Sorry, this was sent prematurely and should have been split into two
patches. It has been resent properly.
On Sat, May 30, 2020 at 8:32 AM Kevin P. Fleming <kevin+linux@xxxxxxx> wrote:
>
> All of the parts supported by this driver can make use of a
> small capacitor to improve the accuracy of the autocalibration
> process for their RC oscillators. If a capacitor is connected,
> a configuration register must be set to enable its use, so a
> new Device Tree property has been added for that purpose.
>
> Signed-off-by: Kevin P. Fleming <kevin+linux@xxxxxxx>
> Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> To: linux-rtc@xxxxxxxxxxxxxxx
> To: devicetree@xxxxxxxxxxxxxxx
> ---
> .../bindings/rtc/abracon,abx80x.txt | 6 ++++
> drivers/rtc/rtc-abx80x.c | 34 +++++++++++++++++++
> 2 files changed, 40 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/rtc/abracon,abx80x.txt b/Documentation/devicetree/bindings/rtc/abracon,abx80x.txt
> index 2405e35a1bc0..ad5d59ed6f24 100644
> --- a/Documentation/devicetree/bindings/rtc/abracon,abx80x.txt
> +++ b/Documentation/devicetree/bindings/rtc/abracon,abx80x.txt
> @@ -29,3 +29,9 @@ and valid to enable charging:
> - "abracon,tc-diode": should be "standard" (0.6V) or "schottky" (0.3V)
> - "abracon,tc-resistor": should be <0>, <3>, <6> or <11>. 0 disables the output
> resistor, the other values are in kOhm.
> +
> +All of the devices can have a 47pf capacitor attached to increase the
> +autocalibration accuracy of their RC oscillators. To enable usage of the
> +capacitor the following property has to be defined:
> +
> + - "abracon,autocal-filter"
> diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
> index 3521d8e8dc38..be5a814e8c0b 100644
> --- a/drivers/rtc/rtc-abx80x.c
> +++ b/drivers/rtc/rtc-abx80x.c
> @@ -76,6 +76,9 @@
> #define ABX8XX_CFG_KEY_OSC 0xa1
> #define ABX8XX_CFG_KEY_MISC 0x9d
>
> +#define ABX8XX_REG_AFCTRL 0x26
> +#define ABX8XX_AUTOCAL_FILTER_ENABLE 0xa0
> +
> #define ABX8XX_REG_ID0 0x28
>
> #define ABX8XX_REG_OUT_CTRL 0x30
> @@ -130,6 +133,31 @@ static int abx80x_is_rc_mode(struct i2c_client *client)
> return (flags & ABX8XX_OSS_OMODE) ? 1 : 0;
> }
>
> +static int abx80x_enable_autocal_filter(struct i2c_client *client)
> +{
> + int err;
> +
> + /*
> + * Write the configuration key register to enable access to the AFCTRL
> + * register
> + */
> + err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
> + ABX8XX_CFG_KEY_MISC);
> + if (err < 0) {
> + dev_err(&client->dev, "Unable to write configuration key\n");
> + return -EIO;
> + }
> +
> + err = i2c_smbus_write_byte_data(client, ABX8XX_REG_AFCTRL,
> + ABX8XX_AUTOCAL_FILTER_ENABLE);
> + if (err < 0) {
> + dev_err(&client->dev, "Unable to write autocal filter register\n");
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> static int abx80x_enable_trickle_charger(struct i2c_client *client,
> u8 trickle_cfg)
> {
> @@ -825,6 +853,12 @@ static int abx80x_probe(struct i2c_client *client,
> return err;
> }
>
> + if (of_property_read_bool(np, "abracon,autocal_filter")) {
> + err = abx80x_enable_autocal_filter(client);
> + if (err)
> + return err;
> + }
> +
> if (client->irq > 0) {
> dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
> err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> --
> 2.26.2
>
