This adds 3 Mikrotik rb4xx series drivers as follows:
rb4xx-cpld: This is in the mfd subsystem, and is the parent CPLD device
that interfaces between the SoC SPI bus and its two children below.
rb4xx-gpio: This is the GPIO expander.
rb4xx-nand: This is the NAND driver.
The history of this code comes in three phases.
1. The first is a May 2015 attempt to push the equivalient ar71xx rb4xx
drivers upstream. See https://lore.kernel.org/patchwork/patch/940880/.
Module-author: Gabor Juhos <juhosg@openwrt.org>
Module-author: Imre Kaloz <kaloz@openwrt.org>
Module-author: Bert Vermeulen <bert@biot.com>
2. Next several ar71xx patches were applied bringing the code current.
commit 7bbf4117c6
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
commit af79fdbe4a
commit 889272d92d
commit e21cb649a2
commit 7c09fa4a74
Signed-off-by: Felix Fietkau <nbd@nbd.name>
3. Finally a heavy refactor to split the driver into the three new
subsystems, and updated to work with the device tree configuration, plus
updates and review feedback incorporated
Reviewed-by: Thibaut VARÈNE <hacks@slashdirt.org>
Signed-off-by: Christopher Hill <ch6574@gmail.com>
