drivers/mtd/mtdcore.c

   1 /*
   2  * $Id: mtdcore.c,v 1.47 2005/11/07 11:14:20 gleixner Exp $
   3  *
   4  * Core registration and callback routines for MTD
   5  * drivers and users.
   6  *
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/slab.h>
  14 #include <linux/string.h>
  15 #include <linux/timer.h>
  16 #include <linux/major.h>
  17 #include <linux/fs.h>
  18 #include <linux/ioctl.h>
  19 #include <linux/init.h>
  20 #include <linux/mtd/compatmac.h>
  21 #include <linux/proc_fs.h>
  22
  23 #include <linux/mtd/mtd.h>
  24
  25 /* These are exported solely for the purpose of mtd_blkdevs.c. You
  26    should not use them for _anything_ else */
  27 DEFINE_MUTEX(mtd_table_mutex);
  28 struct mtd_info *mtd_table[MAX_MTD_DEVICES];
  29
  30 EXPORT_SYMBOL_GPL(mtd_table_mutex);
  31 EXPORT_SYMBOL_GPL(mtd_table);
  32
  33 static LIST_HEAD(mtd_notifiers);
  34
  35 /**
  36  *      add_mtd_device - register an MTD device
  37  *      @mtd: pointer to new MTD device info structure
  38  *
  39  *      Add a device to the list of MTD devices present in the system, and
  40  *      notify each currently active MTD 'user' of its arrival. Returns
  41  *      zero on success or 1 on failure, which currently will only happen
  42  *      if the number of present devices exceeds MAX_MTD_DEVICES (i.e. 16)
  43  */
  44
  45 int add_mtd_device(struct mtd_info *mtd)
  46 {
  47         int i;
  48
  49         BUG_ON(mtd->writesize == 0);
  50         mutex_lock(&mtd_table_mutex);
  51
  52         for (i=0; i < MAX_MTD_DEVICES; i++)
  53                 if (!mtd_table[i]) {
  54                         struct list_head *this;
  55
  56                         mtd_table[i] = mtd;
  57                         mtd->index = i;
  58                         mtd->usecount = 0;
  59
  60                         DEBUG(0, "mtd: Giving out device %d to %s\n",i, mtd->name);
  61                         /* No need to get a refcount on the module containing
  62                            the notifier, since we hold the mtd_table_mutex */
  63                         list_for_each(this, &mtd_notifiers) {
  64                                 struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list);
  65                                 not->add(mtd);
  66                         }
  67
  68                         mutex_unlock(&mtd_table_mutex);
  69                         /* We _know_ we aren't being removed, because
  70                            our caller is still holding us here. So none
  71                            of this try_ nonsense, and no bitching about it
  72                            either. :) */
  73                         __module_get(THIS_MODULE);
  74                         return 0;
  75                 }
  76
  77         mutex_unlock(&mtd_table_mutex);
  78         return 1;
  79 }
  80
  81 /**
  82  *      del_mtd_device - unregister an MTD device
  83  *      @mtd: pointer to MTD device info structure
  84  *
  85  *      Remove a device from the list of MTD devices present in the system,
  86  *      and notify each currently active MTD 'user' of its departure.
  87  *      Returns zero on success or 1 on failure, which currently will happen
  88  *      if the requested device does not appear to be present in the list.
  89  */
  90
  91 int del_mtd_device (struct mtd_info *mtd)
  92 {
  93         int ret;
  94
  95         mutex_lock(&mtd_table_mutex);
  96
  97         if (mtd_table[mtd->index] != mtd) {
  98                 ret = -ENODEV;
  99         } else if (mtd->usecount) {
 100                 printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
 101                        mtd->index, mtd->name, mtd->usecount);
 102                 ret = -EBUSY;
 103         } else {
 104                 struct list_head *this;
 105
 106                 /* No need to get a refcount on the module containing
 107                    the notifier, since we hold the mtd_table_mutex */
 108                 list_for_each(this, &mtd_notifiers) {
 109                         struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list);
 110                         not->remove(mtd);
 111                 }
 112
 113                 mtd_table[mtd->index] = NULL;
 114
 115                 module_put(THIS_MODULE);
 116                 ret = 0;
 117         }
 118
 119         mutex_unlock(&mtd_table_mutex);
 120         return ret;
 121 }
 122
 123 /**
 124  *      register_mtd_user - register a 'user' of MTD devices.
 125  *      @new: pointer to notifier info structure
 126  *
 127  *      Registers a pair of callbacks function to be called upon addition
 128  *      or removal of MTD devices. Causes the 'add' callback to be immediately
 129  *      invoked for each MTD device currently present in the system.
 130  */
 131
 132 void register_mtd_user (struct mtd_notifier *new)
 133 {
 134         int i;
 135
 136         mutex_lock(&mtd_table_mutex);
 137
 138         list_add(&new->list, &mtd_notifiers);
 139
 140         __module_get(THIS_MODULE);
 141
 142         for (i=0; i< MAX_MTD_DEVICES; i++)
 143                 if (mtd_table[i])
 144                         new->add(mtd_table[i]);
 145
 146         mutex_unlock(&mtd_table_mutex);
 147 }
 148
 149 /**
 150  *      unregister_mtd_user - unregister a 'user' of MTD devices.
 151  *      @old: pointer to notifier info structure
 152  *
 153  *      Removes a callback function pair from the list of 'users' to be
 154  *      notified upon addition or removal of MTD devices. Causes the
 155  *      'remove' callback to be immediately invoked for each MTD device
 156  *      currently present in the system.
