linux-kernel - Re: [PATCH 2/2] watchdog: sp5100_tco: Enable watchdog on Family 17h devices if disabled

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Message-ID: <2e35ac70-deca-d414-e8a6-2815bdd638d4@siemens.com>
Date:   Thu, 10 Sep 2020 18:55:08 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] watchdog: sp5100_tco: Enable watchdog on Family 17h
 devices if disabled

On 10.09.20 18:53, Guenter Roeck wrote:
> Hi Jan,
> 
> On 9/10/20 9:34 AM, Jan Kiszka wrote:
>> On 10.09.20 18:31, Guenter Roeck wrote:
>>> On Family 17h (Ryzen) devices, the WatchdogTmrEn bit of PmDecodeEn not only
>>> enables watchdog memory decoding at 0xfeb00000, it also enables the
>>> watchdog hardware itself. Use this information to enable the watchdog if
>>> it is not already enabled.
>>>
>>> Cc: Jan Kiszka <jan.kiszka@...mens.com>
>>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>>> ---
>>>  drivers/watchdog/sp5100_tco.c | 18 ++++++++++++++++++
>>>  1 file changed, 18 insertions(+)
>>>
>>> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
>>> index 85e9664318c9..a730ecbf78cd 100644
>>> --- a/drivers/watchdog/sp5100_tco.c
>>> +++ b/drivers/watchdog/sp5100_tco.c
>>> @@ -17,6 +17,12 @@
>>>   *	    AMD Publication 51192 "AMD Bolton FCH Register Reference Guide"
>>>   *	    AMD Publication 52740 "BIOS and Kernel Developer’s Guide (BKDG)
>>>   *				for AMD Family 16h Models 30h-3Fh Processors"
>>> + *	    AMD Publication 55570-B1-PUB "Processor Programming Reference (PPR)
>>> + *				for AMD Family 17h Model 18h, Revision B1
>>> + *				Processors (PUB)
>>> + *	    AMD Publication 55772-A1-PUB "Processor Programming Reference (PPR)
>>> + *				for AMD Family 17h Model 20h, Revision A1
>>> + *				Processors (PUB)
>>>   */
>>>  
>>>  /*
>>> @@ -241,6 +247,18 @@ static int sp5100_tco_setupdevice(struct device *dev,
>>>  		break;
>>>  	case efch:
>>>  		dev_name = SB800_DEVNAME;
>>> +		/*
>>> +		 * On Family 17h devices, the EFCH_PM_DECODEEN_WDT_TMREN bit of
>>> +		 * EFCH_PM_DECODEEN not only enables the EFCH_PM_WDT_ADDR memory
>>> +		 * region, it also enables the watchdog itself.
>>> +		 */
>>> +		if (boot_cpu_data.x86 == 0x17) {
>>> +			val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
>>> +			if (!(val & EFCH_PM_DECODEEN_WDT_TMREN)) {
>>> +				sp5100_tco_update_pm_reg8(EFCH_PM_DECODEEN, 0xff,
>>> +							  EFCH_PM_DECODEEN_WDT_TMREN);
>>> +			}
>>> +		}
>>>  		val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
>>>  		if (val & EFCH_PM_DECODEEN_WDT_TMREN)
>>>  			mmio_addr = EFCH_PM_WDT_ADDR;
>>>
>>
>> Won't that bring us EFCH_PM_WDT_ADDR as address, rather than
>> EFCH_PM_ACPI_MMIO_ADDR which worked in my case? Or is one an alias of
>> the other.
>>
> 
> Yes, it does use EFCH_PM_WDT_ADDR. EFCH_PM_ACPI_MMIO_ADDR works as well,
> but is meant to be a fallback. Both point to the watchdog memory space.
> 

OK, will test, possibly only on the weekend, and confirm this also on my
board.

Jan

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