Re: [PATCH v3 3/4] rtc: sophgo: add rtc support for Sophgo CV1800 SoC

[Jingbao Qiu]

On Wed, Dec 27, 2023 at 9:50 PM Alexandre Belloni
<alexandre.belloni@xxxxxxxxxxx> wrote:
>
> On 27/12/2023 16:03:56+0800, Jingbao Qiu wrote:
> > On Tue, Dec 26, 2023 at 8:37 PM Alexandre Belloni
> > <alexandre.belloni@xxxxxxxxxxx> wrote:
> > >
> > > Hello,
> > >
> > > please run checkpatch.pl --strict, there are a few issues.
> > >
> > > On 26/12/2023 18:04:30+0800, Jingbao Qiu wrote:
> > > > +struct cv1800_rtc_priv {
> > > > +     struct rtc_device *rtc_dev;
> > > > +     struct device *dev;
> > > > +     struct regmap *rtc_map;
> > > > +     struct clk *clk;
> > > > +     spinlock_t rtc_lock;
> > >
> > > This lock seems unnecessary, please check
> > >
> >
> > you are right. I will fix it.
> >
> > > > +     int irq;
> > > > +};
> > > > +
> > > > +static int cv1800_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
> > > > +{
> > > > +     struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
> > > > +
> > > > +     if (enabled)
> > > > +             regmap_write(info->rtc_map, ALARM_ENABLE, REG_ENABLE_FUN);
> > > > +     else
> > > > +             regmap_write(info->rtc_map, ALARM_ENABLE, REG_DISABLE_FUN);
> > > > +
> > >
> > > This could be:
> > >         regmap_write(info->rtc_map, ALARM_ENABLE, enabled);
> >
> > you are right, i will fix it.
> >
> > >
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static int cv1800_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> > > > +{
> > > > +     struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
> > > > +     unsigned long alarm_time;
> > > > +
> > > > +     alarm_time = rtc_tm_to_time64(&alrm->time);
> > > > +
> > > > +     if (alarm_time > SEC_MAX_VAL)
> > > > +             return -EINVAL;
> > >
> > > The core is already checking fr this.
> >
> > Thanks, I will remove it.
> >
> > >
> > > > +
> > > > +     regmap_write(info->rtc_map, ALARM_ENABLE, REG_DISABLE_FUN);
> > > > +
> > > > +     udelay(DEALY_TIME_PREPARE);
> > >
> > > Why is this needed?
> >
> > This doesn't seem to require waiting, I will check it.
> >
> > >
> > > > +
> > > > +     regmap_write(info->rtc_map, ALARM_TIME, alarm_time);
> > > > +     regmap_write(info->rtc_map, ALARM_ENABLE, REG_ENABLE_FUN);
> > >
> > > You must follow alrm->enabled instead of unconditionally enabling the
> > > alarm.
> >
> > ok,i will fix it.
> >
> > >
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > >
> > >
> > > > +static int cv1800_rtc_32k_coarse_val_calib(struct cv1800_rtc_priv *info)
> > >
> > > Please explain those two calibration functions. I don't think you can
> > > achieve what you want to do.
> >
> > The goal of these two calibration functions is to achieve calibration
> > of RTC time.
> > The code is written according to the data manual.
> >
> > The calibration circuit uses 25MHz crystal clock to sample 32KHz
> > clock. In coarse
> > tune mode, the 25MHz crystal clock samples one 32KHz clock cycle period and
> > report the counting results.
> >
> > the datasheet link:
> > Link: https://github.com/milkv-duo/duo-files/blob/main/duo/datasheet/CV1800B-CV1801B-Preliminary-Datasheet-full-en.pdf
> > page:195
>
>
> I'm really curious as to why this is calibrated using a 25MHz crystal as
> it may be as imprecise as the 32kHz one. I'm asking because we have an
> interface to get calibration done properly so you can use a precise clock
> like GPS, NTP or PTP. This is what you should probably implement
> instead or on top of it.
>

Thanks, I will communicate with the IC designers later.

