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         uint32_t    start;
  31         uint32_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 void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  40         uint8_t *data, size_t len, uint8_t *ecc)
  41 {
  42         int i;
  43         uint16_t par[prz->ecc_size];
  44
  45         /* Initialize the parity buffer */
  46         memset(par, 0, sizeof(par));
  47         encode_rs8(prz->rs_decoder, data, len, par, 0);
  48         for (i = 0; i < prz->ecc_size; i++)
  49                 ecc[i] = par[i];
  50 }
  51
  52 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
  53         void *data, size_t len, uint8_t *ecc)
  54 {
  55         int i;
  56         uint16_t par[prz->ecc_size];
  57
  58         for (i = 0; i < prz->ecc_size; i++)
  59                 par[i] = ecc[i];
  60         return decode_rs8(prz->rs_decoder, data, par, len,
  61                                 NULL, 0, NULL, 0, NULL);
  62 }
  63
  64 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
  65         unsigned int count)
  66 {
  67         struct persistent_ram_buffer *buffer = prz->buffer;
  68         uint8_t *buffer_end = buffer->data + prz->buffer_size;
  69         uint8_t *block;
  70         uint8_t *par;
  71         int ecc_block_size = prz->ecc_block_size;
  72         int ecc_size = prz->ecc_size;
  73         int size = prz->ecc_block_size;
  74
  75         if (!prz->ecc)
  76                 return;
  77
  78         block = buffer->data + (buffer->start & ~(ecc_block_size - 1));
  79         par = prz->par_buffer +
  80               (buffer->start / ecc_block_size) * prz->ecc_size;
  81         do {
  82                 if (block + ecc_block_size > buffer_end)
  83                         size = buffer_end - block;
  84                 persistent_ram_encode_rs8(prz, block, size, par);
  85                 block += ecc_block_size;
  86                 par += ecc_size;
  87         } while (block < buffer->data + buffer->start + count);
  88 }
  89
  90 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
  91 {
  92         struct persistent_ram_buffer *buffer = prz->buffer;
  93
  94         if (!prz->ecc)
  95                 return;
  96
  97         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
  98                                   prz->par_header);
  99 }
 100
 101 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 102 {
 103         struct persistent_ram_buffer *buffer = prz->buffer;
 104         uint8_t *block;
 105         uint8_t *par;
 106
 107         if (!prz->ecc)
 108                 return;
 109
 110         block = buffer->data;
 111         par = prz->par_buffer;
 112         while (block < buffer->data + buffer->size) {
 113                 int numerr;
 114                 int size = prz->ecc_block_size;
 115                 if (block + size > buffer->data + prz->buffer_size)
 116                         size = buffer->data + prz->buffer_size - block;
 117                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 118                 if (numerr > 0) {
 119                         pr_devel("persistent_ram: error in block %p, %d\n",
 120                                block, numerr);
 121                         prz->corrected_bytes += numerr;
 122                 } else if (numerr < 0) {
 123                         pr_devel("persistent_ram: uncorrectable error in block %p\n",
 124                                 block);
 125                         prz->bad_blocks++;
 126                 }
 127                 block += prz->ecc_block_size;
 128                 par += prz->ecc_size;
 129         }
 130 }
 131
 132 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 133         size_t buffer_size)
 134 {
 135         int numerr;
 136         struct persistent_ram_buffer *buffer = prz->buffer;
 137         int ecc_blocks;
 138
 139         if (!prz->ecc)
 140                 return 0;
 141
 142         prz->ecc_block_size = 128;
 143         prz->ecc_size = 16;
 144         prz->ecc_symsize = 8;
 145         prz->ecc_poly = 0x11d;
 146
 147         ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
 148         prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
 149
 150         if (prz->buffer_size > buffer_size) {
 151                 pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
 152                        buffer_size, prz->buffer_size);
 153                 return -EINVAL;
 154         }
 155
 156         prz->par_buffer = buffer->data + prz->buffer_size;
