Enabling the 5th UART on Apalis iMX6Q

Technical Support
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1

I am using an Apalis iMX6Q IT 2GB module on a custom carrier board and need to utilize all 5 UART’s on the module. The OS is a custom build based on BSP 5.1.0-devel+git.a2f08dfd79ae. UART’s 1-4 seem to be functioning normally and show in /dev as “apalis-uart1 … 4”. However I cannot seem to get UART 5 to show. I do however have “ttymxc0 … 4” which I believe is the UARTs. My device tree files are as follows

  1. imx6q-apalis-acu3.dts
  2. imx6qdl-apalis.dtsi
  3. imx6qdl-apalis-acu3.dtsi

I have made the following to these files

imx6qdl-apalis.dtsi - Added too

&uart3 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart3_dte>;
	fsl,dte-mode;
	status = "disabled";
};

&iomuxc {

    .....

    pinctrl_uart3_dce: uart3dcegrp {
	fsl,pins = <
 		   MX6QDL_PAD_EIM_D24__UART3_TX_DATA    0x1b0b1
			MX6QDL_PAD_EIM_D25__UART3_RX_DATA    0x1b0b1
		>;
	};

	/* DTE mode */
	pinctrl_uart3_dte: uart3dtegrp { 
		fsl,pins = <
			MX6QDL_PAD_EIM_D24__UART3_RX_DATA   0x1b0b1
			MX6QDL_PAD_EIM_D25__UART3_TX_DATA   0x1b0b1
		>;
	};

    .....

};

imx6qdl-apalis-acu3.dtsi - Added too

&uart3 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart3_dte>;
};

What am I missing here? Is it possible that since this 5th UART is not technically apart of the apalis standard UART’s that all that will show is the appropriate ttymxc and /dev will never have an apalis-uart5? I have attached the full device tree files here. Any help on this would be greatly appreciated.

2

Everything looks OK. You don’t need a pinctrl_uart3_dce group though you can keep it. If you compile and deploy your dtb file correctly you should get a new device file - /dev/ttymxc2

3

@alex.tx I have

/dev/ttymxc2

so does that mean that I should have the 5th UART? I do not have a apalis-uart5 device file though.

4

Apalis imx6 UARTs have device files with manes /dev/ttymxcN. Please check this article.

Apalis UART5 is iMX6 uart3 and its device file is /dev/ttymxc2