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From 1a990fefb641398fb580a0ea0be99b0ff27cbb9b Mon Sep 17 00:00:00 2001
From: Baruch Siach <baruch@tkos.co.il>
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 <baruch@tkos.co.il>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
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);
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