 157         prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
 158
 159         /*
 160          * first consecutive root is 0
 161          * primitive element to generate roots = 1
 162          */
 163         prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
 164                                   prz->ecc_size);
 165         if (prz->rs_decoder == NULL) {
 166                 pr_info("persistent_ram: init_rs failed\n");
 167                 return -EINVAL;
 168         }
 169
 170         prz->corrected_bytes = 0;
 171         prz->bad_blocks = 0;
 172
 173         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 174                                            prz->par_header);
 175         if (numerr > 0) {
 176                 pr_info("persistent_ram: error in header, %d\n", numerr);
 177                 prz->corrected_bytes += numerr;
 178         } else if (numerr < 0) {
 179                 pr_info("persistent_ram: uncorrectable error in header\n");
 180                 prz->bad_blocks++;
 181         }
 182
 183         return 0;
 184 }
 185
 186 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 187         char *str, size_t len)
 188 {
 189         ssize_t ret;
 190
 191         if (prz->corrected_bytes || prz->bad_blocks)
 192                 ret = snprintf(str, len, ""
 193                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 194                         prz->corrected_bytes, prz->bad_blocks);
 195         else
 196                 ret = snprintf(str, len, "\nNo errors detected\n");
 197
 198         return ret;
 199 }
 200
 201 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 202         const void *s, unsigned int count)
 203 {
 204         struct persistent_ram_buffer *buffer = prz->buffer;
 205         memcpy(buffer->data + buffer->start, s, count);
 206         persistent_ram_update_ecc(prz, count);
 207 }
 208
 209 static void __init
 210 persistent_ram_save_old(struct persistent_ram_zone *prz)
 211 {
 212         struct persistent_ram_buffer *buffer = prz->buffer;
 213         size_t old_log_size = buffer->size;
 214         char *dest;
 215
 216         persistent_ram_ecc_old(prz);
 217
 218         dest = kmalloc(old_log_size, GFP_KERNEL);
 219         if (dest == NULL) {
 220                 pr_err("persistent_ram: failed to allocate buffer\n");
 221                 return;
 222         }
 223
 224         prz->old_log = dest;
 225         prz->old_log_size = old_log_size;
 226         memcpy(prz->old_log,
 227                &buffer->data[buffer->start], buffer->size - buffer->start);
 228         memcpy(prz->old_log + buffer->size - buffer->start,
 229                &buffer->data[0], buffer->start);
 230 }
 231
 232 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 233         const void *s, unsigned int count)
 234 {
 235         int rem;
 236         int c = count;
 237         struct persistent_ram_buffer *buffer = prz->buffer;
 238
 239         if (c > prz->buffer_size) {
 240                 s += c - prz->buffer_size;
 241                 c = prz->buffer_size;
 242         }
 243         rem = prz->buffer_size - buffer->start;
 244         if (rem < c) {
 245                 persistent_ram_update(prz, s, rem);
 246                 s += rem;
 247                 c -= rem;
 248                 buffer->start = 0;
 249                 buffer->size = prz->buffer_size;
 250         }
 251         persistent_ram_update(prz, s, c);
 252
 253         buffer->start += c;
 254         if (buffer->size < prz->buffer_size)
 255                 buffer->size += c;
 256         persistent_ram_update_header_ecc(prz);
 257
 258         return count;
 259 }
 260
 261 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 262 {
 263         return prz->old_log_size;
 264 }
 265
 266 void *persistent_ram_old(struct persistent_ram_zone *prz)
 267 {
 268         return prz->old_log;
 269 }
 270
 271 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 272 {
 273         kfree(prz->old_log);
 274         prz->old_log = NULL;
 275         prz->old_log_size = 0;
 276 }
 277
 278 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 279                 struct persistent_ram_zone *prz)
 280 {
 281         struct page **pages;
 282         phys_addr_t page_start;
 283         unsigned int page_count;
 284         pgprot_t prot;
 285         unsigned int i;
 286
 287         page_start = start - offset_in_page(start);
 288         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 289