> > >
> > > > +}
> > > > +
> > > > +static int cv1800_rtc_read_time(struct device *dev, struct rtc_time *tm)
> > > > +{
> > > > +     struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
> > > > +     unsigned int sec;
> > > > +     unsigned int sec_ro_t;
> > > > +     unsigned long flag;
> > > > +
> > > > +     spin_lock_irqsave(&info->rtc_lock, flag);
> > > > +
> > > > +     regmap_read(info->rtc_map, SEC_CNTR_VAL, &sec);
> > > > +     regmap_read(info->rtc_map, MACRO_RO_T, &sec_ro_t);
> > > > +
> > > > +     if (sec_ro_t > (SET_SEC_CNTR_VAL_UPDATE)) {
> > > > +             sec = sec_ro_t;
> > > > +             regmap_write(info->rtc_map, SET_SEC_CNTR_VAL, sec);
> > > > +             regmap_write(info->rtc_map, SET_SEC_CNTR_TRIG, REG_ENABLE_FUN);
> > >
> > > What does this do?
> >
> > the sec_ro_t be considered to have high accuracy after calibration.
> > So every time read the time, update the RTC time.
>
> So why don't you always use sec_ro_t instead of sec?
> Also, why is this done conditionally on a arbitrary value? As it stands,
> it will happen if the date is after 1995-07-09T16:12:48 for no good
> reason.
> This is awful because the alarm is matching SEC_CNTR_VAL with ALARM_TIME
> so if this means the calibration doesn't affect SEC_CNTR_VAL (which I
> seriously doubt), the alarm will end up being imprecise anyway
>

Thanks, I will communicate with the IC designers later.

> > > > +static int cv1800_rtc_probe(struct platform_device *pdev)
> > > > +{
> > > > +     struct cv1800_rtc_priv *rtc;
> > > > +     uint32_t ctrl_val;
> > > > +     int ret;
> > > > +
> > > > +     rtc = devm_kzalloc(&pdev->dev, sizeof(struct cv1800_rtc_priv),
> > > > +                        GFP_KERNEL);
> > > > +     if (!rtc)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     rtc->dev = &pdev->dev;
> > > > +
> > > > +     rtc->rtc_map = syscon_node_to_regmap(rtc->dev->of_node->parent);
> > > > +     if (IS_ERR(rtc->rtc_map))
> > > > +             return PTR_ERR(rtc->rtc_map);
> > > > +
> > > > +     rtc->irq = platform_get_irq(pdev, 0);
> > > > +     if (rtc->irq < 0)
> > > > +             return rtc->irq;
> > > > +
> > > > +     ret = devm_request_irq(&pdev->dev, rtc->irq, cv1800_rtc_irq_handler,
> > > > +                            IRQF_TRIGGER_HIGH, "alarm", &pdev->dev);
> > > > +     if (ret)
> > > > +             return dev_err_probe(&pdev->dev, ret,
> > > > +                                  "cannot register interrupt handler\n");
> > > > +
> > > > +     rtc->clk = devm_clk_get(rtc->dev, NULL);
> > > > +     if (IS_ERR(rtc->clk))
> > > > +             return PTR_ERR(rtc->clk);
> > > > +
> > >
> > > You are going to leak rtc->clk after the next call.
> >
> > I will release him at the appropriate time. And add the remove
> > function to release.
> >
> > >
> > > > +     rtc->clk = devm_clk_get_enabled(&pdev->dev, NULL);
> > > > +     if (IS_ERR(rtc->clk))
> > > > +             return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
> > > > +                                  "clk not found\n");
> > > > +
> > > > +     platform_set_drvdata(pdev, rtc);
> > > > +
> > > > +     spin_lock_init(&rtc->rtc_lock);
> > > > +
> > > > +     rtc->rtc_dev = devm_rtc_device_register(&pdev->dev,
> > > > +                                                             dev_name(&pdev->dev),
> > > > +                                                             &cv800b_rtc_ops,
> > > > +                                                             THIS_MODULE);
> > > > +     if (IS_ERR(rtc->rtc_dev))
> > > > +             return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_dev),
> > > > +                                  "can't register rtc device\n");
> > >
> > > Please use devm_rtc_allocate_device and devm_rtc_register_device
> >
> > ok,I will use it.
>
> Also you have to set the RTC range properly.

Thanks,I will fix it.

Best regards,
Jingbao Qiu

>
>
> --
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com