init code */

static int __init init_mtd(void)
{
        if ((proc_mtd = create_proc_entry( "mtd", 0, NULL )))
                proc_mtd->read_proc = mtd_read_proc;
        return 0;
}

static void __exit cleanup_mtd(void)
{
        if (proc_mtd)
                remove_proc_entry( "mtd", NULL);
}

module_init(init_mtd);
module_exit(cleanup_mtd);

#endif /* CONFIG_PROC_FS */


MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("Core MTD registration and access routines");