[PATCH 0/2] enable PCF85063 RTC support for S32G274A-RDB2 and S32G399A-RDB3 boards

[PATCH 0/2] enable PCF85063 RTC support for S32G274A-RDB2 and S32G399A-RDB3 boards

[Ciprian Costea]

From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>

This patch series handles PCF85063 RTC support for boards which do not
have the PCF85063 RTC battery backed.

In this case, the PCF85063 RTC oscillator is manually started during
startup.

Ciprian Marian Costea (2):
  dt-bindings: rtc: nxp,pcf85063: add 'no-battery' property
  rtc: pcf85063: handle stopped oscillator at startup

 Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml | 5 +++++
 drivers/rtc/rtc-pcf85063.c                              | 8 ++++++++
 2 files changed, 13 insertions(+)

-- 
2.45.2

[PATCH 1/2] dt-bindings: rtc: nxp,pcf85063: add 'no-battery' property

[Ciprian Costea]

From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>

In case the RTC is not linked to any battery, the oscillator will
be stopped at startup, triggering a SW reset command for the PCF85063 RTC.
For this setup, introduce 'no-battery' property which can be used to
manually start the oscillator.

Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
---
 Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
index 2f892f8640d1..b342eb13fb2e 100644
--- a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
@@ -36,6 +36,11 @@ properties:
     enum: [7000, 12500]
     default: 7000
 
+  no-battery:
+    description: Used in case the RTC is not linked to any battery so the
+      oscillator is stopped at startup.
+    type: boolean
+
   clock:
     $ref: /schemas/clock/fixed-clock.yaml
     description:
-- 
2.45.2

Re: [PATCH 1/2] dt-bindings: rtc: nxp,pcf85063: add 'no-battery' property

[Frank Li]

On Thu, Apr 10, 2025 at 11:25:47AM +0300, Ciprian Costea wrote:
> From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
>
> In case the RTC is not linked to any battery, the oscillator will
> be stopped at startup, triggering a SW reset command for the PCF85063 RTC.
> For this setup, introduce 'no-battery' property which can be used to
> manually start the oscillator.
>
> Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
> Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
> ---
>  Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
> index 2f892f8640d1..b342eb13fb2e 100644
> --- a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
> +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
> @@ -36,6 +36,11 @@ properties:
>      enum: [7000, 12500]
>      default: 7000
>
> +  no-battery:
> +    description: Used in case the RTC is not linked to any battery so the
> +      oscillator is stopped at startup.
> +    type: boolean

Can you use optional regulator such as, vbat-supply?

Frank

> +
>    clock:
>      $ref: /schemas/clock/fixed-clock.yaml
>      description:
> --
> 2.45.2
>

Re: [PATCH 1/2] dt-bindings: rtc: nxp,pcf85063: add 'no-battery' property

[Ciprian Marian Costea]

On 4/10/2025 5:46 PM, Frank Li wrote:
> On Thu, Apr 10, 2025 at 11:25:47AM +0300, Ciprian Costea wrote:
>> From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
>>
>> In case the RTC is not linked to any battery, the oscillator will
>> be stopped at startup, triggering a SW reset command for the PCF85063 RTC.
>> For this setup, introduce 'no-battery' property which can be used to
>> manually start the oscillator.
>>
>> Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
>> Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
>> ---
>>   Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
>> index 2f892f8640d1..b342eb13fb2e 100644
>> --- a/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
>> +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85063.yaml
>> @@ -36,6 +36,11 @@ properties:
>>       enum: [7000, 12500]
>>       default: 7000
>>
>> +  no-battery:
>> +    description: Used in case the RTC is not linked to any battery so the
>> +      oscillator is stopped at startup.
>> +    type: boolean
> 
> Can you use optional regulator such as, vbat-supply?
> 
> Frank
> 

Hello Frank,

Please disregard this patchset, as stated in the next patch review [1]

[1] 
https://lore.kernel.org/all/e64083ee-3374-4bdf-92a3-ce91e1402b13@oss.nxp.com/

Regards,
Ciprian

>> +
>>     clock:
>>       $ref: /schemas/clock/fixed-clock.yaml
>>       description:
>> --
>> 2.45.2
>>

[PATCH 2/2] rtc: pcf85063: handle stopped oscillator at startup

[Ciprian Costea]

From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>

If the RTC is not linked to any battery, the oscillator is stopped at
startup and a SW reset command is generated to the PCF85063 RTC.
Manually start the oscillator in case the PCF85063 RTC is not battery
backed.

Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
---
 drivers/rtc/rtc-pcf85063.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 4fa5c4ecdd5a..6de7344d2469 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -590,6 +590,14 @@ static int pcf85063_probe(struct i2c_client *client)
 
 	i2c_set_clientdata(client, pcf85063);
 
+	if (of_property_read_bool(client->dev.of_node, "no-battery")) {
+		err = regmap_update_bits(pcf85063->regmap, PCF85063_REG_SC,
+					 PCF85063_REG_SC_OS, 0);
+		if (err)
+			return dev_err_probe(&client->dev, err,
+					"Failed to start the oscillator\n");
+	}
+
 	err = regmap_read(pcf85063->regmap, PCF85063_REG_SC, &tmp);
 	if (err)
 		return dev_err_probe(&client->dev, err, "RTC chip is not present\n");
-- 
2.45.2

Re: [PATCH 2/2] rtc: pcf85063: handle stopped oscillator at startup

[Alexandre Belloni]

On 10/04/2025 11:25:48+0300, Ciprian Costea wrote:
> From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
> 
> If the RTC is not linked to any battery, the oscillator is stopped at
> startup and a SW reset command is generated to the PCF85063 RTC.
> Manually start the oscillator in case the PCF85063 RTC is not battery
> backed.
> 

No, there is no point in starting the oscillator with a know wrong
time/date. The oscillator must only be started once the time is known
good, that is in .set_time

> Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
> Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
> ---
>  drivers/rtc/rtc-pcf85063.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
> index 4fa5c4ecdd5a..6de7344d2469 100644
> --- a/drivers/rtc/rtc-pcf85063.c
> +++ b/drivers/rtc/rtc-pcf85063.c
> @@ -590,6 +590,14 @@ static int pcf85063_probe(struct i2c_client *client)
>  
>  	i2c_set_clientdata(client, pcf85063);
>  
> +	if (of_property_read_bool(client->dev.of_node, "no-battery")) {
> +		err = regmap_update_bits(pcf85063->regmap, PCF85063_REG_SC,
> +					 PCF85063_REG_SC_OS, 0);
> +		if (err)
> +			return dev_err_probe(&client->dev, err,
> +					"Failed to start the oscillator\n");
> +	}
> +
>  	err = regmap_read(pcf85063->regmap, PCF85063_REG_SC, &tmp);
>  	if (err)
>  		return dev_err_probe(&client->dev, err, "RTC chip is not present\n");
> -- 
> 2.45.2
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH 2/2] rtc: pcf85063: handle stopped oscillator at startup

[Ciprian Marian Costea]

On 4/10/2025 12:17 PM, Alexandre Belloni wrote:
> On 10/04/2025 11:25:48+0300, Ciprian Costea wrote:
>> From: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
>>
>> If the RTC is not linked to any battery, the oscillator is stopped at
>> startup and a SW reset command is generated to the PCF85063 RTC.
>> Manually start the oscillator in case the PCF85063 RTC is not battery
>> backed.
>>
> 
> No, there is no point in starting the oscillator with a know wrong
> time/date. The oscillator must only be started once the time is known
> good, that is in .set_time
> 

Hello Alexandre,

Thanks for your review.
You are correct, please disregard this patchset. I've looked into the 
'set_time' callback and indeed the oscillator is being started here [1].

I've tested, so even with no battery provided for the PCF85036 RTC, 
after setting the hardware clock from userspace, the RTC works as 
expected because of the manual starting of the oscillator from 'set_time'.

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/rtc/rtc-pcf85063.c#n129

Ciprian

>> Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
>> Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
>> ---
>>   drivers/rtc/rtc-pcf85063.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
>> index 4fa5c4ecdd5a..6de7344d2469 100644
>> --- a/drivers/rtc/rtc-pcf85063.c
>> +++ b/drivers/rtc/rtc-pcf85063.c
>> @@ -590,6 +590,14 @@ static int pcf85063_probe(struct i2c_client *client)
>>   
>>   	i2c_set_clientdata(client, pcf85063);
>>   
>> +	if (of_property_read_bool(client->dev.of_node, "no-battery")) {
>> +		err = regmap_update_bits(pcf85063->regmap, PCF85063_REG_SC,
>> +					 PCF85063_REG_SC_OS, 0);
>> +		if (err)
>> +			return dev_err_probe(&client->dev, err,
>> +					"Failed to start the oscillator\n");
>> +	}
>> +
>>   	err = regmap_read(pcf85063->regmap, PCF85063_REG_SC, &tmp);
>>   	if (err)
>>   		return dev_err_probe(&client->dev, err, "RTC chip is not present\n");
>> -- 
>> 2.45.2
>>
>