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[0/7] Enable backup switch mode on RTCs via devicetree

Message ID 20230201143431.863784-1-frieder@fris.de
Headers show
Series Enable backup switch mode on RTCs via devicetree | expand

Message

Frieder Schrempf Feb. 1, 2023, 2:34 p.m. UTC 
From: Frieder Schrempf <frieder.schrempf@kontron.de>

Some RTC devices like the RV3028 have BSM disabled as factory default.
This makes the RTC quite useless if it is expected to preserve the
time on hardware that has a battery-buffered supply for the RTC.

Let boards that have a buffered supply for the RTC force the BSM to the
desired value via devicetree by setting the 'backup-switch-mode' property.

That way the RTC on the boards work as one would expect them to do without
any per-board intervention through userspace tools to enable BSM.

Frieder Schrempf (7):
  dt-bindings: rtc: Move RV3028 to separate binding file
  dt-bindings: rtc: Add backup-switch-mode property
  dt-bindings: rtc: microcrystal,rv3032: Add backup-switch-mode property
  rtc: Move BSM defines to separate header for DT usage
  rtc: class: Support setting backup switch mode from devicetree
  arm64: dts: imx8mm-kontron: Remove useless trickle-diode-disable from
    RTC node
  arm64: dts: imx8mm-kontron: Enable backup switch mode for RTC on OSM-S
    module

 .../bindings/rtc/microcrystal,rv3028.yaml     | 60 +++++++++++++++++++
 .../devicetree/bindings/rtc/rtc.yaml          |  7 +++
 .../devicetree/bindings/rtc/trivial-rtc.yaml  |  2 -
 .../dts/freescale/imx8mm-kontron-osm-s.dtsi   |  3 +-
 drivers/rtc/class.c                           | 14 +++++
 include/dt-bindings/rtc/rtc.h                 | 11 ++++
 include/uapi/linux/rtc.h                      |  6 +-
 7 files changed, 95 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
 create mode 100644 include/dt-bindings/rtc/rtc.h

Comments

Krzysztof Kozlowski Feb. 2, 2023, 9:10 a.m. UTC | #1 
On 01/02/2023 15:34, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
> 
> The RV3028 driver uses properties that are not covered by the
> trivial-rtc bindings. Use custom bindings for it.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
>  .../bindings/rtc/microcrystal,rv3028.yaml     | 56 +++++++++++++++++++
>  .../devicetree/bindings/rtc/trivial-rtc.yaml  |  2 -
>  2 files changed, 56 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
> 
> diff --git a/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml b/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
> new file mode 100644
> index 000000000000..4667ba86fd0c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
> @@ -0,0 +1,56 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/rtc/microcrystal,rv3028.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip RV-3028 RTC
> +
> +allOf:
> +  - $ref: "rtc.yaml#"

Drop quotes

> +
> +maintainers:
> +  - Alexandre Belloni <alexandre.belloni@bootlin.com>
> +
> +properties:
> +  compatible:
> +    const: microcrystal,rv3028
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  start-year: true

This should be dropped as well and then...

> +
> +  trickle-resistor-ohms:
> +    enum:
> +      - 3000
> +      - 5000
> +      - 9000
> +      - 15000
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false

...switch to unevaluatedProperties: false

> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        rtc@51 {

Rob's pointed missing testing.

But more important - please rebase your patches on current tree. Looks
like all the changes are already done...