 290         prot = pgprot_noncached(PAGE_KERNEL);
 291
 292         pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
 293         if (!pages) {
 294                 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
 295                         page_count);
 296                 return -ENOMEM;
 297         }
 298
 299         for (i = 0; i < page_count; i++) {
 300                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 301                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 302         }
 303         prz->vaddr = vmap(pages, page_count, VM_MAP, prot);
 304         kfree(pages);
 305         if (!prz->vaddr) {
 306                 pr_err("%s: Failed to map %u pages\n", __func__, page_count);
 307                 return -ENOMEM;
 308         }
 309
 310         prz->buffer = prz->vaddr + offset_in_page(start);
 311         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 312
 313         return 0;
 314 }
 315
 316 static int __init persistent_ram_buffer_init(const char *name,
 317                 struct persistent_ram_zone *prz)
 318 {
 319         int i;
 320         struct persistent_ram *ram;
 321         struct persistent_ram_descriptor *desc;
 322         phys_addr_t start;
 323
 324         list_for_each_entry(ram, &persistent_ram_list, node) {
 325                 start = ram->start;
 326                 for (i = 0; i < ram->num_descs; i++) {
 327                         desc = &ram->descs[i];
 328                         if (!strcmp(desc->name, name))
 329                                 return persistent_ram_buffer_map(start,
 330                                                 desc->size, prz);
 331                         start += desc->size;
 332                 }
 333         }
 334
 335         return -EINVAL;
 336 }
 337
 338 static  __init
 339 struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
 340 {
 341         struct persistent_ram_zone *prz;
 342         int ret = -ENOMEM;
 343
 344         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 345         if (!prz) {
 346                 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
 347                 goto err;
 348         }
 349
 350         INIT_LIST_HEAD(&prz->node);
 351
 352         ret = persistent_ram_buffer_init(dev_name(dev), prz);
 353         if (ret) {
 354                 pr_err("persistent_ram: failed to initialize buffer\n");
 355                 goto err;
 356         }
 357
 358         prz->ecc = ecc;
 359         ret = persistent_ram_init_ecc(prz, prz->buffer_size);
 360         if (ret)
 361                 goto err;
 362
 363         if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
 364                 if (prz->buffer->size > prz->buffer_size
 365                     || prz->buffer->start > prz->buffer->size)
 366                         pr_info("persistent_ram: found existing invalid buffer, size %d, start %d\n",
 367                                prz->buffer->size, prz->buffer->start);
 368                 else {
 369                         pr_info("persistent_ram: found existing buffer, size %d, start %d\n",
 370                                prz->buffer->size, prz->buffer->start);
 371                         persistent_ram_save_old(prz);
 372                 }
 373         } else {
 374                 pr_info("persistent_ram: no valid data in buffer (sig = 0x%08x)\n",
 375                         prz->buffer->sig);
 376         }
 377
 378         prz->buffer->sig = PERSISTENT_RAM_SIG;
 379         prz->buffer->start = 0;
 380         prz->buffer->size = 0;
 381
 382         return prz;
 383 err:
 384         kfree(prz);
 385         return ERR_PTR(ret);
 386 }
 387
 388 struct persistent_ram_zone * __init
 389 persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
 390 {
 391         return __persistent_ram_init(dev, ecc);
 392 }
 393
 394 int __init persistent_ram_early_init(struct persistent_ram *ram)
 395 {
 396         int ret;
 397
 398         ret = memblock_reserve(ram->start, ram->size);
 399         if (ret) {
 400                 pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
 401                         (long)ram->start, (long)(ram->start + ram->size - 1));
 402                 return ret;
 403         }
 404
 405         list_add_tail(&ram->node, &persistent_ram_list);
 406
 407         pr_info("Initialized persistent memory from %08lx-%08lx\n",
 408                 (long)ram->start, (long)(ram->start + ram->size - 1));
 409
 410         return 0;
 411 }