drivers/mtd/mtdcore.c

   1 /*
   2  * Core registration and callback routines for MTD
   3  * drivers and users.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/mtd/mtd.h>
  11 #include <linux/mtd/compat.h>
  12 #include <ubi_uboot.h>
  13
  14 struct mtd_info *mtd_table[MAX_MTD_DEVICES];
  15
  16 int add_mtd_device(struct mtd_info *mtd)
  17 {
  18         int i;
  19
  20         BUG_ON(mtd->writesize == 0);
  21
  22         for (i = 0; i < MAX_MTD_DEVICES; i++)
  23                 if (!mtd_table[i]) {
  24                         mtd_table[i] = mtd;
  25                         mtd->index = i;
  26                         mtd->usecount = 0;
  27
  28                         /* No need to get a refcount on the module containing
  29                            the notifier, since we hold the mtd_table_mutex */
  30
  31                         /* We _know_ we aren't being removed, because
  32                            our caller is still holding us here. So none
  33                            of this try_ nonsense, and no bitching about it
  34                            either. :) */
  35                         return 0;
  36                 }
  37
  38         return 1;
  39 }
  40
  41 /**
  42  *      del_mtd_device - unregister an MTD device
  43  *      @mtd: pointer to MTD device info structure
  44  *
  45  *      Remove a device from the list of MTD devices present in the system,
  46  *      and notify each currently active MTD 'user' of its departure.
  47  *      Returns zero on success or 1 on failure, which currently will happen
  48  *      if the requested device does not appear to be present in the list.
  49  */
  50 int del_mtd_device(struct mtd_info *mtd)
  51 {
  52         int ret;
  53
  54         if (mtd_table[mtd->index] != mtd) {
  55                 ret = -ENODEV;
  56         } else if (mtd->usecount) {
  57                 printk(KERN_NOTICE "Removing MTD device #%d (%s)"
  58                                 " with use count %d\n",
  59                                 mtd->index, mtd->name, mtd->usecount);
  60                 ret = -EBUSY;
  61         } else {
  62                 /* No need to get a refcount on the module containing
  63                  * the notifier, since we hold the mtd_table_mutex */
  64                 mtd_table[mtd->index] = NULL;
  65
  66                 ret = 0;
  67         }
  68
  69         return ret;
  70 }
  71
  72 /**
  73  *      get_mtd_device - obtain a validated handle for an MTD device
  74  *      @mtd: last known address of the required MTD device
  75  *      @num: internal device number of the required MTD device
  76  *
  77  *      Given a number and NULL address, return the num'th entry in the device
  78  *      table, if any.  Given an address and num == -1, search the device table
  79  *      for a device with that address and return if it's still present. Given
  80  *      both, return the num'th driver only if its address matches. Return
  81  *      error code if not.
  82  */
  83 struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
  84 {
  85         struct mtd_info *ret = NULL;
  86         int i, err = -ENODEV;
  87
  88         if (num == -1) {
  89                 for (i = 0; i < MAX_MTD_DEVICES; i++)
  90                         if (mtd_table[i] == mtd)
  91                                 ret = mtd_table[i];
  92         } else if (num < MAX_MTD_DEVICES) {
  93                 ret = mtd_table[num];
  94                 if (mtd && mtd != ret)
  95                         ret = NULL;
  96         }
  97
  98         if (!ret)
  99                 goto out_unlock;
 100
 101         ret->usecount++;
 102         return ret;
 103
 104 out_unlock:
 105         return ERR_PTR(err);
 106 }
 107
 108 /**
 109  *      get_mtd_device_nm - obtain a validated handle for an MTD device by
 110  *      device name
 111  *      @name: MTD device name to open
 112  *
 113  *      This function returns MTD device description structure in case of
 114  *      success and an error code in case of failure.
 115  */
 116 struct mtd_info *get_mtd_device_nm(const char *name)
 117 {
 118         int i, err = -ENODEV;
 119         struct mtd_info *mtd = NULL;
 120
 121         for (i = 0; i < MAX_MTD_DEVICES; i++) {
 122                 if (mtd_table[i] && !strcmp(name, mtd_table[i]->name)) {
 123                         mtd = mtd_table[i];
 124                         break;
 125                 }
 126         }
 127
 128         if (!mtd)
 129                 goto out_unlock;
 130
 131         mtd->usecount++;
 132         return mtd;
 133
 134 out_unlock:
 135         return ERR_PTR(err);
 136 }
 137
 138 void put_mtd_device(struct mtd_info *mtd)
 139 {
 140         int c;
 141
 142         c = --mtd->usecount;
 143         BUG_ON(c < 0);
 144 }