]> git.kernelconcepts.de Git - karo-tx-uboot.git/blobdiff - drivers/mtd/nand/nand_util.c
Merge branch 'master' of git://git.denx.de/u-boot-video
[karo-tx-uboot.git] / drivers / mtd / nand / nand_util.c
index 22c741169476269d167d42b8207da08f500768ae..d81972ca27baa9f851af9aa872da262386f31d2c 100644 (file)
@@ -11,6 +11,9 @@
  *             nandwrite.c by Steven J. Hill (sjhill@realitydiluted.com)
  *                            and Thomas Gleixner (tglx@linutronix.de)
  *
+ * Copyright (C) 2008 Nokia Corporation: drop_ffs() function by
+ * Artem Bityutskiy <dedekind1@gmail.com> from mtd-utils
+ *
  * See file CREDITS for list of people who contributed to this
  * project.
  *
 #include <nand.h>
 #include <jffs2/jffs2.h>
 
-typedef struct erase_info erase_info_t;
-typedef struct mtd_info          mtd_info_t;
+typedef struct erase_info      erase_info_t;
+typedef struct mtd_info                mtd_info_t;
 
 /* support only for native endian JFFS2 */
 #define cpu_to_je16(x) (x)
 #define cpu_to_je32(x) (x)
 
-/*****************************************************************************/
-static int nand_block_bad_scrub(struct mtd_info *mtd, loff_t ofs, int getchip)
-{
-       return 0;
-}
-
 /**
  * nand_erase_opts: - erase NAND flash with support for various options
- *                   (jffs2 formating)
+ *                   (jffs2 formatting)
  *
  * @param meminfo      NAND device to erase
  * @param opts         options,  @see struct nand_erase_options
@@ -79,13 +76,12 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
        int bbtest = 1;
        int result;
        int percent_complete = -1;
-       int (*nand_block_bad_old)(struct mtd_info *, loff_t, int) = NULL;
        const char *mtd_device = meminfo->name;
        struct mtd_oob_ops oob_opts;
        struct nand_chip *chip = meminfo->priv;
 
-       if ((opts->offset & (meminfo->writesize - 1)) != 0) {
-               printf("Attempt to erase non page aligned data\n");
+       if ((opts->offset & (meminfo->erasesize - 1)) != 0) {
+               printf("Attempt to erase non block-aligned data\n");
                return -1;
        }
 
@@ -98,8 +94,8 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
        erase_length = lldiv(opts->length + meminfo->erasesize - 1,
                             meminfo->erasesize);
 
-       cleanmarker.magic = cpu_to_je16 (JFFS2_MAGIC_BITMASK);
-       cleanmarker.nodetype = cpu_to_je16 (JFFS2_NODETYPE_CLEANMARKER);
+       cleanmarker.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+       cleanmarker.nodetype = cpu_to_je16(JFFS2_NODETYPE_CLEANMARKER);
        cleanmarker.totlen = cpu_to_je32(8);
 
        /* scrub option allows to erase badblock. To prevent internal
@@ -107,27 +103,25 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
         * and disable bad block table while erasing.
         */
        if (opts->scrub) {
-               struct nand_chip *priv_nand = meminfo->priv;
-
-               nand_block_bad_old = priv_nand->block_bad;
-               priv_nand->block_bad = nand_block_bad_scrub;
-               /* we don't need the bad block table anymore...
+               erase.scrub = opts->scrub;
+               /*
+                * We don't need the bad block table anymore...
                 * after scrub, there are no bad blocks left!
                 */
-               if (priv_nand->bbt) {
-                       kfree(priv_nand->bbt);
+               if (chip->bbt) {
+                       kfree(chip->bbt);
                }
-               priv_nand->bbt = NULL;
+               chip->bbt = NULL;
        }
 
        for (erased_length = 0;
             erased_length < erase_length;
             erase.addr += meminfo->erasesize) {
 
