From: Alexandre Belloni <alexandre.belloni@bootlin.com> To: Milton Miller II <miltonm@us.ibm.com> Cc: Paul Fertser <fercerpav@gmail.com>, Ivan Mikhaylov <i.mikhaylov@yadro.com>, Alessandro Zummo <a.zummo@towertech.it>, openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] rtc: pch-rtc: add Intel Series PCH built-in read-only RTC Date: Tue, 17 Aug 2021 22:05:45 +0200 [thread overview] Message-ID: <YRwWmeQiVC3dGAjH@piout.net> (raw) In-Reply-To: <OFBF96A764.75CCED3A-ON00258734.0062B30C-00258734.00634222@ibm.com> On 17/08/2021 18:04:09+0000, Milton Miller II wrote: > > On Aug 16, 2021, Alexandre Belloni wrote: > >On 15/08/2021 01:42:15+0300, Paul Fertser wrote: > >> On Tue, Aug 10, 2021 at 06:44:34PM +0300, Ivan Mikhaylov wrote: > >> > Add RTC driver with dt binding tree document. Also this driver > >adds one sysfs > >> > attribute for host power control which I think is odd for RTC > >driver. > >> > Need I cut it off and use I2C_SLAVE_FORCE? I2C_SLAVE_FORCE is not > >good > >> > way too from my point of view. Is there any better approach? > >> > >> Reading the C620 datasheet I see this interface also allows other > >> commands (wake up, watchdog feeding, reboot etc.) and reading > >statuses > >> (e.g Intruder Detect, POWER_OK_BAD). > >> > >> I think if there's any plan to use anything other but RTC via this > >> interface then the driver should be registered as an MFD. > >> > > > >This is not the current thinking, if everything is integrated, then > >there is no issue registering a watchdog from the RTC driver. I'll > >let > >you check with Lee... > > I think the current statement is "if they are truly disjoint > hardware controls" then an MFD might suffice, but if they require > software cordination the new auxillary bus seems to be desired. > Honestly, the auxiliary bus doesn't provide anything that you can't do by registering a device in multiple subsystem from a single driver. (Lee Jones, Mark Brown and I did complain at the time that this was yet another back channel for misuses). > >>However, I'm not sure what is the correct interface for > >poweroff/reboot > >control. > > While there is a gpio interface to a simple regulator switch, > the project to date has been asserting direct or indirect > gpios etc to control the host. If these are events to > trigger a change in state and not a direct state change > that some controller trys to follow, maybe a message delivery > model? (this is not to reboot or cycle the bmc). > > milton -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Belloni <alexandre.belloni@bootlin.com> To: Milton Miller II <miltonm@us.ibm.com> Cc: Paul Fertser <fercerpav@gmail.com>, Ivan Mikhaylov <i.mikhaylov@yadro.com>, openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org, Alessandro Zummo <a.zummo@towertech.it> Subject: Re: [PATCH 0/2] rtc: pch-rtc: add Intel Series PCH built-in read-only RTC Date: Tue, 17 Aug 2021 22:05:45 +0200 [thread overview] Message-ID: <YRwWmeQiVC3dGAjH@piout.net> (raw) In-Reply-To: <OFBF96A764.75CCED3A-ON00258734.0062B30C-00258734.00634222@ibm.com> On 17/08/2021 18:04:09+0000, Milton Miller II wrote: > > On Aug 16, 2021, Alexandre Belloni wrote: > >On 15/08/2021 01:42:15+0300, Paul Fertser wrote: > >> On Tue, Aug 10, 2021 at 06:44:34PM +0300, Ivan Mikhaylov wrote: > >> > Add RTC driver with dt binding tree document. Also this driver > >adds one sysfs > >> > attribute for host power control which I think is odd for RTC > >driver. > >> > Need I cut it off and use I2C_SLAVE_FORCE? I2C_SLAVE_FORCE is not > >good > >> > way too from my point of view. Is there any better approach? > >> > >> Reading the C620 datasheet I see this interface also allows other > >> commands (wake up, watchdog feeding, reboot etc.) and reading > >statuses > >> (e.g Intruder Detect, POWER_OK_BAD). > >> > >> I think if there's any plan to use anything other but RTC via this > >> interface then the driver should be registered as an MFD. > >> > > > >This is not the current thinking, if everything is integrated, then > >there is no issue registering a watchdog from the RTC driver. I'll > >let > >you check with Lee... > > I think the current statement is "if they are truly disjoint > hardware controls" then an MFD might suffice, but if they require > software cordination the new auxillary bus seems to be desired. > Honestly, the auxiliary bus doesn't provide anything that you can't do by registering a device in multiple subsystem from a single driver. (Lee Jones, Mark Brown and I did complain at the time that this was yet another back channel for misuses). > >>However, I'm not sure what is the correct interface for > >poweroff/reboot > >control. > > While there is a gpio interface to a simple regulator switch, > the project to date has been asserting direct or indirect > gpios etc to control the host. If these are events to > trigger a change in state and not a direct state change > that some controller trys to follow, maybe a message delivery > model? (this is not to reboot or cycle the bmc). > > milton -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
next prev parent reply other threads:[~2021-08-17 20:05 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-10 15:44 [PATCH 0/2] rtc: pch-rtc: add Intel Series PCH built-in read-only RTC Ivan Mikhaylov 2021-08-10 15:44 ` Ivan Mikhaylov 2021-08-10 15:44 ` [PATCH 1/2] rtc: pch-rtc: add RTC driver for Intel Series PCH Ivan Mikhaylov 2021-08-10 15:44 ` Ivan Mikhaylov 2021-08-14 22:52 ` Paul Fertser 2021-08-20 12:34 ` Ivan Mikhaylov 2021-08-20 12:34 ` Ivan Mikhaylov 2021-09-25 22:24 ` Alexandre Belloni 2021-09-25 22:24 ` Alexandre Belloni 2021-08-10 15:44 ` [PATCH 2/2] dt-bindings: rtc: provide RTC PCH device tree binding doc Ivan Mikhaylov 2021-08-10 15:44 ` Ivan Mikhaylov 2021-08-14 22:42 ` [PATCH 0/2] rtc: pch-rtc: add Intel Series PCH built-in read-only RTC Paul Fertser 2021-08-14 23:22 ` Alexandre Belloni 2021-08-17 18:04 ` Milton Miller II 2021-08-17 18:04 ` Milton Miller II 2021-08-17 20:05 ` Alexandre Belloni [this message] 2021-08-17 20:05 ` Alexandre Belloni 2021-08-30 11:56 ` Ivan Mikhaylov 2021-08-30 11:56 ` Ivan Mikhaylov 2021-09-14 23:52 ` Ivan Mikhaylov 2021-09-14 23:52 ` Ivan Mikhaylov
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