uboot/drivers/mtd/nand/docg4.c
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   1/*
   2 * drivers/mtd/nand/docg4.c
   3 *
   4 * Copyright (C) 2013 Mike Dunn <mikedunn@newsguy.com>
   5 *
   6 * SPDX-License-Identifier:     GPL-2.0+
   7 *
   8 * mtd nand driver for M-Systems DiskOnChip G4
   9 *
  10 * Tested on the Palm Treo 680.  The G4 is also present on Toshiba Portege, Asus
  11 * P526, some HTC smartphones (Wizard, Prophet, ...), O2 XDA Zinc, maybe others.
  12 * Should work on these as well.  Let me know!
  13 *
  14 * TODO:
  15 *
  16 *  Mechanism for management of password-protected areas
  17 *
  18 *  Hamming ecc when reading oob only
  19 *
  20 *  According to the M-Sys documentation, this device is also available in a
  21 *  "dual-die" configuration having a 256MB capacity, but no mechanism for
  22 *  detecting this variant is documented.  Currently this driver assumes 128MB
  23 *  capacity.
  24 *
  25 *  Support for multiple cascaded devices ("floors").  Not sure which gadgets
  26 *  contain multiple G4s in a cascaded configuration, if any.
  27 */
  28
  29
  30#include <common.h>
  31#include <asm/arch/hardware.h>
  32#include <asm/io.h>
  33#include <asm/bitops.h>
  34#include <asm/errno.h>
  35#include <malloc.h>
  36#include <nand.h>
  37#include <linux/bch.h>
  38#include <linux/bitrev.h>
  39#include <linux/mtd/docg4.h>
  40
  41/*
  42 * The device has a nop register which M-Sys claims is for the purpose of
  43 * inserting precise delays.  But beware; at least some operations fail if the
  44 * nop writes are replaced with a generic delay!
  45 */
  46static inline void write_nop(void __iomem *docptr)
  47{
  48        writew(0, docptr + DOC_NOP);
  49}
  50
  51
  52static int poll_status(void __iomem *docptr)
  53{
  54        /*
  55         * Busy-wait for the FLASHREADY bit to be set in the FLASHCONTROL
  56         * register.  Operations known to take a long time (e.g., block erase)
  57         * should sleep for a while before calling this.
  58         */
  59
  60        uint8_t flash_status;
  61
  62        /* hardware quirk requires reading twice initially */
  63        flash_status = readb(docptr + DOC_FLASHCONTROL);
  64
  65        do {
  66                flash_status = readb(docptr + DOC_FLASHCONTROL);
  67        } while (!(flash_status & DOC_CTRL_FLASHREADY));
  68
  69        return 0;
  70}
  71
  72static void write_addr(void __iomem *docptr, uint32_t docg4_addr)
  73{
  74        /* write the four address bytes packed in docg4_addr to the device */
  75
  76        writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
  77        docg4_addr >>= 8;
  78        writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
  79        docg4_addr >>= 8;
  80        writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
  81        docg4_addr >>= 8;
  82        writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
  83}
  84
  85/*
  86 * This is a module parameter in the linux kernel version of this driver.  It is
  87 * hard-coded to 'off' for u-boot.  This driver uses oob to mark bad blocks.
  88 * This can be problematic when dealing with data not intended for the mtd/nand
  89 * subsystem.  For example, on boards that boot from the docg4 and use the IPL
  90 * to load an spl + u-boot image, the blocks containing the image will be
  91 * reported as "bad" because the oob of the first page of each block contains a
  92 * magic number that the IPL looks for, which causes the badblock scan to
  93 * erroneously add them to the bad block table.  To erase such a block, use
  94 * u-boot's 'nand scrub'.  scrub is safe for the docg4.  The device does have a
  95 * factory bad block table, but it is read-only, and is used in conjunction with
  96 * oob bad block markers that are written by mtd/nand when a block is deemed to
  97 * be bad.  To read data from "bad" blocks, use 'read.raw'.  Unfortunately,
  98 * read.raw does not use ecc, which would still work fine on such misidentified
  99 * bad blocks.  TODO: u-boot nand utilities need the ability to ignore bad
 100 * blocks.
 101 */
 102static const int ignore_badblocks; /* remains false */
 103
 104struct docg4_priv {
 105        int status;
 106        struct {
 107                unsigned int command;
 108                int column;
 109                int page;
 110        } last_command;
 111        uint8_t oob_buf[16];
 112        uint8_t ecc_buf[7];
 113        int oob_page;
 114        struct bch_control *bch;
 115};
 116/*
 117 * Oob bytes 0 - 6 are available to the user.
 118 * Byte 7 is hamming ecc for first 7 bytes.  Bytes 8 - 14 are hw-generated ecc.
 119 * Byte 15 (the last) is used by the driver as a "page written" flag.
