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