1 /*====================================================================== 2 3 This driver provides a method to access memory not used by the kernel 4 itself (i.e. if the kernel commandline mem=xxx is used). To actually 5 use slram at least mtdblock or mtdchar is required (for block or 6 character device access). 7 8 Usage: 9 10 if compiled as loadable module: 11 modprobe slram map=<name>,<start>,<end/offset> 12 if statically linked into the kernel use the following kernel cmd.line 13 slram=<name>,<start>,<end/offset> 14 15 <name>: name of the device that will be listed in /proc/mtd 16 <start>: start of the memory region, decimal or hex (0xabcdef) 17 <end/offset>: end of the memory region. It's possible to use +0x1234 18 to specify the offset instead of the absolute address 19 20 NOTE: 21 With slram it's only possible to map a contigous memory region. Therfore 22 if there's a device mapped somewhere in the region specified slram will 23 fail to load (see kernel log if modprobe fails). 24 25 - 26 27 Jochen Schaeuble <psionic@psionic.de> 28 29 ======================================================================*/ 30 31 32 #include <linux/module.h> 33 #include <asm/uaccess.h> 34 #include <linux/types.h> 35 #include <linux/kernel.h> 36 #include <linux/ptrace.h> 37 #include <linux/slab.h> 38 #include <linux/string.h> 39 #include <linux/timer.h> 40 #include <linux/major.h> 41 #include <linux/fs.h> 42 #include <linux/ioctl.h> 43 #include <linux/init.h> 44 #include <asm/io.h> 45 #include <asm/system.h> 46 47 #include <linux/mtd/mtd.h> 48 49 #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */ 50 #define SLRAM_BLK_SZ 0x4000 51 52 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args) 53 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args) 54 55 typedef struct slram_priv { 56 u_char *start; 57 u_char *end; 58 } slram_priv_t; 59 60 typedef struct slram_mtd_list { 61 struct mtd_info *mtdinfo; 62 struct slram_mtd_list *next; 63 } slram_mtd_list_t; 64 65 #ifdef MODULE 66 static char *map[SLRAM_MAX_DEVICES_PARAMS]; 67 68 module_param_array(map, charp, NULL, 0); 69 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\""); 70 #else 71 static char *map; 72 #endif 73 74 static slram_mtd_list_t *slram_mtdlist = NULL; 75 76 static int slram_erase(struct mtd_info *, struct erase_info *); 77 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **, 78 resource_size_t *); 79 static void slram_unpoint(struct mtd_info *, loff_t, size_t); 80 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *); 81 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *); 82 83 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr) 84 { 85 slram_priv_t *priv = mtd->priv; 86 87 if (instr->addr + instr->len > mtd->size) { 88 return(-EINVAL); 89 } 90 91 memset(priv->start + instr->addr, 0xff, instr->len); 92 93 /* This'll catch a few races. Free the thing before returning :) 94 * I don't feel at all ashamed. This kind of thing is possible anyway 95 * with flash, but unlikely. 96 */ 97 98 instr->state = MTD_ERASE_DONE; 99 100 mtd_erase_callback(instr); 101 102 return(0); 103 } 104 105 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len, 106 size_t *retlen, void **virt, resource_size_t *phys) 107 { 108 slram_priv_t *priv = mtd->priv; 109 110 /* can we return a physical address with this driver? */ 111 if (phys) 112 return -EINVAL; 113 114 if (from + len > mtd->size) 115 return -EINVAL; 116 117 *virt = priv->start + from; 118 *retlen = len; 119 return(0); 120 } 121 122 static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len) 123 { 124 } 125 126 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len, 127 size_t *retlen, u_char *buf) 128 { 129 slram_priv_t *priv = mtd->priv; 130 131 if (from > mtd->size) 132 return -EINVAL; 133 134 if (from + len > mtd->size) 135 len = mtd->size - from; 136 137 memcpy(buf, priv->start + from, len); 138 139 *retlen = len; 140 return(0); 141 } 142 143 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len, 144 size_t *retlen, const u_char *buf) 145 { 146 slram_priv_t *priv = mtd->priv; 147 148 if (to + len > mtd->size) 149 return -EINVAL; 150 151 memcpy(priv->start + to, buf, len); 152 153 *retlen = len; 154 return(0); 155 } 156 157 /*====================================================================*/ 158 159 static int register_device(char *name, unsigned long start, unsigned long length) 160 { 161 slram_mtd_list_t **curmtd; 162 163 curmtd = &slram_mtdlist; 164 while (*curmtd) { 165 curmtd = &(*curmtd)->next; 166 } 167 168 *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL); 169 if (!(*curmtd)) { 170 E("slram: Cannot allocate new MTD device.\n"); 171 return(-ENOMEM); 172 } 173 (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL); 174 (*curmtd)->next = NULL; 175 176 if ((*curmtd)->mtdinfo) { 177 (*curmtd)->mtdinfo->priv = 178 kzalloc(sizeof(slram_priv_t), GFP_KERNEL); 179 180 if (!(*curmtd)->mtdinfo->priv) { 181 kfree((*curmtd)->mtdinfo); 182 (*curmtd)->mtdinfo = NULL; 183 } 184 } 185 186 if (!