slram.c revision 21c8db9eff95260e543535dfc6f27164c4c0c0ff
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 58typedef struct slram_priv { 59 u_char *start; 60 u_char *end; 61} slram_priv_t; 62 63typedef struct slram_mtd_list { 64 struct mtd_info *mtdinfo; 65 struct slram_mtd_list *next; 66} slram_mtd_list_t; 67 68#ifdef MODULE 69static char *map[SLRAM_MAX_DEVICES_PARAMS]; 70 71module_param_array(map, charp, NULL, 0); 72MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\""); 73#else 74static char *map; 75#endif 76 77static slram_mtd_list_t *slram_mtdlist = NULL; 78 79static int slram_erase(struct mtd_info *, struct erase_info *); 80static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **); 81static void slram_unpoint(struct mtd_info *, u_char *, loff_t, size_t); 82static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *); 83static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *); 84 85static 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 107static 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 120static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len) 121{ 122} 123 124static 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 141static 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 157static 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_CAP_RAM; 204 (*curmtd)->mtdinfo->erase = slram_erase; 205 (*curmtd)->mtdinfo->point = slram_point; 206 (*curmtd)->mtdinfo->unpoint = slram_unpoint; 207 (*curmtd)->mtdinfo->read = slram_read; 208 (*curmtd)->mtdinfo->write = slram_write; 209 (*curmtd)->mtdinfo->owner = THIS_MODULE; 210 (*curmtd)->mtdinfo->type = MTD_RAM; 211 (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; 212 213 if (add_mtd_device((*curmtd)->mtdinfo)) { 214 E("slram: Failed to register new device\n"); 215 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); 216 kfree((*curmtd)->mtdinfo->priv); 217 kfree((*curmtd)->mtdinfo); 218 return(-EAGAIN); 219 } 220 T("slram: Registered device %s from %luKiB to %luKiB\n", name, 221 (start / 1024), ((start + length) / 1024)); 222 T("slram: Mapped from 0x%p to 0x%p\n", 223 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, 224 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); 225 return(0); 226} 227 228static void unregister_devices(void) 229{ 230 slram_mtd_list_t *nextitem; 231 232 while (slram_mtdlist) { 233 nextitem = slram_mtdlist->next; 234 del_mtd_device(slram_mtdlist->mtdinfo); 235 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); 236 kfree(slram_mtdlist->mtdinfo->priv); 237 kfree(slram_mtdlist->mtdinfo); 238 kfree(slram_mtdlist); 239 slram_mtdlist = nextitem; 240 } 241} 242 243static unsigned long handle_unit(unsigned long value, char *unit) 244{ 245 if ((*unit == 'M') || (*unit == 'm')) { 246 return(value * 1024 * 1024); 247 } else if ((*unit == 'K') || (*unit == 'k')) { 248 return(value * 1024); 249 } 250 return(value); 251} 252 253static int parse_cmdline(char *devname, char *szstart, char *szlength) 254{ 255 char *buffer; 256 unsigned long devstart; 257 unsigned long devlength; 258 259 if ((!devname) || (!szstart) || (!szlength)) { 260 unregister_devices(); 261 return(-EINVAL); 262 } 263 264 devstart = simple_strtoul(szstart, &buffer, 0); 265 devstart = handle_unit(devstart, buffer); 266 267 if (*(szlength) != '+') { 268 devlength = simple_strtoul(szlength, &buffer, 0); 269 devlength = handle_unit(devlength, buffer) - devstart; 270 } else { 271 devlength = simple_strtoul(szlength + 1, &buffer, 0); 272 devlength = handle_unit(devlength, buffer); 273 } 274 T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", 275 devname, devstart, devlength); 276 if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) { 277 E("slram: Illegal start / length parameter.\n"); 278 return(-EINVAL); 279 } 280 281 if ((devstart = register_device(devname, devstart, devlength))){ 282 unregister_devices(); 283 return((int)devstart); 284 } 285 return(0); 286} 287 288#ifndef MODULE 289 290static int __init mtd_slram_setup(char *str) 291{ 292 map = str; 293 return(1); 294} 295 296__setup("slram=", mtd_slram_setup); 297 298#endif 299 300static int init_slram(void) 301{ 302 char *devname; 303 int i; 304 305#ifndef MODULE 306 char *devstart; 307 char *devlength; 308 309 i = 0; 310 311 if (!map) { 312 E("slram: not enough parameters.\n"); 313 return(-EINVAL); 314 } 315 while (map) { 316 devname = devstart = devlength = NULL; 317 318 if (!(devname = strsep(&map, ","))) { 319 E("slram: No devicename specified.\n"); 320 break; 321 } 322 T("slram: devname = %s\n", devname); 323 if ((!map) || (!(devstart = strsep(&map, ",")))) { 324 E("slram: No devicestart specified.\n"); 325 } 326 T("slram: devstart = %s\n", devstart); 327 if ((!map) || (!(devlength = strsep(&map, ",")))) { 328 E("slram: No devicelength / -end specified.\n"); 329 } 330 T("slram: devlength = %s\n", devlength); 331 if (parse_cmdline(devname, devstart, devlength) != 0) { 332 return(-EINVAL); 333 } 334 } 335#else 336 int count; 337 338 for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS); 339 count++) { 340 } 341 342 if ((count % 3 != 0) || (count == 0)) { 343 E("slram: not enough parameters.\n"); 344 return(-EINVAL); 345 } 346 for (i = 0; i < (count / 3); i++) { 347 devname = map[i * 3]; 348 349 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { 350 return(-EINVAL); 351 } 352 353 } 354#endif /* !MODULE */ 355 356 return(0); 357} 358 359static void __exit cleanup_slram(void) 360{ 361 unregister_devices(); 362} 363 364module_init(init_slram); 365module_exit(cleanup_slram); 366 367MODULE_LICENSE("GPL"); 368MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); 369MODULE_DESCRIPTION("MTD driver for uncached system RAM"); 370