1 /*====================================================================== 2 3 $Id: slram.c,v 1.36 2005/11/07 11:14:25 gleixner Exp $ 4 5 This driver provides a method to access memory not used by the kernel 6 itself (i.e. if the kernel commandline mem=xxx is used). To actually 7 use slram at least mtdblock or mtdchar is required (for block or 8 character device access). 9 10 Usage: 11 12 if compiled as loadable module: 13 modprobe slram map=<name>,<start>,<end/offset> 14 if statically linked into the kernel use the following kernel cmd.line 15 slram=<name>,<start>,<end/offset> 16 17 <name>: name of the device that will be listed in /proc/mtd 18 <start>: start of the memory region, decimal or hex (0xabcdef) 19 <end/offset>: end of the memory region. It's possible to use +0x1234 20 to specify the offset instead of the absolute address 21 22 NOTE: 23 With slram it's only possible to map a contigous memory region. Therfore 24 if there's a device mapped somewhere in the region specified slram will 25 fail to load (see kernel log if modprobe fails). 26 27 - 28 29 Jochen Schaeuble <psionic@psionic.de> 30 31 ======================================================================*/ 32 33 34 #include <linux/module.h> 35 #include <asm/uaccess.h> 36 #include <linux/types.h> 37 #include <linux/kernel.h> 38 #include <linux/ptrace.h> 39 #include <linux/slab.h> 40 #include <linux/string.h> 41 #include <linux/timer.h> 42 #include <linux/major.h> 43 #include <linux/fs.h> 44 #include <linux/ioctl.h> 45 #include <linux/init.h> 46 #include <asm/io.h> 47 #include <asm/system.h> 48 49 #include <linux/mtd/mtd.h> 50 51 #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */ 52 #define SLRAM_BLK_SZ 0x4000 53 54 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args) 55 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args) 56 57 typedef struct slram_priv { 58 u_char *start; 59 u_char *end; 60 } slram_priv_t; 61 62 typedef struct slram_mtd_list { 63 struct mtd_info *mtdinfo; 64 struct slram_mtd_list *next; 65 } slram_mtd_list_t; 66 67 #ifdef MODULE 68 static char *map[SLRAM_MAX_DEVICES_PARAMS]; 69 70 module_param_array(map, charp, NULL, 0); 71 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\""); 72 #else 73 static char *map; 74 #endif 75 76 static slram_mtd_list_t *slram_mtdlist = NULL; 77 78 static int slram_erase(struct mtd_info *, struct erase_info *); 79 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **); 80 static void slram_unpoint(struct mtd_info *, u_char *, loff_t, size_t); 81 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *); 82 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *); 83 84 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr) 85 { 86 slram_priv_t *priv = mtd->priv; 87 88 if (instr->addr + instr->len > mtd->size) { 89 return(-EINVAL); 90 } 91 92 memset(priv->start + instr->addr, 0xff, instr->len); 93 94 /* This'll catch a few races. Free the thing before returning :) 95 * I don't feel at all ashamed. This kind of thing is possible anyway 96 * with flash, but unlikely. 97 */ 98 99 instr->state = MTD_ERASE_DONE; 100 101 mtd_erase_callback(instr); 102 103 return(0); 104 } 105 106 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len, 107 size_t *retlen, u_char **mtdbuf) 108 { 109 slram_priv_t *priv = mtd->priv; 110 111 if (from + len > mtd->size) 112 return -EINVAL; 113 114 *mtdbuf = priv->start + from; 115 *retlen = len; 116 return(0); 117 } 118 119 static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len) 120 { 121 } 122 123 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len, 124 size_t *retlen, u_char *buf) 125 { 126 slram_priv_t *priv = mtd->priv; 127 128 if (from > mtd->size) 129 return -EINVAL; 130 131 if (from + len > mtd->size) 132 len = mtd->size - from; 133 134 memcpy(buf, priv->start + from, len); 135 136 *retlen = len; 137 return(0); 138 } 139 140 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len, 141 size_t *retlen, const u_char *buf) 142 { 143 slram_priv_t *priv = mtd->priv; 144 145 if (to + len > mtd->size) 146 return -EINVAL; 147 148 memcpy(priv->start + to, buf, len); 149 150 *retlen = len; 151 return(0); 152 } 153 154 /*====================================================================*/ 155 156 static int register_device(char *name, unsigned long start, unsigned long length) 157 { 158 slram_mtd_list_t **curmtd; 159 160 curmtd = &slram_mtdlist; 161 while (*curmtd) { 162 curmtd = &(*curmtd)->next; 163 } 164 165 *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL); 166 if (!(*curmtd)) { 167 E("slram: Cannot allocate new MTD device.\n"); 168 return(-ENOMEM); 169 } 170 (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL); 171 (*curmtd)->next = NULL; 172 173 if ((*curmtd)->mtdinfo) { 174 (*curmtd)->mtdinfo->priv = 175 kzalloc(sizeof(slram_priv_t), GFP_KERNEL); 176 177 if (!(*curmtd)->mtdinfo->priv) { 178 kfree((*curmtd)->mtdinfo); 179 (*curmtd)->mtdinfo = NULL; 180 } 181 } 182 183 if (!