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Date: Mon, 27 Sep 2021 12:08:37 +0530
From: Srinivas Neeli <srinivas.neeli@...inx.com>
To: <a.zummo@...ertech.it>, <alexandre.belloni@...tlin.com>,
<michal.simek@...inx.com>, <sgoud@...inx.com>,
<shubhraj@...inx.com>
CC: <linux-rtc@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <git@...inx.com>,
Srinivas Neeli <srinivas.neeli@...inx.com>
Subject: [PATCH V2] rtc: zynqmp: Add calibration set and get support
Zynqmp RTC controller has a calibration feature to compensate
time deviation due to input clock inaccuracy.
Set and get calibration API's are used for setting and getting
calibration value from the controller calibration register.
Signed-off-by: Srinivas Neeli <srinivas.neeli@...inx.com>
---
Changes in V2:
-Removed unused macro.
-Updated code with review comments.
---
drivers/rtc/rtc-zynqmp.c | 100 ++++++++++++++++++++++++++++++++-------
1 file changed, 83 insertions(+), 17 deletions(-)
diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index f440bb52be92..3731ddfbd90f 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -36,10 +36,15 @@
#define RTC_OSC_EN BIT(24)
#define RTC_BATT_EN BIT(31)
-#define RTC_CALIB_DEF 0x198233
+#define RTC_CALIB_DEF 0x8000
#define RTC_CALIB_MASK 0x1FFFFF
#define RTC_ALRM_MASK BIT(1)
#define RTC_MSEC 1000
+#define RTC_FR_MASK 0xF0000
+#define RTC_FR_MAX_TICKS 16
+#define RTC_OFFSET_MAX 150000
+#define RTC_OFFSET_MIN -150000
+#define RTC_PPB 1000000000LL
struct xlnx_rtc_dev {
struct rtc_device *rtc;
@@ -61,13 +66,6 @@ static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
*/
new_time = rtc_tm_to_time64(tm) + 1;
- /*
- * Writing into calibration register will clear the Tick Counter and
- * force the next second to be signaled exactly in 1 second period
- */
- xrtcdev->calibval &= RTC_CALIB_MASK;
- writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
-
writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
/*
@@ -174,14 +172,76 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
rtc_ctrl |= RTC_BATT_EN;
writel(rtc_ctrl, xrtcdev->reg_base + RTC_CTRL);
- /*
- * Based on crystal freq of 33.330 KHz
- * set the seconds counter and enable, set fractions counter
- * to default value suggested as per design spec
- * to correct RTC delay in frequency over period of time.
+ /* Update calibvalue */
+ xrtcdev->calibval = readl(xrtcdev->reg_base + RTC_CALIB_RD);
+}
+
+static int xlnx_rtc_read_offset(struct device *dev, long *offset)
+{
+ struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+ long offset_val = 0;
+ unsigned int tick_mult = RTC_PPB / (xrtcdev->calibval & RTC_TICK_MASK);
+
+ /* Offset with seconds ticks */
+ offset_val = xrtcdev->calibval & RTC_TICK_MASK;
+ offset_val = offset_val - RTC_CALIB_DEF;
+ offset_val = offset_val * tick_mult;
+
+ /* Offset with fractional ticks */
+ if (xrtcdev->calibval & RTC_FR_EN)
+ offset_val += ((xrtcdev->calibval & RTC_FR_MASK) >> RTC_FR_DATSHIFT)
+ * (tick_mult / RTC_FR_MAX_TICKS);
+ *offset = offset_val;
+
+ return 0;
+}
+
+static int xlnx_rtc_set_offset(struct device *dev, long offset)
+{
+ struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+ short int max_tick;
+ unsigned char fract_tick = 0;
+ unsigned int calibval;
+ int fract_offset;
+ unsigned int tick_mult = RTC_PPB / (xrtcdev->calibval & RTC_TICK_MASK);
+
+ /* Make sure offset value is within supported range */
+ if (offset < RTC_OFFSET_MIN || offset > RTC_OFFSET_MAX)
+ return -ERANGE;
+
+ /* Number ticks for given offset */
+ max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
+
+ /* Number fractional ticks for given offset */
+ if (fract_offset) {
+ if (fract_offset < 0) {
+ fract_offset = fract_offset + tick_mult;
+ max_tick--;
+ }
+ if (fract_offset > (tick_mult / RTC_FR_MAX_TICKS)) {
+ for (fract_tick = 1; fract_tick < 16; fract_tick++) {
+ if (fract_offset <=
+ (fract_tick *
+ (tick_mult / RTC_FR_MAX_TICKS)))
+ break;
+ }
+ }
+ }
+
+ /* Zynqmp RTC uses second and fractional tick
+ * counters for compensation
*/
- xrtcdev->calibval &= RTC_CALIB_MASK;
- writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+ calibval = max_tick + RTC_CALIB_DEF;
+
+ if (fract_tick)
+ calibval |= RTC_FR_EN;
+
+ calibval |= (fract_tick << RTC_FR_DATSHIFT);
+
+ writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+ xrtcdev->calibval = calibval;
+
+ return 0;
}
static const struct rtc_class_ops xlnx_rtc_ops = {
@@ -190,6 +250,8 @@ static const struct rtc_class_ops xlnx_rtc_ops = {
.read_alarm = xlnx_rtc_read_alarm,
.set_alarm = xlnx_rtc_set_alarm,
.alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
+ .read_offset = xlnx_rtc_read_offset,
+ .set_offset = xlnx_rtc_set_offset,
};
static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
@@ -215,6 +277,7 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
{
struct xlnx_rtc_dev *xrtcdev;
int ret;
+ unsigned int calibval;
xrtcdev = devm_kzalloc(&pdev->dev, sizeof(*xrtcdev), GFP_KERNEL);
if (!xrtcdev)
@@ -256,9 +319,12 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
}
ret = of_property_read_u32(pdev->dev.of_node, "calibration",
- &xrtcdev->calibval);
+ &calibval);
if (ret)
- xrtcdev->calibval = RTC_CALIB_DEF;
+ calibval = RTC_CALIB_DEF;
+ ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
+ if (!ret)
+ writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
xlnx_init_rtc(xrtcdev);
--
2.17.1
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