 120 */
 121static struct nand_ecclayout docg4_oobinfo = {
 122        .eccbytes = 9,
 123        .eccpos = {7, 8, 9, 10, 11, 12, 13, 14, 15},
 124        .oobavail = 7,
 125        .oobfree = { {0, 7} }
 126};
 127
 128static void reset(void __iomem *docptr)
 129{
 130        /* full device reset */
 131
 132        writew(DOC_ASICMODE_RESET | DOC_ASICMODE_MDWREN, docptr + DOC_ASICMODE);
 133        writew(~(DOC_ASICMODE_RESET | DOC_ASICMODE_MDWREN),
 134               docptr + DOC_ASICMODECONFIRM);
 135        write_nop(docptr);
 136
 137        writew(DOC_ASICMODE_NORMAL | DOC_ASICMODE_MDWREN,
 138               docptr + DOC_ASICMODE);
 139        writew(~(DOC_ASICMODE_NORMAL | DOC_ASICMODE_MDWREN),
 140               docptr + DOC_ASICMODECONFIRM);
 141
 142        writew(DOC_ECCCONF1_ECC_ENABLE, docptr + DOC_ECCCONF1);
 143
 144        poll_status(docptr);
 145}
 146
 147static void docg4_select_chip(struct mtd_info *mtd, int chip)
 148{
 149        /*
 150         * Select among multiple cascaded chips ("floors").  Multiple floors are
 151         * not yet supported, so the only valid non-negative value is 0.
 152         */
 153        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 154
 155        if (chip < 0)
 156                return;         /* deselected */
 157
 158        if (chip > 0)
 159                printf("multiple floors currently unsupported\n");
 160
 161        writew(0, docptr + DOC_DEVICESELECT);
 162}
 163
 164static void read_hw_ecc(void __iomem *docptr, uint8_t *ecc_buf)
 165{
 166        /* read the 7 hw-generated ecc bytes */
 167
 168        int i;
 169        for (i = 0; i < 7; i++) { /* hw quirk; read twice */
 170                ecc_buf[i] = readb(docptr + DOC_BCH_SYNDROM(i));
 171                ecc_buf[i] = readb(docptr + DOC_BCH_SYNDROM(i));
 172        }
 173}
 174
 175static int correct_data(struct mtd_info *mtd, uint8_t *buf, int page)
 176{
 177        /*
 178         * Called after a page read when hardware reports bitflips.
 179         * Up to four bitflips can be corrected.
 180         */
 181
 182        struct nand_chip *nand = mtd->priv;
 183        struct docg4_priv *doc = nand->priv;
 184        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 185        int i, numerrs;
 186        unsigned int errpos[4];
 187        const uint8_t blank_read_hwecc[8] = {
 188                0xcf, 0x72, 0xfc, 0x1b, 0xa9, 0xc7, 0xb9, 0 };
 189
 190        read_hw_ecc(docptr, doc->ecc_buf); /* read 7 hw-generated ecc bytes */
 191
 192        /* check if read error is due to a blank page */
 193        if (!memcmp(doc->ecc_buf, blank_read_hwecc, 7))
 194                return 0;       /* yes */
 195
 196        /* skip additional check of "written flag" if ignore_badblocks */
 197        if (!ignore_badblocks) {
 198                /*
 199                 * If the hw ecc bytes are not those of a blank page, there's
 200                 * still a chance that the page is blank, but was read with
 201                 * errors.  Check the "written flag" in last oob byte, which
 202                 * is set to zero when a page is written.  If more than half
 203                 * the bits are set, assume a blank page.  Unfortunately, the
 204                 * bit flips(s) are not reported in stats.
 205                 */
 206
 207                if (doc->oob_buf[15]) {
 208                        int bit, numsetbits = 0;
 209                        unsigned long written_flag = doc->oob_buf[15];
 210
 211                        for (bit = 0; bit < 8; bit++) {
 212                                if (written_flag & 0x01)
 213                                        numsetbits++;
 214                                written_flag >>= 1;
 215                        }
 216                        if (numsetbits > 4) { /* assume blank */
 217                                printf("errors in blank page at offset %08x\n",
 218                                       page * DOCG4_PAGE_SIZE);
 219                                return 0;
 220                        }
 221                }
 222        }
 223
 224        /*
 225         * The hardware ecc unit produces oob_ecc ^ calc_ecc.  The kernel's bch
 226         * algorithm is used to decode this.  However the hw operates on page
 227         * data in a bit order that is the reverse of that of the bch alg,
 228         * requiring that the bits be reversed on the result.  Thanks to Ivan
 229         * Djelic for his analysis!
 230         */
 231        for (i = 0; i < 7; i++)
 232                doc->ecc_buf[i] = bitrev8(doc->ecc_buf[i]);
 233
 234        numerrs = decode_bch(doc->bch, NULL, DOCG4_USERDATA_LEN, NULL,
 235                             doc->ecc_buf, NULL, errpos);
 236
 237        if (numerrs == -EBADMSG) {
 238                printf("uncorrectable errors at offset %08x\n",
 239                       page * DOCG4_PAGE_SIZE);
 240                return -EBADMSG;
 241        }
 242
 243        BUG_ON(numerrs < 0);    /* -EINVAL, or anything other than -EBADMSG */
 244
 245        /* undo last step in BCH alg (modulo mirroring not needed) */
 246        for (i = 0; i < numerrs; i++)
 247                errpos[i] = (errpos[i] & ~7)|(7-(errpos[i] & 7));
 248
 249        /* fix the errors */
 250        for (i = 0; i < numerrs; i++) {
 251                /* ignore if error within oob ecc bytes */
 252                if (errpos[i] > DOCG4_USERDATA_LEN * 8)
 253                        continue;
 254
 255                /* if error within oob area preceeding ecc bytes... */
 256                if (errpos[i] > DOCG4_PAGE_SIZE * 8)
 257                        __change_bit(errpos[i] - DOCG4_PAGE_SIZE * 8,
 258                                     (unsigned long *)doc->oob_buf);
 259
 260                else    /* error in page data */
 261                        __change_bit(errpos[i], (unsigned long *)buf);
 262        }
 263
 264        printf("%d error(s) corrected at offset %08x\n",
 265               numerrs, page * DOCG4_PAGE_SIZE);
 266
 267        return numerrs;
 268}
 269
 270static int read_progstatus(struct docg4_priv *doc, void __iomem *docptr)
 271{
 272        /*
 273         * This apparently checks the status of programming.  Done after an
 274         * erasure, and after page data is written.  On error, the status is
 275         * saved, to be later retrieved by the nand infrastructure code.
