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