(*curmtd)->mtdinfo) { 184 E("slram: Cannot allocate new MTD device.\n"); 185 return(-ENOMEM); 186 } 187 188 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start = 189 ioremap(start, length))) { 190 E("slram: ioremap failed\n"); 191 return -EIO; 192 } 193 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = 194 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; 195 196 197 (*curmtd)->mtdinfo->name = name; 198 (*curmtd)->mtdinfo->size = length; 199 (*curmtd)->mtdinfo->flags = MTD_CAP_RAM; 200 (*curmtd)->mtdinfo->erase = slram_erase; 201 (*curmtd)->mtdinfo->point = slram_point; 202 (*curmtd)->mtdinfo->unpoint = slram_unpoint; 203 (*curmtd)->mtdinfo->read = slram_read; 204 (*curmtd)->mtdinfo->write = slram_write; 205 (*curmtd)->mtdinfo->owner = THIS_MODULE; 206 (*curmtd)->mtdinfo->type = MTD_RAM; 207 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; 208 (*curmtd)->mtdinfo->writesize = 1; 209 210 if (add_mtd_device((*curmtd)->mtdinfo)) { 211 E("slram: Failed to register new device\n"); 212 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 213 kfree((*curmtd)->mtdinfo->priv); 214 kfree((*curmtd)->mtdinfo); 215 return(-EAGAIN); 216 } 217 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 218 (start / 1024), ((start + length) / 1024)); 219 T("slram: Mapped from 0x%p to 0x%p\n", 220 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 221 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 222 return(0); 223 } 224 225 static void unregister_devices(void) 226 { 227 slram_mtd_list_t *nextitem; 228 229 while (slram_mtdlist) { 230 nextitem = slram_mtdlist->next; 231 del_mtd_device(slram_mtdlist->mtdinfo); 232 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 233 kfree(slram_mtdlist->mtdinfo->priv); 234 kfree(slram_mtdlist->mtdinfo); 235 kfree(slram_mtdlist); 236 slram_mtdlist = nextitem; 237 } 238 } 239 240 static unsigned long handle_unit(unsigned long value, char *unit) 241 { 242 if ((*unit == 'M') || (*unit == 'm')) { 243 return(value * 1024 * 1024); 244 } else if ((*unit == 'K') || (*unit == 'k')) { 245 return(value * 1024); 246 } 247 return(value); 248 } 249 250 static int parse_cmdline(char *devname, char *szstart, char *szlength) 251 { 252 char *buffer; 253 unsigned long devstart; 254 unsigned long devlength; 255 256 if ((!devname) || (!szstart) || (!szlength)) { 257 unregister_devices(); 258 return(-EINVAL); 259 } 260 261 devstart = simple_strtoul(szstart, &buffer, 0); 262 devstart = handle_unit(devstart, buffer); 263 264 if (*(szlength) != '+') { 265 devlength = simple_strtoul(szlength, &buffer, 0); 266 devlength = handle_unit(devlength, buffer) - devstart; 267 } else { 268 devlength = simple_strtoul(szlength + 1, &buffer, 0); 269 devlength = handle_unit(devlength, buffer); 270 } 271 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 272 devname, devstart, devlength); 273 if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) { 274 E("slram: Illegal start / length parameter.\n"); 275 return(-EINVAL); 276 } 277 278 if ((devstart = register_device(devname, devstart, devlength))){ 279 unregister_devices(); 280 return((int)devstart); 281 } 282 return(0); 283 } 284 285 #ifndef MODULE 286 287 static int __init mtd_slram_setup(char *str) 288 { 289 map = str; 290 return(1); 291 } 292 293 __setup("slram=", mtd_slram_setup); 294 295 #endif 296 297 static int init_slram(void) 298 { 299 char *devname; 300 int i; 301 302 #ifndef MODULE 303 char *devstart; 304 char *devlength; 305 306 i = 0; 307 308 if (!map) { 309 E("slram: not enough parameters.\n"); 310 return(-EINVAL); 311 } 312 while (map) { 313 devname = devstart = devlength = NULL; 314 315 if (!(devname = strsep(&map, ","))) { 316 E("slram: No devicename specified.\n"); 317 break; 318 } 319 T("slram: devname = %s\n", devname); 320 if ((!map) || (!(devstart = strsep(&map, ",")))) { 321 E("slram: No devicestart specified.\n"); 322 } 323 T("slram: devstart = %s\n", devstart); 324 if ((!map) || (!(devlength = strsep(&map, ",")))) { 325 E("slram: No devicelength / -end specified.\n"); 326 } 327 T("slram: devlength = %s\n", devlength); 328 if (parse_cmdline(devname, devstart, devlength) != 0) { 329 return(-EINVAL); 330 } 331 } 332 #else 333 int count; 334 335 for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS); 336 count++) { 337 } 338 339 if ((count % 3 != 0) || (count == 0)) { 340 E("slram: not enough parameters.\n"); 341 return(-EINVAL); 342 } 343 for (i = 0; i < (count / 3); i++) { 344 devname = map[i * 3]; 345 346 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 347 return(-EINVAL); 348 } 349 350 } 351 #endif /* !MODULE */ 352 353 return(0); 354 } 355 356 static void __exit cleanup_slram(void) 357 { 358 unregister_devices(); 359 } 360 361 module_init(init_slram); 362 module_exit(cleanup_slram); 363 364 MODULE_LICENSE("GPL"); 365 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 366 MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 367