 157  */
 158
 159 int unregister_mtd_user (struct mtd_notifier *old)
 160 {
 161         int i;
 162
 163         mutex_lock(&mtd_table_mutex);
 164
 165         module_put(THIS_MODULE);
 166
 167         for (i=0; i< MAX_MTD_DEVICES; i++)
 168                 if (mtd_table[i])
 169                         old->remove(mtd_table[i]);
 170
 171         list_del(&old->list);
 172         mutex_unlock(&mtd_table_mutex);
 173         return 0;
 174 }
 175
 176
 177 /**
 178  *      get_mtd_device - obtain a validated handle for an MTD device
 179  *      @mtd: last known address of the required MTD device
 180  *      @num: internal device number of the required MTD device
 181  *
 182  *      Given a number and NULL address, return the num'th entry in the device
 183  *      table, if any.  Given an address and num == -1, search the device table
 184  *      for a device with that address and return if it's still present. Given
 185  *      both, return the num'th driver only if its address matches. Return NULL
 186  *      if not.
 187  */
 188
 189 struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
 190 {
 191         struct mtd_info *ret = NULL;
 192         int i;
 193
 194         mutex_lock(&mtd_table_mutex);
 195
 196         if (num == -1) {
 197                 for (i=0; i< MAX_MTD_DEVICES; i++)
 198                         if (mtd_table[i] == mtd)
 199                                 ret = mtd_table[i];
 200         } else if (num < MAX_MTD_DEVICES) {
 201                 ret = mtd_table[num];
 202                 if (mtd && mtd != ret)
 203                         ret = NULL;
 204         }
 205
 206         if (ret && !try_module_get(ret->owner))
 207                 ret = NULL;
 208
 209         if (ret)
 210                 ret->usecount++;
 211
 212         mutex_unlock(&mtd_table_mutex);
 213         return ret;
 214 }
 215
 216 void put_mtd_device(struct mtd_info *mtd)
 217 {
 218         int c;
 219
 220         mutex_lock(&mtd_table_mutex);
 221         c = --mtd->usecount;
 222         mutex_unlock(&mtd_table_mutex);
 223         BUG_ON(c < 0);
 224
 225         module_put(mtd->owner);
 226 }
 227
 228 /* default_mtd_writev - default mtd writev method for MTD devices that
 229  *                      dont implement their own
 230  */
 231
 232 int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
 233                        unsigned long count, loff_t to, size_t *retlen)
 234 {
 235         unsigned long i;
 236         size_t totlen = 0, thislen;
 237         int ret = 0;
 238
 239         if(!mtd->write) {
 240                 ret = -EROFS;
 241         } else {
 242                 for (i=0; i<count; i++) {
 243                         if (!vecs[i].iov_len)
 244                                 continue;
 245                         ret = mtd->write(mtd, to, vecs[i].iov_len, &thislen, vecs[i].iov_base);
 246                         totlen += thislen;
 247                         if (ret || thislen != vecs[i].iov_len)
 248                                 break;
 249                         to += vecs[i].iov_len;
 250                 }
 251         }
 252         if (retlen)
 253                 *retlen = totlen;
 254         return ret;
 255 }
 256
 257 EXPORT_SYMBOL(add_mtd_device);
 258 EXPORT_SYMBOL(del_mtd_device);
 259 EXPORT_SYMBOL(get_mtd_device);
 260 EXPORT_SYMBOL(put_mtd_device);
 261 EXPORT_SYMBOL(register_mtd_user);
 262 EXPORT_SYMBOL(unregister_mtd_user);
 263 EXPORT_SYMBOL(default_mtd_writev);
 264
 265 #ifdef CONFIG_PROC_FS
 266
 267 /*====================================================================*/
 268 /* Support for /proc/mtd */
 269
 270 static struct proc_dir_entry *proc_mtd;
 271
 272 static inline int mtd_proc_info (char *buf, int i)
 273 {
 274         struct mtd_info *this = mtd_table[i];
 275
 276         if (!this)
 277                 return 0;
 278
 279         return sprintf(buf, "mtd%d: %8.8x %8.8x \"%s\"\n", i, this->size,
 280                        this->erasesize, this->name);
 281 }
 282
 283 static int mtd_read_proc (char *page, char **start, off_t off, int count,
 284                           int *eof, void *data_unused)
 285 {
 286         int len, l, i;
 287         off_t   begin = 0;
 288
 289         mutex_lock(&mtd_table_mutex);
 290
 291         len = sprintf(page, "dev:    size   erasesize  name\n");
 292         for (i=0; i< MAX_MTD_DEVICES; i++) {
 293
 294                 l = mtd_proc_info(page + len, i);
 295                 len += l;
 296                 if (len+begin > off+count)
 297                         goto done;
 298                 if (len+begin < off) {
 299                         begin += len;
 300                         len = 0;
 301                 }
 302         }
 303
 304         *eof = 1;
 305
 306 done:
 307         mutex_unlock(&mtd_table_mutex);
 308         if (off >= len+begin)
 309                 return 0;
 310         *start = page + (off-begin);
 311         return ((count < begin+len-off) ? count : begin+len-off);
 312 }
 313
 314 /*====================================================================*/
 315 /* Init code */
 316
 317 static int __init init_mtd(void)
 318 {
 319         if ((proc_mtd = create_proc_entry( "mtd", 0, NULL )))
 320                 proc_mtd->read_proc = mtd_read_proc;
 321         return 0;
 322 }
 323
 324 static void __exit cleanup_mtd(void)
 325 {
 326         if (proc_mtd)
 327                 remove_proc_entry( "mtd", NULL);
 328 }
 329
 330 module_init(init_mtd);
 331 module_exit(cleanup_mtd);
 332
 333 #endif /* CONFIG_PROC_FS */
 334
 335
 336 MODULE_LICENSE("GPL");
 337 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 338 MODULE_DESCRIPTION("Core MTD registration and access routines");