Hi Alexandre,

Thanks for your valuable suggestions on the driver.

I added comments inline and will have following-ups in the next version

	Sean

On Thu, 2017-10-12 at 23:20 +0200, Alexandre Belloni wrote:

Hi,

On 22/09/2017 at 11:33:15 +0800, sean.wang@mediatek.com wrote:

quoted

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.

It's okay for naming with rtc-mt7622.c at this moment. But if more SoCs
support gets into the driver, I will consider again to give a more
generic name for the driver.

quoted

+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.

SoC runs on LE mode. I also think it's fine and enough to use _relaxed
version instead of __raw version.

quoted

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

quoted

+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.

You're right. I made something stupid here. Only checking on sec is
enough and will give simpler and better code.

quoted

+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.

Okay. I will exchange the order for alarm stopping and the examination
whether the alarm is really expired. 

quoted

+	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_RTredundantC_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?

I made something stupid again here: rtc hardware doesn't have such the
limitation. I just felt alarm set up prior to 2100 is enough in my
initial thought, but it seemed I shouldn't do this. I will remove the
sanity condition.

quoted

+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.

Ditto. those condition will be removed.

quoted

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

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

Okay. the redundant and specific log prompt would be removed as well.