pinctrl: Add support for Kendryte K210 FPIOA

The Fully-Programmable Input/Output Array (FPIOA) device controls pin
multiplexing on the K210. The FPIOA can remap any supported function to any
multifunctional IO pin. It can also perform basic GPIO functions, such as
reading the current value of a pin. However, GPIO functionality remains
largely unimplemented (in favor of the dedicated GPIO peripherals).

Signed-off-by: Sean Anderson <[email protected]>
Reviewed-by: Simon Glass <[email protected]>

MAINTAINERS

@@ -935,7 +935,9 @@ RISC-V KENDRYTE
 M:	Sean Anderson <[email protected]>
 S:	Maintained
 F:	doc/device-tree-bindings/mfd/kendryte,k210-sysctl.txt
+F:	doc/device-tree-bindings/pinctrl/kendryte,k210-fpioa.txt
 F:	drivers/clk/kendryte/
+F:	drivers/pinctrl/kendryte/
 F:	include/kendryte/
 
 RNG

doc/device-tree-bindings/pinctrl/kendryte,k210-fpioa.txt

@@ -0,0 +1,102 @@
+Kendryte K210 FPIOA
+
+This binding describes the Fully-Programmable Input/Output Array (FPIOA) found
+in Kendryte K210 SoCs. Any of the 256 functions can be mapped to any of the 48
+pins.
+
+Required properties:
+- compatible: should be "kendryte,k210-fpioa"
+- reg: address and length of the FPIOA registers
+- kendryte,sysctl: phandle to the "sysctl" register map node
+- kendryte,power-offset: offset in the register map of the power bank control
+  register (in bytes)
+
+Configuration nodes
+
+Pin configuration nodes are documented in pinctrl-bindings.txt
+
+Required properties for pin-configuration nodes or sub-nodes are:
+- groups: list of power groups to which the configuration applies. Valid groups
+  are:
+	A0, A1, A2, B0, B1, B2, C0, C1
+  (either this or "pinmux" must be specified)
+- pinmux: integer array representing pin multiplexing configuration. In addition
+  to the 256 standard functions, each pin can also output the direction
+  indicator (DO) of any function. This signal is high whenever the function
+  would normally drive the output. Helper macros to ease assembling the "pinmux"
+  arguments from the pin and function are provided by the FPIOA header file at:
+  <dt-bindings/pinctrl/k210-pinctrl.h>
+  Integer values in the "pinmux" argument list are assembled as:
+  ((PIN << 16) | (DO << 8) | (FUNC))
+  Valid values for PIN are numbers 0 through 47.
+  Valid values for DO are 0 or 1.
+  Valid values for FUNC are numbers 0 through 255. For a complete list of
+  acceptable functions, consult the FPIOA header file.
+  (either this or "groups" must be specified)
+
+Optional properties for "pinmux" nodes are:
+	bias-disable, bias-pull-down, bias-pull-up, drive-strength,
+	drive-strength-ua, input-enable, input-disable, input-schmitt-enable,
+	input-schmitt-disable, output-low, output-high, output-enable,
+	output-disable, slew-rate, output-polarity-invert, input-polarity-invert
+
+Optional properties for "groups" nodes are:
+	power-source
+
+Notes on specific properties include:
+- bias-pull-up, -down, and -pin-default: The pull strength cannot be configured.
+- drive-strength: There are 8 drive strength settings between 11 and 50 mA.
+- input- and output-polarity-invert: Invert the polarity of either the input or
+  the output, respectively.
+- power-source: Controls the output voltage of a bank of pins. Either
+  K210_PC_POWER_1V8 or K210_PC_POWER_3V3 may be specified.
+- slew-rate: Specifying this property reduces the slew rate.
+
+Example:
+fpioa: pinmux@502B0000 {
+	compatible = "kendryte,k210-fpioa";
+	reg = <0x502B0000 0x100>;
+	kendryte,sysctl = <&sysctl>;
+	kendryte,power-offset = <K210_SYSCTL_POWER_SEL>;
+
+	/* JTAG running at 3.3V and driven at 11 mA */
+	fpioa_jtag: jtag {
+		voltage {
+			group = "A0";
+			power-source = <K210_PC_POWER_3V3>;
+		};
+
+		jtag {
+			pinmux = <K210_FPIOA(0, K210_PCF_JTAG_TCK)>,
+				 <K210_FPIOA(1, K210_PCF_JTAG_TDI)>,
+				 <K210_FPIOA(2, K210_PCF_JTAG_TMS)>,
+				 <K210_FPIOA(3, K210_PCF_JTAG_TDO)>;
+			drive-strength = <11>;
+		}
+	};
+
+	/* I2C configured for use with a TCA9800 level shifter */
+	fpioa_i2c: i2c {
+		i2c {
+			pinmux = <K210_FPIOA(6, K210_PCF_I2C0_SCLK)>,
+				 <K210_FPIOA(7, K210_PCF_I2C0_SDA)>;
+		};
+
+		direction {
+			pinmux = <K210_FPIOA_DO(8, K210_PCF_I2C0_SDA)>;
+			output-polarity-invert;
+		};
+	};
+
+	/* UART with an active-high TX status LED */
+	fpioa_uart1: uart1 {
+		uart {
+			pinmux = <K210_FPIOA(9, K210_PCF_UART1_TX)>,
+				 <K210_FPIOA(10, K210_PCF_UART1_RX)>;
+		};
+
+		status {
+			pinmux = <K210_FPIOA_DO(11, K210_PCF_UART1_TX)>;
+		};
+	};
+};

drivers/pinctrl/Kconfig

@@ -291,6 +291,13 @@ config ASPEED_AST2500_PINCTRL
 	  uses Generic Pinctrl framework and is compatible with the Linux
 	  driver, i.e. it uses the same device tree configuration.
 
+config PINCTRL_K210
+	bool "Kendryte K210 Fully-Programmable Input/Output Array driver"
+	depends on DM && PINCTRL_GENERIC
+	help
+	  Support pin multiplexing on the K210. The "FPIOA" can remap any
+	  supported function to any multifunctional IO pin. It can also perform
+	  basic GPIO functions, such as reading the current value of a pin.
 endif
 
 source "drivers/pinctrl/broadcom/Kconfig"

drivers/pinctrl/Makefile

@@ -17,6 +17,7 @@ obj-$(CONFIG_PINCTRL_SANDBOX)	+= pinctrl-sandbox.o
 obj-$(CONFIG_PINCTRL_UNIPHIER)	+= uniphier/
 obj-$(CONFIG_PINCTRL_PIC32)	+= pinctrl_pic32.o
 obj-$(CONFIG_PINCTRL_EXYNOS)	+= exynos/
+obj-$(CONFIG_PINCTRL_K210)	+= pinctrl-kendryte.o
 obj-$(CONFIG_PINCTRL_MESON)	+= meson/
 obj-$(CONFIG_PINCTRL_MTK)	+= mediatek/
 obj-$(CONFIG_PINCTRL_MSCC)	+= mscc/