Re: [PATCH v4 1/9] dt-bindings: mfd: Add TI-Nspire misc registers
From: Andrew Davis
Date: Wed Nov 02 2022 - 21:14:21 EST
On 11/2/22 4:26 PM, Rob Herring wrote:
On Wed, Nov 02, 2022 at 02:05:28PM -0500, Andrew Davis wrote:
On 11/2/22 12:35 PM, Rob Herring wrote:
On Tue, Nov 01, 2022 at 04:57:56PM -0500, Andrew Davis wrote:
The TI Nspire devices contain a set of registers with a seemingly
miscellaneous set of functionality. This area is known simply as the
"misc" region.
Signed-off-by: Andrew Davis <afd@xxxxxx>
---
.../bindings/mfd/ti,nspire-misc.yaml | 55 +++++++++++++++++++
1 file changed, 55 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mfd/ti,nspire-misc.yaml
diff --git a/Documentation/devicetree/bindings/mfd/ti,nspire-misc.yaml b/Documentation/devicetree/bindings/mfd/ti,nspire-misc.yaml
new file mode 100644
index 0000000000000..d409eae7537bd
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/ti,nspire-misc.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) 2022 Texas Instruments Incorporated - https://www.ti.com/
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mfd/ti,nspire-misc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI Nspire MISC hardware block
+
+maintainers:
+ - Andrew Davis <afd@xxxxxx>
+
+description: |
+ System controller node represents a register region containing a set
+ of miscellaneous registers. The registers are not cohesive enough to
+ represent as any specific type of device. The typical use-case is
+ for some other node's driver, or platform-specific code, to acquire
+ a reference to the syscon node (e.g. by phandle, node path, or
+ search using a specific compatible value), interrogate the node (or
+ associated OS driver) to determine the location of the registers,
+ and access the registers directly.
Looks like you copied the generic description? Describe what MISC
contains.
I don't know what all MISC contains (or maybe I do, but it is not
publicly available so I'm not going to add anything that hasn't
already been found by clean-room reverse engineering [0]).
Put whatever you are comfortable with, but not a duplicate generic
description. You know it at least it has reboot registers...
This is the point I was trying to make in that thread on v3. The
node's content *is* the hardware description. Every time a new
register is found it could have just been added to the DT. But now
we also have to go back here and add the exact same information
to the binding, every time. We don't require that for simple-bus,
should simple-mfd be given the same flexibility?
The thing with any MFD is it makes up a device even if it's 'simple', so
it's important to get a full picture of the device. It could evolve to
not being 'simple'.
It would not evolve as a generic simple-mfd binding would not allow
any extra non-node properties.
'^.*$':
type: object
additionalProperties: false
Maybe I'm thinking about this group of registers wrong, maybe it
is a simple-bus not a simple-mfd. I mean from software what else
is a bus but a space of addressable registers.. The issue would
be each child node of a simple-bus needs a unit-address and 'reg'.
Which we *could* do here if not for all this syscon weirdness :(
For example, if you came along and wanted to make it a clock provider,
you'd probably create a clock child node that's just a compatible and
'#clock-cells'. The feedback would be just add '#clock-cells' to the
'ti,nspire-misc' node. So yes, I want to see additions.
And then that would still fail the dtbs_check, since the simple-mfd binding
would only allow for child nodes, nothing else, that's what makes them "simple".
Each child node would need a compatible and therefor a binding. You would
still see everything and could prevent malformed nodes just the same.
Andrew