-               WATCHDOG_RESET ();
+               WATCHDOG_RESET();
 
                if (!opts->scrub && bbtest) {
-                       int ret = meminfo->block_isbad(meminfo, erase.addr);
+                       int ret = mtd_block_isbad(meminfo, erase.addr);
                        if (ret > 0) {
                                if (!opts->quiet)
                                        printf("\rSkipping bad block at  "
@@ -150,7 +144,7 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
 
                erased_length++;
 
-               result = meminfo->erase(meminfo, &erase);
+               result = mtd_erase(meminfo, &erase);
                if (result != 0) {
                        printf("\n%s: MTD Erase failure: %d\n",
                               mtd_device, result);
@@ -159,15 +153,16 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
 
                /* format for JFFS2 ? */
                if (opts->jffs2 && chip->ecc.layout->oobavail >= 8) {
-                       chip->ops.ooblen = 8;
-                       chip->ops.datbuf = NULL;
-                       chip->ops.oobbuf = (uint8_t *)&cleanmarker;
-                       chip->ops.ooboffs = 0;
-                       chip->ops.mode = MTD_OOB_AUTO;
-
-                       result = meminfo->write_oob(meminfo,
+                       struct mtd_oob_ops ops;
+                       ops.ooblen = 8;
+                       ops.datbuf = NULL;
+                       ops.oobbuf = (uint8_t *)&cleanmarker;
+                       ops.ooboffs = 0;
+                       ops.mode = MTD_OPS_AUTO_OOB;
+
+                       result = mtd_write_oob(meminfo,
                                                    erase.addr,
-                                                   &chip->ops);
+                                                   &ops);
                        if (result != 0) {
                                printf("\n%s: MTD writeoob failure: %d\n",
                                       mtd_device, result);
@@ -201,12 +196,8 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
        if (!opts->quiet)
                printf("\n");
 
-       if (nand_block_bad_old) {
-               struct nand_chip *priv_nand = meminfo->priv;
-
-               priv_nand->block_bad = nand_block_bad_old;
-               priv_nand->scan_bbt(meminfo);
-       }
+       if (opts->scrub)
+               chip->scan_bbt(meminfo);
 
        return 0;
 }
@@ -217,12 +208,6 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
  * Support for locking / unlocking operations of some NAND devices
  *****************************************************************************/
 
-#define NAND_CMD_LOCK          0x2a
-#define NAND_CMD_LOCK_TIGHT    0x2c
-#define NAND_CMD_UNLOCK1       0x23
-#define NAND_CMD_UNLOCK2       0x24
-#define NAND_CMD_LOCK_STATUS   0x7a
-
 /**
  * nand_lock: Set all pages of NAND flash chip to the LOCK or LOCK-TIGHT
  *           state
@@ -253,6 +238,14 @@ int nand_lock(struct mtd_info *mtd, int tight)
        /* select the NAND device */
        chip->select_chip(mtd, 0);
 
+       /* check the Lock Tight Status */
+       chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, 0);
+       if (chip->read_byte(mtd) & NAND_LOCK_STATUS_TIGHT) {
+               printf("nand_lock: Device is locked tight!\n");
+               ret = -1;
+               goto out;
+       }
+
        chip->cmdfunc(mtd,
                      (tight ? NAND_CMD_LOCK_TIGHT : NAND_CMD_LOCK),
                      -1, -1);
@@ -265,6 +258,7 @@ int nand_lock(struct mtd_info *mtd, int tight)
                ret = -1;
        }
 
