mtd: parsers: ofpart: add workaround for #size-cells 0

Add a mechanism to handle the case in which partitions are present as
direct child of the nand controller node and #size-cells is set to <0>.

This could happen if the nand-controller node in the DTS is supposed to
have #size-cells set to 0, but for some historical reason/bug it was set
to 1 in the past, and the firmware (e.g. U-Boot) is adding the partition
as direct children of the nand-controller defaulting to #size-cells
being to 1.

This prevents a real boot failure on colibri-imx7 that happened during v6.1
development cycles.

Link: https://lore.kernel.org/all/Y4dgBTGNWpM6SQXI@francesco-nb.int.toradex.com/
Link: https://lore.kernel.org/all/20221202071900.1143950-1-francesco@dolcini.it/
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230124104444.330913-1-francesco@dolcini.it

mtd: parsers: ofpart: fix parsing subpartitions

ofpart was recently patched to not scan random partition nodes as
subpartitions. That change unfortunately broke scanning valid
subpartitions like:

partitions {
compatible = "fixed-partitions";
#address-cells = <1>;
#size-cells = <1>;

partition@0 {
compatible = "fixed-partitions";
label = "bootloader";
reg = <0x0 0x100000>;

partition@0 {
label = "config";
reg = <0x80000 0x80000>;
};
};
};

Fix that regression by adding 1 more code path. We actually need 3
conditional blocks to support 3 possible cases. This change also makes
code easier to understand & follow.

Reported-by: David Bauer <mail@david-bauer.net>
Fixes: 2d751203aacf ("mtd: parsers: ofpart: limit parsing of deprecated DT syntax
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Tested-by: Andrew Cameron <apcameron@softhome.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210508173214.28365-1-zajec5@gmail.com

mtd: parsers: ofpart: support Linksys Northstar partitions

This allows extending ofpart parser with support for Linksys Northstar
devices. That support uses recently added quirks mechanism.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210312134919.7767-2-zajec5@gmail.com

mtd: parsers: ofpart: make symbol 'bcm4908_partitions_quirks' static

The sparse tool complains as follows:

drivers/mtd/parsers/ofpart_core.c:25:32: warning:
symbol 'bcm4908_partitions_quirks' was not declared. Should it be static?

This symbol is not used outside of ofpart_core.c, so this
commit marks it static.

Fixes: 457da931b608 ("mtd: parsers: ofpart: support BCM4908 fixed partitions")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210304064600.3279138-1-weiyongjun1@huawei.com

mtd: parsers: ofpart: limit parsing of deprecated DT syntax

For backward compatibility ofpart still supports the old syntax like:
spi-flash@0 {
compatible = "jedec,spi-nor";
reg = <0x0>;

partition@0 {
label = "bootloader";
reg = <0x0 0x100000>;
};
};
(without "partitions" subnode).

There is no reason however to support nested partitions without a clear
"compatible" string like:
partitions {
compatible = "fixed-partitions";
#address-cells = <1>;
#size-cells = <1>;

partition@0 {
label = "bootloader";
reg = <0x0 0x100000>;

partition@0 {
label = "config";
reg = <0x80000 0x80000>;
};
};
};
(we never officially supported or documented that).

Make sure ofpart doesn't attempt to parse above.

Cc: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210302190012.1255-1-zajec5@gmail.com

mtd: parsers: ofpart: support BCM4908 fixed partitions

Some devices use fixed partitioning with some partitions requiring some
extra logic. E.g. BCM4908 may have multiple firmware partitions but
detecting currently used one requires checking bootloader parameters.

To support such cases without duplicating a lot of code (without copying
most of the ofpart.c code) support for post-parsing callback was added.

BCM4908 support in ofpart can be enabled using config option and results
in compiling & executing a specific callback. It simply reads offset of
currently used firmware partition from the DT. Bootloader specifies it
using the "brcm_blparms" property.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210301105823.31032-1-zajec5@gmail.com