From 1a990fefb641398fb580a0ea0be99b0ff27cbb9b Mon Sep 17 00:00:00 2001 From: Baruch Siach Date: Thu, 21 Jun 2018 20:40:23 +0300 Subject: [PATCH] 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: Baruch Siach Acked-by: Gregory CLEMENT Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-armada38x.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) --- a/drivers/rtc/rtc-armada38x.c +++ b/drivers/rtc/rtc-armada38x.c @@ -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(struc 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 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);