ath79: add Mikrotik rb4xx series drivers

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 7bbf4117c6fe4b764d9d7c62fb2bcf6dd93bff2c
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

commit af79fdbe4af32a287798b579141204bda056b8aa
commit 889272d92db689fd9c910243635e44c9d8323095
commit e21cb649a235180563363b8af5ba8296b9ac0baa
commit 7c09fa4a7492ca436f2c94bd9a465b7c5bbeed6f
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>

1 files changed, 69 insertions, 0 deletions

diff --git a/target/linux/ath79/patches-4.19/920-mikrotik-rb4xx.patch b/target/linux/ath79/patches-4.19/920-mikrotik-rb4xx.patch
new file mode 100644
index 0000000000..8d84b9e1cd
--- /dev/null
+++ b/target/linux/ath79/patches-4.19/920-mikrotik-rb4xx.patch
@@ -0,0 +1,69 @@
+--- a/drivers/mfd/Kconfig
++++ b/drivers/mfd/Kconfig
+@@ -1899,5 +1899,13 @@ config RAVE_SP_CORE
+ 	  Select this to get support for the Supervisory Processor
+ 	  device found on several devices in RAVE line of hardware.
+ 
++config MFD_RB4XX_CPLD
++	tristate "CPLD driver for Mikrotik RB4xx series boards
++	select MFD_CORE
++	depends on ATH79 || COMPILE_TEST
++	help
++	  Enables support for the CPLD chip (NAND & GPIO) on Mikrotik
++	  Routerboard RB4xx series.
++
+ endmenu
+ endif
+--- a/drivers/mfd/Makefile
++++ b/drivers/mfd/Makefile
+@@ -241,3 +241,4 @@ obj-$(CONFIG_MFD_SC27XX_PMIC)	+= sprd-sc
+ obj-$(CONFIG_RAVE_SP_CORE)	+= rave-sp.o
+ obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
+ 
++obj-$(CONFIG_MFD_RB4XX_CPLD)	+= rb4xx-cpld.o
+--- a/drivers/gpio/Kconfig
++++ b/drivers/gpio/Kconfig
+@@ -1371,6 +1371,12 @@ config GPIO_XRA1403
+ 	help
+ 	  GPIO driver for EXAR XRA1403 16-bit SPI-based GPIO expander.
+ 
++config GPIO_RB4XX
++	tristate "GPIO expander for Mikrotik RB4xx series boards"
++	depends on MFD_RB4XX_CPLD
++	help
++	  GPIO driver for Mikrotik Routerboard RB4xx series.
++
+ endmenu
+ 
+ menu "USB GPIO expanders"
+--- a/drivers/gpio/Makefile
++++ b/drivers/gpio/Makefile
+@@ -159,3 +159,4 @@ obj-$(CONFIG_GPIO_ZEVIO)	+= gpio-zevio.o
+ obj-$(CONFIG_GPIO_ZYNQ)		+= gpio-zynq.o
+ obj-$(CONFIG_GPIO_ZX)		+= gpio-zx.o
+ obj-$(CONFIG_GPIO_LOONGSON1)	+= gpio-loongson1.o
++obj-$(CONFIG_GPIO_RB4XX)	+= gpio-rb4xx.o
+--- a/drivers/mtd/nand/raw/Kconfig
++++ b/drivers/mtd/nand/raw/Kconfig
+@@ -569,4 +569,11 @@ config MTD_NAND_AR934X
+ 	  Enables support for NAND controller on Qualcomm Atheros SoCs.
+ 	  This controller is found on AR934x and QCA955x SoCs.
+ 
++config MTD_NAND_RB4XX
++	tristate "Support for NAND driver for Mikrotik RB4xx series boards"
++	depends on MFD_RB4XX_CPLD
++	help
++	  Enables support for the NAND flash chip on Mikrotik Routerboard
++	  RB4xx series.
++
+ endif # MTD_NAND
+--- a/drivers/mtd/nand/raw/Makefile
++++ b/drivers/mtd/nand/raw/Makefile
+@@ -58,6 +58,7 @@ obj-$(CONFIG_MTD_NAND_QCOM)		+= qcom_nan
+ obj-$(CONFIG_MTD_NAND_MTK)		+= mtk_ecc.o mtk_nand.o
+ obj-$(CONFIG_MTD_NAND_TEGRA)		+= tegra_nand.o
+ obj-$(CONFIG_MTD_NAND_AR934X)		+= ar934x_nand.o
++obj-$(CONFIG_MTD_NAND_RB4XX)		+= nand_rb4xx.o
+ 
+ nand-objs := nand_base.o nand_bbt.o nand_timings.o nand_ids.o
+ nand-objs += nand_amd.o