1 /*====================================================================== 2 3 $Id: slram.c,v 1.33 2005/01/05 18:05:13 dwmw2 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 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 *mtdbuf = priv->start + from; 112 *retlen = len; 113 return(0); 114 } 115 116 static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len) 117 { 118 } 119 120 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len, 121 size_t *retlen, u_char *buf) 122 { 123 slram_priv_t *priv = mtd->priv; 124 125 memcpy(buf, priv->start + from, len); 126 127 *retlen = len; 128 return(0); 129 } 130 131 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len, 132 size_t *retlen, const u_char *buf) 133 { 134 slram_priv_t *priv = mtd->priv; 135 136 memcpy(priv->start + to, buf, len); 137 138 *retlen = len; 139 return(0); 140 } 141 142 /*====================================================================*/ 143 144 static int register_device(char *name, unsigned long start, unsigned long length) 145 { 146 slram_mtd_list_t **curmtd; 147 148 curmtd = &slram_mtdlist; 149 while (*curmtd) { 150 curmtd = &(*curmtd)->next; 151 } 152 153 *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL); 154 if (!(*curmtd)) { 155 E("slram: Cannot allocate new MTD device.\n"); 156 return(-ENOMEM); 157 } 158 (*curmtd)->mtdinfo = kmalloc(sizeof(struct mtd_info), GFP_KERNEL); 159 (*curmtd)->next = NULL; 160 161 if ((*curmtd)->mtdinfo) { 162 memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info)); 163 (*curmtd)->mtdinfo->priv = 164 kmalloc(sizeof(slram_priv_t), GFP_KERNEL); 165 166 if (!(*curmtd)->mtdinfo->priv) { 167 kfree((*curmtd)->mtdinfo); 168 (*curmtd)->mtdinfo = NULL; 169 } else { 170 memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t)); 171 } 172 } 173 174 if (!(*curmtd)->mtdinfo) { 175 E("slram: Cannot allocate new MTD device.\n"); 176 return(-ENOMEM); 177 } 178 179 if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start = 180 ioremap(start, length))) { 181 E("slram: ioremap failed\n"); 182 return -EIO; 183 } 184 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = 185 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; 186 187 188 (*curmtd)->mtdinfo->name = name; 189 (*curmtd)->mtdinfo->size = length; 190 (*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS | 191 MTD_WRITEB_WRITEABLE | MTD_VOLATILE; 192 (*curmtd)->mtdinfo->erase = slram_erase; 193 (*curmtd)->mtdinfo->point = slram_point; 194 (*curmtd)->mtdinfo->unpoint = slram_unpoint; 195 (*curmtd)->mtdinfo->read = slram_read; 196 (*curmtd)->mtdinfo->write = slram_write; 197 (*curmtd)->mtdinfo->owner = THIS_MODULE; 198 (*curmtd)->mtdinfo->type = MTD_RAM; 199 (*curmtd)->mtdinfo->erasesize = 0x0; 200 201 if (add_mtd_device((*curmtd)->mtdinfo)) { 202 E("slram: Failed to register new device\n"); 203 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 204 kfree((*curmtd)->mtdinfo->priv); 205 kfree((*curmtd)->mtdinfo); 206 return(-EAGAIN); 207 } 208 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 209 (start / 1024), ((start + length) / 1024)); 210 T("slram: Mapped from 0x%p to 0x%p\n", 211 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 212 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 213 return(0); 214 } 215 216 static void unregister_devices(void) 217 { 218 slram_mtd_list_t *nextitem; 219 220 while (slram_mtdlist) { 221 nextitem = slram_mtdlist->next; 222 del_mtd_device(slram_mtdlist->mtdinfo); 223 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 224 kfree(slram_mtdlist->mtdinfo->priv); 225 kfree(slram_mtdlist->mtdinfo); 226 kfree(slram_mtdlist); 227 slram_mtdlist = nextitem; 228 } 229 } 230 231 static unsigned long handle_unit(unsigned long value, char *unit) 232 { 233 if ((*unit == 'M') || (*unit == 'm')) { 234 return(value * 1024 * 1024); 235 } else if ((*unit == 'K') || (*unit == 'k')) { 236 return(value * 1024); 237 } 238 return(value); 239 } 240 241 static int parse_cmdline(char *devname, char *szstart, char *szlength) 242 { 243 char *buffer; 244 unsigned long devstart; 245 unsigned long devlength; 246 247 if ((!devname) || (!szstart) || (!szlength)) { 248 unregister_devices(); 249 return(-EINVAL); 250 } 251 252 devstart = simple_strtoul(szstart, &buffer, 0); 253 devstart = handle_unit(devstart, buffer); 254 255 if (*(szlength) != '+') { 256 devlength = simple_strtoul(szlength, &buffer, 0); 257 devlength = handle_unit(devlength, buffer) - devstart; 258 } else { 259 devlength = simple_strtoul(szlength + 1, &buffer, 0); 260 devlength = handle_unit(devlength, buffer); 261 } 262 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 263 devname, devstart, devlength); 264 if ((devstart < 0) || (devlength < 0)) { 265 E("slram: Illegal start / length parameter.\n"); 266 return(-EINVAL); 267 } 268 269 if ((devstart = register_device(devname, devstart, devlength))){ 270 unregister_devices(); 271 return((int)devstart); 272 } 273 return(0); 274 } 275 276 #ifndef MODULE 277 278 static int __init mtd_slram_setup(char *str) 279 { 280 map = str; 281 return(1); 282 } 283 284 __setup("slram=", mtd_slram_setup); 285 286 #endif 287 288 static int init_slram(void) 289 { 290 char *devname; 291 int i; 292 293 #ifndef MODULE 294 char *devstart; 295 char *devlength; 296 297 i = 0; 298 299 if (!map) { 300 E("slram: not enough parameters.\n"); 301 return(-EINVAL); 302 } 303 while (map) { 304 devname = devstart = devlength = NULL; 305 306 if (!(devname = strsep(&map, ","))) { 307 E("slram: No devicename specified.\n"); 308 break; 309 } 310 T("slram: devname = %s\n", devname); 311 if ((!map) || (!(devstart = strsep(&map, ",")))) { 312 E("slram: No devicestart specified.\n"); 313 } 314 T("slram: devstart = %s\n", devstart); 315 if ((!map) || (!(devlength = strsep(&map, ",")))) { 316 E("slram: No devicelength / -end specified.\n"); 317 } 318 T("slram: devlength = %s\n", devlength); 319 if (parse_cmdline(devname, devstart, devlength) != 0) { 320 return(-EINVAL); 321 } 322 } 323 #else 324 int count; 325 326 for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS); 327 count++) { 328 } 329 330 if ((count % 3 != 0) || (count == 0)) { 331 E("slram: not enough parameters.\n"); 332 return(-EINVAL); 333 } 334 for (i = 0; i < (count / 3); i++) { 335 devname = map[i * 3]; 336 337 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 338 return(-EINVAL); 339 } 340 341 } 342 #endif /* !MODULE */ 343 344 return(0); 345 } 346 347 static void __exit cleanup_slram(void) 348 { 349 unregister_devices(); 350 } 351 352 module_init(init_slram); 353 module_exit(cleanup_slram); 354 355 MODULE_LICENSE("GPL"); 356 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 357 MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 358