| Message ID | 20190108185414.26922-1-sam@ravnborg.org |
|---|---|
| Headers | show |
| Series | add quartz load support to NXP rtc drivers | expand |
On 08/01/2019 19:54:13+0100, Sam Ravnborg wrote: > Add support for specifying the xtal load capacitance in the DT node. > The pcf8523 supports xtal load capacitance of 7pF or 12.5pF. > If the rtc has the wrong configuration the time will > drift several hours/week. > > The driver use the default value 12.5pF. > > The DT may specify either 7000fF or 12500fF. > (The DT uses femto Farad to avoid decimal numbers). > Other values are warned and the driver uses the default value. > > Signed-off-by: Sam Ravnborg <sam@ravnborg.org> > Cc: Alessandro Zummo <a.zummo@towertech.it> > Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> > --- > drivers/rtc/rtc-pcf8523.c | 28 ++++++++++++++++++++-------- > 1 file changed, 20 insertions(+), 8 deletions(-) > > diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c > index 3fcd2cbafc84..dbbc00b53b50 100644 > --- a/drivers/rtc/rtc-pcf8523.c > +++ b/drivers/rtc/rtc-pcf8523.c > @@ -97,8 +97,9 @@ static int pcf8523_voltage_low(struct i2c_client *client) > return !!(value & REG_CONTROL3_BLF); > } > > -static int pcf8523_select_capacitance(struct i2c_client *client, bool high) > +static int pcf8523_load_capacitance(struct i2c_client *client) > { > + u32 load; > u8 value; > int err; > > @@ -106,14 +107,24 @@ static int pcf8523_select_capacitance(struct i2c_client *client, bool high) > if (err < 0) > return err; > > - if (!high) > - value &= ~REG_CONTROL1_CAP_SEL; > - else > + load = 12500; > + of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads", > + &load); > + > + switch (load) { > + default: > + dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500", > + load); This alignment is not correct, as you will be respinning for the DT doc, please fix ;) > + /* fall through */ > + case 12500: > value |= REG_CONTROL1_CAP_SEL; > + break; > + case 7000: > + value &= ~REG_CONTROL1_CAP_SEL; > + break; > + } > > err = pcf8523_write(client, REG_CONTROL1, value); > - if (err < 0) > - return err; > > return err; > } > @@ -347,9 +358,10 @@ static int pcf8523_probe(struct i2c_client *client, > if (!pcf) > return -ENOMEM; > > - err = pcf8523_select_capacitance(client, true); > + err = pcf8523_load_capacitance(client); > if (err < 0) > - return err; > + dev_warn(&client->dev, "failed to set xtal load capacitance: %d", > + err); Ditto > > err = pcf8523_set_pm(client, 0); > if (err < 0) > -- > 2.12.0 >
On 08/01/2019 19:54:14+0100, Sam Ravnborg wrote: > Add support for specifying the xtal load capacitance in the DT node. > The pcf85063 supports xtal load capacitance of 7pF or 12.5pF. > If the rtc has the wrong configuration the time will > drift several hours/week. > > The driver use the default value 7pF. > > The DT may specify either 7000fF or 12500fF. > (The DT uses femto Farad to avoid decimal numbers). > Other values are warned and the driver uses the default value. > > Signed-off-by: Sam Ravnborg <sam@ravnborg.org> > Cc: Alessandro Zummo <a.zummo@towertech.it> > Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> > Cc: Urs Fässler <urs.fassler@bbv.ch> > --- > drivers/rtc/rtc-pcf85063.c | 39 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 39 insertions(+) > > diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c > index 283c2335b01b..0c0b6030627e 100644 > --- a/drivers/rtc/rtc-pcf85063.c > +++ b/drivers/rtc/rtc-pcf85063.c > @@ -27,6 +27,7 @@ > */ > > #define PCF85063_REG_CTRL1 0x00 /* status */ > +#define PCF85063_REG_CTRL1_CAP_SEL BIT(0) > #define PCF85063_REG_CTRL1_STOP BIT(5) > #define PCF85063_REG_CTRL2 0x01 > > @@ -180,6 +181,39 @@ static const struct rtc_class_ops pcf85063_rtc_ops = { > .set_time = pcf85063_rtc_set_time > }; > > +static int pcf85063_load_capacitance(struct i2c_client *client) > +{ > + u32 load; > + int rc; > + u8 reg; > + > + rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); > + if (rc < 0) > + return rc; > + > + reg = rc; > + load = 7000; > + of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads", > + &load); > + > + switch (load) { > + default: > + dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 7000", > + load); Alignment is not correct > + /* fall through */ > + case 7000: > + reg &= ~PCF85063_REG_CTRL1_CAP_SEL; > + break; > + case 12500: > + reg |= PCF85063_REG_CTRL1_CAP_SEL; > + break; > + } > + > + rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg); > + > + return rc; > +} > + > static int pcf85063_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > @@ -197,6 +231,11 @@ static int pcf85063_probe(struct i2c_client *client, > return err; > } > > + err = pcf85063_load_capacitance(client); > + if (err < 0) > + dev_warn(&client->dev, "failed to set xtal load capacitance: %d", > + err); This should be using more tabs. As you can see, I don't have much to add and I'm quite pleased with the series. As Rob pointed out, quartz-load-femtofarads should be added in rtc.txt
pcf8523 hardcode the quartz load to 12.5pF pcf85063 uses the reset default of 7pF Introduce a new generic property "quartz-load-femtofarad" to specify the quartz load. The default value is selected to match the current Linux drivers, so there are no behavior changes if a binding do not specify the quarts-load. The unit is femtofarads because several RTC's define the quarts load in steps of 0.5 pF. The two drivers rtc-pcf8523 and rtc-pcf85063 are both updated to use the new binding. The fix is tested on a proprietary board for both RTC variants. v2: - Introduce a generic property "quartz-load-femtofarads" - Add femtofarads to property-units.txt - Make the changes backward compatible - Reduced logging - Warn, when we continue with a default value - Tested, by Søren Andersen, on real HW - Rebased on top of v5.0-rc1 Sam Sam Ravnborg (5): devicetree: property-units: Add femtofarads unit dt-binding: pcf8523: add xtal load capacitance dt-binding: pcf85063: add xtal load capacitance rtc: pcf8523: set xtal load capacitance from DT rtc: pcf85063: set xtal load capacitance from DT .../devicetree/bindings/property-units.txt | 1 + .../devicetree/bindings/rtc/nxp,pcf85063.txt | 18 ++++++++++ .../devicetree/bindings/rtc/nxp,pcf8523.txt | 18 ++++++++++ Documentation/devicetree/bindings/rtc/rtc.txt | 2 -- drivers/rtc/rtc-pcf85063.c | 39 ++++++++++++++++++++++ drivers/rtc/rtc-pcf8523.c | 28 +++++++++++----- 6 files changed, 96 insertions(+), 10 deletions(-)