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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 | // SPDX-License-Identifier: GPL-2.0-only /*====================================================================== This driver provides a method to access memory not used by the kernel itself (i.e. if the kernel commandline mem=xxx is used). To actually use slram at least mtdblock or mtdchar is required (for block or character device access). Usage: if compiled as loadable module: modprobe slram map=<name>,<start>,<end/offset> if statically linked into the kernel use the following kernel cmd.line slram=<name>,<start>,<end/offset> <name>: name of the device that will be listed in /proc/mtd <start>: start of the memory region, decimal or hex (0xabcdef) <end/offset>: end of the memory region. It's possible to use +0x1234 to specify the offset instead of the absolute address NOTE: With slram it's only possible to map a contiguous memory region. Therefore if there's a device mapped somewhere in the region specified slram will fail to load (see kernel log if modprobe fails). - Jochen Schaeuble <psionic@psionic.de> ======================================================================*/ #include <linux/module.h> #include <linux/uaccess.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/ptrace.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/timer.h> #include <linux/major.h> #include <linux/fs.h> #include <linux/ioctl.h> #include <linux/init.h> #include <linux/io.h> #include <linux/mtd/mtd.h> #define SLRAM_MAX_DEVICES_PARAMS 6 /* 3 parameters / device */ #define SLRAM_BLK_SZ 0x4000 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args) #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args) typedef struct slram_priv { u_char *start; u_char *end; } slram_priv_t; typedef struct slram_mtd_list { struct mtd_info *mtdinfo; struct slram_mtd_list *next; } slram_mtd_list_t; #ifdef MODULE static char *map[SLRAM_MAX_DEVICES_PARAMS]; module_param_array(map, charp, NULL, 0); MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\""); #else static char *map; #endif static slram_mtd_list_t *slram_mtdlist = NULL; static int slram_erase(struct mtd_info *, struct erase_info *); static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **, resource_size_t *); static int slram_unpoint(struct mtd_info *, loff_t, size_t); static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *); static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *); static int slram_erase(struct mtd_info *mtd, struct erase_info *instr) { slram_priv_t *priv = mtd->priv; memset(priv->start + instr->addr, 0xff, instr->len); return(0); } static int slram_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, void **virt, resource_size_t *phys) { slram_priv_t *priv = mtd->priv; *virt = priv->start + from; *retlen = len; return(0); } static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len) { return 0; } static int slram_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) { slram_priv_t *priv = mtd->priv; memcpy(buf, priv->start + from, len); *retlen = len; return(0); } static int slram_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) { slram_priv_t *priv = mtd->priv; memcpy(priv->start + to, buf, len); *retlen = len; return(0); } /*====================================================================*/ static int register_device(char *name, unsigned long start, unsigned long length) { slram_mtd_list_t **curmtd; curmtd = &slram_mtdlist; while (*curmtd) { curmtd = &(*curmtd)->next; } *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL); if (!(*curmtd)) { E("slram: Cannot allocate new MTD device.\n"); return(-ENOMEM); } (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL); (*curmtd)->next = NULL; if ((*curmtd)->mtdinfo) { (*curmtd)->mtdinfo->priv = kzalloc(sizeof(slram_priv_t), GFP_KERNEL); if (!(*curmtd)->mtdinfo->priv) { kfree((*curmtd)->mtdinfo); (*curmtd)->mtdinfo = NULL; } } if (!(*curmtd)->mtdinfo) { E("slram: Cannot allocate new MTD device.