 276         */
 277
 278        /* status is read from the I/O reg */
 279        uint16_t status1 = readw(docptr + DOC_IOSPACE_DATA);
 280        uint16_t status2 = readw(docptr + DOC_IOSPACE_DATA);
 281        uint16_t status3 = readw(docptr + DOCG4_MYSTERY_REG);
 282
 283        MTDDEBUG(MTD_DEBUG_LEVEL3, "docg4: %s: %02x %02x %02x\n",
 284            __func__, status1, status2, status3);
 285
 286        if (status1 != DOCG4_PROGSTATUS_GOOD ||
 287            status2 != DOCG4_PROGSTATUS_GOOD_2 ||
 288            status3 != DOCG4_PROGSTATUS_GOOD_2) {
 289                doc->status = NAND_STATUS_FAIL;
 290                printf("read_progstatus failed: %02x, %02x, %02x\n",
 291                       status1, status2, status3);
 292                return -EIO;
 293        }
 294        return 0;
 295}
 296
 297static int pageprog(struct mtd_info *mtd)
 298{
 299        /*
 300         * Final step in writing a page.  Writes the contents of its
 301         * internal buffer out to the flash array, or some such.
 302         */
 303
 304        struct nand_chip *nand = mtd->priv;
 305        struct docg4_priv *doc = nand->priv;
 306        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 307        int retval = 0;
 308
 309        MTDDEBUG(MTD_DEBUG_LEVEL3, "docg4: %s\n", __func__);
 310
 311        writew(DOCG4_SEQ_PAGEPROG, docptr + DOC_FLASHSEQUENCE);
 312        writew(DOC_CMD_PROG_CYCLE2, docptr + DOC_FLASHCOMMAND);
 313        write_nop(docptr);
 314        write_nop(docptr);
 315
 316        /* Just busy-wait; usleep_range() slows things down noticeably. */
 317        poll_status(docptr);
 318
 319        writew(DOCG4_SEQ_FLUSH, docptr + DOC_FLASHSEQUENCE);
 320        writew(DOCG4_CMD_FLUSH, docptr + DOC_FLASHCOMMAND);
 321        writew(DOC_ECCCONF0_READ_MODE | 4, docptr + DOC_ECCCONF0);
 322        write_nop(docptr);
 323        write_nop(docptr);
 324        write_nop(docptr);
 325        write_nop(docptr);
 326        write_nop(docptr);
 327
 328        retval = read_progstatus(doc, docptr);
 329        writew(0, docptr + DOC_DATAEND);
 330        write_nop(docptr);
 331        poll_status(docptr);
 332        write_nop(docptr);
 333
 334        return retval;
 335}
 336
 337static void sequence_reset(void __iomem *docptr)
 338{
 339        /* common starting sequence for all operations */
 340
 341        writew(DOC_CTRL_UNKNOWN | DOC_CTRL_CE, docptr + DOC_FLASHCONTROL);
 342        writew(DOC_SEQ_RESET, docptr + DOC_FLASHSEQUENCE);
 343        writew(DOC_CMD_RESET, docptr + DOC_FLASHCOMMAND);
 344        write_nop(docptr);
 345        write_nop(docptr);
 346        poll_status(docptr);
 347        write_nop(docptr);
 348}
 349
 350static void read_page_prologue(void __iomem *docptr, uint32_t docg4_addr)
 351{
 352        /* first step in reading a page */
 353
 354        sequence_reset(docptr);
 355
 356        writew(DOCG4_SEQ_PAGE_READ, docptr + DOC_FLASHSEQUENCE);
 357        writew(DOCG4_CMD_PAGE_READ, docptr + DOC_FLASHCOMMAND);
 358        write_nop(docptr);
 359
 360        write_addr(docptr, docg4_addr);
 361
 362        write_nop(docptr);
 363        writew(DOCG4_CMD_READ2, docptr + DOC_FLASHCOMMAND);
 364        write_nop(docptr);
 365        write_nop(docptr);
 366
 367        poll_status(docptr);
 368}
 369
 370static void write_page_prologue(void __iomem *docptr, uint32_t docg4_addr)
 371{
 372        /* first step in writing a page */
 373
 374        sequence_reset(docptr);
 375        writew(DOCG4_SEQ_PAGEWRITE, docptr + DOC_FLASHSEQUENCE);
 376        writew(DOCG4_CMD_PAGEWRITE, docptr + DOC_FLASHCOMMAND);
 377        write_nop(docptr);
 378        write_addr(docptr, docg4_addr);
 379        write_nop(docptr);
 380        write_nop(docptr);
 381        poll_status(docptr);
 382}
 383
 384static uint32_t mtd_to_docg4_address(int page, int column)
 385{
 386        /*
 387         * Convert mtd address to format used by the device, 32 bit packed.
