IOMUX Usage Instructions#

Overview#

This section mainly describes iomux configuration under Linux. For iomux configuration under uboot, please refer to iomux configuration under uboot

The K230 IOMUX driver provides pin function control for the Canaan Kendryte K230 SoC. This driver implements the Linux pinctrl subsystem and is used to manage:

Pin function multiplexing (each pin has 8 function selections)
Pin configuration (pull-up/pull-down, drive strength, slew rate, etc.)

This document mainly describes the definition of K230 iomux-related registers, device tree configuration, and the usage of the userspace iomux tool. The main files related to this document are as follows:

File	Description
`pinctrl-k230-iomux.c`	Main driver source code implementing pinctrl/pinmux/pinconf operations
`dt-bindings/pinctrl/canaan,k230-iomux.h`	Header file containing pin names and function selectors
`k230_iomux.py`	Python tool for runtime pin configuration
`Documentation/devicetree/bindings/pinctrl/canaan,k230-iomux.yaml`	Device Tree binding schema

Register and Function Description#

Registers#

K230 has 2 iomux controller modules:

Main IOMUX: 0x91105000 (64 pins)
PMU IOMUX: 0x91000080 (8 pins)

Each pin has a 32-bit register at the base address offset pin * 4.

The register bit layout is as follows (refer to TRM Section 12.9.2)

Bit	Field	Type	Description
31	DI	RO	Input data
30:14	-	RO	Reserved
13:11	IO_SEL	RW	Function selection (000=func1, and so on)
10	SL	RW	Slew rate enable
9	MSC	RW	Voltage control (dual-voltage pad)
8	IE	RW	Input enable (1=enabled)
7	OE	RW	Output enable (1=enabled)
6	PU	RW	Pull-up (1=enabled)
5	PD	RW	Pull-down (1=enabled)
4:1	DS	RW	Drive strength selection (0-15)
0	ST	RW	Schmitt trigger (1=enabled)

Function Description#

Each pin supports up to 8 functions (IO_SEL[2:0]). The configurable functions of each pin are as follows:

Controller 0 (io0-io63)

