Hi Baruch,
On jeu., juin 21 2018, Baruch Siach <baruch@xxxxxxxxxx> wrote:
> 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.
It also matches my notes to reset the RTC on Armada 8K:
devmem2 0xf428401c w 0
devmem2 0xf4284018 w 0x2000
Acked-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxx>
Thanks,
Gregory
>
> Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
> ---
> drivers/rtc/rtc-armada38x.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c
> index 4d62a54fd5d6..0b50276dce6d 100644
> --- 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(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);
> --
> 2.17.1
>
--
Gregory Clement, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com
