target/linux/generic/pending-4.19/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch

   1 From: Daniel Golle <daniel@makrotopia.org>
   2 Subject: ubi: auto-attach mtd device named "ubi" or "data" on boot
   3
   4 Signed-off-by: Daniel Golle <daniel@makrotopia.org>
   5 ---
   6  drivers/mtd/ubi/build.c | 36 ++++++++++++++++++++++++++++++++++++
   7  1 file changed, 36 insertions(+)
   8
   9 --- a/drivers/mtd/ubi/build.c
  10 +++ b/drivers/mtd/ubi/build.c
  11 @@ -1181,6 +1181,73 @@ static struct mtd_info * __init open_mtd
  12         return mtd;
  13  }
  14
  15 +/*
  16 + * This function tries attaching mtd partitions named either "ubi" or "data"
  17 + * during boot.
  18 + */
  19 +static void __init ubi_auto_attach(void)
  20 +{
  21 +       int err;
  22 +       struct mtd_info *mtd;
  23 +       loff_t offset = 0;
  24 +       size_t len;
  25 +       char magic[4];
  26 +
  27 +       /* try attaching mtd device named "ubi" or "data" */
  28 +       mtd = open_mtd_device("ubi");
  29 +       if (IS_ERR(mtd))
  30 +               mtd = open_mtd_device("data");
  31 +
  32 +       if (IS_ERR(mtd))
  33 +               return;
  34 +
  35 +       /* get the first not bad block */
  36 +       if (mtd_can_have_bb(mtd))
  37 +               while (mtd_block_isbad(mtd, offset)) {
  38 +                       offset += mtd->erasesize;
  39 +
  40 +                       if (offset > mtd->size) {
  41 +                               pr_err("UBI error: Failed to find a non-bad "
  42 +                                      "block on mtd%d\n", mtd->index);
  43 +                               goto cleanup;
  44 +                       }
  45 +               }
  46 +
  47 +       /* check if the read from flash was successful */
  48 +       err = mtd_read(mtd, offset, 4, &len, (void *) magic);
  49 +       if ((err && !mtd_is_bitflip(err)) || len != 4) {
  50 +               pr_err("UBI error: unable to read from mtd%d\n", mtd->index);
  51 +               goto cleanup;
  52 +       }
  53 +
  54 +       /* check for a valid ubi magic */
  55 +       if (strncmp(magic, "UBI#", 4)) {
  56 +               pr_err("UBI error: no valid UBI magic found inside mtd%d\n", mtd->index);
  57 +               goto cleanup;
  58 +       }
  59 +
  60 +       /* don't auto-add media types where UBI doesn't makes sense */
  61 +       if (mtd->type != MTD_NANDFLASH &&
  62 +           mtd->type != MTD_NORFLASH &&
  63 +           mtd->type != MTD_DATAFLASH &&
  64 +           mtd->type != MTD_MLCNANDFLASH)
  65 +               goto cleanup;
  66 +
  67 +       mutex_lock(&ubi_devices_mutex);
  68 +       pr_notice("UBI: auto-attach mtd%d\n", mtd->index);
  69 +       err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0);
  70 +       mutex_unlock(&ubi_devices_mutex);
  71 +       if (err < 0) {
  72 +               pr_err("UBI error: cannot attach mtd%d\n", mtd->index);
  73 +               goto cleanup;
  74 +       }
  75 +
  76 +       return;
  77 +
  78 +cleanup:
  79 +       put_mtd_device(mtd);
  80 +}
  81 +
  82  static int __init ubi_init(void)
  83  {
  84         int err, i, k;
  85 @@ -1264,6 +1331,12 @@ static int __init ubi_init(void)
  86                 }
  87         }
  88
  89 +       /* auto-attach mtd devices only if built-in to the kernel and no ubi.mtd
  90 +        * parameter was given */
  91 +       if (IS_ENABLED(CONFIG_MTD_ROOTFS_ROOT_DEV) &&
  92 +           !ubi_is_module() && !mtd_devs)
  93 +               ubi_auto_attach();
  94 +
  95         err = ubiblock_init();
  96         if (err) {
  97                 pr_err("UBI error: block: cannot initialize, error %d\n", err);