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Commit 1a990fef authored by Baruch Siach's avatar Baruch Siach Committed by Alexandre Belloni
Browse files

rtc: armada38x: reset after rtc power loss 



When the RTC block looses power it needs a reset sequence to make it
usable again. Otherwise, writes to the time register have no effect.

This reset sequence combines information from the mvebu_rtc driver in
the Marvell provided U-Boot, and the SolidRun provided U-Boot repo.

Tested on the Armada 388 based SolidRun Clearfog Base.

Signed-off-by: default avatarBaruch Siach <baruch@tkos.co.il>
Acked-by: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent dff700fa

drivers/rtc/rtc-armada38x.c

+23 −0
Original line number Diff line number Diff line
@@ -30,6 +30,8 @@ 
#define RTC_IRQ_FREQ_1HZ	    BIT(2)

#define RTC_CCR		    0x18

#define RTC_CCR_MODE		    BIT(15)

#define RTC_CONF_TEST	    0x1C

#define RTC_NOMINAL_TIMING	    BIT(13)



#define RTC_TIME	    0xC

#define RTC_ALARM1	    0x10
@@ -75,6 +77,7 @@ struct armada38x_rtc { 
	void __iomem	    *regs_soc;

	spinlock_t	    lock;

	int		    irq;

	bool		    initialized;

	struct value_to_freq *val_to_freq;

	struct armada38x_rtc_data *data;

};
@@ -226,6 +229,23 @@ static int armada38x_rtc_read_time(struct device *dev, struct rtc_time *tm) 
	return 0;

}



static void armada38x_rtc_reset(struct armada38x_rtc *rtc)

{

	u32 reg;



	reg = rtc->data->read_rtc_reg(rtc, RTC_CONF_TEST);

	/* If bits [7:0] are non-zero, assume RTC was uninitialized */

	if (reg & 0xff) {

		rtc_delayed_write(0, rtc, RTC_CONF_TEST);

		msleep(500); /* Oscillator startup time */

		rtc_delayed_write(0, rtc, RTC_TIME);

		rtc_delayed_write(SOC_RTC_ALARM1 | SOC_RTC_ALARM2, rtc,

				  RTC_STATUS);

		rtc_delayed_write(RTC_NOMINAL_TIMING, rtc, RTC_CCR);

	}

	rtc->initialized = true;

}



static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm)

{

	struct armada38x_rtc *rtc = dev_get_drvdata(dev);
@@ -237,6 +257,9 @@ static int armada38x_rtc_set_time(struct device *dev, struct rtc_time *tm) 
	if (ret)

		goto out;



	if (!rtc->initialized)

		armada38x_rtc_reset(rtc);



	spin_lock_irqsave(&rtc->lock, flags);

	rtc_delayed_write(time, rtc, RTC_TIME);

	spin_unlock_irqrestore(&rtc->lock, flags);