linux-kernel - Re: [PATCH] rtc: zynqmp: Add calibration set and get support

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Message-ID: <00b3e6dd-50d6-f5a7-a861-e6db91f6eafb@xilinx.com>
Date:   Mon, 24 Feb 2020 12:16:36 +0100
From:   Michal Simek <michal.simek@...inx.com>
To:     Srinivas Neeli <srinivas.neeli@...inx.com>, 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 Goud <srinivas.goud@...inx.com>
Subject: Re: [PATCH] rtc: zynqmp: Add calibration set and get support

On 20. 02. 20 10:31, Srinivas Neeli wrote:
> 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 Goud <srinivas.goud@...inx.com>
> Signed-off-by: Srinivas Neeli <srinivas.neeli@...inx.com>
> ---
>  drivers/rtc/rtc-zynqmp.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> index 4b1077e2f826..b4118e9e4fcc 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -40,6 +40,12 @@
>  #define RTC_CALIB_MASK		0x1FFFFF
>  #define RTC_ALRM_MASK          BIT(1)
>  #define RTC_MSEC               1000
> +#define RTC_FR_MASK             0xF0000
> +#define RTC_SEC_MAX_VAL         0xFFFFFFFF
> +#define RTC_FR_MAX_TICKS        16
> +#define RTC_OFFSET_MAX          150000
> +#define RTC_OFFSET_MIN          -150000
> +#define RTC_PPB                 1000000000LL
>  

please use tabs here.

>  struct xlnx_rtc_dev {
>  	struct rtc_device	*rtc;
> @@ -184,12 +190,84 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
>  	writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
>  }
>  
> +static int xlnx_rtc_read_offset(struct device *dev, long *offset)
> +{
> +	struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
> +	long offset_val;
> +	unsigned int reg;
> +	unsigned int tick_mult = RTC_PPB / xrtcdev->calibval;
> +
> +	reg = readl(xrtcdev->reg_base + RTC_CALIB_RD);
> +
> +	/* Offset with seconds ticks */
> +	offset_val = reg & RTC_TICK_MASK;
> +	offset_val = offset_val - xrtcdev->calibval;
> +	offset_val = offset_val * tick_mult;
> +
> +	/* Offset with fractional ticks */
> +	if (reg & RTC_FR_EN)
> +		offset_val += ((reg & 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;

double space.

> +	int fract_offset;
> +	unsigned int tick_mult = RTC_PPB / xrtcdev->calibval;
> +
> +	/* 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
> +	 */
> +	calibval = max_tick + xrtcdev->calibval;
> +
> +	if (fract_tick)
> +		calibval |= RTC_FR_EN;
> +
> +	calibval |= (fract_tick <<  RTC_FR_DATSHIFT);

here is double space.

> +
> +	writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
> +
> +	return 0;
> +}
> +
>  static const struct rtc_class_ops xlnx_rtc_ops = {
>  	.set_time	  = xlnx_rtc_set_time,
>  	.read_time	  = xlnx_rtc_read_time,
>  	.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,

use tabs as is done above.

>  };
>  
>  static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
> 

The rest looks good.

Thanks,
Michal