The NXP i.MX6 CPU has seven general purpose input/output (GPIO) ports. Each port can generate and control 32 signals.
The Dialog PMIC DA9063 has 16 configurable GPIO pins.
GPIOs on the ConnectCore 6 platforms
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On the ConnectCore 6 system-on-module:
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Many of the i.MX6 GPIOs are available at the system-on-module, multiplexed with other functions (labeled GPIOxIOy where _x is the port and y is the GPIO pin). See Hardware reference manuals for information about GPIO pins and their multiplexed functionality.
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Eight PMIC GPIO pins are available (labeled PMIC_GPIOx where x is the GPIO pin).
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On the ConnectCore 6 SBC, the expansion connector allows direct access to eight i.MX6 GPIOs.
GPIOs on the SOM and carrier board are used for many purposes, such as:
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Power enable line for transceivers
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Reset line for controllers
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LCD backlight control
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Interrupt line
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User LEDs
Kernel configuration
You can manage the GPIO driver support through the kernel configuration option:
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Dialog Semiconductor DA9063 GPIO (
CONFIG_GPIO_DA9063)
This option is enabled as built-in on the ConnectCore 6 SBC kernel configuration file.
Support for i.MX6 GPIOs is automatically provided through the non-visible option CONFIG_GPIO_MXC.
Kernel driver
The i.MX6 GPIO driver is located at drivers/gpio/gpio-mxc.c.
The Dialog DA9063 GPIO driver is located at drivers/gpio/gpio-da9063.c.
Device tree bindings and customization
The i.MX6 GPIO device tree binding is documented at
Documentation/devicetree/bindings/gpio/fsl-imx-gpio.yaml.
One GPIO controller is defined for each i.MX6 GPIO port in the common i.MX6 device tree file:
gpio1: gpio@0209c000 {
compatible = "fsl,imx6q-gpio", "fsl,imx35-gpio";
reg = <0x0209c000 0x4000>;
interrupts = <0 66 IRQ_TYPE_LEVEL_HIGH>,
<0 67 IRQ_TYPE_LEVEL_HIGH>;
gpio-controller;
#gpio-cells = <2>;
interrupt-controller;
#interrupt-cells = <2>;
};
[...]
gpio7: gpio@020b4000 {
compatible = "fsl,imx6q-gpio", "fsl,imx35-gpio";
reg = <0x020b4000 0x4000>;
interrupts = <0 78 IRQ_TYPE_LEVEL_HIGH>,
<0 79 IRQ_TYPE_LEVEL_HIGH>;
gpio-controller;
#gpio-cells = <2>;
interrupt-controller;
#interrupt-cells = <2>;
};The Dialog DA9063 GPIO device tree binding is documented at
Documentation/devicetree/bindings/gpio/gpio-da9063.txt.
The DA9063 PMIC GPIO controller is defined in the ConnectCore 6 device tree file:
&i2c2 {
clock-frequency = <100000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c2>;
status = "okay";
pmic_dialog: dialog@58 {
compatible = "dlg,da9063";
[...]
gpio_extender: gpio {
compatible = "dlg,da9063-gpio";
gpio-controller;
#gpio-cells = <2>;
};
[...]
};
};The ConnectCore 6 device tree include file and the ConnectCore 6 SBC device tree files use the i.MX6 and DA9063 PMIC GPIOs.
For example, on the ConnectCore 6 SBC, GPIO1_IO25 is used to reset the PHY of the Ethernet interface:
&fec {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet>;
phy-mode = "rgmii";
phy-reset-gpios = <&gpio1 25 GPIO_ACTIVE_HIGH>;
phy-reset-duration = <10>;
phy-reset-wait = <1>;
phy-supply = <&ldo4>;
fsl,magic-packet;
};IOMUX configuration
You must configure the pads that are to be used as i.MX6 GPIOs. See Pin multiplexing (IOMUX).
For GPIOs that are managed by other drivers, you must configure their pad IOMUX inside the driver node specific pinctrl-0 to work according to the specified interface functionalities.
On the ConnectCore 6 SBC example from above, fec node configures pinctrl_enet:
pinctrl_enet: enet {
fsl,pins = <
MX6QDL_PAD_ENET_MDIO__ENET_MDIO 0x1b0b0
MX6QDL_PAD_ENET_MDC__ENET_MDC 0x1b0b0
[...]
