These patches add support for the quartz-load-femtofarads property in
the pcf85363 device driver and new bindings for the pcf85263 and
pcf85363 Real Time Clocks.
The driver has been tested with a PCF85263ATT RTC and a CTS3-32.768-12.5-20
oscillator that needs a 12.5 pF load capacitor. With no property
support the 7 pF default value leads to at least 2 Hz output frequency
deviations, while setting the right value the deviation decreased to
0.15 Hz. These measurements were made with a high precision oscilloscope
(SIGLENT SDS5104X).
This modification does not affect existing designs where the
quartz-load-femtofarads is not defined because in that case the default
value is used.
Javier Carrasco (2):
dt-bindings: rtc: nxp,pcf8563: move pcf85263/pcf85363 to a dedicated
binding
rtc: pcf85363: add support for the quartz-load-femtofarads property
.../devicetree/bindings/rtc/nxp,pcf85363.yaml | 60 +++++++++++++++++++
.../devicetree/bindings/rtc/nxp,pcf8563.yaml | 2 -
drivers/rtc/rtc-pcf85363.c | 37 +++++++++++-
3 files changed, 96 insertions(+), 3 deletions(-)
create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
--
2.37.2
These Real Time Clocks are managed by the rtc-pcf85363 device driver,
which now supports the quartz-load-femtofarads property.
Signed-off-by: Javier Carrasco <[email protected]>
---
v2:
- create new bindings instead of adding conditional properties to an
existing one.
.../devicetree/bindings/rtc/nxp,pcf85363.yaml | 60 +++++++++++++++++++
.../devicetree/bindings/rtc/nxp,pcf8563.yaml | 2 -
2 files changed, 60 insertions(+), 2 deletions(-)
create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
new file mode 100644
index 000000000000..52aa3e2091e9
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/nxp,pcf85363.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Philips PCF85263/PCF85363 Real Time Clock
+
+maintainers:
+ - Alexandre Belloni <[email protected]>
+
+allOf:
+ - $ref: rtc.yaml#
+
+properties:
+ compatible:
+ enum:
+ - nxp,pcf85263
+ - nxp,pcf85363
+
+ reg:
+ maxItems: 1
+
+ "#clock-cells":
+ const: 0
+
+ clock-output-names:
+ maxItems: 1
+
+ interrupts:
+ maxItems: 1
+
+ quartz-load-femtofarads:
+ description:
+ The capacitive load of the quartz(x-tal).
+ enum: [6000, 7000, 12500]
+ default: 7000
+
+ start-year: true
+ wakeup-source: true
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ rtc@51 {
+ compatible = "nxp,pcf85363";
+ reg = <0x51>;
+ #clock-cells = <0>;
+ quartz-load-femtofarads = <12500>;
+ };
+ };
diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8563.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf8563.yaml
index a98b72752349..22909a96123e 100644
--- a/Documentation/devicetree/bindings/rtc/nxp,pcf8563.yaml
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8563.yaml
@@ -19,8 +19,6 @@ properties:
- microcrystal,rv8564
- nxp,pca8565
- nxp,pcf8563
- - nxp,pcf85263
- - nxp,pcf85363
reg:
maxItems: 1
--
2.37.2
The quartz oscillator load capacitance of the PCF85263 and PCF85363 can
be adjusted to 6 pF, 7 pF (default) and 12.5 pF with the CL[1:0] bits in
the oscillator control register (address 25h).
Signed-off-by: Javier Carrasco <[email protected]>
---
v2:
- simple assignment operator instead of |= for the "value" variable.
