Re: [PATCH v5 6/7] rtc: support i.MX95 BBM RTC

Alexandre Belloni
2024-07-11T20:33:39Z

Hello,

On 21/06/2024 15:04:41+0800, Peng Fan (OSS) wrote:
> + ret = bbnsm->ops->rtc_time_get(ph, 0, &val);
> + if (ret) {
> + dev_err(dev, "%s: %d\n", __func__, ret);

This is not super useful, you should drop the various dev_err or pr_err
as there is no action the user can take to solve the erro apart from
retrying.

> + return ret;
> + }
> +
> + rtc_time64_to_tm(val, tm);
> +
> + return 0;
> +}
> +
> +static int scmi_imx_bbm_set_time(struct device *dev, struct rtc_time *tm)
> +{
> + struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
> + struct scmi_protocol_handle *ph = bbnsm->ph;
> + u64 val;
> + int ret;
> +
> + val = rtc_tm_to_time64(tm);
> +
> + ret = bbnsm->ops->rtc_time_set(ph, 0, val);
> + if (ret)
> + dev_err(dev, "%s: %d\n", __func__, ret);
> +
> + return ret;
> +}
> +
> +static int scmi_imx_bbm_alarm_irq_enable(struct device *dev, unsigned int enable)
> +{

How can userspace disable the alarm?

> + return 0;
> +}
> +
> +static int scmi_imx_bbm_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> + struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
> + struct scmi_protocol_handle *ph = bbnsm->ph;
> + struct rtc_time *alrm_tm = &alrm->time;
> + u64 val;
> + int ret;
> +
> + val = rtc_tm_to_time64(alrm_tm);
> +
> + ret = bbnsm->ops->rtc_alarm_set(ph, 0, val);
> + if (ret)
> + dev_err(dev, "%s: %d\n", __func__, ret);
> +
> + return ret;
> +}
> +
> +static const struct rtc_class_ops smci_imx_bbm_rtc_ops = {
> + .read_time = scmi_imx_bbm_read_time,
> + .set_time = scmi_imx_bbm_set_time,
> + .set_alarm = scmi_imx_bbm_set_alarm,
> + .alarm_irq_enable = scmi_imx_bbm_alarm_irq_enable,
> +};
> +
> +static int scmi_imx_bbm_rtc_notifier(struct notifier_block *nb, unsigned long event, void *data)
> +{
> + struct scmi_imx_bbm *bbnsm = container_of(nb, struct scmi_imx_bbm, nb);
> + struct scmi_imx_bbm_notif_report *r = data;
> +
> + if (r->is_rtc)
> + rtc_update_irq(bbnsm->rtc_dev, 1, RTC_AF | RTC_IRQF);
> + else
> + pr_err("Unexpected bbm event: %s\n", __func__);
> +
> + return 0;
> +}
> +
> +static int scmi_imx_bbm_rtc_init(struct scmi_device *sdev)
> +{
> + const struct scmi_handle *handle = sdev->handle;
> + struct device *dev = &sdev->dev;
> + struct scmi_imx_bbm *bbnsm = dev_get_drvdata(dev);
> + int ret;
> +
> + bbnsm->rtc_dev = devm_rtc_allocate_device(dev);
> + if (IS_ERR(bbnsm->rtc_dev))
> + return PTR_ERR(bbnsm->rtc_dev);
> +
> + bbnsm->rtc_dev->ops = &smci_imx_bbm_rtc_ops;
> + bbnsm->rtc_dev->range_min = 0;

range_min is set to 0 by default, this is not necessary

> + bbnsm->rtc_dev->range_max = U32_MAX;
> +
> + ret = devm_rtc_register_device(bbnsm->rtc_dev);
> + if (ret)
> + return ret;
> +
> + bbnsm->nb.notifier_call = &scmi_imx_bbm_rtc_notifier;
> + return handle->notify_ops->devm_event_notifier_register(sdev, SCMI_PROTOCOL_IMX_BBM,
> + SCMI_EVENT_IMX_BBM_RTC,
> + NULL, &bbnsm->nb);

Note that failing after devm_rtc_register_device opens the driver to a
race condition as the character device will exist at that time.

--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering