drivers/staging/android/persistent_ram.c

   1 /*
   2  * Copyright (C) 2012 Google, Inc.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/errno.h>
  18 #include <linux/kernel.h>
  19 #include <linux/init.h>
  20 #include <linux/io.h>
  21 #include <linux/list.h>
  22 #include <linux/memblock.h>
  23 #include <linux/rslib.h>
  24 #include <linux/slab.h>
  25 #include <linux/vmalloc.h>
  26 #include "persistent_ram.h"
  27
  28 struct persistent_ram_buffer {
  29         uint32_t    sig;
  30         atomic_t    start;
  31         atomic_t    size;
  32         uint8_t     data[0];
  33 };
  34
  35 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
  36
  37 static __initdata LIST_HEAD(persistent_ram_list);
  38
  39 static inline size_t buffer_size(struct persistent_ram_zone *prz)
  40 {
  41         return atomic_read(&prz->buffer->size);
  42 }
  43
  44 static inline size_t buffer_start(struct persistent_ram_zone *prz)
  45 {
  46         return atomic_read(&prz->buffer->start);
  47 }
  48
  49 /* increase and wrap the start pointer, returning the old value */
  50 static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
  51 {
  52         int old;
  53         int new;
  54
  55         do {
  56                 old = atomic_read(&prz->buffer->start);
  57                 new = old + a;
  58                 while (unlikely(new > prz->buffer_size))
  59                         new -= prz->buffer_size;
  60         } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
  61
  62         return old;
  63 }
  64
  65 /* increase the size counter until it hits the max size */
  66 static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
  67 {
  68         size_t old;
  69         size_t new;
  70
  71         if (atomic_read(&prz->buffer->size) == prz->buffer_size)
  72                 return;
  73
  74         do {
  75                 old = atomic_read(&prz->buffer->size);
  76                 new = old + a;
  77                 if (new > prz->buffer_size)
  78                         new = prz->buffer_size;
  79         } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
  80 }
  81
  82 /* increase the size counter, retuning an error if it hits the max size */
  83 static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz,
  84         size_t a)
  85 {
  86         size_t old;
  87         size_t new;
  88
  89         do {
  90                 old = atomic_read(&prz->buffer->size);
  91                 new = old + a;
  92                 if (new > prz->buffer_size)
  93                         return -ENOMEM;
  94         } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
  95
  96         return 0;
  97 }
  98
  99 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
 100         uint8_t *data, size_t len, uint8_t *ecc)
 101 {
 102         int i;
 103         uint16_t par[prz->ecc_size];
 104
 105         /* Initialize the parity buffer */
 106         memset(par, 0, sizeof(par));
 107         encode_rs8(prz->rs_decoder, data, len, par, 0);
 108         for (i = 0; i < prz->ecc_size; i++)
 109                 ecc[i] = par[i];
 110 }
 111
 112 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 113         void *data, size_t len, uint8_t *ecc)
 114 {
 115         int i;
 116         uint16_t par[prz->ecc_size];
 117
 118         for (i = 0; i < prz->ecc_size; i++)
 119                 par[i] = ecc[i];
 120         return decode_rs8(prz->rs_decoder, data, par, len,
 121                                 NULL, 0, NULL, 0, NULL);
 122 }
 123
 124 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 125         unsigned int start, unsigned int count)
 126 {
 127         struct persistent_ram_buffer *buffer = prz->buffer;
 128         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 129         uint8_t *block;
 130         uint8_t *par;
 131         int ecc_block_size = prz->ecc_block_size;
 132         int ecc_size = prz->ecc_size;
 133         int size = prz->ecc_block_size;
 134
 135         if (!prz->ecc)
 136                 return;
 137
 138         block = buffer->data + (start & ~(ecc_block_size - 1));
 139         par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
 140
 141         do {
 142                 if (block + ecc_block_size > buffer_end)
 143                         size = buffer_end - block;
 144                 persistent_ram_encode_rs8(prz, block, size, par);
 145                 block += ecc_block_size;
 146                 par += ecc_size;
 147         } while (block < buffer->data + start + count);
 148 }
 149
 150 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 151 {
 152         struct persistent_ram_buffer *buffer = prz->buffer;
 153
 154         if (!prz->ecc)
 155                 return;
 156
 157         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 158                                   prz->par_header);
 159 }
 160
 161 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 162 {
 163         struct persistent_ram_buffer *buffer = prz->buffer;
 164         uint8_t *block;
 165         uint8_t *par;
 166
 167         if (!prz->ecc)
 168                 return;
 169
 170         block = buffer->data;
 171         par = prz->par_buffer;
 172         while (block < buffer->data + buffer_size(prz)) {
 173                 int numerr;
 174                 int size = prz->ecc_block_size;
 175                 if (block + size > buffer->data + prz->buffer_size)
 176                         size = buffer->data + prz->buffer_size - block;
 177                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 178                 if (numerr > 0) {
 179                         pr_devel("persistent_ram: error in block %p, %d\n",
 180                                block, numerr);
 181                         prz->corrected_bytes += numerr;
 182                 } else if (numerr < 0) {
 183                         pr_devel("persistent_ram: uncorrectable error in block %p\n",
 184                                 block);
 185                         prz->bad_blocks++;
 186                 }
 187                 block += prz->ecc_block_size;
 188                 par += prz->ecc_size;
 189         }
 190 }
 191
 192 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 193         size_t buffer_size)
 194 {
 195         int numerr;
 196         struct persistent_ram_buffer *buffer = prz->buffer;
 197         int ecc_blocks;
 198
 199         if (!prz->ecc)
 200                 return 0;
 201
 202         prz->ecc_block_size = 128;
 203         prz->ecc_size = 16;
 204         prz->ecc_symsize = 8;
 205         prz->ecc_poly = 0x11d;
 206
 207         ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
 208         prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
 209
 210         if (prz->buffer_size > buffer_size) {
 211                 pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
 212                        buffer_size, prz->buffer_size);
 213                 return -EINVAL;
 214         }
 215
 216         prz->par_buffer = buffer->data + prz->buffer_size;
 217         prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
 218
 219         /*
 220          * first consecutive root is 0
 221          * primitive element to generate roots = 1
 222          */
 223         prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
 224                                   prz->ecc_size);
 225         if (prz->rs_decoder == NULL) {
 226                 pr_info("persistent_ram: init_rs failed\n");
 227                 return -EINVAL;
 228         }
 229
 230         prz->corrected_bytes = 0;
 231         prz->bad_blocks = 0;
 232
 233         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 234                                            prz->par_header);
 235         if (numerr > 0) {
 236                 pr_info("persistent_ram: error in header, %d\n", numerr);
 237                 prz->corrected_bytes += numerr;
 238         } else if (numerr < 0) {
 239                 pr_info("persistent_ram: uncorrectable error in header\n");
 240                 prz->bad_blocks++;
 241         }
 242
 243         return 0;
 244 }
 245
 246 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 247         char *str, size_t len)
 248 {
 249         ssize_t ret;
 250
 251         if (prz->corrected_bytes || prz->bad_blocks)
 252                 ret = snprintf(str, len, ""
 253                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 254                         prz->corrected_bytes, prz->bad_blocks);
 255         else
 256                 ret = snprintf(str, len, "\nNo errors detected\n");
 257
 258         return ret;
 259 }
 260
 261 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 262         const void *s, unsigned int start, unsigned int count)
 263 {
 264         struct persistent_ram_buffer *buffer = prz->buffer;
 265         memcpy(buffer->data + start, s, count);
 266         persistent_ram_update_ecc(prz, start, count);
 267 }
 268
 269 static void __init
 270 persistent_ram_save_old(struct persistent_ram_zone *prz)
 271 {
 272         struct persistent_ram_buffer *buffer = prz->buffer;
 273         size_t size = buffer_size(prz);
 274         size_t start = buffer_start(prz);
 275         char *dest;
 276
 277         persistent_ram_ecc_old(prz);
 278
 279         dest = kmalloc(size, GFP_KERNEL);
 280         if (dest == NULL) {
 281                 pr_err("persistent_ram: failed to allocate buffer\n");
 282                 return;
 283         }
 284
 285         prz->old_log = dest;
 286         prz->old_log_size = size;
 287         memcpy(prz->old_log, &buffer->data[start], size - start);
 288         memcpy(prz->old_log + size - start, &buffer->data[0], start);
 289 }
 290
 291 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 292         const void *s, unsigned int count)
 293 {
 294         int rem;
 295         int c = count;
 296         size_t start;
 297
 298         if (unlikely(c > prz->buffer_size)) {
 299                 s += c - prz->buffer_size;
 300                 c = prz->buffer_size;
 301         }
 302
 303         buffer_size_add_clamp(prz, c);
 304
 305         start = buffer_start_add(prz, c);
 306
 307         rem = prz->buffer_size - start;
 308         if (unlikely(rem < c)) {
 309                 persistent_ram_update(prz, s, start, rem);
 310                 s += rem;
 311                 c -= rem;
 312                 start = 0;
 313         }
 314         persistent_ram_update(prz, s, start, c);
 315
 316         persistent_ram_update_header_ecc(prz);
 317
 318         return count;
 319 }
 320
 321 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 322 {
