| Message ID | 20240124122204.730370-5-o.rempel@pengutronix.de (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | Introduction of PSCR Framework and Related Components | expand |
On 24/01/2024 13:22, Oleksij Rempel wrote: > Add device tree bindings that describe hardware implementations of > Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons > (PSCR). A nit, subject: drop second/last, redundant "bindings for". The "dt-bindings" prefix is already stating that these are bindings. See also: https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18 > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > --- > .../bindings/power/reset/pscrr-nvmem.yaml | 53 +++++++++++++++++++ > 1 file changed, 53 insertions(+) > create mode 100644 Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml > > diff --git a/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml > new file mode 100644 > index 000000000000..779920dea283 > --- /dev/null > +++ b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml > @@ -0,0 +1,53 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/power/reset/pscrr-nvmem.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Generic NVMEM Power State Change Reason Recorder > + > +maintainers: > + - Oleksij Rempel <o.rempel@pengutronix.de> > + > +description: This binding describes the Non-Volatile Memory (NVMEM) hardware Same comment and also: describe the hardware, not the binding. s/This binding describes/something useful/ > + that stores Power State Change Reasons (PSCR). > + > +allOf: > + - $ref: pscrr.yaml# > + > +properties: > + compatible: > + const: pscrr-nvmem > + So that's a driver :/. Maybe Rob will like it, but it's a no from me. Please come up with something really suiting DEVICES, not DRIVERS. > + nvmem-cells: > + description: | Do not need '|' unless you need to preserve formatting. > + A phandle pointing to the nvmem-cells node where the power state change > + reasons are stored. > + maxItems: 1 > + Best regards, Krzysztof
On Thu, Jan 25, 2024 at 11:57:18AM +0100, Krzysztof Kozlowski wrote: > On 24/01/2024 13:22, Oleksij Rempel wrote: > > Add device tree bindings that describe hardware implementations of > > Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons > > (PSCR). > > + that stores Power State Change Reasons (PSCR). > > + > > +allOf: > > + - $ref: pscrr.yaml# > > + > > +properties: > > + compatible: > > + const: pscrr-nvmem > > + > > So that's a driver :/. Maybe Rob will like it, but it's a no from me. > Please come up with something really suiting DEVICES, not DRIVERS. If I understand your distinction between 'DEVICES' and 'DRIVERS' correctly, 'DEVICES' in the device tree context are meant to represent physical hardware components, while 'DRIVERS' refer to software abstractions of these components. However, there are numerous device tree instances, like software-based implementations for SPI, I2C, or GPIO, which could also be interpreted as 'DRIVERS' in the context of your email. Similarly, the binding for PSCRR represents functionality not fully implemented in hardware but supported by the hardware component of NVMEM, akin to how ramoops or other functionalities are represented. If I'm misunderstanding your distinction between 'DEVICES' and 'DRIVERS', please clarify with an example of how a proper binding should be implemented for a case like this. Regards, Oleksij
On 25/01/2024 18:11, Oleksij Rempel wrote: > On Thu, Jan 25, 2024 at 11:57:18AM +0100, Krzysztof Kozlowski wrote: >> On 24/01/2024 13:22, Oleksij Rempel wrote: >>> Add device tree bindings that describe hardware implementations of >>> Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons >>> (PSCR). >>> + that stores Power State Change Reasons (PSCR). >>> + >>> +allOf: >>> + - $ref: pscrr.yaml# >>> + >>> +properties: >>> + compatible: >>> + const: pscrr-nvmem >>> + >> >> So that's a driver :/. Maybe Rob will like it, but it's a no from me. >> Please come up with something really suiting DEVICES, not DRIVERS. > > If I understand your distinction between 'DEVICES' and 'DRIVERS' > correctly, 'DEVICES' in the device tree context are meant to represent > physical hardware components, while 'DRIVERS' refer to software Yes. > abstractions of these components. However, there are numerous device > tree instances, like software-based implementations for SPI, I2C, or > GPIO, which could also be interpreted as 'DRIVERS' in the context of True. Yet they are still for physical interfaces. There is no DTS having some virtual I2C for a board which does not have I2C. > your email. Similarly, the binding for PSCRR represents functionality not > fully implemented in hardware but supported by the hardware component of > NVMEM, akin to how ramoops or other functionalities are represented. You don't need a binding for your case. Instantiate it whatever you wish - modprobe for example - and configure through approved kernel interfaces - sysfs for example. Best regards, Krzysztof