+ out:
        /* de-select the NAND device */
        chip->select_chip(mtd, -1);
        return ret;
@@ -275,13 +269,12 @@ int nand_lock(struct mtd_info *mtd, int tight)
  *                        flash
  *
  * @param mtd          nand mtd instance
- * @param offset       page address to query (muss be page aligned!)
+ * @param offset       page address to query (must be page-aligned!)
  *
  * @return             -1 in case of error
  *                     >0 lock status:
  *                       bitfield with the following combinations:
  *                       NAND_LOCK_STATUS_TIGHT: page in tight state
- *                       NAND_LOCK_STATUS_LOCK:  page locked
  *                       NAND_LOCK_STATUS_UNLOCK: page unlocked
  *
  */
@@ -298,7 +291,7 @@ int nand_get_lock_status(struct mtd_info *mtd, loff_t offset)
 
 
        if ((offset & (mtd->writesize - 1)) != 0) {
-               printf ("nand_get_lock_status: "
+               printf("nand_get_lock_status: "
                        "Start address must be beginning of "
                        "nand page!\n");
                ret = -1;
@@ -310,7 +303,6 @@ int nand_get_lock_status(struct mtd_info *mtd, loff_t offset)
        chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, page & chip->pagemask);
 
        ret = chip->read_byte(mtd) & (NAND_LOCK_STATUS_TIGHT
-                                         | NAND_LOCK_STATUS_LOCK
                                          | NAND_LOCK_STATUS_UNLOCK);
 
  out:
@@ -327,18 +319,21 @@ int nand_get_lock_status(struct mtd_info *mtd, loff_t offset)
  * @param start                start byte address
  * @param length       number of bytes to unlock (must be a multiple of
  *                     page size nand->writesize)
+ * @param allexcept    if set, unlock everything not selected
  *
  * @return             0 on success, -1 in case of error
  */
-int nand_unlock(struct mtd_info *mtd, ulong start, ulong length)
+int nand_unlock(struct mtd_info *mtd, loff_t start, size_t length,
+       int allexcept)
 {
        int ret = 0;
        int chipnr;
        int status;
        int page;
        struct nand_chip *chip = mtd->priv;
-       printf ("nand_unlock: start: %08x, length: %d!\n",
-               (int)start, (int)length);
+
+       debug("nand_unlock%s: start: %08llx, length: %d!\n",
+               allexcept ? " (allexcept)" : "", start, length);
 
        /* select the NAND device */
        chipnr = (int)(start >> chip->chip_shift);
@@ -347,20 +342,29 @@ int nand_unlock(struct mtd_info *mtd, ulong start, ulong length)
        /* check the WP bit */
        chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
        if (!(chip->read_byte(mtd) & NAND_STATUS_WP)) {
-               printf ("nand_unlock: Device is write protected!\n");
+               printf("nand_unlock: Device is write protected!\n");
+               ret = -1;
+               goto out;
+       }
+
+       /* check the Lock Tight Status */
+       page = (int)(start >> chip->page_shift);
+       chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, page & chip->pagemask);
+       if (chip->read_byte(mtd) & NAND_LOCK_STATUS_TIGHT) {
+               printf("nand_unlock: Device is locked tight!\n");
                ret = -1;
                goto out;
        }
 
        if ((start & (mtd->erasesize - 1)) != 0) {
-               printf ("nand_unlock: Start address must be beginning of "
+               printf("nand_unlock: Start address must be beginning of "
                        "nand block!\n");
                ret = -1;
                goto out;
        }
 
        if (length == 0 || (length & (mtd->erasesize - 1)) != 0) {
-               printf ("nand_unlock: Length must be a multiple of nand block "
+               printf("nand_unlock: Length must be a multiple of nand block "
                        "size %08x!\n", mtd->erasesize);
                ret = -1;
                goto out;
@@ -373,11 +377,19 @@ int nand_unlock(struct mtd_info *mtd, ulong start, ulong length)
        length -= mtd->erasesize;
 
        /* submit address of first page to unlock */
-       page = (int)(start >> chip->page_shift);
        chip->cmdfunc(mtd, NAND_CMD_UNLOCK1, -1, page & chip->pagemask);
 
        /* submit ADDRESS of LAST page to unlock */
        page += (int)(length >> chip->page_shift);
+
+       /*
+        * Page addresses for unlocking are supposed to be block-aligned.
+        * At least some NAND chips use the low bit to indicate that the
+        * page range should be inverted.
+        */
+       if (allexcept)
+               page |= 1;
+
        chip->cmdfunc(mtd, NAND_CMD_UNLOCK2, -1, page & chip->pagemask);
 