(*curmtd)->mtdinfo) { 187 E("slram: Cannot allocate new MTD device.\n"); 188 return(-ENOMEM); 189 } 190 191 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start = 192 ioremap(start, length))) { 193 E("slram: ioremap failed\n"); 194 return -EIO; 195 } 196 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = 197 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; 198 199 200 (*curmtd)->mtdinfo->name = name; 201 (*curmtd)->mtdinfo->size = length; 202 (*curmtd)->mtdinfo->flags = MTD_CAP_RAM; 203 (*curmtd)->mtdinfo->erase = slram_erase; 204 (*curmtd)->mtdinfo->point = slram_point; 205 (*curmtd)->mtdinfo->unpoint = slram_unpoint; 206 (*curmtd)->mtdinfo->read = slram_read; 207 (*curmtd)->mtdinfo->write = slram_write; 208 (*curmtd)->mtdinfo->owner = THIS_MODULE; 209 (*curmtd)->mtdinfo->type = MTD_RAM; 210 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; 211 (*curmtd)->mtdinfo->writesize = 1; 212 213 if (add_mtd_device((*curmtd)->mtdinfo)) { 214 E("slram: Failed to register new device\n"); 215 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 216 kfree((*curmtd)->mtdinfo->priv); 217 kfree((*curmtd)->mtdinfo); 218 return(-EAGAIN); 219 } 220 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 221 (start / 1024), ((start + length) / 1024)); 222 T("slram: Mapped from 0x%p to 0x%p\n", 223 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 224 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 225 return(0); 226 } 227 228 static void unregister_devices(void) 229 { 230 slram_mtd_list_t *nextitem; 231 232 while (slram_mtdlist) { 233 nextitem = slram_mtdlist->next; 234 del_mtd_device(slram_mtdlist->mtdinfo); 235 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 236 kfree(slram_mtdlist->mtdinfo->priv); 237 kfree(slram_mtdlist->mtdinfo); 238 kfree(slram_mtdlist); 239 slram_mtdlist = nextitem; 240 } 241 } 242 243 static unsigned long handle_unit(unsigned long value, char *unit) 244 { 245 if ((*unit == 'M') || (*unit == 'm')) { 246 return(value * 1024 * 1024); 247 } else if ((*unit == 'K') || (*unit == 'k')) { 248 return(value * 1024); 249 } 250 return(value); 251 } 252 253 static int parse_cmdline(char *devname, char *szstart, char *szlength) 254 { 255 char *buffer; 256 unsigned long devstart; 257 unsigned long devlength; 258 259 if ((!devname) || (!szstart) || (!szlength)) { 260 unregister_devices(); 261 return(-EINVAL); 262 } 263 264 devstart = simple_strtoul(szstart, &buffer, 0); 265 devstart = handle_unit(devstart, buffer); 266 267 if (*(szlength) != '+') { 268 devlength = simple_strtoul(szlength, &buffer, 0); 269 devlength = handle_unit(devlength, buffer) - devstart; 270 if (devlength < devstart) 271 goto err_out; 272 273 devlength -= devstart; 274 } else { 275 devlength = simple_strtoul(szlength + 1, &buffer, 0); 276 devlength = handle_unit(devlength, buffer); 277 } 278 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 279 devname, devstart, devlength); 280 if (devlength % SLRAM_BLK_SZ != 0) 281 goto err_out; 282 283 if ((devstart = register_device(devname, devstart, devlength))){ 284 unregister_devices(); 285 return((int)devstart); 286 } 287 return(0); 288 289 err_out: 290 E("slram: Illegal length parameter.\n"); 291 return(-EINVAL); 292 } 293 294 #ifndef MODULE 295 296 static int __init mtd_slram_setup(char *str) 297 { 298 map = str; 299 return(1); 300 } 301 302 __setup("slram=", mtd_slram_setup); 303 304 #endif 305 306 static int __init init_slram(void) 307 { 308 char *devname; 309 int i; 310 311 #ifndef MODULE 312 char *devstart; 313 char *devlength; 314 315 i = 0; 316 317 if (!map) { 318 E("slram: not enough parameters.\n"); 319 return(-EINVAL); 320 } 321 while (map) { 322 devname = devstart = devlength = NULL; 323 324 if (!(devname = strsep(&map, ","))) { 325 E("slram: No devicename specified.\n"); 326 break; 327 } 328 T("slram: devname = %s\n", devname); 329 if ((!map) || (!(devstart = strsep(&map, ",")))) { 330 E("slram: No devicestart specified.\n"); 331 } 332 T("slram: devstart = %s\n", devstart); 333 if ((!map) || (!(devlength = strsep(&map, ",")))) { 334 E("slram: No devicelength / -end specified.\n"); 335 } 336 T("slram: devlength = %s\n", devlength); 337 if (parse_cmdline(devname, devstart, devlength) != 0) { 338 return(-EINVAL); 339 } 340 } 341 #else 342 int count; 343 344 for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count]; 345 count++) { 346 } 347 348 if ((count % 3 != 0) || (count == 0)) { 349 E("slram: not enough parameters.\n"); 350 return(-EINVAL); 351 } 352 for (i = 0; i < (count / 3); i++) { 353 devname = map[i * 3]; 354 355 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 356 return(-EINVAL); 357 } 358 359 } 360 #endif /* !MODULE */ 361 362 return(0); 363 } 364 365 static void __exit cleanup_slram(void) 366 { 367 unregister_devices(); 368 } 369 370 module_init(init_slram); 371 module_exit(cleanup_slram); 372 373 MODULE_LICENSE("GPL"); 374 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 375 MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 376