On Fri, Jan 26, 2024 at 10:03:51AM +0100, Krzysztof Kozlowski wrote: > On 25/01/2024 18:11, Oleksij Rempel wrote: > > On Thu, Jan 25, 2024 at 11:57:18AM +0100, Krzysztof Kozlowski wrote: > >> On 24/01/2024 13:22, Oleksij Rempel wrote: > >>> Add device tree bindings that describe hardware implementations of > >>> Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons > >>> (PSCR). > >>> + that stores Power State Change Reasons (PSCR). > >>> + > >>> +allOf: > >>> + - $ref: pscrr.yaml# > >>> + > >>> +properties: > >>> + compatible: > >>> + const: pscrr-nvmem > >>> + > >> > >> So that's a driver :/. Maybe Rob will like it, but it's a no from me. > >> Please come up with something really suiting DEVICES, not DRIVERS. > > > > If I understand your distinction between 'DEVICES' and 'DRIVERS' > > correctly, 'DEVICES' in the device tree context are meant to represent > > physical hardware components, while 'DRIVERS' refer to software > > Yes. > > > abstractions of these components. However, there are numerous device > > tree instances, like software-based implementations for SPI, I2C, or > > GPIO, which could also be interpreted as 'DRIVERS' in the context of > > True. Yet they are still for physical interfaces. There is no DTS having > some virtual I2C for a board which does not have I2C. > > > your email. Similarly, the binding for PSCRR represents functionality not > > fully implemented in hardware but supported by the hardware component of > > NVMEM, akin to how ramoops or other functionalities are represented. > > You don't need a binding for your case. Instantiate it whatever you wish > - modprobe for example - and configure through approved kernel > interfaces - sysfs for example. About using sysfs for the NVMEM cell, it won't work for my needs because I have to know about reboot events before the filesystem is ready. So, I'm thinking of using a boot parameter for the kernel. It would look like this: pscrr-nvmem.nvmem_cell_alias=nvmem-cell0. This way, I can set up the NVMEM cell right at the system's start. I'll need to use stable NVMEM cell names for this. Is it ok to introduce NVMEM cell aliases in the devicetree? Best Regards, Oleksij
On 26/01/2024 17:51, Oleksij Rempel wrote: > On Fri, Jan 26, 2024 at 10:03:51AM +0100, Krzysztof Kozlowski wrote: >> On 25/01/2024 18:11, Oleksij Rempel wrote: >>> On Thu, Jan 25, 2024 at 11:57:18AM +0100, Krzysztof Kozlowski wrote: >>>> On 24/01/2024 13:22, Oleksij Rempel wrote: >>>>> Add device tree bindings that describe hardware implementations of >>>>> Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons >>>>> (PSCR). >>>>> + that stores Power State Change Reasons (PSCR). >>>>> + >>>>> +allOf: >>>>> + - $ref: pscrr.yaml# >>>>> + >>>>> +properties: >>>>> + compatible: >>>>> + const: pscrr-nvmem >>>>> + >>>> >>>> So that's a driver :/. Maybe Rob will like it, but it's a no from me. >>>> Please come up with something really suiting DEVICES, not DRIVERS. >>> >>> If I understand your distinction between 'DEVICES' and 'DRIVERS' >>> correctly, 'DEVICES' in the device tree context are meant to represent >>> physical hardware components, while 'DRIVERS' refer to software >> >> Yes. >> >>> abstractions of these components. However, there are numerous device >>> tree instances, like software-based implementations for SPI, I2C, or >>> GPIO, which could also be interpreted as 'DRIVERS' in the context of >> >> True. Yet they are still for physical interfaces. There is no DTS having >> some virtual I2C for a board which does not have I2C. >> >>> your email. Similarly, the binding for PSCRR represents functionality not >>> fully implemented in hardware but supported by the hardware component of >>> NVMEM, akin to how ramoops or other functionalities are represented. >> >> You don't need a binding for your case. Instantiate it whatever you wish >> - modprobe for example - and configure through approved kernel >> interfaces - sysfs for example. > > About using sysfs for the NVMEM cell, it won't work for my needs because > I have to know about reboot events before the filesystem is ready. So, initrd can configure it before mounting filesystem. > I'm thinking of using a boot parameter for the kernel. It would look > like this: pscrr-nvmem.nvmem_cell_alias=nvmem-cell0. This way, I can set > up the NVMEM cell right at the system's start. I'll need to use stable > NVMEM cell names for this. Is it ok to introduce NVMEM cell aliases in > the devicetree? In my opinion no, because the point of Devicetree is not to solve your system init problems. You add pure software node which should not be in your DTS for many reasons: it is not a hardware description and it is a software policy enforced on all users of DTS without actually consulting them. Also, this solution ignores ACPI systems. Developing a proper interface would work on ACPI as well. Best regards, Krzysztof
diff --git a/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml new file mode 100644 index 000000000000..779920dea283 --- /dev/null +++ b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml @@ -0,0 +1,53 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/power/reset/pscrr-nvmem.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Generic NVMEM Power State Change Reason Recorder + +maintainers: + - Oleksij Rempel <o.rempel@pengutronix.de> + +description: This binding describes the Non-Volatile Memory (NVMEM) hardware + that stores Power State Change Reasons (PSCR). + +allOf: + - $ref: pscrr.yaml# + +properties: + compatible: + const: pscrr-nvmem + + nvmem-cells: + description: | + A phandle pointing to the nvmem-cells node where the power state change + reasons are stored. + maxItems: 1 + + nvmem-cell-names: + items: + - const: pscr + + pscr-under-voltage: true + pscr-over-current: true + pscr-regulator-failure: true + pscr-over-temperature: true + +required: + - compatible + - nvmem-cells + - nvmem-cell-names + +additionalProperties: false + +examples: + - | + power-state-change-reason { + compatible = "pscrr-nvmem"; + nvmem-cells = <&pscr_cell>; + nvmem-cell-names = "pscr"; + pscr-under-voltage = <1>; + pscr-over-temperature = <2>; + }; +...
Add device tree bindings that describe hardware implementations of Non-Volatile Memory (NVMEM) used for storing Power State Change Reasons (PSCR). Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- .../bindings/power/reset/pscrr-nvmem.yaml | 53 +++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml