misc: Add iop driver for Sunplus SP7021

IOP (IO Processor) embedded inside SP7021 which is used as
Processor for I/O control, RTC wake-up and cooperation with
CPU & PMC in power management purpose.
The IOP core is DQ8051, so also named IOP8051,
it supports dedicated JTAG debug pins which share with SP7021.
In standby mode operation, the power spec reach 400uA.

Signed-off-by: Tony Huang <tonyhuang.sunplus@gmail.com>

Documentation/ABI/testing/sysfs-platform-soc@B

@@ -0,0 +1,22 @@
+What:		/sys/devices/platform/soc@B/9c000400.iop/sp_iop_state1
+Date:		December 2021
+KernelVersion:	5.15
+Contact:	Tony Huang <tonyhuang.sunplus@gmail.com>
+Description:
+		SP7021 has three power states:S0, S1 and S3.
+		S0:Default domain is on. IOP domain is on. AO domain is on.
+		S1:Default domain is off. IOP domain is on. AO domain is on.
+		S3:Default domain is off. IOP domain is off. AO domain is on.
+		Read sysfs sp_iop_s1mode, system enter S1 mode.
+
+What:		/sys/devices/platform/soc@B/9c000400.iop/sp_iop_mode
+Date:		December 2021
+KernelVersion:	5.15
+Contact:	Tony Huang <tonyhuang.sunplus@gmail.com>
+Description:
+		Operation mode of IOP is switched to standby mode by writing
+		"1" to sysfs.
+		Operation mode of IOP is switched to normal mode by writing
+		"0" to sysfs.
+
+

MAINTAINERS

@@ -18247,7 +18247,9 @@ F:	drivers/net/ethernet/dlink/sundance.c
 SUNPLUS IOP DRIVER
 M:	Tony Huang <tonyhuang.sunplus@gmail.com>
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-platform-soc@B
 F:	Documentation/devicetree/bindings/misc/sunplu-iop.yaml
+F:	drivers/misc/sunplus_iop.c
 
 SUPERH
 M:	Yoshinori Sato <ysato@users.sourceforge.jp>

drivers/misc/Kconfig

@@ -470,6 +470,18 @@ config HISI_HIKEY_USB
 	  switching between the dual-role USB-C port and the USB-A host ports
 	  using only one USB controller.
 
+config SUNPLUS_IOP
+	tristate "Sunplus IOP support"
+	default ARCH_SUNPLUS
+	help
+	  Sunplus I/O processor (8051) driver.
+	  Processor for I/O control, RTC wake-up proceduce management,
+	  and cooperation with CPU&PMC in power management.
+	  Need Install DQ8051, The DQ8051 bin file generated by keil C.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ad525x_dpot.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -52,6 +52,7 @@ obj-$(CONFIG_DW_XDATA_PCIE)	+= dw-xdata-pcie.o
 obj-$(CONFIG_PCI_ENDPOINT_TEST)	+= pci_endpoint_test.o
 obj-$(CONFIG_OCXL)		+= ocxl/
 obj-$(CONFIG_BCM_VK)		+= bcm-vk/
+obj-$(CONFIG_SUNPLUS_IOP)	+= sunplus_iop.o
 obj-y				+= cardreader/
 obj-$(CONFIG_PVPANIC)   	+= pvpanic/
 obj-$(CONFIG_HABANA_AI)		+= habanalabs/