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