 388         *
 389         * Some notes on G4 addressing... The M-Sys documentation on this device
 390         * claims that pages are 2K in length, and indeed, the format of the
 391         * address used by the device reflects that.  But within each page are
 392         * four 512 byte "sub-pages", each with its own oob data that is
 393         * read/written immediately after the 512 bytes of page data.  This oob
 394         * data contains the ecc bytes for the preceeding 512 bytes.
 395         *
 396         * Rather than tell the mtd nand infrastructure that page size is 2k,
 397         * with four sub-pages each, we engage in a little subterfuge and tell
 398         * the infrastructure code that pages are 512 bytes in size.  This is
 399         * done because during the course of reverse-engineering the device, I
 400         * never observed an instance where an entire 2K "page" was read or
 401         * written as a unit.  Each "sub-page" is always addressed individually,
 402         * its data read/written, and ecc handled before the next "sub-page" is
 403         * addressed.
 404         *
 405         * This requires us to convert addresses passed by the mtd nand
 406         * infrastructure code to those used by the device.
 407         *
 408         * The address that is written to the device consists of four bytes: the
 409         * first two are the 2k page number, and the second is the index into
 410         * the page.  The index is in terms of 16-bit half-words and includes
 411         * the preceeding oob data, so e.g., the index into the second
 412         * "sub-page" is 0x108, and the full device address of the start of mtd
 413         * page 0x201 is 0x00800108.
 414         */
 415        int g4_page = page / 4;                       /* device's 2K page */
 416        int g4_index = (page % 4) * 0x108 + column/2; /* offset into page */
 417        return (g4_page << 16) | g4_index;            /* pack */
 418}
 419
 420static void docg4_command(struct mtd_info *mtd, unsigned command, int column,
 421                          int page_addr)
 422{
 423        /* handle standard nand commands */
 424
 425        struct nand_chip *nand = mtd->priv;
 426        struct docg4_priv *doc = nand->priv;
 427        uint32_t g4_addr = mtd_to_docg4_address(page_addr, column);
 428
 429        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s %x, page_addr=%x, column=%x\n",
 430            __func__, command, page_addr, column);
 431
 432        /*
 433         * Save the command and its arguments.  This enables emulation of
 434         * standard flash devices, and also some optimizations.
 435         */
 436        doc->last_command.command = command;
 437        doc->last_command.column = column;
 438        doc->last_command.page = page_addr;
 439
 440        switch (command) {
 441        case NAND_CMD_RESET:
 442                reset(CONFIG_SYS_NAND_BASE);
 443                break;
 444
 445        case NAND_CMD_READ0:
 446                read_page_prologue(CONFIG_SYS_NAND_BASE, g4_addr);
 447                break;
 448
 449        case NAND_CMD_STATUS:
 450                /* next call to read_byte() will expect a status */
 451                break;
 452
 453        case NAND_CMD_SEQIN:
 454                write_page_prologue(CONFIG_SYS_NAND_BASE, g4_addr);
 455
 456                /* hack for deferred write of oob bytes */
 457                if (doc->oob_page == page_addr)
 458                        memcpy(nand->oob_poi, doc->oob_buf, 16);
 459                break;
 460
 461        case NAND_CMD_PAGEPROG:
 462                pageprog(mtd);
 463                break;
 464
 465        /* we don't expect these, based on review of nand_base.c */
 466        case NAND_CMD_READOOB:
 467        case NAND_CMD_READID:
 468        case NAND_CMD_ERASE1:
 469        case NAND_CMD_ERASE2:
 470                printf("docg4_command: unexpected nand command 0x%x\n",
 471                       command);
 472                break;
 473        }
 474}
 475
 476static void docg4_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 477{
 478        int i;
 479        struct nand_chip *nand = mtd->priv;
 480        uint16_t *p = (uint16_t *)buf;
 481        len >>= 1;
 482
 483        for (i = 0; i < len; i++)
 484                p[i] = readw(nand->IO_ADDR_R);
 485}
 486
 487static int docg4_read_oob(struct mtd_info *mtd, struct nand_chip *nand,
 488                          int page)
 489{
 490        struct docg4_priv *doc = nand->priv;
 491        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 492        uint16_t status;
 493
 494        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s: page %x\n", __func__, page);
 495
 496        /*
 497         * Oob bytes are read as part of a normal page read.  If the previous
 498         * nand command was a read of the page whose oob is now being read, just
 499         * copy the oob bytes that we saved in a local buffer and avoid a
 500         * separate oob read.
 501         */
 502        if (doc->last_command.command == NAND_CMD_READ0 &&
 503            doc->last_command.page == page) {
 504                memcpy(nand->oob_poi, doc->oob_buf, 16);
 505                return 0;
 506        }
 507
 508        /*
 509         * Separate read of oob data only.