 323         return prz->old_log_size;
 324 }
 325
 326 void *persistent_ram_old(struct persistent_ram_zone *prz)
 327 {
 328         return prz->old_log;
 329 }
 330
 331 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 332 {
 333         kfree(prz->old_log);
 334         prz->old_log = NULL;
 335         prz->old_log_size = 0;
 336 }
 337
 338 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 339                 struct persistent_ram_zone *prz)
 340 {
 341         struct page **pages;
 342         phys_addr_t page_start;
 343         unsigned int page_count;
 344         pgprot_t prot;
 345         unsigned int i;
 346
 347         page_start = start - offset_in_page(start);
 348         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 349
 350         prot = pgprot_noncached(PAGE_KERNEL);
 351
 352         pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
 353         if (!pages) {
 354                 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
 355                         page_count);
 356                 return -ENOMEM;
 357         }
 358
 359         for (i = 0; i < page_count; i++) {
 360                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 361                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 362         }
 363         prz->vaddr = vmap(pages, page_count, VM_MAP, prot);
 364         kfree(pages);
 365         if (!prz->vaddr) {
 366                 pr_err("%s: Failed to map %u pages\n", __func__, page_count);
 367                 return -ENOMEM;
 368         }
 369
 370         prz->buffer = prz->vaddr + offset_in_page(start);
 371         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 372
 373         return 0;
 374 }
 375
 376 static int __init persistent_ram_buffer_init(const char *name,
 377                 struct persistent_ram_zone *prz)
 378 {
 379         int i;
 380         struct persistent_ram *ram;
 381         struct persistent_ram_descriptor *desc;
 382         phys_addr_t start;
 383
 384         list_for_each_entry(ram, &persistent_ram_list, node) {
 385                 start = ram->start;
 386                 for (i = 0; i < ram->num_descs; i++) {
 387                         desc = &ram->descs[i];
 388                         if (!strcmp(desc->name, name))
 389                                 return persistent_ram_buffer_map(start,
 390                                                 desc->size, prz);
 391                         start += desc->size;
 392                 }
 393         }
 394
 395         return -EINVAL;
 396 }
 397
 398 static  __init
 399 struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
 400 {
 401         struct persistent_ram_zone *prz;
 402         int ret;
 403
 404         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 405         if (!prz) {
 406                 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
 407                 return ERR_PTR(-ENOMEM);
 408         }
 409
 410         INIT_LIST_HEAD(&prz->node);
 411
 412         ret = persistent_ram_buffer_init(dev_name(dev), prz);
 413         if (ret) {
 414                 pr_err("persistent_ram: failed to initialize buffer\n");
 415                 return ERR_PTR(ret);
 416         }
 417
 418         prz->ecc = ecc;
 419         ret = persistent_ram_init_ecc(prz, prz->buffer_size);
 420         if (ret)
 421                 return ERR_PTR(ret);
 422
 423         if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
 424                 if (buffer_size(prz) > prz->buffer_size ||
 425                     buffer_start(prz) > buffer_size(prz))
 426                         pr_info("persistent_ram: found existing invalid buffer,"
 427                                 " size %zu, start %zu\n",
 428                                buffer_size(prz), buffer_start(prz));
 429                 else {
 430                         pr_info("persistent_ram: found existing buffer,"
 431                                 " size %zu, start %zu\n",
 432                                buffer_size(prz), buffer_start(prz));
 433                         persistent_ram_save_old(prz);
 434                 }
 435         } else {
 436                 pr_info("persistent_ram: no valid data in buffer"
 437                         " (sig = 0x%08x)\n", prz->buffer->sig);
 438         }
 439
 440         prz->buffer->sig = PERSISTENT_RAM_SIG;
 441         atomic_set(&prz->buffer->start, 0);
 442         atomic_set(&prz->buffer->size, 0);
 443
 444         return prz;
 445 }
 446
 447 struct persistent_ram_zone * __init
 448 persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
 449 {
 450         return __persistent_ram_init(dev, ecc);
 451 }
 452
 453 int __init persistent_ram_early_init(struct persistent_ram *ram)
 454 {
 455         int ret;
 456
 457         ret = memblock_reserve(ram->start, ram->size);
 458         if (ret) {
 459                 pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
 460                         (long)ram->start, (long)(ram->start + ram->size - 1));
 461                 return ret;
 462         }
 463
 464         list_add_tail(&ram->node, &persistent_ram_list);
 465
 466         pr_info("Initialized persistent memory from %08lx-%08lx\n",
 467                 (long)ram->start, (long)(ram->start + ram->size - 1));
 468
 469         return 0;
 470 }