MX6QDL_PAD_ENET_TX_EN__GPIO1_IO28 0x1b0b0
MX6QDL_PAD_ENET_CRS_DV__GPIO1_IO25 0x1b0b0
>;
};For GPIOs that are not associated with any interface or that can’t be handled by a driver, see Configure independent pin IOMUX and pad control. The following external pads are configured as GPIOs on the default device tree:
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On the ConnectCore 6 SBC GPIO connector:
Pad Signal GPIO 6
EXP_GPIO_0
GPIO2_IO05
7
EXP_GPIO_1
GPIO2_IO06
8
EXP_GPIO_2
GPIO2_IO07
9
EXP_GPIO_3
GPIO2_IO24
10
EXP_GPIO_4
GPIO2_IO28
11
EXP_GPIO_5
GPIO2_IO29
12
EXP_GPIO_6
GPIO7_IO13
13
EXP_GPIO_7
GPIO4_IO05
SION bit
It is not possible to read the real signal level of a GPIO pin that is configured as an output. You can use the software input on (SION) bit to read the value of an output GPIO.
| SION bit mode increases the power consumption of the module, so it is disabled by default. |
To enable the SION bit, set the bit 30 (special value). For example, to enable the SION bit for EXP_GPIO_0, use the following in the device tree (note that 0x80000000 | (1 << 30) = 0xC0000000 ):
hog {
pinctrl_hog: hog {
fsl,pins = <
...
/* EXP_GPIO_0 */
MX6QDL_PAD_NANDF_D5__GPIO2_IO05 0xC0000000
};
};
};For more information, see the NXP Application Note AN5078.
Using the GPIOs
The package libgpiod (added by packagegroup-dey-core) provides a set of tools (such as gpioget, gpioget, etc.) for controlling the GPIOs from user space.
| You can still control the GPIOs from the sysfs, but this ABI is not recommended. See https://www.kernel.org/doc/html/latest/userspace-api/gpio/sysfs.html. |
Detect GPIO ports
Use gpiodetect to list the GPIO ports detected by the kernel:
# gpiodetect
gpiochip0 [gpio1] (32 lines)
gpiochip1 [gpio2] (32 lines)
gpiochip2 [gpio3] (32 lines)
gpiochip3 [gpio4] (32 lines)
gpiochip4 [gpio5] (32 lines)
gpiochip5 [gpio6] (32 lines)
gpiochip6 [gpio7] (32 lines)
gpiochip7 [da9063-gpio] (16 lines)where:
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Ports gpio0 to gpio6 are the i.MX6 GPIO ports.
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Port mda9063ca-gpio is the DA9063 PMIC GPIO port.
Information about a GPIO port
Use gpioinfo to list the lines of a given port:
# gpioinfo gpio1
gpiochip0 - 32 lines:
line 0: unnamed unused input active-high
line 1: unnamed unused input active-high
line 2: unnamed unused input active-high
line 3: unnamed "rts" output active-high [used]
line 4: unnamed "mca-fw-update" output active-high [used]
line 5: unnamed unused input active-high
line 6: unnamed "5v_board" output active-high [used]
line 7: unnamed "sysfs" output active-high [used]
line 8: unnamed "sysfs" output active-high [used]
line 9: unnamed unused input active-high
line 10: unnamed unused input active-high
line 11: unnamed unused input active-high
line 12: unnamed unused output active-high
line 13: unnamed unused input active-high
line 14: unnamed unused input active-high
line 15: unnamed unused input active-high
line 16: unnamed unused input active-high
line 17: unnamed unused input active-high
line 18: unnamed unused input active-high
line 19: unnamed unused input active-high
line 20: unnamed unused input active-high
line 21: unnamed unused input active-high
line 22: unnamed unused input active-high
line 23: unnamed unused input active-high
line 24: unnamed unused input active-high
line 25: unnamed unused input active-high
line 26: unnamed unused input active-high
line 27: unnamed unused input active-high
line 28: unnamed unused input active-high
line 29: unnamed unused input active-high
line 30: unnamed unused input active-high
line 31: unnamed unused input active-highSet an output high/low
Use gpioset to set a i.MX6 GPIO as output, such as GPIO5_IO27.
Use =1 to set it high, or =0 to set it low:
# gpioset gpio5 27=1
# gpioset gpio5 27=0Read an input
Use gpioget to read the value of a i.MX6 GPIO input, such as GPIO5_IO27:
# gpioget gpio5 27
0