 510         */
 511        docg4_command(mtd, NAND_CMD_READ0, nand->ecc.size, page);
 512
 513        writew(DOC_ECCCONF0_READ_MODE | DOCG4_OOB_SIZE, docptr + DOC_ECCCONF0);
 514        write_nop(docptr);
 515        write_nop(docptr);
 516        write_nop(docptr);
 517        write_nop(docptr);
 518        write_nop(docptr);
 519
 520        /* the 1st byte from the I/O reg is a status; the rest is oob data */
 521        status = readw(docptr + DOC_IOSPACE_DATA);
 522        if (status & DOCG4_READ_ERROR) {
 523                printf("docg4_read_oob failed: status = 0x%02x\n", status);
 524                return -EIO;
 525        }
 526
 527        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s: status = 0x%x\n", __func__, status);
 528
 529        docg4_read_buf(mtd, nand->oob_poi, 16);
 530
 531        write_nop(docptr);
 532        write_nop(docptr);
 533        write_nop(docptr);
 534        writew(0, docptr + DOC_DATAEND);
 535        write_nop(docptr);
 536
 537        return 0;
 538}
 539
 540static int docg4_write_oob(struct mtd_info *mtd, struct nand_chip *nand,
 541                           int page)
 542{
 543        /*
 544         * Writing oob-only is not really supported, because MLC nand must write
 545         * oob bytes at the same time as page data.  Nonetheless, we save the
 546         * oob buffer contents here, and then write it along with the page data
 547         * if the same page is subsequently written.  This allows user space
 548         * utilities that write the oob data prior to the page data to work
 549         * (e.g., nandwrite).  The disdvantage is that, if the intention was to
 550         * write oob only, the operation is quietly ignored.  Also, oob can get
 551         * corrupted if two concurrent processes are running nandwrite.
 552         */
 553
 554        /* note that bytes 7..14 are hw generated hamming/ecc and overwritten */
 555        struct docg4_priv *doc = nand->priv;
 556        doc->oob_page = page;
 557        memcpy(doc->oob_buf, nand->oob_poi, 16);
 558        return 0;
 559}
 560
 561static int docg4_block_neverbad(struct mtd_info *mtd, loff_t ofs, int getchip)
 562{
 563        /* only called when module_param ignore_badblocks is set */
 564        return 0;
 565}
 566
 567static void docg4_write_buf16(struct mtd_info *mtd, const uint8_t *buf, int len)
 568{
 569        int i;
 570        struct nand_chip *nand = mtd->priv;
 571        uint16_t *p = (uint16_t *)buf;
 572        len >>= 1;
 573
 574        for (i = 0; i < len; i++)
 575                writew(p[i], nand->IO_ADDR_W);
 576}
 577
 578static int write_page(struct mtd_info *mtd, struct nand_chip *nand,
 579                       const uint8_t *buf, int use_ecc)
 580{
 581        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 582        uint8_t ecc_buf[8];
 583
 584        writew(DOC_ECCCONF0_ECC_ENABLE |
 585               DOC_ECCCONF0_UNKNOWN |
 586               DOCG4_BCH_SIZE,
 587               docptr + DOC_ECCCONF0);
 588        write_nop(docptr);
 589
 590        /* write the page data */
 591        docg4_write_buf16(mtd, buf, DOCG4_PAGE_SIZE);
 592
 593        /* oob bytes 0 through 5 are written to I/O reg */
 594        docg4_write_buf16(mtd, nand->oob_poi, 6);
 595
 596        /* oob byte 6 written to a separate reg */
 597        writew(nand->oob_poi[6], docptr + DOCG4_OOB_6_7);
 598
 599        write_nop(docptr);
 600        write_nop(docptr);
 601
 602        /* write hw-generated ecc bytes to oob */
 603        if (likely(use_ecc)) {
 604                /* oob byte 7 is hamming code */
 605                uint8_t hamming = readb(docptr + DOC_HAMMINGPARITY);
 606                hamming = readb(docptr + DOC_HAMMINGPARITY); /* 2nd read */
 607                writew(hamming, docptr + DOCG4_OOB_6_7);
 608                write_nop(docptr);
 609
 610                /* read the 7 bch bytes from ecc regs */
 611                read_hw_ecc(docptr, ecc_buf);
 612                ecc_buf[7] = 0;         /* clear the "page written" flag */
 613        }
 614
 615        /* write user-supplied bytes to oob */
 616        else {
 617                writew(nand->oob_poi[7], docptr + DOCG4_OOB_6_7);
 618                write_nop(docptr);
 619                memcpy(ecc_buf, &nand->oob_poi[8], 8);
 620        }
 621
 622        docg4_write_buf16(mtd, ecc_buf, 8);
 623        write_nop(docptr);
 624        write_nop(docptr);
 625        writew(0, docptr + DOC_DATAEND);
 626        write_nop(docptr);
 627
 628        return 0;
 629}
 630
 631static int docg4_write_page_raw(struct mtd_info *mtd, struct nand_chip *nand,
 632                                 const uint8_t *buf, int oob_required)
 633{
 634        return write_page(mtd, nand, buf, 0);
 635}
 636
 637static int docg4_write_page(struct mtd_info *mtd, struct nand_chip *nand,
 638                             const uint8_t *buf, int oob_required)
 639{
 640        return write_page(mtd, nand, buf, 1);
 641}
 642
 643static int read_page(struct mtd_info *mtd, struct nand_chip *nand,
 644                     uint8_t *buf, int page, int use_ecc)
 645{
 646        struct docg4_priv *doc = nand->priv;
 647        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 648        uint16_t status, edc_err, *buf16;
 649
 650        writew(DOC_ECCCONF0_READ_MODE |
 651               DOC_ECCCONF0_ECC_ENABLE |
 652               DOC_ECCCONF0_UNKNOWN |
 653               DOCG4_BCH_SIZE,
 654               docptr + DOC_ECCCONF0);
 655        write_nop(docptr);
 656        write_nop(docptr);
 657        write_nop(docptr);
 658        write_nop(docptr);
 659        write_nop(docptr);
 660
 661        /* the 1st byte from the I/O reg is a status; the rest is page data */
 662        status = readw(docptr + DOC_IOSPACE_DATA);
 663        if (status & DOCG4_READ_ERROR) {
 664                printf("docg4_read_page: bad status: 0x%02x\n", status);
 665                writew(0, docptr + DOC_DATAEND);
 666                return -EIO;
 667        }
 668
 669        docg4_read_buf(mtd, buf, DOCG4_PAGE_SIZE); /* read the page data */
 670
 671        /* first 14 oob bytes read from I/O reg */
 672        docg4_read_buf(mtd, nand->oob_poi, 14);
 673
 674        /* last 2 read from another reg */
 675        buf16 = (uint16_t *)(nand->oob_poi + 14);
 676        *buf16 = readw(docptr + DOCG4_MYSTERY_REG);
 677
 678        /*
 679         * Diskonchips read oob immediately after a page read.  Mtd
 680         * infrastructure issues a separate command for reading oob after the
 681         * page is read.  So we save the oob bytes in a local buffer and just
 682         * copy it if the next command reads oob from the same page.
