im7: reset the board using wdog 4

[vsiles]

Hi,

I'm trying to implement a watchdog driver for my secure kernel, and I decided to use WDOG 4.

I setting the wdog as follow (timeout is 9 seconds, service event 2 seconds before)

WCR register := (17 << 8) | WCR_SRS | WCR_WDE

then I service the wdog with the 0x5555 0xaaaa sequence to make it start.

I have two issues:

- if I use WDOG1, I correctly get the interrupt after 7 seconds to be able to service it. I don't service it and 2 seconds later the boards reset, but U-boot hangs. I only get

U-Boot SPL 2015.04-00003-gdefdcdc (Aug 05 2016 - 10:00:29)

and the boards is stuck

- if I use WDOG4, I get the interrupt after 7 seconds. I don't service it and the board never reset.

How can I reset the board using wdog4 ?

Best,

Vincent

[hemanttiwari199]

Hi,

I was going through the Design files for i.MX 7Dual (REV D). Can anyone please briefly explain the circuit attached below. I wanted to know the working of watchdog with U37 (TPS3808).

Regards

Hemant

[Yuri]

@hemanttiwari199 
Hello,

  It is highly recommended to remove power from all components on the board in the event of a processor reset in order to avoid checking states of components, critical for rebooting the system, if they are in the necessary state to support reboot. So, full system (board) Power On Reset may be recommended for reboot (via WDOG). Look at TPS3808G30DBVT (U37) circuit on the reference design.

Regards,
Yuri.

[igorpadykov]

Hi Vincent

on Sabre SD board wdog1 resets pmic with PMIC_PWRON using U37 on sch-28590 p.23

Schematics (2)

Design files for i.MX 7Dual (REV D)

Design files, including hardware schematics, Gerbers, and OrCAD files for i.MX 7Dual (REV D)

http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-process...

The same solution should be used with wdog4.

Best regards

igor

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[vsiles]

Thank you, it was quite helpful.

From IMX7DCEC.pdf I can read that WDOG2 is reserved for secure use, so I'll try with it (this was missing from thereference manual). Also I can read that:

NOTE
WDOGx_B output signals (for each one of the Watchdog modules) do not
have dedicated pins, but are muxed out through the IOMUX. See the IOMUXC chapter of the
i.MX 7Dual Application Processor Reference Manual (IMX7DRM) for detailed information.

Does it mean I need to configure the IOMUX to achieve reset ?

[Yuri]

Hello,

Correct, it is needed to configure the IOMUX to achieve (hardware) reset

Regards,

Yuri.