topic Re: JTAG in device tree configuration in i.MX Processors

JTAG in device tree configuration

jaimepena — Mon, 03 Jul 2017 12:38:08 GMT

I have a imx6dp with a custom board and I want to modifie the control pad configuration of jtag in the device tree.

I define the variables in this way because there is no definition for jtag.

#define MX6QDL_PAD_JTAG_TMS__SJC_TMS 0x0 0x678 0x0000 0 0
#define MX6QDL_PAD_JTAG_MOD__SJC_MOD 0x0 0x67C 0x0000 0 0
#define MX6QDL_PAD_JTAG_TMS__SJC_TRSTB 0x0 0x680 0x0000 0 0
#define MX6QDL_PAD_JTAG_TDI__SJC_TDI 0x0 0x684 0x0000 0 0
#define MX6QDL_PAD_JTAG_TCK__SJC_TCK 0x0 0x688 0x0000 0 0
#define MX6QDL_PAD_JTAG_TDO__SJC_TDO 0x0 0x68C 0x0000 0 0

pinctrl_jtag : jtaggrp{
fsl,pins = <
MX6QDL_PAD_JTAG_TMS__SJC_TMS 0x07060
MX6QDL_PAD_JTAG_MOD__SJC_MOD 0x07060
MX6QDL_PAD_JTAG_TMS__SJC_TRSTB 0x07060
MX6QDL_PAD_JTAG_TDI__SJC_TDI 0x07060
MX6QDL_PAD_JTAG_TCK__SJC_TCK 0x07060
MX6QDL_PAD_JTAG_TDO__SJC_TDO 0x090B1
>;
};

My question is how to configure the device in the device tree file to use the pinctrl for the jtag. There is no definition of this device imx6qdl.dtsi file neither with the dtb of the sabreauto and it uses jtag.

Thanks,

Re: JTAG in device tree configuration

Carlos_Musich — Mon, 03 Jul 2017 17:52:05 GMT

Hi Jaime,

the short answer is that it is not possible as JTAG pins are dedicated.

IOMUX module is described in chapter 36 of Reference Manual. here you can find that the JTAG pins are not listed on any of the mux registers and they are also not listed in the imx6q_pinfunc.h file.

Just for reference, in the thread below I explain with detail how to configure a pin in the device tree. Here you can see and understand what I am talking about.

32Khz clock on CCM_CLKO2 (SD1_WP)

Best regards,
Carlos

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Re: JTAG in device tree configuration

jaimepena — Mon, 03 Jul 2017 19:38:37 GMT

Hello Carlos

Thank for your answer. I already configured the pins of the jtag as you can see in the first post. I have that pinctrl_jtag : jtaggrp{ with the values of the parameters of the signals. My question is more about where has to be this pinctrl specified

like for example :

&uart4 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart4>;
	status = "okay";
	};

you specify the pinctrl_uart in the iomux to define the pins and set the status okay to enable it. In the case of jtag, where do you call the pinctrl_jtag and enable it?

Thanks for your kind answer.

Regards