 683         */
 684        memcpy(doc->oob_buf, nand->oob_poi, 16);
 685
 686        write_nop(docptr);
 687
 688        if (likely(use_ecc)) {
 689                /* read the register that tells us if bitflip(s) detected  */
 690                edc_err = readw(docptr + DOC_ECCCONF1);
 691                edc_err = readw(docptr + DOC_ECCCONF1);
 692
 693                /* If bitflips are reported, attempt to correct with ecc */
 694                if (edc_err & DOC_ECCCONF1_BCH_SYNDROM_ERR) {
 695                        int bits_corrected = correct_data(mtd, buf, page);
 696                        if (bits_corrected == -EBADMSG)
 697                                mtd->ecc_stats.failed++;
 698                        else
 699                                mtd->ecc_stats.corrected += bits_corrected;
 700                }
 701        }
 702
 703        writew(0, docptr + DOC_DATAEND);
 704        return 0;
 705}
 706
 707
 708static int docg4_read_page_raw(struct mtd_info *mtd, struct nand_chip *nand,
 709                               uint8_t *buf, int oob_required, int page)
 710{
 711        return read_page(mtd, nand, buf, page, 0);
 712}
 713
 714static int docg4_read_page(struct mtd_info *mtd, struct nand_chip *nand,
 715                           uint8_t *buf, int oob_required, int page)
 716{
 717        return read_page(mtd, nand, buf, page, 1);
 718}
 719
 720static void docg4_erase_block(struct mtd_info *mtd, int page)
 721{
 722        struct nand_chip *nand = mtd->priv;
 723        struct docg4_priv *doc = nand->priv;
 724        void __iomem *docptr = CONFIG_SYS_NAND_BASE;
 725        uint16_t g4_page;
 726
 727        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s: page %04x\n", __func__, page);
 728
 729        sequence_reset(docptr);
 730
 731        writew(DOCG4_SEQ_BLOCKERASE, docptr + DOC_FLASHSEQUENCE);
 732        writew(DOC_CMD_PROG_BLOCK_ADDR, docptr + DOC_FLASHCOMMAND);
 733        write_nop(docptr);
 734
 735        /* only 2 bytes of address are written to specify erase block */
 736        g4_page = (uint16_t)(page / 4);  /* to g4's 2k page addressing */
 737        writeb(g4_page & 0xff, docptr + DOC_FLASHADDRESS);
 738        g4_page >>= 8;
 739        writeb(g4_page & 0xff, docptr + DOC_FLASHADDRESS);
 740        write_nop(docptr);
 741
 742        /* start the erasure */
 743        writew(DOC_CMD_ERASECYCLE2, docptr + DOC_FLASHCOMMAND);
 744        write_nop(docptr);
 745        write_nop(docptr);
 746
 747        poll_status(docptr);
 748        writew(DOCG4_SEQ_FLUSH, docptr + DOC_FLASHSEQUENCE);
 749        writew(DOCG4_CMD_FLUSH, docptr + DOC_FLASHCOMMAND);
 750        writew(DOC_ECCCONF0_READ_MODE | 4, docptr + DOC_ECCCONF0);
 751        write_nop(docptr);
 752        write_nop(docptr);
 753        write_nop(docptr);
 754        write_nop(docptr);
 755        write_nop(docptr);
 756
 757        read_progstatus(doc, docptr);
 758
 759        writew(0, docptr + DOC_DATAEND);
 760        write_nop(docptr);
 761        poll_status(docptr);
 762        write_nop(docptr);
 763}
 764
 765static int read_factory_bbt(struct mtd_info *mtd)
 766{
 767        /*
 768         * The device contains a read-only factory bad block table.  Read it and
 769         * update the memory-based bbt accordingly.