drivers/rtc/rtc-pcf85363.c | 37 ++++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
index c05b722f0060..219fbca8c47f 100644
--- a/drivers/rtc/rtc-pcf85363.c
+++ b/drivers/rtc/rtc-pcf85363.c
@@ -101,6 +101,10 @@
#define PIN_IO_INTA_OUT 2
#define PIN_IO_INTA_HIZ 3
+#define OSC_CAP_SEL GENMASK(1, 0)
+#define OSC_CAP_6000 0x01
+#define OSC_CAP_12500 0x02
+
#define STOP_EN_STOP BIT(0)
#define RESET_CPR 0xa4
@@ -117,6 +121,32 @@ struct pcf85x63_config {
unsigned int num_nvram;
};
+static int pcf85363_load_capacitance(struct pcf85363 *pcf85363, struct device_node *node)
+{
+ u32 load = 7000;
+ u8 value = 0;
+
+ of_property_read_u32(node, "quartz-load-femtofarads", &load);
+
+ switch (load) {
+ default:
+ dev_warn(&pcf85363->rtc->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 7000",
+ load);
+ fallthrough;
+ case 7000:
+ break;
+ case 6000:
+ value = OSC_CAP_6000;
+ break;
+ case 12500:
+ value = OSC_CAP_12500;
+ break;
+ }
+
+ return regmap_update_bits(pcf85363->regmap, CTRL_OSCILLATOR,
+ OSC_CAP_SEL, value);
+}
+
static int pcf85363_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
@@ -372,7 +402,7 @@ static int pcf85363_probe(struct i2c_client *client)
.reg_write = pcf85363_nvram_write,
},
};
- int ret, i;
+ int ret, i, err;
if (data)
config = data;
@@ -394,6 +424,11 @@ static int pcf85363_probe(struct i2c_client *client)
if (IS_ERR(pcf85363->rtc))
return PTR_ERR(pcf85363->rtc);
+ err = pcf85363_load_capacitance(pcf85363, client->dev.of_node);
+ if (err < 0)
+ dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
+ err);
+
pcf85363->rtc->ops = &rtc_ops;
pcf85363->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
pcf85363->rtc->range_max = RTC_TIMESTAMP_END_2099;
--
2.37.2
On 15/02/2023 09:18, Javier Carrasco wrote:
> These Real Time Clocks are managed by the rtc-pcf85363 device driver,
> which now supports the quartz-load-femtofarads property.
>
> Signed-off-by: Javier Carrasco <[email protected]>
> ---
> v2:
> - create new bindings instead of adding conditional properties to an
> existing one.
>
> .../devicetree/bindings/rtc/nxp,pcf85363.yaml | 60 +++++++++++++++++++
> .../devicetree/bindings/rtc/nxp,pcf8563.yaml | 2 -
> 2 files changed, 60 insertions(+), 2 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
>
> diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
> new file mode 100644
> index 000000000000..52aa3e2091e9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf85363.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/rtc/nxp,pcf85363.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Philips PCF85263/PCF85363 Real Time Clock
> +
> +maintainers:
> + - Alexandre Belloni <[email protected]>
> +
> +allOf:
> + - $ref: rtc.yaml#
> +
> +properties:
> + compatible:
> + enum:
> + - nxp,pcf85263
> + - nxp,pcf85363
> +
> + reg:
> + maxItems: 1
> +
> + "#clock-cells":
> + const: 0
> +
> + clock-output-names:
> + maxItems: 1
> +
> + interrupts:
> + maxItems: 1
> +
> + quartz-load-femtofarads:
> + description:
> + The capacitive load of the quartz(x-tal).
> + enum: [6000, 7000, 12500]
> + default: 7000
> +
> + start-year: true
> + wakeup-source: true
You could drop these two and use "unevaluatedProperties: false" instead
of additionalProp - less coding and binding already will be prepared for
any new RTC common properties. But it is fine for me as is.
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Best regards,
Krzysztof
On Wed, 15 Feb 2023 09:18:13 +0100, Javier Carrasco wrote:
> These patches add support for the quartz-load-femtofarads property in
> the pcf85363 device driver and new bindings for the pcf85263 and
> pcf85363 Real Time Clocks.
>
> The driver has been tested with a PCF85263ATT RTC and a CTS3-32.768-12.5-20
> oscillator that needs a 12.5 pF load capacitor. With no property
> support the 7 pF default value leads to at least 2 Hz output frequency
> deviations, while setting the right value the deviation decreased to
> 0.15 Hz. These measurements were made with a high precision oscilloscope
> (SIGLENT SDS5104X).
>
> [...]
Applied, thanks!
[1/2] dt-bindings: rtc: nxp,pcf8563: move pcf85263/pcf85363 to a dedicated binding
commit: 1b2f85a8bac67b9909f2ee4be1bc11548a7aeaf3
[2/2] rtc: pcf85363: add support for the quartz-load-femtofarads property
commit: fd9a6a13949af81062f4cd04f2c1b28ca5311e71
Best regards,
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com