Pin	alt0	alt1	alt2	alt3	alt4
io0	GPIO0	BOOT0	-	TEST_PIN0	-
io1	GPIO1	BOOT1	-	TEST_PIN1	-
io2	GPIO2	JTAG_TCK	PULSE_CNTR0	TEST_PIN2	-
io3	GPIO3	JTAG_TDI	PULSE_CNTR1	UART1_TXD	TEST_PIN0
io4	GPIO4	JTAG_TDO	PULSE_CNTR2	UART1_RXD	TEST_PIN1
io5	GPIO5	JTAG_TMS	PULSE_CNTR3	UART2_TXD	TEST_PIN2
io6	GPIO6	JTAG_RST	PULSE_CNTR4	UART2_RXD	TEST_PIN3
io7	GPIO7	PWM2	I2C4_SCL	TEST_PIN3	DI0
io8	GPIO8	PWM3	I2C4_SDA	TEST_PIN4	DI1
io9	GPIO9	PWM4	UART1_TXD	I2C1_SCL	DI2
io10	GPIO10	3D_CTRL_IN	UART1_RXD	I2C1_SDA	DI3
io11	GPIO11	3D_CTRL_OUT1	UART2_TXD	I2C2_SCL	DO0
io12	GPIO12	3D_CTRL_OUT2	UART2_RXD	I2C2_SDA	DO1
io13	GPIO13	M_CLK1	-	-	DO2
io14	GPIO14	OSPI_CS	TEST_PIN5	QSPI0_CS0	DO3
io15	GPIO15	OSPI_CLK	TEST_PIN6	QSPI0_CLK	CO3
io16	GPIO16	OSPI_D0	QSPI1_CS4	QSPI0_D0	CO2
io17	GPIO17	OSPI_D1	QSPI1_CS3	QSPI0_D1	CO1
io18	GPIO18	OSPI_D2	QSPI1_CS2	QSPI0_D2	CO0
io19	GPIO19	OSPI_D3	QSPI1_CS1	QSPI0_D3	TEST_PIN4
io20	GPIO20	OSPI_D4	QSPI1_CS0	PULSE_CNTR0	TEST_PIN5
io21	GPIO21	OSPI_D5	QSPI1_CLK	PULSE_CNTR1	TEST_PIN6
io22	GPIO22	OSPI_D6	QSPI1_D0	PULSE_CNTR2	TEST_PIN7
io23	GPIO23	OSPI_D7	QSPI1_D1	PULSE_CNTR3	TEST_PIN8
io24	GPIO24	OSPI_DQS	QSPI1_D2	PULSE_CNTR4	TEST_PIN9
io25	GPIO25	PWM5	QSPI1_D3	PULSE_CNTR5	TEST_PIN10
io26	GPIO26	MMC1_CLK	TEST_PIN7	PDM_CLK	-
io27	GPIO27	MMC1_CMD	PULSE_CNTR5	PDM_IN0	CI0
io28	GPIO28	MMC1_D0	UART3_TXD	PDM_IN1	CI1
io29	GPIO29	MMC1_D1	UART3_RXD	3D_CTRL_IN	CI2
io30	GPIO30	MMC1_D2	UART3_RTS	3D_CTRL_OUT1	CI3
io31	GPIO31	MMC1_D3	UART3_CTS	3D_CTRL_OUT2	TEST_PIN11
io32	GPIO32	I2C0_SCL	IIS_CLK	UART3_TXD	TEST_PIN12
io33	GPIO33	I2C0_SDA	IIS_WS	UART3_RXD	TEST_PIN13
io34	GPIO34	I2C1_SCL	IIS_D_IN0_PDM_IN3	UART3_RTS	TEST_PIN14
io35	GPIO35	I2C1_SDA	IIS_D_OUT0_PDM_IN1	UART3_CTS	TEST_PIN15
io36	GPIO36	I2C3_SCL	IIS_D_IN1_PDM_IN2	UART4_TXD	TEST_PIN16
io37	GPIO37	I2C3_SDA	IIS_D_OUT1_PDM_IN0	UART4_RXD	TEST_PIN17
io38	GPIO38	UART0_TXD	TEST_PIN8	QSPI1_CS0	HSYNC0
io39	GPIO39	UART0_RXD	TEST_PIN9	QSPI1_CLK	VSYNC0
io40	GPIO40	UART1_TXD	I2C1_SCL	QSPI1_D0	TEST_PIN18
io41	GPIO41	UART1_RXD	I2C1_SDA	QSPI1_D1	TEST_PIN19
io42	GPIO42	UART1_RTS	PWM0	QSPI1_D2	TEST_PIN20
io43	GPIO43	UART1_CTS	PWM1	QSPI1_D3	TEST_PIN21
io44	GPIO44	UART2_TXD	I2C3_SCL	TEST_PIN10	SPI2AXI_CLK
io45	GPIO45	UART2_RXD	I2C3_SDA	TEST_PIN11	SPI2AXI_CS
io46	GPIO46	UART2_RTS	PWM2	I2C4_SCL	TEST_PIN22
io47	GPIO47	UART2_CTS	PWM3	I2C4_SDA	TEST_PIN23
io48	GPIO48	UART4_TXD	TEST_PIN12	I2C0_SCL	SPI2AXI_DIN
io49	GPIO49	UART4_RXD	TEST_PIN13	I2C0_SDA	SPI2AXI_DOUT
io50	GPIO50	UART3_TXD	I2C2_SCL	QSPI0_CS4	TEST_PIN24
io51	GPIO51	UART3_RXD	I2C2_SDA	QSPI0_CS3	TEST_PIN25
io52	GPIO52	UART3_RTS	PWM4	I2C3_SCL	TEST_PIN26
io53	GPIO53	UART3_CTS	PWM5	I2C3_SDA	-
io54	GPIO54	QSPI0_CS0	MMC1_CMD	PWM0	TEST_PIN27
io55	GPIO55	QSPI0_CLK	MMC1_CLK	PWM1	TEST_PIN28
io56	GPIO56	QSPI0_D0	MMC1_D0	PWM2	TEST_PIN29
io57	GPIO57	QSPI0_D1	MMC1_D1	PWM3	TEST_PIN30
io58	GPIO58	QSPI0_D2	MMC1_D2	PWM4	TEST_PIN31
io59	GPIO59	QSPI0_D3	MMC1_D3	PWM5	-
io60	GPIO60	PWM0	I2C0_SCL	QSPI0_CS2	HSYNC1
io61	GPIO61	PWM1	I2C0_SDA	QSPI0_CS1	VSYNC1
io62	GPIO62	M_CLK2	UART3_DE	TEST_PIN14	-
io63	GPIO63	M_CLK3	UART3_RE	TEST_PIN15	-

Controller 1 (io0-io7, PMUIOMUX)

Pin	alt1	alt2
io0	GPIO64	INT0
io1	GPIO65	INT1
io2	GPIO66	INT2
io3	GPIO67	INT3
io4	GPIO68	INT4
io5	GPIO69	INT5
io6	GPIO70	OUT1
io7	GPIO71	OUT2

Device Tree Configuration#

Example#

UART0 Configuration#

&iomux {
    uart0_pins: uart0-pins {
        pinmux {
            pins = "io38", "io39";
            function = "alt1";
            bias-disable;
            drive-strength = <8>;
            slew-rate = <1>;
        };
    };
};

&uart0 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&uart0_pins>;
};

I2C0 Configuration#

&iomux {
    i2c0_pins: i2c0-pins {
        pinmux {
            pins = "io32", "io33";
            function = "alt1";
            bias-pull-up;
            drive-strength = <8>;
        };
    };
};

&i2c0 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&i2c0_pins>;
    clock-frequency = <100000>;
};

PWM Configuration#

&iomux {
    pwm2_pins: pwm2-pins {
        pinmux {
            pins = "io46";
            function = "alt2";  // PWM2 function
            drive-strength = <8>;
        };
    };
};

&pwm0_2 {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&pwm2_pins>;
};

Description#

/*arch/riscv/boot/dts/canaan/k230.dtsi*/
iomux: iomux@91105000 {
    compatible = "canaan,k230-iomux";
    reg = <0x0 0x91105000 0x0 0x100>;
    #pinctrl-cells = <1>;
    clocks = <&iomux_pclk_gate>;
    clock-names = "apb";
    status = "okay";
};
pmuiomux: pmuiomux@91000080 {
    compatible = "canaan,k230-iomux";
    reg = <0x0 0x91000080 0x0 0x20>;
    #pinctrl-cells = <1>;
    clocks = <&iomux_pclk_gate>;
    clock-names = "apb";
    status = "okay";
};

uart0_pins: uart0-pins {
    pinmux {
        pins = "io38", "io39";
        function = "alt1";  // UART0_TXD / UART0_RXD
        bias-disable;
        drive-strength = <8>;
        slew-rate = <1>;    // 快速
    };
};

Available Pin Names

Main IOMUX: io0 to io63
PMU IOMUX: io0 to io7 (mapped to pins 64-71)

Available Pin Configuration Properties

bias-pull-up - Enable pull-up resistor
bias-pull-down - Enable pull-down resistor
bias-disable - Disable pull-up/pull-down
drive-strength - Drive strength (0-15, refer to TRM for specific current values)
slew-rate - Slew rate control (0=disable, 1=enable)
input-enable - Enable input buffer
output-enable - Enable output buffer
input-schmitt - Enable Schmitt trigger

