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rtc: zynqmp: Add calibration set and get support

Browse source 
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@xilinx.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220626070817.3780977-3-srinivas.neeli@xilinx.com
This commit is contained in:
Srinivas Neeli 2022-06-26 12:38:17 +05:30 committed by Alexandre Belloni
parent 85cab027d4
commit 07dcc6f9c7
1 changed files with 94 additions and 19 deletions
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113
drivers/rtc/rtc-zynqmp.c
View file

@ -6,6 +6,7 @@
*
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
@ -40,13 +41,19 @@
#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_PPB 1000000000LL
#define RTC_MIN_OFFSET -32768000
#define RTC_MAX_OFFSET 32767000
struct xlnx_rtc_dev {
struct rtc_device *rtc;
void __iomem *reg_base;
int alarm_irq;
int sec_irq;
unsigned int calibval;
struct clk *rtc_clk;
unsigned int freq;
};
static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
@ -61,13 +68,6 @@ 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);
/*
@ -173,15 +173,76 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
rtc_ctrl = readl(xrtcdev->reg_base + RTC_CTRL);
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.
static int xlnx_rtc_read_offset(struct device *dev, long *offset)
{
struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
unsigned long long rtc_ppb = RTC_PPB;
unsigned int tick_mult = do_div(rtc_ppb, xrtcdev->freq);
unsigned int calibval;
long offset_val;
calibval = readl(xrtcdev->reg_base + RTC_CALIB_RD);
/* Offset with seconds ticks */
offset_val = calibval & RTC_TICK_MASK;
offset_val = offset_val - RTC_CALIB_DEF;
offset_val = offset_val * tick_mult;
/* Offset with fractional ticks */
if (calibval & RTC_FR_EN)
offset_val += ((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);
unsigned long long rtc_ppb = RTC_PPB;
unsigned int tick_mult = do_div(rtc_ppb, xrtcdev->freq);
unsigned char fract_tick;
unsigned int calibval;
short int max_tick;
int fract_offset;
if (offset < RTC_MIN_OFFSET || offset > RTC_MAX_OFFSET)
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));
return 0;
}
static const struct rtc_class_ops xlnx_rtc_ops = {
@ -190,6 +251,8 @@ 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)
@ -255,10 +318,22 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
return ret;
}
ret = of_property_read_u32(pdev->dev.of_node, "calibration",
&xrtcdev->calibval);
if (ret)
xrtcdev->calibval = RTC_CALIB_DEF;
/* Getting the rtc_clk info */
xrtcdev->rtc_clk = devm_clk_get_optional(&pdev->dev, "rtc_clk");
if (IS_ERR(xrtcdev->rtc_clk)) {
if (PTR_ERR(xrtcdev->rtc_clk) != -EPROBE_DEFER)
dev_warn(&pdev->dev, "Device clock not found.\n");
}
xrtcdev->freq = clk_get_rate(xrtcdev->rtc_clk);
if (!xrtcdev->freq) {
ret = of_property_read_u32(pdev->dev.of_node, "calibration",
&xrtcdev->freq);
if (ret)
xrtcdev->freq = RTC_CALIB_DEF;
}
ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
if (!ret)
writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
xlnx_init_rtc(xrtcdev);