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[1/2] rtc: pcf85363: add support for the quartz-load-femtofarads property

Message ID 20230213095018.2255225-2-javier.carrasco@wolfvision.net
State Accepted
Commit fd9a6a13949af81062f4cd04f2c1b28ca5311e71
Headers show
Series [1/2] rtc: pcf85363: add support for the quartz-load-femtofarads property | expand

Commit Message

Javier Carrasco Feb. 13, 2023, 9:50 a.m. UTC 
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 <javier.carrasco@wolfvision.net>
---
 drivers/rtc/rtc-pcf85363.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
index c05b722f0060..941f9264cf0a 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;