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 <asm/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 ioremap(start, length))) { 167 E("slram: ioremap failed\n"); 168 return -EIO; 169 } 170 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = 171 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; 172 173 174 (*curmtd)->mtdinfo->name = name; 175 (*curmtd)->mtdinfo->size = length; 176 (*curmtd)->mtdinfo->flags = MTD_CAP_RAM; 177 (*curmtd)->mtdinfo->_erase = slram_erase; 178 (*curmtd)->mtdinfo->_point = slram_point; 179 (*curmtd)->mtdinfo->_unpoint = slram_unpoint; 180 (*curmtd)->mtdinfo->_read = slram_read; 181 (*curmtd)->mtdinfo->_write = slram_write; 182 (*curmtd)->mtdinfo->owner = THIS_MODULE; 183 (*curmtd)->mtdinfo->type = MTD_RAM; 184 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; 185 (*curmtd)->mtdinfo->writesize = 1; 186 187 if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0)) { 188 E("slram: Failed to register new device\n"); 189 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 190 kfree((*curmtd)->mtdinfo->priv); 191 kfree((*curmtd)->mtdinfo); 192 return(-EAGAIN); 193 } 194 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 195 (start / 1024), ((start + length) / 1024)); 196 T("slram: Mapped from 0x%p to 0x%p\n", 197 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 198 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 199 return(0); 200 } 201 202 static void unregister_devices(void) 203 { 204 slram_mtd_list_t *nextitem; 205 206 while (slram_mtdlist) { 207 nextitem = slram_mtdlist->next; 208 mtd_device_unregister(slram_mtdlist->mtdinfo); 209 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 210 kfree(slram_mtdlist->mtdinfo->priv); 211 kfree(slram_mtdlist->mtdinfo); 212 kfree(slram_mtdlist); 213 slram_mtdlist = nextitem; 214 } 215 } 216 217 static unsigned long handle_unit(unsigned long value, char *unit) 218 { 219 if ((*unit == 'M') || (*unit == 'm')) { 220 return(value * 1024 * 1024); 221 } else if ((*unit == 'K') || (*unit == 'k')) { 222 return(value * 1024); 223 } 224 return(value); 225 } 226 227 static int parse_cmdline(char *devname, char *szstart, char *szlength) 228 { 229 char *buffer; 230 unsigned long devstart; 231 unsigned long devlength; 232 233 if ((!devname) || (!szstart) || (!szlength)) { 234 unregister_devices(); 235 return(-EINVAL); 236 } 237 238 devstart = simple_strtoul(szstart, &buffer, 0); 239 devstart = handle_unit(devstart, buffer); 240 241 if (*(szlength) != '+') { 242 devlength = simple_strtoul(szlength, &buffer, 0); 243 devlength = handle_unit(devlength, buffer); 244 if (devlength < devstart) 245 goto err_out; 246 247 devlength -= devstart; 248 } else { 249 devlength = simple_strtoul(szlength + 1, &buffer, 0); 250 devlength = handle_unit(devlength, buffer); 251 } 252 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 253 devname, devstart, devlength); 254 if (devlength % SLRAM_BLK_SZ != 0) 255 goto err_out; 256 257 if ((devstart = register_device(devname, devstart, devlength))){ 258 unregister_devices(); 259 return((int)devstart); 260 } 261 return(0); 262 263 err_out: 264 E("slram: Illegal length parameter.\n"); 265 return(-EINVAL); 266 } 267 268 #ifndef MODULE 269 270 static int __init mtd_slram_setup(char *str) 271 { 272 map = str; 273 return(1); 274 } 275 276 __setup("slram=", mtd_slram_setup); 277 278 #endif 279 280 static int __init init_slram(void) 281 { 282 char *devname; 283 284 #ifndef MODULE 285 char *devstart; 286 char *devlength; 287 288 if (!map) { 289 E("slram: not enough parameters.\n"); 290 return(-EINVAL); 291 } 292 while (map) { 293 devname = devstart = devlength = NULL; 294 295 if (!(devname = strsep(&map, ","))) { 296 E("slram: No devicename specified.\n"); 297 break; 298 } 299 T("slram: devname = %s\n", devname); 300 if ((!map) || (!(devstart = strsep(&map, ",")))) { 301 E("slram: No devicestart specified.\n"); 302 } 303 T("slram: devstart = %s\n", devstart); 304 if ((!map) || (!(devlength = strsep(&map, ",")))) { 305 E("slram: No devicelength / -end specified.\n"); 306 } 307 T("slram: devlength = %s\n", devlength); 308 if (parse_cmdline(devname, devstart, devlength) != 0) { 309 return(-EINVAL); 310 } 311 } 312 #else 313 int count; 314 int i; 315 316 for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count]; 317 count++) { 318 } 319 320 if ((count % 3 != 0) || (count == 0)) { 321 E("slram: not enough parameters.\n"); 322 return(-EINVAL); 323 } 324 for (i = 0; i < (count / 3); i++) { 325 devname = map[i * 3]; 326 327 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 328 return(-EINVAL); 329 } 330 331 } 332 #endif /* !MODULE */ 333 334 return(0); 335 } 336 337 static void __exit cleanup_slram(void) 338 { 339 unregister_devices(); 340 } 341 342 module_init(init_slram); 343 module_exit(cleanup_slram); 344 345 MODULE_LICENSE("GPL"); 346 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 347 MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 348