        /* call wait ready function */
@@ -405,11 +417,13 @@ int nand_unlock(struct mtd_info *mtd, ulong start, ulong length)
  * @param nand NAND device
  * @param offset offset in flash
  * @param length image length
+ * @param used length of flash needed for the requested length
  * @return 0 if the image fits and there are no bad blocks
  *         1 if the image fits, but there are bad blocks
  *        -1 if the image does not fit
  */
-static int check_skip_len(nand_info_t *nand, loff_t offset, size_t length)
+static int check_skip_len(nand_info_t *nand, loff_t offset, size_t length,
+               size_t *used)
 {
        size_t len_excl_bad = 0;
        int ret = 0;
@@ -431,33 +445,95 @@ static int check_skip_len(nand_info_t *nand, loff_t offset, size_t length)
                        ret = 1;
 
                offset += block_len;
+               *used += block_len;
        }
 
+       /* If the length is not a multiple of block_len, adjust. */
+       if (len_excl_bad > length)
+               *used -= (len_excl_bad - length);
+
        return ret;
 }
 
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+static size_t drop_ffs(const nand_info_t *nand, const u_char *buf,
+                       const size_t *len)
+{
+       size_t l = *len;
+       ssize_t i;
+
+       for (i = l - 1; i >= 0; i--)
+               if (buf[i] != 0xFF)
+                       break;
+
+       /* The resulting length must be aligned to the minimum flash I/O size */
+       l = i + 1;
+       l = (l + nand->writesize - 1) / nand->writesize;
+       l *=  nand->writesize;
+
+       /*
+        * since the input length may be unaligned, prevent access past the end
+        * of the buffer
+        */
+       return min(l, *len);
+}
+#endif
+
 /**
  * nand_write_skip_bad:
  *
  * Write image to NAND flash.
  * Blocks that are marked bad are skipped and the is written to the next
  * block instead as long as the image is short enough to fit even after
- * skipping the bad blocks.
+ * skipping the bad blocks.  Due to bad blocks we may not be able to
+ * perform the requested write.  In the case where the write would
+ * extend beyond the end of the NAND device, both length and actual (if
+ * not NULL) are set to 0.  In the case where the write would extend
+ * beyond the limit we are passed, length is set to 0 and actual is set
+ * to the required length.
  *
  * @param nand         NAND device
  * @param offset       offset in flash
  * @param length       buffer length
- * @param buf           buffer to read from
+ * @param actual       set to size required to write length worth of
+ *                     buffer or 0 on error, if not NULL
+ * @param lim          maximum size that actual may be in order to not
+ *                     exceed the buffer
+ * @param buffer        buffer to read from
+ * @param flags                flags modifying the behaviour of the write to NAND
  * @return             0 in case of success
  */
 int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
-                       u_char *buffer)
+               size_t *actual, loff_t lim, u_char *buffer, int flags)
 {
-       int rval;
+       int rval = 0, blocksize;
        size_t left_to_write = *length;
+       size_t used_for_write = 0;
        u_char *p_buffer = buffer;
        int need_skip;
 
+       if (actual)
+               *actual = 0;
+
+#ifdef CONFIG_CMD_NAND_YAFFS
+       if (flags & WITH_YAFFS_OOB) {
+               if (flags & ~WITH_YAFFS_OOB)
+                       return -EINVAL;
+
+               int pages;
+               pages = nand->erasesize / nand->writesize;
+               blocksize = (pages * nand->oobsize) + nand->erasesize;
+               if (*length % (nand->writesize + nand->oobsize)) {
+                       printf("Attempt to write incomplete page"
+                               " in yaffs mode\n");
+                       return -EINVAL;
+               }
+       } else
+#endif
+       {
+               blocksize = nand->erasesize;
+       }
+
        /*
         * nand_write() handles unaligned, partial page writes.
         *
@@ -470,58 +546,108 @@ int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
         * partition boundary).  So don't try to handle that.
         */
        if ((offset & (nand->writesize - 1)) != 0) {
-               printf ("Attempt to write non page aligned data\n");
+               printf("Attempt to write non page-aligned data\n");
                *length = 0;
                return -EINVAL;
        }
 
