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 } 145