Set free_count to zero before walking through ai->erase list
in wl_init().

As U-Boot has no workqueue/threads, it immediately calls
erase_worker(), which increase for each erased block
free_count. Without this patch, free_count gets after
this initialized to zero in wl_init(), so the free_count
variable always has the maybe wrong value 0.

Detected this behaviour on the dxr2 board, where the
UBI fastmap gets not written when attaching/dettaching
on an empty NAND. It drops instead the error message:

could not find any anchor PEB

With this patch, fastmap gets written on dettach.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

BUILD_BUG_* macros have been defined in several headers.  It would
be nice to collect them in include/linux/bug.h like Linux.

This commit is cherry-picking useful macros from include/linux/bug.h
of Linux 4.4.

I did not import BUILD_BUG_ON_MSG() because it would not work if it
is used with include/common.h in U-Boot.  I'd like to postpone it
until the root cause (the "error()" macro in include/common.h causes
the name conflict with "__attribute__((error()))") is fixed.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

drivers/mtd/ubi/io.c:1354:3: error: 'dump_len' undeclared (first use in
this function)
   dump_len = max_t(int, 128, len - i);

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>

Use the is_power_of_2() definition from log2.h to align with the
kernel implementation.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Jagan Teki <jteki@openedev.com>

The PEB array is an array of __be32, so let's fix the
scan_pool() prototype accordingly.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>

Signed-off-by: Heiko Schocher <hs@denx.de>

sync with linux v4.2

commit 64291f7db5bd8150a74ad2036f1037e6a0428df2
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Aug 30 11:34:09 2015 -0700

    Linux 4.2

This update is needed, as it turned out, that fastmap
was in experimental/broken state in kernel v3.15, which
was the last base for U-Boot.

Signed-off-by: Heiko Schocher <hs@denx.de>
Tested-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>

if "ubi part" fails, reset also mtd_devs to 0, as
further "ubi part" would use wrong mtd_devs.

Signed-off-by: Heiko Schocher <hs@denx.de>

U-Boot has imported various source files from other projects,
mostly Linux.

Something like

  #ifdef __UBOOT__
    [ modification for U-Boot ]
  #else
    [ original code ]
  #endif

is an often used strategy for clarification of adjusted parts,
that is, easier re-sync in future.

Instead of defining __UBOOT__ in each source file,
passing it from the top Makefile would be easier.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>

snyc with linux v3.15:

commit 1860e379875dfe7271c649058aeddffe5afd9d0d
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Jun 8 11:19:54 2014 -0700

    Linux 3.15

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@ti.com>

resync ubi subsystem with linux:

commit 455c6fdbd219161bd09b1165f11699d6d73de11c
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Mar 30 20:40:15 2014 -0700

    Linux 3.14

A nice side effect of this, is we introduce UBI Fastmap support
to U-Boot.

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Tom Rini <trini@ti.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Sergey Lapin <slapin@ossfans.org>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Joerg Krause <jkrause@posteo.de>