target/linux/generic/backport-4.9/065-v4.13-0001-mtd-handle-partitioning-on-devices-with-0-erasesize.patch

   1 From 1eeef2d7483a7e3f8d2dd2a5b9939b3b814dc549 Mon Sep 17 00:00:00 2001
   2 From: Chris Packham <chris.packham@alliedtelesis.co.nz>
   3 Date: Fri, 9 Jun 2017 15:58:31 +1200
   4 Subject: [PATCH] mtd: handle partitioning on devices with 0 erasesize
   5
   6 erasesize is meaningful for flash devices but for SRAM there is no
   7 concept of an erase block so erasesize is set to 0. When partitioning
   8 these devices instead of ensuring partitions fall on erasesize
   9 boundaries we ensure they fall on writesize boundaries.
  10
  11 Helped-by: Boris Brezillon <boris.brezillon@free-electrons.com>
  12 Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
  13 Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
  14 Signed-off-by: Brian Norris <computersforpeace@gmail.com>
  15 ---
  16  drivers/mtd/mtdpart.c | 26 +++++++++++++++++---------
  17  1 file changed, 17 insertions(+), 9 deletions(-)
  18
  19 --- a/drivers/mtd/mtdpart.c
  20 +++ b/drivers/mtd/mtdpart.c
  21 @@ -393,8 +393,12 @@ static struct mtd_part *allocate_partiti
  22                         const struct mtd_partition *part, int partno,
  23                         uint64_t cur_offset)
  24  {
  25 +       int wr_alignment = (master->flags & MTD_NO_ERASE) ? master->writesize:
  26 +                                                           master->erasesize;
  27         struct mtd_part *slave;
  28 +       u32 remainder;
  29         char *name;
  30 +       u64 tmp;
  31
  32         /* allocate the partition structure */
  33         slave = kzalloc(sizeof(*slave), GFP_KERNEL);
  34 @@ -499,10 +503,11 @@ static struct mtd_part *allocate_partiti
  35         if (slave->offset == MTDPART_OFS_APPEND)
  36                 slave->offset = cur_offset;
  37         if (slave->offset == MTDPART_OFS_NXTBLK) {
  38 +               tmp = cur_offset;
  39                 slave->offset = cur_offset;
  40 -               if (mtd_mod_by_eb(cur_offset, master) != 0) {
  41 -                       /* Round up to next erasesize */
  42 -                       slave->offset = (mtd_div_by_eb(cur_offset, master) + 1) * master->erasesize;
  43 +               remainder = do_div(tmp, wr_alignment);
  44 +               if (remainder) {
  45 +                       slave->offset += wr_alignment - remainder;
  46                         printk(KERN_NOTICE "Moving partition %d: "
  47                                "0x%012llx -> 0x%012llx\n", partno,
  48                                (unsigned long long)cur_offset, (unsigned long long)slave->offset);
  49 @@ -567,19 +572,22 @@ static struct mtd_part *allocate_partiti
  50                 slave->mtd.erasesize = master->erasesize;
  51         }
  52
  53 -       if ((slave->mtd.flags & MTD_WRITEABLE) &&
  54 -           mtd_mod_by_eb(slave->offset, &slave->mtd)) {
  55 +       tmp = slave->offset;
  56 +       remainder = do_div(tmp, wr_alignment);
  57 +       if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
  58                 /* Doesn't start on a boundary of major erase size */
  59                 /* FIXME: Let it be writable if it is on a boundary of
  60                  * _minor_ erase size though */
  61                 slave->mtd.flags &= ~MTD_WRITEABLE;
  62 -               printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
  63 +               printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
  64                         part->name);
  65         }
  66 -       if ((slave->mtd.flags & MTD_WRITEABLE) &&
  67 -           mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
  68 +
  69 +       tmp = slave->mtd.size;
  70 +       remainder = do_div(tmp, wr_alignment);
  71 +       if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
  72                 slave->mtd.flags &= ~MTD_WRITEABLE;
  73 -               printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
  74 +               printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
  75                         part->name);
  76         }
  77