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SubjectRe: [PATCH 2/4] rtc: mediatek: add driver for RTC on MT7622 SoC
Hi,

On 22/09/2017 at 11:33:15 +0800, sean.wang@mediatek.com wrote:
> diff --git a/drivers/rtc/rtc-mediatek.c b/drivers/rtc/rtc-mediatek.c

I'm pretty sure this should be named rtc-mt7622.c instead of
rtc-mediatek.c, exactly for the same reason you have patch 3/4.

> +static void mtk_w32(struct mtk_rtc *rtc, u32 reg, u32 val)
> +{
> + __raw_writel(val, rtc->base + reg);

Do you really need the __raw accessors? What about running your SoC in
BE mode? I guess the _relaxed version are fast enough.

> +}
> +
> +static u32 mtk_r32(struct mtk_rtc *rtc, u32 reg)
> +{
> + return __raw_readl(rtc->base + reg);
> +}
> +


> +static void mtk_rtc_hw_init(struct mtk_rtc *hw)
> +{
> + /* The setup of the init sequence is for allowing RTC got to work */
> + mtk_w32(hw, MTK_RTC_PWRCHK1, RTC_PWRCHK1_MAGIC);
> + mtk_w32(hw, MTK_RTC_PWRCHK2, RTC_PWRCHK2_MAGIC);
> + mtk_w32(hw, MTK_RTC_KEY, RTC_KEY_MAGIC);
> + mtk_w32(hw, MTK_RTC_PROT1, RTC_PROT1_MAGIC);
> + mtk_w32(hw, MTK_RTC_PROT2, RTC_PROT2_MAGIC);
> + mtk_w32(hw, MTK_RTC_PROT3, RTC_PROT3_MAGIC);
> + mtk_w32(hw, MTK_RTC_PROT4, RTC_PROT4_MAGIC);
> + mtk_rmw(hw, MTK_RTC_DEBNCE, RTC_DEBNCE_MASK, 0);
> + mtk_clr(hw, MTK_RTC_CTL, RTC_RC_STOP);
> +}
> +
> +static void mtk_rtc_get_alarm_or_time(struct mtk_rtc *hw, struct rtc_time *tm,
> + int time_alarm)
> +{
> + u32 year, mon, mday, wday, hour, min, sec;
> +
> + /*
> + * Read again until all fields are not changed for all fields in the
> + * consistent state.
> + */
> + do {
> + year = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_YEA));
> + mon = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MON));
> + wday = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOW));
> + mday = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOM));
> + hour = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_HOU));
> + min = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MIN));
> + sec = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_SEC));
> + } while (year != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_YEA)) ||
> + mon != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MON)) ||
> + mday != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOM)) ||
> + wday != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOW)) ||
> + hour != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_HOU)) ||
> + min != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MIN)) ||
> + sec != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_SEC))
> + );

I'm pretty sure only checking sec is enough because it is highly
unlikely that 7 reads take a minute.

> +static irqreturn_t mtk_rtc_alarmirq(int irq, void *id)
> +{
> + struct mtk_rtc *hw = (struct mtk_rtc *)id;
> + u32 irq_sta;
> +
> + /* Stop alarm also implicitly disable the alarm interrupt */
> + mtk_w32(hw, MTK_RTC_AL_CTL, 0);

You stop the alarm here, before testing whether the alarm really
happened.

> + irq_sta = mtk_r32(hw, MTK_RTC_INT);
> + if (irq_sta & RTC_INT_AL_STA) {
> + rtc_update_irq(hw->rtc, 1, RTC_IRQF | RTC_AF);
> +
> + /* Ack alarm interrupt status */
> + mtk_w32(hw, MTK_RTC_INT, RTC_INT_AL_STA);
> + return IRQ_HANDLED;
> + }
> +
> + return IRQ_NONE;
> +}
> +
> +static int mtk_rtc_gettime(struct device *dev, struct rtc_time *tm)
> +{
> + struct mtk_rtc *hw = dev_get_drvdata(dev);
> +
> + mtk_rtc_get_alarm_or_time(hw, tm, MTK_TC);
> +
> + return rtc_valid_tm(tm);
> +}
> +
> +static int mtk_rtc_settime(struct device *dev, struct rtc_time *tm)
> +{
> + struct mtk_rtc *hw = dev_get_drvdata(dev);
> +
> + /* Stop time counter before setting a new one*/
> + mtk_set(hw, MTK_RTC_CTL, RTC_RC_STOP);
> +
> + /* Epoch == 1900 */
> + if (tm->tm_year < 100 || tm->tm_year > 199)
> + return -EINVAL;

Year is a 32 bits register, what makes the RTC fail in 2100? Is it
because of the leap year handling?

> +static int mtk_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> +{
> + struct mtk_rtc *hw = dev_get_drvdata(dev);
> + struct rtc_time *alrm_tm = &wkalrm->time;
> +
> + /* Epoch == 1900 */
> + if (alrm_tm->tm_year < 100 || alrm_tm->tm_year > 199)
> + return -EINVAL;
> +

Ditto.

> +
> + dev_info(&pdev->dev, "MediaTek SoC based RTC enabled\n");
> +

I think the rtc core is verbose enough that this message is not needed.


--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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