Configurable functions can be found in previous sections

For more information, please refer to Documentation/devicetree/bindings/pinctrl/canaan,k230-iomux.yaml

User-space Companion Tools#

k230_iomux.py is a user-space tool for debugging and viewing iomux configurations

Usage Examples#

# View all pin configurations (controller 0)
python3 k230_iomux.py

# View specific pin
python3 k230_iomux.py --pin io38

# View pin and all available functions
python3 k230_iomux.py --pin io38 --funcs

# Set pin to a specific function
python3 k230_iomux.py --set io38 alt1

# Set pin with configuration options
python3 k230_iomux.py --set io38 alt1 --ie --oe --pu --ds 8

# Set pin using a specific function name
python3 k230_iomux.py --set io38 UART0_TXD

# View the second IOMUX controller (PMUIOMUX)
python3 k230_iomux.py --iomux 1

##### Set pin on the second controller
python3 k230_iomux.py --iomux 1 --set io3 alt1

Usage Instructions#

[root@canaan ~ ]#k230_iomux.py  -h
usage: k230_iomux.py [-h] [--pin PIN] [--funcs] [--set PIN FUNC]
                     [--iomux {0,1}] [--ie] [--no-ie] [--oe] [--no-oe] [--pu]
                     [--pd] [--no-pull] [--ds 1-15] [--sl] [--no-sl] [--st]
                     [--no-st]

K230 IOMUX Pin Configuration Tool

options:
  -h, --help          show this help message and exit
  --pin, -p PIN       Specific pin to view (e.g., io38)
  --funcs, -f         Show all available functions for a pin
  --set, -s PIN FUNC  Set pin to function (e.g., io38 alt1)
  --iomux, -i {0,1}   IOMUX controller index (0=main, 1=pmuiomux)
  --ie                Enable input
  --no-ie             Disable input
  --oe                Enable output
  --no-oe             Disable output
  --pu                Enable pull-up
  --pd                Enable pull-down
  --no-pull           Disable pull-up/down
  --ds 1-15           Drive strength (1-15)
  --sl                Enable slew rate
  --no-sl             Disable slew rate
  --st                Enable schmitt trigger
  --no-st             Disable schmitt trigger

Examples:
  # View all pin configurations (controller 0)
  python3 k230_iomux.py

  # View specific pin
  python3 k230_iomux.py --pin io38

  # View pin with all available functions
  python3 k230_iomux.py --pin io38 --funcs

  # Set pin to alt1 function
  python3 k230_iomux.py --set io38 alt1

  # Set pin with configuration options
  python3 k230_iomux.py --set io38 alt1 --ie --oe --pu --ds 8

  # Set pin using specific function name (must specify pin)
  python3 k230_iomux.py --set io38 UART0_TXD

  # View controller 1 (PMUIOMUX at 0x91000080)
  python3 k230_iomux.py --iomux 1

  # Set pin on controller 1
  python3 k230_iomux.py --iomux 1 --set io3 alt1

[root@canaan ~ ]#



#Command Line Parameters

| Parameter | Description |
| --- | --- |
| `--pin`, `-p` | Specific pin to view (e.g., `io38`) |
| `--funcs`, `-f` | Show all available functions for a pin |
| `--set`, `-s` | Set pin to function (e.g., `io38 alt1`) |
| `--iomux`, `-i` | IOMUX controller index (0=main, 1=pmuiomux) |
| `--ie` | Enable input |
| `--no-ie` | Disable input |
| `--oe` | Enable output |
| `--no-oe` | Disable output |
| `--pu` | Enable pull-up |
| `--pd` | Enable pull-down |
| `--no-pull` | Disable pull-up/down |
| `--ds` | Drive strength (1-15) |
| `--sl` | Enable slew rate |
| `--no-sl` | Disable slew rate |
| `--st` | Enable schmitt trigger |
| `--no-st` | Disable schmitt trigger |