-       need_skip = check_skip_len(nand, offset, *length);
+       need_skip = check_skip_len(nand, offset, *length, &used_for_write);
+
+       if (actual)
+               *actual = used_for_write;
+
        if (need_skip < 0) {
-               printf ("Attempt to write outside the flash area\n");
+               printf("Attempt to write outside the flash area\n");
                *length = 0;
                return -EINVAL;
        }
 
-       if (!need_skip) {
-               rval = nand_write (nand, offset, length, buffer);
+       if (used_for_write > lim) {
+               puts("Size of write exceeds partition or device limit\n");
+               *length = 0;
+               return -EFBIG;
+       }
+
+       if (!need_skip && !(flags & WITH_DROP_FFS)) {
+               rval = nand_write(nand, offset, length, buffer);
                if (rval == 0)
                        return 0;
 
                *length = 0;
-               printf ("NAND write to offset %llx failed %d\n",
+               printf("NAND write to offset %llx failed %d\n",
                        offset, rval);
                return rval;
        }
 
        while (left_to_write > 0) {
                size_t block_offset = offset & (nand->erasesize - 1);
-               size_t write_size;
+               size_t write_size, truncated_write_size;
 
-               WATCHDOG_RESET ();
+               WATCHDOG_RESET();
 
-               if (nand_block_isbad (nand, offset & ~(nand->erasesize - 1))) {
-                       printf ("Skip bad block 0x%08llx\n",
+               if (nand_block_isbad(nand, offset & ~(nand->erasesize - 1))) {
+                       printf("Skip bad block 0x%08llx\n",
                                offset & ~(nand->erasesize - 1));
                        offset += nand->erasesize - block_offset;
                        continue;
                }
 
-               if (left_to_write < (nand->erasesize - block_offset))
+               if (left_to_write < (blocksize - block_offset))
                        write_size = left_to_write;
                else
-                       write_size = nand->erasesize - block_offset;
+                       write_size = blocksize - block_offset;
+
+#ifdef CONFIG_CMD_NAND_YAFFS
+               if (flags & WITH_YAFFS_OOB) {
+                       int page, pages;
+                       size_t pagesize = nand->writesize;
+                       size_t pagesize_oob = pagesize + nand->oobsize;
+                       struct mtd_oob_ops ops;
+
+                       ops.len = pagesize;
+                       ops.ooblen = nand->oobsize;
+                       ops.mode = MTD_OPS_AUTO_OOB;
+                       ops.ooboffs = 0;
+
+                       pages = write_size / pagesize_oob;
+                       for (page = 0; page < pages; page++) {
+                               WATCHDOG_RESET();
+
+                               ops.datbuf = p_buffer;
+                               ops.oobbuf = ops.datbuf + pagesize;
+
+                               rval = mtd_write_oob(nand, offset, &ops);
+                               if (rval != 0)
+                                       break;
+
+                               offset += pagesize;
+                               p_buffer += pagesize_oob;
+                       }
+               }
+               else
+#endif
+               {
+                       truncated_write_size = write_size;
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+                       if (flags & WITH_DROP_FFS)
+                               truncated_write_size = drop_ffs(nand, p_buffer,
+                                               &write_size);
+#endif
+
+                       rval = nand_write(nand, offset, &truncated_write_size,
+                                       p_buffer);
+                       offset += write_size;
+                       p_buffer += write_size;
+               }
 
