On 31/05/2023 22:44, Marek Vasut wrote: > On 5/31/23 21:37, Krzysztof Kozlowski wrote: >> On 24/05/2023 05:30, Marek Vasut wrote: >>> On 5/18/23 16:26, Krzysztof Kozlowski wrote: >>>> On 17/05/2023 17:25, Marek Vasut wrote: >>>>> Add trivial bindings for driver which permits exposing syscon backed >>>>> register to userspace. This is useful e.g. to expose U-Boot boot >>>>> counter on various platforms where the boot counter is stored in >>>>> random volatile register, like STM32MP15xx TAMP_BKPxR register. >>>>> >>>>> Signed-off-by: Marek Vasut <marex@xxxxxxx> >>>>> --- >>>>> Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx> >>>>> Cc: Conor Dooley <conor+dt@xxxxxxxxxx> >>>>> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx> >>>>> Cc: Marek Vasut <marex@xxxxxxx> >>>>> Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx> >>>>> Cc: Rob Herring <robh+dt@xxxxxxxxxx> >>>>> Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> >>>>> Cc: devicetree@xxxxxxxxxxxxxxx >>>>> Cc: kernel@xxxxxxxxxxxxxxxxxx >>>>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>>>> Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx >>>>> --- >>>>> V2: Use generic syscon supernode >>>>> --- >>>>> .../bindings/nvmem/nvmem-syscon.yaml | 39 +++++++++++++++++++ >>>>> 1 file changed, 39 insertions(+) >>>>> create mode 100644 Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml b/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml >>>>> new file mode 100644 >>>>> index 0000000000000..7c1173a1a6218 >>>>> --- /dev/null >>>>> +++ b/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml >>>>> @@ -0,0 +1,39 @@ >>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) >>>>> +%YAML 1.2 >>>>> +--- >>>>> +$id: http://devicetree.org/schemas/nvmem/nvmem-syscon.yaml# >>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml# >>>>> + >>>>> +title: Generic syscon backed nvmem >>>>> + >>>>> +maintainers: >>>>> + - Marek Vasut <marex@xxxxxxx> >>>>> + >>>>> +allOf: >>>>> + - $ref: "nvmem.yaml#" >>>> >>>> Usual comment: drop quotes. We removed them everywhere, so you based >>>> your work on some old tree. >>>> >>>>> + >>>>> +properties: >>>>> + compatible: >>>>> + enum: >>>>> + - nvmem-syscon >>>>> + >>>>> + reg: >>>>> + maxItems: 1 >>>> >>>> Rob's questions are not solved. >>> >>> Can you reiterate this one ? I likely missed it. >> >> You did not solve the case of more than one register. This isn't an odd >> case. > > So why not just extend the bindings to support > > reg = <0x14c 0x4>, <0x180 0x10>, ... ; > > this kind of stuff ? Does not look right. Look at nvmem bindings and don't do it differently. > >>>> The nvmem.yaml schema expects here to >>>> allow children. This should not be created per-register, but per entire >>>> block of registers. >>> >>> This thing works the other way around, I have a syscon register block >>> already, and I want to expose subset of it to userspace as read/write >>> accessible file to expose bootcounter available in that register (so I >>> can read it and reset it from user application). >> >> And this makes it too limited. I would expect one device exposing >> multiple blocks or registers, just like all nvmem providers are doing. > > What would be the real-world use case of that ? The same as the real world use cases for nvmem. One syscon block has multiple registers so I can easily imagine wanting boottrap, bootstat, boot-whatever you want. Best regards, Krzysztof
