Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: watchdog: sp5100_tco support for AMD V/R/E series
To:     Jan Kiszka <jan.kiszka@siemens.com>, linux-watchdog@vger.kernel.org
Cc:     Wim Van Sebroeck <wim@linux-watchdog.org>,
        linux-kernel@vger.kernel.org,
        "Awan, Arsalan" <Arsalan_Awan@mentor.com>,
        "Hombourger, Cedric" <Cedric_Hombourger@mentor.com>,
        "Farnsworth, Wade" <wade_farnsworth@mentor.com>
References: <15c8913e-9026-2649-9911-71d6f1c79519@siemens.com>
 <f7e3233b-97e4-1f25-e18e-edb39ca86ce9@roeck-us.net>
 <9e270546-7962-932b-2e4c-3c833b7d4b30@siemens.com>
From:   Guenter Roeck <linux@roeck-us.net>
Autocrypt: addr=linux@roeck-us.net; keydata=
 xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN
 RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7
 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl
 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh
 gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX
 IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC
 kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0
 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s
 jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk
 BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv
 ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL
 CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA
 nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx
 hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1
 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9
 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu
 GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI
 sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT
 Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l
 HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8
 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA
 l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq
 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7
 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM
 J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi
 pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz
 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w
 ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF
 I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT
 nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY
 HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX
 JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+
 J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW
 cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG
 wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh
 hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H
 nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng
 QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj
 trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk
 WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI
 HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU
 mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q=
Message-ID: <a70578a9-4e55-602b-68fe-56a01805965e@roeck-us.net>
Date:   Mon, 7 Sep 2020 12:18:48 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <9e270546-7962-932b-2e4c-3c833b7d4b30@siemens.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 9/7/20 8:46 AM, Jan Kiszka wrote:
> On 07.09.20 17:31, Guenter Roeck wrote:
>> On 9/7/20 4:20 AM, Jan Kiszka wrote:
>>> Hi all,
>>>
>>> Arsalan reported that the upstream driver for sp5100_tco does not work
>>> for embedded Ryzen. Meanwhile, I was able to confirm that on an R1505G:
>>>
>>> [   11.607251] sp5100_tco: SP5100/SB800 TCO WatchDog Timer Driver
>>> [   11.607337] sp5100-tco sp5100-tco: Using 0xfed80b00 for watchdog MMIO address
>>> [   11.607344] sp5100-tco sp5100-tco: Watchdog hardware is disabled
>>>
>>> ..and fix it:
>>>
>>> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
>>> index 85e9664318c9..5482154fde42 100644
>>> --- a/drivers/watchdog/sp5100_tco.c
>>> +++ b/drivers/watchdog/sp5100_tco.c
>>> @@ -193,7 +193,8 @@ static void tco_timer_enable(struct sp5100_tco *tco)
>>>  		/* Set the Watchdog timer resolution to 1 sec and enable */
>>>  		sp5100_tco_update_pm_reg8(EFCH_PM_DECODEEN3,
>>>  					  ~EFCH_PM_WATCHDOG_DISABLE,
>>> -					  EFCH_PM_DECODEEN_SECOND_RES);
>>> +					  EFCH_PM_DECODEEN_SECOND_RES |
>>> +					  EFCH_PM_DECODEEN_WDT_TMREN);
>>
>> Confusing. The register in question is a 32-bit register, but only a byte
>> is written into it. Bit 24-25 are supposed to be the resolution, bit 25-26
>> set to 0 enable the watchdog. Bit 7 is supposed to enable MMIO decoding.
>> This is from AMD Publication 52740. So something in the existing code
>> is (or seems to be) wrong, but either case I don't see how setting bit 7
>> (or 31 ?) would enable the watchdog hardware.
>>
>> Hmm, I wrote that code. Guess I'll need to to spend some time figuring out
>> what is going on.
> 
> The logic came from [1] which inspired [2] - that's where I pointed out
> the large overlap with the existing upstream driver. I would love to see
> all that consolidated.
> 
> BTW, the R1505G is family 0x17. Maybe something changed there, and that
> bit 7 was just reserved/ignored so far. ENOSPECS
> 

Thanks for the pointers.

I think you are talking about bit 31. Bit 7 is and was WatchdogTmrEn, but that
supposedly only enables watchdog timer memory access at 0xfeb00000. From what
I glance from the other drivers, the existing code is wrong. It should set
the disable and resolution bits in register offset 3 (bit 24..27), not 0.
In other words, EFCH_PM_DECODEEN3 should be defined as 0x03, not as 0x00.
Which actually makes sense from the name.

Playing with my hardware, turns out that setting bit 7 in EFCH_PM_DECODEEN
(register offset 0) does indeed enable the watchdog. I'll need to check
if it actually works. Either case, -ENOSPECS is really a problem here.

Guenter

> Jan
> 
> [1]
> https://git.yoctoproject.org/cgit/cgit.cgi/meta-amd/commit/meta-amd-bsp/recipes-kernel/amd-wdt/files/amd_wdt.c?id=cd760c9f04d276382a0f5156dabdb766594ace56
> [2]
> https://github.com/siemens/efibootguard/commit/3a702aa96d193f26571ea4e70db29ef01a0d4d5f
>