MT7621 : Enable I2C Driver

[milavsoni]

Hello Guys,

I want to enable I2C Module for Unielec - u7621-06 development kit for RTC communication.

My kernel version is 4.4.198.

In mt7621.dtsi file I see below code,

i2c@0 {
			compatible = "i2c-gpio";
			gpios = <&gpio0 3 1>, <&gpio0 4 1>;
			i2c-gpio,delay-us = <3>;
			#address-cells = <1>;
			#size-cells = <0>;
			status = "okay";
			pinctrl-names = "default";
			pinctrl-0 = <&i2c_pins>;
		};

and in my device specific dts file below code is available..

&pinctrl {
	state_default: pinctrl0 {
		gpio {
			mtk,group = "i2c";
			mtk,function = "gpio";
		};

		uart2 {
			mtk,group = "uart2";
			mtk,function = "uart2";
		};

		uart3 {
			mtk,group = "uart3";
			mtk,function = "uart3";
		};

	};
};

When I build above kernel, I cannot see i2c driver in the kernel boot log.

I also tried by adding below code in device specific dts, but I received device tree error during building

&i2c {
	status = "okay";
};

I also check in kernel config file...
CONFIG_I2C=y and CONFIG_I2C_MT7621=y

Can you guys help me to sort out this problem?

Thanks,

[milavsoni]

Hello,

I enable below in menu config then I will see below kernel log. I see some error in that.

Kernel log..

root@LEDE:/# dmesg | grep i2c
[   30.670378] i2c /dev entries driver
[   30.676775] mtkmips-pinmux pinctrl: pin io3 already requested by pinctrl; cannot claim for 1e000000.palmbus:i2c@0
[   30.687102] mtkmips-pinmux pinctrl: pin-3 (1e000000.palmbus:i2c@0) status -22
[   30.694423] mtkmips-pinmux pinctrl: could not request pin 3 (io3) from group i2c  on device rt2880-pinmux
[   30.704173] i2c-gpio 1e000000.palmbus:i2c@0: Error applying setting, reverse things back
[   30.712939] i2c-gpio 1e000000.palmbus:i2c@0: using pins 3 (SDA) and 4 (SCL)

Can you guys please tell me is I2C Configure correctly or not?

Thanks

[AndrewZ]

Please consider switching to the current OpenWrt version first.

[milavsoni]

Hello @AndrewZ

Thank you for your response.

I should develop all logic in the same above version.

Can you please help me out on this error?

Thank You

[AndrewZ]

I have no experience with the version you're using.

[andyboeh]

If you use the hardware i2c engine, that is on pins 3 and 4, then you must not configure your pins as GPIO but as i2c. Since this is the default, remove the lines:

		gpio {
			mtk,group = "i2c";
			mtk,function = "gpio";
		};

from your DTS.

NB: This is for the current version of OpenWrt, I have absolutely no idea about your fork or ancient release.

[milavsoni]

Dear @andyboeh

Thank you for your response.

I convert it to i2c as show in below.

Still, I get below log.

root@LEDE:~# dmesg | grep i2c
[   28.678392] i2c /dev entries driver
[   28.687026] mtkmips-pinmux pinctrl: pin io3 already requested by pinctrl; cannot claim for 1e000000.palmbus:i2c@0
[   28.697452] mtkmips-pinmux pinctrl: pin-3 (1e000000.palmbus:i2c@0) status -22
[   28.704709] mtkmips-pinmux pinctrl: could not request pin 3 (io3) from group i2c  on device rt2880-pinmux
[   28.714335] i2c-gpio 1e000000.palmbus:i2c@0: Error applying setting, reverse things back
[   28.723407] i2c-gpio 1e000000.palmbus:i2c@0: using pins 3 (SDA) and 4 (SCL)

Moreover, I also enable below config. is there any problem of below config?

Waiting for your helpful response.

Thank You

[andyboeh]

@milavsoni

Still, I get below log.

Something else has already requested io3, so it's not available for the i2c driver.

@milavsoni

Moreover, I also enable below config. is there any problem of below config?

I repeat myself and @AndrewZ here: Upgrade to the current codebase, I have zero knowledge about your version.

[123serge123]

I think that something wrong here:

@milavsoni

i2c@0 {
			compatible = "i2c-gpio";
			gpios = <&gpio0 3 1>, <&gpio0 4 1>;
			i2c-gpio,delay-us = <3>;
			#address-cells = <1>;
			#size-cells = <0>;
			status = "okay";
			pinctrl-names = "default";
			pinctrl-0 = <&i2c_pins>;
		};

If you want to use software i2c-gpio driver (instead of mediatek i2c-driver) you must remove these lines:

			pinctrl-names = "default";
			pinctrl-0 = <&i2c_pins>;

which implicitly request i2c mode for i2c_pins group and conflict with your explicit request for the same group to gpio mode:

		gpio {
			mtk,group = "i2c";
			mtk,function = "gpio";
		};