Best regards,
Krzysztof
Frieder Schrempf Feb. 2, 2023, 10:17 a.m. UTC | #2 
On 02.02.23 10:10, Krzysztof Kozlowski wrote:
> On 01/02/2023 15:34, Frieder Schrempf wrote:
>> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>>
>> The RV3028 driver uses properties that are not covered by the
>> trivial-rtc bindings. Use custom bindings for it.
>>
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
>> ---
>>  .../bindings/rtc/microcrystal,rv3028.yaml     | 56 +++++++++++++++++++
>>  .../devicetree/bindings/rtc/trivial-rtc.yaml  |  2 -
>>  2 files changed, 56 insertions(+), 2 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml b/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
>> new file mode 100644
>> index 000000000000..4667ba86fd0c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/rtc/microcrystal,rv3028.yaml
>> @@ -0,0 +1,56 @@
>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Frtc%2Fmicrocrystal%2Crv3028.yaml%23&data=05%7C01%7Cfrieder.schrempf%40kontron.de%7Ca99c626bce484657aee508db04fd470f%7C8c9d3c973fd941c8a2b1646f3942daf1%7C0%7C0%7C638109258107205830%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=z8nsgRaxC3AcIoXteA7Xj7EpCKrA%2FkRPyrYeS1fig8I%3D&reserved=0
>> +$schema: https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&data=05%7C01%7Cfrieder.schrempf%40kontron.de%7Ca99c626bce484657aee508db04fd470f%7C8c9d3c973fd941c8a2b1646f3942daf1%7C0%7C0%7C638109258107205830%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1RPGw%2FEf7UUNrJZPAHDw7BHnuroLg1oVR4xLq2%2FgIHU%3D&reserved=0
>> +
>> +title: Microchip RV-3028 RTC
>> +
>> +allOf:
>> +  - $ref: "rtc.yaml#"
> 
> Drop quotes
> 
>> +
>> +maintainers:
>> +  - Alexandre Belloni <alexandre.belloni@bootlin.com>
>> +
>> +properties:
>> +  compatible:
>> +    const: microcrystal,rv3028
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  start-year: true
> 
> This should be dropped as well and then...
> 
>> +
>> +  trickle-resistor-ohms:
>> +    enum:
>> +      - 3000
>> +      - 5000
>> +      - 9000
>> +      - 15000
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
>> +additionalProperties: false
> 
> ...switch to unevaluatedProperties: false
> 
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/irq.h>
>> +    i2c {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        rtc@51 {
> 
> Rob's pointed missing testing.
> 
> But more important - please rebase your patches on current tree. Looks
> like all the changes are already done...

Oops, I need to remember to check patchwork/linux-next. Thanks anyway!
Frieder Schrempf Feb. 13, 2023, 9:18 a.m. UTC | #3 
Hi Alexandre,

On 01.02.23 17:26, Frieder Schrempf wrote:
> On 01.02.23 17:15, Alexandre Belloni wrote:
>> Hello,
>>
>> You can't do that, this breaks an important use case and it is the
>> reason why I didn't use device tree in the beginning. What is wrong with
>> setting BSM from userspace? You will anyway have to set the time and
>> date from userspace for it to be saved.
> 
> Ok, I was already afraid there is something I missed. Can you give a
> short explanation of what use case this would break?
> 
> There is nothing wrong with setting BSM from userspace. It's just the
> fact that users expect BSM to be enabled in any case as there is a
> battery on the board. It is much more effort to ensure that production,
> user, etc. are aware of an extra step required than to let the kernel
> deal with it behind the scenes.

Would you mind elaborating on your argument that this would break stuff?
I currently don't see how an additional optional devicetree property
would break anything.

Thanks
Frieder
Frieder Schrempf March 6, 2023, 1:27 p.m. UTC | #4 
On 13.02.23 10:18, Frieder Schrempf wrote:
> Hi Alexandre,
> 
> On 01.02.23 17:26, Frieder Schrempf wrote:
>> On 01.02.23 17:15, Alexandre Belloni wrote:
>>> Hello,
>>>
>>> You can't do that, this breaks an important use case and it is the
>>> reason why I didn't use device tree in the beginning. What is wrong with
>>> setting BSM from userspace? You will anyway have to set the time and
>>> date from userspace for it to be saved.
>>
>> Ok, I was already afraid there is something I missed. Can you give a
>> short explanation of what use case this would break?
>>
>> There is nothing wrong with setting BSM from userspace. It's just the
>> fact that users expect BSM to be enabled in any case as there is a
>> battery on the board. It is much more effort to ensure that production,
>> user, etc. are aware of an extra step required than to let the kernel
>> deal with it behind the scenes.
> 
> Would you mind elaborating on your argument that this would break stuff?
> I currently don't see how an additional optional devicetree property
> would break anything.

Ping!?