-               rval = nand_write (nand, offset, &write_size, p_buffer);
                if (rval != 0) {
-                       printf ("NAND write to offset %llx failed %d\n",
+                       printf("NAND write to offset %llx failed %d\n",
                                offset, rval);
                        *length -= left_to_write;
                        return rval;
                }
 
                left_to_write -= write_size;
-               offset        += write_size;
-               p_buffer      += write_size;
        }
 
        return 0;
@@ -531,44 +657,66 @@ int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
  * nand_read_skip_bad:
  *
  * Read image from NAND flash.
- * Blocks that are marked bad are skipped and the next block is readen
- * instead as long as the image is short enough to fit even after skipping the
- * bad blocks.
+ * Blocks that are marked bad are skipped and the next block is read
+ * instead as long as the image is short enough to fit even after
+ * skipping the bad blocks.  Due to bad blocks we may not be able to
+ * perform the requested read.  In the case where the read would extend
+ * beyond the end of the NAND device, both length and actual (if not
+ * NULL) are set to 0.  In the case where the read would extend beyond
+ * the limit we are passed, length is set to 0 and actual is set to the
+ * required length.
  *
  * @param nand NAND device
  * @param offset offset in flash
- * @param length buffer length, on return holds remaining bytes to read
+ * @param length buffer length, on return holds number of read bytes
+ * @param actual set to size required to read length worth of buffer or 0
+ * on error, if not NULL
+ * @param lim maximum size that actual may be in order to not exceed the
+ * buffer
  * @param buffer buffer to write to
  * @return 0 in case of success
  */
 int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
-                      u_char *buffer)
+               size_t *actual, loff_t lim, u_char *buffer)
 {
        int rval;
        size_t left_to_read = *length;
+       size_t used_for_read = 0;
        u_char *p_buffer = buffer;
        int need_skip;
 
        if ((offset & (nand->writesize - 1)) != 0) {
-               printf ("Attempt to read non page aligned data\n");
+               printf("Attempt to read non page-aligned data\n");
                *length = 0;
+               if (actual)
+                       *actual = 0;
                return -EINVAL;
        }
 
-       need_skip = check_skip_len(nand, offset, *length);
+       need_skip = check_skip_len(nand, offset, *length, &used_for_read);
+
+       if (actual)
+               *actual = used_for_read;
+
        if (need_skip < 0) {
-               printf ("Attempt to read outside the flash area\n");
+               printf("Attempt to read outside the flash area\n");
                *length = 0;
                return -EINVAL;
        }
 
+       if (used_for_read > lim) {
+               puts("Size of read exceeds partition or device limit\n");
+               *length = 0;
+               return -EFBIG;
+       }
+
        if (!need_skip) {
-               rval = nand_read (nand, offset, length, buffer);
+               rval = nand_read(nand, offset, length, buffer);
                if (!rval || rval == -EUCLEAN)
                        return 0;
 
                *length = 0;
-               printf ("NAND read from offset %llx failed %d\n",
+               printf("NAND read from offset %llx failed %d\n",
                        offset, rval);
                return rval;
        }
@@ -577,10 +725,10 @@ int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
                size_t block_offset = offset & (nand->erasesize - 1);
                size_t read_length;
 
-               WATCHDOG_RESET ();
+               WATCHDOG_RESET();
 
-               if (nand_block_isbad (nand, offset & ~(nand->erasesize - 1))) {
-                       printf ("Skipping bad block 0x%08llx\n",
+               if (nand_block_isbad(nand, offset & ~(nand->erasesize - 1))) {
+                       printf("Skipping bad block 0x%08llx\n",
                                offset & ~(nand->erasesize - 1));
                        offset += nand->erasesize - block_offset;
                        continue;
@@ -591,9 +739,9 @@ int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
                else
                        read_length = nand->erasesize - block_offset;
 
-               rval = nand_read (nand, offset, &read_length, p_buffer);
+               rval = nand_read(nand, offset, &read_length, p_buffer);
                if (rval && rval != -EUCLEAN) {
-                       printf ("NAND read from offset %llx failed %d\n",
+                       printf("NAND read from offset %llx failed %d\n",
                                offset, rval);
                        *length -= left_to_read;
                        return rval;
@@ -606,3 +754,125 @@ int nand_read_skip_bad(nand_info_t *nand, loff_t offset, size_t *length,
 
        return 0;
 }
+
+#ifdef CONFIG_CMD_NAND_TORTURE
+
+/**
+ * check_pattern:
+ *
+ * Check if buffer contains only a certain byte pattern.
+ *
+ * @param buf buffer to check
+ * @param patt the pattern to check
+ * @param size buffer size in bytes
+ * @return 1 if there are only patt bytes in buf
+ *         0 if something else was found
+ */
+static int check_pattern(const u_char *buf, u_char patt, int size)
+{
+       int i;
+
+       for (i = 0; i < size; i++)
+               if (buf[i] != patt)
+                       return 0;
+       return 1;
+}
+
+/**
+ * nand_torture:
+ *
+ * Torture a block of NAND flash.
+ * This is useful to determine if a block that caused a write error is still
+ * good or should be marked as bad.
+ *
+ * @param nand NAND device
+ * @param offset offset in flash
+ * @return 0 if the block is still good
+ */
+int nand_torture(nand_info_t *nand, loff_t offset)
+{
+       u_char patterns[] = {0xa5, 0x5a, 0x00};
+       struct erase_info instr = {
+               .mtd = nand,
+               .addr = offset,
+               .len = nand->erasesize,
+       };
+       size_t retlen;
+       int err, ret = -1, i, patt_count;
+       u_char *buf;
+
+       if ((offset & (nand->erasesize - 1)) != 0) {
+               puts("Attempt to torture a block at a non block-aligned offset\n");
+               return -EINVAL;
+       }
+
+       if (offset + nand->erasesize > nand->size) {
+               puts("Attempt to torture a block outside the flash area\n");
+               return -EINVAL;
+       }
+
+       patt_count = ARRAY_SIZE(patterns);
+
+       buf = malloc(nand->erasesize);
+       if (buf == NULL) {
+               puts("Out of memory for erase block buffer\n");
+               return -ENOMEM;
+       }
+
+       for (i = 0; i < patt_count; i++) {
+               err = nand->erase(nand, &instr);
+               if (err) {
+                       printf("%s: erase() failed for block at 0x%llx: %d\n",
+                               nand->name, instr.addr, err);
+                       goto out;
+               }
+
+               /* Make sure the block contains only 0xff bytes */
+               err = nand->read(nand, offset, nand->erasesize, &retlen, buf);
+               if ((err && err != -EUCLEAN) || retlen != nand->erasesize) {
+                       printf("%s: read() failed for block at 0x%llx: %d\n",
+                               nand->name, instr.addr, err);
+                       goto out;
+               }
+
+               err = check_pattern(buf, 0xff, nand->erasesize);
+               if (!err) {
+                       printf("Erased block at 0x%llx, but a non-0xff byte was found\n",
+                               offset);
+                       ret = -EIO;
+                       goto out;
+               }
+
+               /* Write a pattern and check it */
+               memset(buf, patterns[i], nand->erasesize);
+               err = nand->write(nand, offset, nand->erasesize, &retlen, buf);
+               if (err || retlen != nand->erasesize) {
+                       printf("%s: write() failed for block at 0x%llx: %d\n",
+                               nand->name, instr.addr, err);
+                       goto out;
+               }
+
+               err = nand->read(nand, offset, nand->erasesize, &retlen, buf);
+               if ((err && err != -EUCLEAN) || retlen != nand->erasesize) {
+                       printf("%s: read() failed for block at 0x%llx: %d\n",
+                               nand->name, instr.addr, err);
+                       goto out;
+               }
+
+               err = check_pattern(buf, patterns[i], nand->erasesize);
+               if (!err) {
+                       printf("Pattern 0x%.2x checking failed for block at "
+                                       "0x%llx\n", patterns[i], offset);
+                       ret = -EIO;
+                       goto out;
+               }
+       }
+
+       ret = 0;
+
+out:
+       free(buf);
+       return ret;
+}
+
+#endif