drivers/mtd/devices/mtdram.c

   1 /*
   2  * mtdram - a test mtd device
   3  * Author: Alexander Larsson <alex@cendio.se>
   4  *
   5  * Copyright (c) 1999 Alexander Larsson <alex@cendio.se>
   6  * Copyright (c) 2005 Joern Engel <joern@wh.fh-wedel.de>
   7  *
   8  * This code is GPL
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/ioport.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mm.h>
  17 #include <linux/init.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/mtd/mtdram.h>
  20
  21 static unsigned long total_size = CONFIG_MTDRAM_TOTAL_SIZE;
  22 static unsigned long erase_size = CONFIG_MTDRAM_ERASE_SIZE;
  23 static unsigned long writebuf_size = 64;
  24 #define MTDRAM_TOTAL_SIZE (total_size * 1024)
  25 #define MTDRAM_ERASE_SIZE (erase_size * 1024)
  26
  27 #ifdef MODULE
  28 module_param(total_size, ulong, 0);
  29 MODULE_PARM_DESC(total_size, "Total device size in KiB");
  30 module_param(erase_size, ulong, 0);
  31 MODULE_PARM_DESC(erase_size, "Device erase block size in KiB");
  32 module_param(writebuf_size, ulong, 0);
  33 MODULE_PARM_DESC(writebuf_size, "Device write buf size in Bytes (Default: 64)");
  34 #endif
  35
  36 // We could store these in the mtd structure, but we only support 1 device..
  37 static struct mtd_info *mtd_info;
  38
  39 static int check_offs_len(struct mtd_info *mtd, loff_t ofs, uint64_t len)
  40 {
  41         int ret = 0;
  42
  43         /* Start address must align on block boundary */
  44         if (mtd_mod_by_eb(ofs, mtd)) {
  45                 pr_debug("%s: unaligned address\n", __func__);
  46                 ret = -EINVAL;
  47         }
  48
  49         /* Length must align on block boundary */
  50         if (mtd_mod_by_eb(len, mtd)) {
  51                 pr_debug("%s: length not block aligned\n", __func__);
  52                 ret = -EINVAL;
  53         }
  54
  55         return ret;
  56 }
  57
  58 static int ram_erase(struct mtd_info *mtd, struct erase_info *instr)
  59 {
  60         if (check_offs_len(mtd, instr->addr, instr->len))
  61                 return -EINVAL;
  62         memset((char *)mtd->priv + instr->addr, 0xff, instr->len);
  63
  64         return 0;
  65 }
  66
  67 static int ram_point(struct mtd_info *mtd, loff_t from, size_t len,
  68                 size_t *retlen, void **virt, resource_size_t *phys)
  69 {
  70         *virt = mtd->priv + from;
  71         *retlen = len;
  72
  73         if (phys) {
  74                 /* limit retlen to the number of contiguous physical pages */
  75                 unsigned long page_ofs = offset_in_page(*virt);
  76                 void *addr = *virt - page_ofs;
  77                 unsigned long pfn1, pfn0 = vmalloc_to_pfn(addr);
  78
  79                 *phys = __pfn_to_phys(pfn0) + page_ofs;
  80                 len += page_ofs;
  81                 while (len > PAGE_SIZE) {
  82                         len -= PAGE_SIZE;
  83                         addr += PAGE_SIZE;
  84                         pfn0++;
  85                         pfn1 = vmalloc_to_pfn(addr);
  86                         if (pfn1 != pfn0) {
  87                                 *retlen = addr - *virt;
  88                                 break;
  89                         }
  90                 }
  91         }
  92
  93         return 0;
  94 }
  95
  96 static int ram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  97 {
  98         return 0;
  99 }
 100
 101 static int ram_read(struct mtd_info *mtd, loff_t from, size_t len,
 102                 size_t *retlen, u_char *buf)
 103 {
 104         memcpy(buf, mtd->priv + from, len);
 105         *retlen = len;
 106         return 0;
 107 }
 108
 109 static int ram_write(struct mtd_info *mtd, loff_t to, size_t len,
 110                 size_t *retlen, const u_char *buf)
 111 {
 112         memcpy((char *)mtd->priv + to, buf, len);
 113         *retlen = len;
 114         return 0;
 115 }
 116
 117 static void __exit cleanup_mtdram(void)
 118 {
 119         if (mtd_info) {
 120                 mtd_device_unregister(mtd_info);
 121                 vfree(mtd_info->priv);
 122                 kfree(mtd_info);
 123         }
 124 }
 125
 126 int mtdram_init_device(struct mtd_info *mtd, void *mapped_address,
 127                 unsigned long size, const char *name)
 128 {
 129         memset(mtd, 0, sizeof(*mtd));
 130
 131         /* Setup the MTD structure */
 132         mtd->name = name;
 133         mtd->type = MTD_RAM;
 134         mtd->flags = MTD_CAP_RAM;
 135         mtd->size = size;
 136         mtd->writesize = 1;
 137         mtd->writebufsize = writebuf_size;
 138         mtd->erasesize = MTDRAM_ERASE_SIZE;
 139         mtd->priv = mapped_address;
 140
 141         mtd->owner = THIS_MODULE;
 142         mtd->_erase = ram_erase;
 143         mtd->_point = ram_point;
 144         mtd->_unpoint = ram_unpoint;
 145         mtd->_read = ram_read;
 146         mtd->_write = ram_write;
 147
 148         if (mtd_device_register(mtd, NULL, 0))
 149                 return -EIO;
 150
 151         return 0;
 152 }
 153
 154 static int __init init_mtdram(void)
 155 {
 156         void *addr;
 157         int err;
 158
 159         if (!total_size)
 160                 return -EINVAL;
 161
 162         /* Allocate some memory */
 163         mtd_info = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
 164         if (!mtd_info)
 165                 return -ENOMEM;
 166
 167         addr = vmalloc(MTDRAM_TOTAL_SIZE);
 168         if (!addr) {
 169                 kfree(mtd_info);
 170                 mtd_info = NULL;
 171                 return -ENOMEM;
 172         }
 173         err = mtdram_init_device(mtd_info, addr, MTDRAM_TOTAL_SIZE, "mtdram test device");
 174         if (err) {
 175                 vfree(addr);
 176                 kfree(mtd_info);
 177                 mtd_info = NULL;
 178                 return err;
 179         }
 180         memset(mtd_info->priv, 0xff, MTDRAM_TOTAL_SIZE);
 181         return err;
 182 }
 183
 184 module_init(init_mtdram);
 185 module_exit(cleanup_mtdram);
 186
 187 MODULE_LICENSE("GPL");
 188 MODULE_AUTHOR("Alexander Larsson <alexl@redhat.com>");
 189 MODULE_DESCRIPTION("Simulated MTD driver for testing");