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 = kmalloc(sizeof(struct mtd_info), GFP_KERNEL); 172 (*curmtd)->next = NULL; 173 174 if ((*curmtd)->mtdinfo) { 175 memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info)); 176 (*curmtd)->mtdinfo->priv = 177 kmalloc(sizeof(slram_priv_t), GFP_KERNEL); 178 179 if (!(*curmtd)->mtdinfo->priv) { 180 kfree((*curmtd)->mtdinfo); 181 (*curmtd)->mtdinfo = NULL; 182 } else { 183 memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t)); 184 } 185 } 186 187 if (!(*curmtd)->mtdinfo) { 188 E("slram: Cannot allocate new MTD device.\n"); 189 return(-ENOMEM); 190 } 191 192 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start = 193 ioremap(start, length))) { 194 E("slram: ioremap failed\n"); 195 return -EIO; 196 } 197 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = 198 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; 199 200 201 (*curmtd)->mtdinfo->name = name; 202 (*curmtd)->mtdinfo->size = length; 203 (*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS | 204 MTD_WRITEB_WRITEABLE | MTD_VOLATILE | MTD_CAP_RAM; 205 (*curmtd)->mtdinfo->erase = slram_erase; 206 (*curmtd)->mtdinfo->point = slram_point; 207 (*curmtd)->mtdinfo->unpoint = slram_unpoint; 208 (*curmtd)->mtdinfo->read = slram_read; 209 (*curmtd)->mtdinfo->write = slram_write; 210 (*curmtd)->mtdinfo->owner = THIS_MODULE; 211 (*curmtd)->mtdinfo->type = MTD_RAM; 212 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; 213 214 if (add_mtd_device((*curmtd)->mtdinfo)) { 215 E("slram: Failed to register new device\n"); 216 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 217 kfree((*curmtd)->mtdinfo->priv); 218 kfree((*curmtd)->mtdinfo); 219 return(-EAGAIN); 220 } 221 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 222 (start / 1024), ((start + length) / 1024)); 223 T("slram: Mapped from 0x%p to 0x%p\n", 224 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 225 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 226 return(0); 227 } 228 229 static void unregister_devices(void) 230 { 231 slram_mtd_list_t *nextitem; 232 233 while (slram_mtdlist) { 234 nextitem = slram_mtdlist->next; 235 del_mtd_device(slram_mtdlist->mtdinfo); 236 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 237 kfree(slram_mtdlist->mtdinfo->priv); 238 kfree(slram_mtdlist->mtdinfo); 239 kfree(slram_mtdlist); 240 slram_mtdlist = nextitem; 241 } 242 } 243 244 static unsigned long handle_unit(unsigned long value, char *unit) 245 { 246 if ((*unit == 'M') || (*unit == 'm')) { 247 return(value * 1024 * 1024); 248 } else if ((*unit == 'K') || (*unit == 'k')) { 249 return(value * 1024); 250 } 251 return(value); 252 } 253 254 static int parse_cmdline(char *devname, char *szstart, char *szlength) 255 { 256 char *buffer; 257 unsigned long devstart; 258 unsigned long devlength; 259 260 if ((!devname) || (!szstart) || (!szlength)) { 261 unregister_devices(); 262 return(-EINVAL); 263 } 264 265 devstart = simple_strtoul(szstart, &buffer, 0); 266 devstart = handle_unit(devstart, buffer); 267 268 if (*(szlength) != '+') { 269 devlength = simple_strtoul(szlength, &buffer, 0); 270 devlength = handle_unit(devlength, buffer) - devstart; 271 } else { 272 devlength = simple_strtoul(szlength + 1, &buffer, 0); 273 devlength = handle_unit(devlength, buffer); 274 } 275 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 276 devname, devstart, devlength); 277 if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) { 278 E("slram: Illegal start / length parameter.\n"); 279 return(-EINVAL); 280 } 281 282 if ((devstart = register_device(devname, devstart, devlength))){ 283 unregister_devices(); 284 return((int)devstart); 285 } 286 return(0); 287 } 288 289 #ifndef MODULE 290 291 static int __init mtd_slram_setup(char *str) 292 { 293 map = str; 294 return(1); 295 } 296 297 __setup("slram=", mtd_slram_setup); 298 299 #endif 300 301 static int init_slram(void) 302 { 303 char *devname; 304 int i; 305 306 #ifndef MODULE 307 char *devstart; 308 char *devlength; 309 310 i = 0; 311 312 if (!map) { 313 E("slram: not enough parameters.\n"); 314 return(-EINVAL); 315 } 316 while (map) { 317 devname = devstart = devlength = NULL; 318 319 if (!(devname = strsep(&map, ","))) { 320 E("slram: No devicename specified.\n"); 321 break; 322 } 323 T("slram: devname = %s\n", devname); 324 if ((!map) || (!(devstart = strsep(&map, ",")))) { 325 E("slram: No devicestart specified.\n"); 326 } 327 T("slram: devstart = %s\n", devstart); 328 if ((!map) || (!(devlength = strsep(&map, ",")))) { 329 E("slram: No devicelength / -end specified.\n"); 330 } 331 T("slram: devlength = %s\n", devlength); 332 if (parse_cmdline(devname, devstart, devlength) != 0) { 333 return(-EINVAL); 334 } 335 } 336 #else 337 int count; 338 339 for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS); 340 count++) { 341 } 342 343 if ((count % 3 != 0) || (count == 0)) { 344 E("slram: not enough parameters.\n"); 345 return(-EINVAL); 346 } 347 for (i = 0; i < (count / 3); i++) { 348 devname = map[i * 3]; 349 350 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 351 return(-EINVAL); 352 } 353 354 } 355 #endif /* !MODULE */ 356 357 return(0); 358 } 359 360 static void __exit cleanup_slram(void) 361 { 362 unregister_devices(); 363 } 364 365 module_init(init_slram); 366 module_exit(cleanup_slram); 367 368 MODULE_LICENSE("GPL"); 369 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 370 MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 371