 770         */
 771
 772        struct nand_chip *nand = mtd->priv;
 773        uint32_t g4_addr = mtd_to_docg4_address(DOCG4_FACTORY_BBT_PAGE, 0);
 774        uint8_t *buf;
 775        int i, block, status;
 776
 777        buf = kzalloc(DOCG4_PAGE_SIZE, GFP_KERNEL);
 778        if (buf == NULL)
 779                return -ENOMEM;
 780
 781        read_page_prologue(CONFIG_SYS_NAND_BASE, g4_addr);
 782        status = docg4_read_page(mtd, nand, buf, 0, DOCG4_FACTORY_BBT_PAGE);
 783        if (status)
 784                goto exit;
 785
 786        /*
 787         * If no memory-based bbt was created, exit.  This will happen if module
 788         * parameter ignore_badblocks is set.  Then why even call this function?
 789         * For an unknown reason, block erase always fails if it's the first
 790         * operation after device power-up.  The above read ensures it never is.
 791         * Ugly, I know.
 792         */
 793        if (nand->bbt == NULL)  /* no memory-based bbt */
 794                goto exit;
 795
 796        /*
 797         * Parse factory bbt and update memory-based bbt.  Factory bbt format is
 798         * simple: one bit per block, block numbers increase left to right (msb
 799         * to lsb).  Bit clear means bad block.
 800         */
 801        for (i = block = 0; block < DOCG4_NUMBLOCKS; block += 8, i++) {
 802                int bitnum;
 803                uint8_t mask;
 804                for (bitnum = 0, mask = 0x80;
 805                     bitnum < 8; bitnum++, mask >>= 1) {
 806                        if (!(buf[i] & mask)) {
 807                                int badblock = block + bitnum;
 808                                nand->bbt[badblock / 4] |=
 809                                        0x03 << ((badblock % 4) * 2);
 810                                mtd->ecc_stats.badblocks++;
 811                                printf("factory-marked bad block: %d\n",
 812                                       badblock);
 813                        }
 814                }
 815        }
 816 exit:
 817        kfree(buf);
 818        return status;
 819}
 820
 821static int docg4_block_markbad(struct mtd_info *mtd, loff_t ofs)
 822{
 823        /*
 824         * Mark a block as bad.  Bad blocks are marked in the oob area of the
 825         * first page of the block.  The default scan_bbt() in the nand
 826         * infrastructure code works fine for building the memory-based bbt
 827         * during initialization, as does the nand infrastructure function that
 828         * checks if a block is bad by reading the bbt.  This function replaces
 829         * the nand default because writes to oob-only are not supported.
 830         */
 831
 832        int ret, i;
 833        uint8_t *buf;
 834        struct nand_chip *nand = mtd->priv;
 835        struct nand_bbt_descr *bbtd = nand->badblock_pattern;
 836        int block = (int)(ofs >> nand->bbt_erase_shift);
 837        int page = (int)(ofs >> nand->page_shift);
 838        uint32_t g4_addr = mtd_to_docg4_address(page, 0);
 839
 840        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s: %08llx\n", __func__, ofs);
 841
 842        if (unlikely(ofs & (DOCG4_BLOCK_SIZE - 1)))
 843                printf("%s: ofs %llx not start of block!\n",
 844                       __func__, ofs);
 845
 846        /* allocate blank buffer for page data */
 847        buf = kzalloc(DOCG4_PAGE_SIZE, GFP_KERNEL);
 848        if (buf == NULL)
 849                return -ENOMEM;
 850
 851        /* update bbt in memory */
 852        nand->bbt[block / 4] |= 0x01 << ((block & 0x03) * 2);
 853
 854        /* write bit-wise negation of pattern to oob buffer */
 855        memset(nand->oob_poi, 0xff, mtd->oobsize);
 856        for (i = 0; i < bbtd->len; i++)
 857                nand->oob_poi[bbtd->offs + i] = ~bbtd->pattern[i];
 858
 859        /* write first page of block */
 860        write_page_prologue(CONFIG_SYS_NAND_BASE, g4_addr);
 861        docg4_write_page(mtd, nand, buf, 1);
 862        ret = pageprog(mtd);
 863        if (!ret)
 864                mtd->ecc_stats.badblocks++;
 865
 866        kfree(buf);
 867
 868        return ret;
 869}
 870
 871static uint8_t docg4_read_byte(struct mtd_info *mtd)
 872{
 873        struct nand_chip *nand = mtd->priv;
 874        struct docg4_priv *doc = nand->priv;
 875
 876        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s\n", __func__);
 877
 878        if (doc->last_command.command == NAND_CMD_STATUS) {
 879                int status;
 880
 881                /*
 882                 * Previous nand command was status request, so nand
 883                 * infrastructure code expects to read the status here.  If an
 884                 * error occurred in a previous operation, report it.
 885                 */
 886                doc->last_command.command = 0;
 887
 888                if (doc->status) {
 889                        status = doc->status;
 890                        doc->status = 0;
 891                }
 892
 893                /* why is NAND_STATUS_WP inverse logic?? */
 894                else
 895                        status = NAND_STATUS_WP | NAND_STATUS_READY;
 896
 897                return status;
 898        }
 899
 900        printf("unexpectd call to read_byte()\n");
 901
 902        return 0;
 903}
 904
 905static int docg4_wait(struct mtd_info *mtd, struct nand_chip *nand)
 906{
 907        struct docg4_priv *doc = nand->priv;
 908        int status = NAND_STATUS_WP;       /* inverse logic?? */
 909        MTDDEBUG(MTD_DEBUG_LEVEL3, "%s...\n", __func__);
 910
 911        /* report any previously unreported error */
 912        if (doc->status) {
 913                status |= doc->status;
 914                doc->status = 0;
 915                return status;
 916        }
 917
 918        status |= poll_status(CONFIG_SYS_NAND_BASE);
 919        return status;
 920}
 921
 922int docg4_nand_init(struct mtd_info *mtd, struct nand_chip *nand, int devnum)
 923{
 924        uint16_t id1, id2;
 925        struct docg4_priv *docg4;
 926        int retval;
 927
 928        docg4 = kzalloc(sizeof(*docg4), GFP_KERNEL);
 929        if (!docg4)
 930                return -1;
 931
 932        mtd->priv = nand;
 933        nand->priv = docg4;
 934
 935        /* These must be initialized here because the docg4 is non-standard
 936         * and doesn't produce an id that the nand code can use to look up
 937         * these values (nand_scan_ident() not called).
