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From: Rob Herring <robh@kernel.org>
To: Andrew Jeffery <andrew@aj.id.au>
Cc: linux-kernel@vger.kernel.org, mark.rutland@arm.com,
	joel@jms.id.au, gregkh@linuxfoundation.org, Eugene.Cho@dell.com,
	a.amelkin@yadro.com, stewart@linux.ibm.com,
	benh@kernel.crashing.org, openbmc@lists.ozlabs.org,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v2 1/4] dt-bindings: misc: Add bindings for misc. BMC control fields
Date: Wed, 11 Jul 2018 14:04:50 -0600
Message-ID: <20180711200450.GB17291@rob-hp-laptop> (raw)
In-Reply-To: <20180711053122.30773-2-andrew@aj.id.au>

On Wed, Jul 11, 2018 at 03:01:19PM +0930, Andrew Jeffery wrote:
> Baseboard Management Controllers (BMCs) are embedded SoCs that exist to
> provide remote management of (primarily) server platforms. BMCs are
> often tightly coupled to the platform in terms of behaviour and provide
> many hardware features integral to booting and running the host system.
> 
> Some of these hardware features are simple, for example scratch
> registers provided by the BMC that are exposed to both the host and the
> BMC. In other cases there's a single bit switch to enable or disable
> some of the provided functionality.
> 
> The documentation defines bindings for fields in registers that do not
> integrate well into other driver models yet must be described to allow
> the BMC kernel to assume control of these features.

So we'll get a new binding when that happens? That will break 
compatibility.

> 
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
> 
> Since RFC v1:
> 
> * Add a commit message
> * Minor changes to documented labels
> 
>  .../bindings/misc/bmc-misc-ctrl.txt           | 252 ++++++++++++++++++
>  MAINTAINERS                                   |   6 +
>  2 files changed, 258 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/bmc-misc-ctrl.txt
> 
> diff --git a/Documentation/devicetree/bindings/misc/bmc-misc-ctrl.txt b/Documentation/devicetree/bindings/misc/bmc-misc-ctrl.txt
> new file mode 100644
> index 000000000000..2c869fcc7ef2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/bmc-misc-ctrl.txt
> @@ -0,0 +1,252 @@
> +BMC Miscellaneous Control Interfaces
> +====================================
> +
> +Baseboard Management Controllers (BMCs) often have an array of hardware
> +features that need to be described but are awkward to sensibly expose.
> +
> +This bindings document provides a generic mechanism for describing such
> +features, covering read-only (RO), read-modify-write (RMW) and
> +write-1-set/write-1-clear (W1SC) semantics.

If we wanted a generic mechanism for single register bits/fields in DT, 
we'd have one already. A node per register bit doesn't scale.

Maybe this should be modelled using GPIO binding? There's a line there 
too as whether the signals are "general purpose" or not.

Rob

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-11  5:31 [RFC PATCH v2 0/4] sysfs interface to miscellaneous BMC controls and fields Andrew Jeffery
2018-07-11  5:31 ` [RFC PATCH v2 1/4] dt-bindings: misc: Add bindings for misc. BMC control fields Andrew Jeffery
2018-07-11 20:04   ` Rob Herring [this message]
2018-07-12  0:14     ` Benjamin Herrenschmidt
2018-07-12  0:53     ` Andrew Jeffery
2018-07-12 15:11       ` Rob Herring
2018-07-13  0:55         ` Benjamin Herrenschmidt
2018-07-13  6:31           ` Andrew Jeffery
2018-07-13 15:14             ` Alexander Amelkin
2018-07-13 18:49               ` Eugene.Cho
2018-07-13 19:03                 ` Greg KH
2018-07-13 19:06                   ` Eugene.Cho
2018-07-15 14:21                     ` Avi Fishman
2018-07-16  0:57               ` Andrew Jeffery
2018-07-16 13:55             ` Rob Herring
2018-07-17  1:04               ` Andrew Jeffery
2018-07-17  4:56               ` Benjamin Herrenschmidt
2018-07-17 23:28                 ` Andrew Jeffery
2018-07-18 19:07                   ` Rob Herring
2018-07-19  1:57                     ` Andrew Jeffery
2018-07-18 19:50                 ` Rob Herring
2018-07-18 23:58                   ` Benjamin Herrenschmidt
2018-07-19  2:28                     ` Andrew Jeffery
2018-07-19  4:35                       ` Benjamin Herrenschmidt
2018-07-20  0:07                         ` Andrew Jeffery
2018-07-20  4:56                           ` Benjamin Herrenschmidt
2018-08-10  0:22                             ` Kun Yi
2018-08-23 15:32                           ` Alexander Amelkin
2018-07-11  5:31 ` [RFC PATCH v2 2/4] Documentation: ABI: Add sysfs-devices-platform-field to testing Andrew Jeffery
2018-07-11  5:31 ` [RFC PATCH v2 3/4] misc: Add bmc-misc-ctrl Andrew Jeffery
2018-07-11  5:31 ` [RFC PATCH v2 4/4] dts: aspeed-g5: Describe VGA, SIO scratch and DAC mux fields Andrew Jeffery

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