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Date: Mon, 1 Apr 2019 18:08:15 +0200
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: linux-rtc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH 11/12] rtc: pcf85063: add offset correction support
The PCF850363 has an offset correction with two modes:
With mode 0, the correction is triggered once every two hours and then
correction pulses are applied once per minute until the programmed
correction values have been implemented. This gives a step of 4.34 ppm.
With mode 1, the correction is triggered once every four minutes and then
correction pulses are applied once per second up to a maximum of 60 pulses.
When correction values greater than 60 pulses are used, additional
correction pulses are made in the 59 th second. This gives a step of 4.069
ppm.
Use the correction closest to the requested value.
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
drivers/rtc/rtc-pcf85063.c | 58 +++++++++++++++++++++++++++++++++++++-
1 file changed, 57 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 04aaa83a5431..1bce53f8a7da 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -38,6 +38,12 @@
#define PCF85063_CTRL2_AF BIT(6)
#define PCF85063_CTRL2_AIE BIT(7)
+#define PCF85063_REG_OFFSET 0x02
+#define PCF85063_OFFSET_SIGN_BIT 6 /* 2's complement sign bit */
+#define PCF85063_OFFSET_MODE BIT(7)
+#define PCF85063_OFFSET_STEP0 4340
+#define PCF85063_OFFSET_STEP1 4069
+
#define PCF85063_REG_RAM 0x03
#define PCF85063_REG_SC 0x04 /* datetime */
@@ -225,14 +231,64 @@ static irqreturn_t pcf85063_rtc_handle_irq(int irq, void *dev_id)
return IRQ_NONE;
}
+static int pcf85063_read_offset(struct device *dev, long *offset)
+{
+ struct pcf85063 *pcf85063 = dev_get_drvdata(dev);
+ long val;
+ u32 reg;
+ int ret;
+
+ ret = regmap_read(pcf85063->regmap, PCF85063_REG_OFFSET, ®);
+ if (ret < 0)
+ return ret;
+
+ val = sign_extend32(reg & ~PCF85063_OFFSET_MODE,
+ PCF85063_OFFSET_SIGN_BIT);
+
+ if (reg & PCF85063_OFFSET_MODE)
+ *offset = val * PCF85063_OFFSET_STEP1;
+ else
+ *offset = val * PCF85063_OFFSET_STEP0;
+
+ return 0;
+}
+
+static int pcf85063_set_offset(struct device *dev, long offset)
+{
+ struct pcf85063 *pcf85063 = dev_get_drvdata(dev);
+ s8 mode0, mode1, reg;
+ unsigned int error0, error1;
+
+ if (offset > PCF85063_OFFSET_STEP0 * 63)
+ return -ERANGE;
+ if (offset < PCF85063_OFFSET_STEP0 * -64)
+ return -ERANGE;
+
+ mode0 = DIV_ROUND_CLOSEST(offset, PCF85063_OFFSET_STEP0);
+ mode1 = DIV_ROUND_CLOSEST(offset, PCF85063_OFFSET_STEP1);
+
+ error0 = abs(offset - (mode0 * PCF85063_OFFSET_STEP0));
+ error1 = abs(offset - (mode1 * PCF85063_OFFSET_STEP1));
+ if (mode1 > 63 || mode1 < -64 || error0 < error1)
+ reg = mode0 & ~PCF85063_OFFSET_MODE;
+ else
+ reg = mode1 | PCF85063_OFFSET_MODE;
+
+ return regmap_write(pcf85063->regmap, PCF85063_REG_OFFSET, reg);
+}
+
static const struct rtc_class_ops pcf85063_rtc_ops = {
.read_time = pcf85063_rtc_read_time,
- .set_time = pcf85063_rtc_set_time
+ .set_time = pcf85063_rtc_set_time,
+ .read_offset = pcf85063_read_offset,
+ .set_offset = pcf85063_set_offset,
};
static const struct rtc_class_ops pcf85063_rtc_ops_alarm = {
.read_time = pcf85063_rtc_read_time,
.set_time = pcf85063_rtc_set_time,
+ .read_offset = pcf85063_read_offset,
+ .set_offset = pcf85063_set_offset,
.read_alarm = pcf85063_rtc_read_alarm,
.set_alarm = pcf85063_rtc_set_alarm,
.alarm_irq_enable = pcf85063_rtc_alarm_irq_enable,
--
2.20.1
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