 938         */
 939        mtd->size = DOCG4_CHIP_SIZE;
 940        mtd->name = "Msys_Diskonchip_G4";
 941        mtd->writesize = DOCG4_PAGE_SIZE;
 942        mtd->erasesize = DOCG4_BLOCK_SIZE;
 943        mtd->oobsize = DOCG4_OOB_SIZE;
 944
 945        nand->IO_ADDR_R =
 946                (void __iomem *)CONFIG_SYS_NAND_BASE + DOC_IOSPACE_DATA;
 947        nand->IO_ADDR_W = nand->IO_ADDR_R;
 948        nand->chipsize = DOCG4_CHIP_SIZE;
 949        nand->chip_shift = DOCG4_CHIP_SHIFT;
 950        nand->bbt_erase_shift = DOCG4_ERASE_SHIFT;
 951        nand->phys_erase_shift = DOCG4_ERASE_SHIFT;
 952        nand->chip_delay = 20;
 953        nand->page_shift = DOCG4_PAGE_SHIFT;
 954        nand->pagemask = 0x3ffff;
 955        nand->badblockpos = NAND_LARGE_BADBLOCK_POS;
 956        nand->badblockbits = 8;
 957        nand->ecc.layout = &docg4_oobinfo;
 958        nand->ecc.mode = NAND_ECC_HW_SYNDROME;
 959        nand->ecc.size = DOCG4_PAGE_SIZE;
 960        nand->ecc.prepad = 8;
 961        nand->ecc.bytes = 8;
 962        nand->ecc.strength = DOCG4_T;
 963        nand->options = NAND_BUSWIDTH_16 | NAND_NO_SUBPAGE_WRITE;
 964        nand->controller = &nand->hwcontrol;
 965
 966        /* methods */
 967        nand->cmdfunc = docg4_command;
 968        nand->waitfunc = docg4_wait;
 969        nand->select_chip = docg4_select_chip;
 970        nand->read_byte = docg4_read_byte;
 971        nand->block_markbad = docg4_block_markbad;
 972        nand->read_buf = docg4_read_buf;
 973        nand->write_buf = docg4_write_buf16;
 974        nand->scan_bbt = nand_default_bbt;
 975        nand->erase_cmd = docg4_erase_block;
 976        nand->ecc.read_page = docg4_read_page;
 977        nand->ecc.write_page = docg4_write_page;
 978        nand->ecc.read_page_raw = docg4_read_page_raw;
 979        nand->ecc.write_page_raw = docg4_write_page_raw;
 980        nand->ecc.read_oob = docg4_read_oob;
 981        nand->ecc.write_oob = docg4_write_oob;
 982
 983        /*
 984         * The way the nand infrastructure code is written, a memory-based bbt
 985         * is not created if NAND_SKIP_BBTSCAN is set.  With no memory bbt,
 986         * nand->block_bad() is used.  So when ignoring bad blocks, we skip the
 987         * scan and define a dummy block_bad() which always returns 0.
 988         */
 989        if (ignore_badblocks) {
 990                nand->options |= NAND_SKIP_BBTSCAN;
 991                nand->block_bad = docg4_block_neverbad;
 992        }
 993
 994        reset(CONFIG_SYS_NAND_BASE);
 995
 996        /* check for presence of g4 chip by reading id registers */
 997        id1 = readw(CONFIG_SYS_NAND_BASE + DOC_CHIPID);
 998        id1 = readw(CONFIG_SYS_NAND_BASE + DOCG4_MYSTERY_REG);
 999        id2 = readw(CONFIG_SYS_NAND_BASE + DOC_CHIPID_INV);
1000        id2 = readw(CONFIG_SYS_NAND_BASE + DOCG4_MYSTERY_REG);
1001        if (id1 != DOCG4_IDREG1_VALUE || id2 != DOCG4_IDREG2_VALUE)
1002                return -1;
1003
1004        /* initialize bch algorithm */
1005        docg4->bch = init_bch(DOCG4_M, DOCG4_T, DOCG4_PRIMITIVE_POLY);
1006        if (docg4->bch == NULL)
1007                return -1;
1008
1009        retval = nand_scan_tail(mtd);
1010        if (retval)
1011                return -1;
1012
1013        /*
1014         * Scan for bad blocks and create bbt here, then add the factory-marked
1015         * bad blocks to the bbt.
1016         */
1017        nand->scan_bbt(mtd);
1018        nand->options |= NAND_BBT_SCANNED;
1019        retval = read_factory_bbt(mtd);
1020        if (retval)
1021                return -1;
1022
1023        retval = nand_register(devnum);
1024        if (retval)
1025                return -1;
1026
1027        return 0;
1028}
1029