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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 <baruch@tkos.co.il>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Baruch Siach 2018-06-21 20:40:23 +03:00 committed by Alexandre Belloni
parent dff700fa81
commit 1a990fefb6
1 changed files with 23 additions and 0 deletions
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23
drivers/rtc/rtc-armada38x.c
View File

@ -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);