\n"); return(-ENOMEM); } if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start = memremap(start, length, MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC))) { E("slram: memremap failed\n"); return -EIO; } ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end = ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length; (*curmtd)->mtdinfo->name = name; (*curmtd)->mtdinfo->size = length; (*curmtd)->mtdinfo->flags = MTD_CAP_RAM; (*curmtd)->mtdinfo->_erase = slram_erase; (*curmtd)->mtdinfo->_point = slram_point; (*curmtd)->mtdinfo->_unpoint = slram_unpoint; (*curmtd)->mtdinfo->_read = slram_read; (*curmtd)->mtdinfo->_write = slram_write; (*curmtd)->mtdinfo->owner = THIS_MODULE; (*curmtd)->mtdinfo->type = MTD_RAM; (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ; (*curmtd)->mtdinfo->writesize = 1; if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0)) { E("slram: Failed to register new device\n"); memunmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start); kfree((*curmtd)->mtdinfo->priv); kfree((*curmtd)->mtdinfo); return(-EAGAIN); } T("slram: Registered device %s from %luKiB to %luKiB\n", name, (start / 1024), ((start + length) / 1024)); T("slram: Mapped from 0x%p to 0x%p\n", ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start, ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end); return(0); } static void unregister_devices(void) { slram_mtd_list_t *nextitem; while (slram_mtdlist) { nextitem = slram_mtdlist->next; mtd_device_unregister(slram_mtdlist->mtdinfo); memunmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start); kfree(slram_mtdlist->mtdinfo->priv); kfree(slram_mtdlist->mtdinfo); kfree(slram_mtdlist); slram_mtdlist = nextitem; } } static unsigned long handle_unit(unsigned long value, char *unit) { if ((*unit == 'M') || (*unit == 'm')) { return(value * 1024 * 1024); } else if ((*unit == 'K') || (*unit == 'k')) { return(value * 1024); } return(value); } static int parse_cmdline(char *devname, char *szstart, char *szlength) { char *buffer; unsigned long devstart; unsigned long devlength; if ((!devname) || (!szstart) || (!szlength)) { unregister_devices(); return(-EINVAL); } devstart = simple_strtoul(szstart, &buffer, 0); devstart = handle_unit(devstart, buffer); if (*(szlength) != '+') { devlength = simple_strtoul(szlength, &buffer, 0); devlength = handle_unit(devlength, buffer); if (devlength < devstart) goto err_out; devlength -= devstart; } else { devlength = simple_strtoul(szlength + 1, &buffer, 0); devlength = handle_unit(devlength, buffer); } T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n", devname, devstart, devlength); if (devlength % SLRAM_BLK_SZ != 0) goto err_out; if ((devstart = register_device(devname, devstart, devlength))){ unregister_devices(); return((int)devstart); } return(0); err_out: E("slram: Illegal length parameter.\n"); return(-EINVAL); } #ifndef MODULE static int __init mtd_slram_setup(char *str) { map = str; return(1); } __setup("slram=", mtd_slram_setup); #endif static int __init init_slram(void) { char *devname; #ifndef MODULE char *devstart; char *devlength; if (!map) { E("slram: not enough parameters.\n"); return(-EINVAL); } while (map) { devname = devstart = devlength = NULL; if (!(devname = strsep(&map, ","))) { E("slram: No devicename specified.\n"); break; } T("slram: devname = %s\n", devname); if ((!map) || (!(devstart = strsep(&map, ",")))) { E("slram: No devicestart specified.\n"); } T("slram: devstart = %s\n", devstart); if ((!map) || (!(devlength = strsep(&map, ",")))) { E("slram: No devicelength / -end specified.\n"); } T("slram: devlength = %s\n", devlength); if (parse_cmdline(devname, devstart, devlength) != 0) { return(-EINVAL); } } #else int count; int i; for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count]; count++) { } if ((count % 3 != 0) || (count == 0)) { E("slram: not enough parameters.\n"); return(-EINVAL); } for (i = 0; i < (count / 3); i++) { devname = map[i * 3]; if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) { return(-EINVAL); } } #endif /* !MODULE */ return(0); } static void __exit cleanup_slram(void) { unregister_devices(); } module_init(init_slram); module_exit(cleanup_slram); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>"); MODULE_DESCRIPTION("MTD driver for uncached system RAM"); |