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Date:   Sat, 24 Aug 2019 15:16:41 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     linux-sunxi@...glegroups.com, megous@...ous.com
Cc:     Mark Rutland <mark.rutland@....com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        devicetree@...r.kernel.org,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-rtc@...r.kernel.org
Subject: Re: [linux-sunxi] [PATCH v2 2/3] rtc: sun6i: Add support for H6 RTC

Dne sobota, 24. avgust 2019 ob 15:05:44 CEST je Ondřej Jirman napisal(a):
> On Sat, Aug 24, 2019 at 02:51:54PM +0200, Jernej Škrabec wrote:
> > Dne sobota, 24. avgust 2019 ob 14:46:54 CEST je Ondřej Jirman napisal(a):
> > > Hi,
> > > 
> > > On Sat, Aug 24, 2019 at 02:32:32PM +0200, Jernej Škrabec wrote:
> > > > Hi!
> > > > 
> > > > Dne torek, 20. avgust 2019 ob 17:19:33 CEST je megous@...ous.com
> > 
> > napisal(a):
> > > > > From: Ondrej Jirman <megous@...ous.com>
> > > > > 
> > > > > RTC on H6 is mostly the same as on H5 and H3. It has slight
> > > > > differences
> > > > > mostly in features that are not yet supported by this driver.
> > > > > 
> > > > > Some differences are already stated in the comments in existing
> > > > > code.
> > > > > One other difference is that H6 has extra bit in LOSC_CTRL_REG,
> > > > > called
> > > > > EXT_LOSC_EN to enable/disable external low speed crystal oscillator.
> > > > > 
> > > > > It also has bit EXT_LOSC_STA in LOSC_AUTO_SWT_STA_REG, to check
> > > > > whether
> > > > > external low speed oscillator is working correctly.
> > > > > 
> > > > > This patch adds support for enabling LOSC when necessary:
> > > > > 
> > > > > - during reparenting
> > > > > - when probing the clock
> > > > > 
> > > > > H6 also has capacbility to automatically reparent RTC clock from
> > > > > external crystal oscillator, to internal RC oscillator, if external
> > > > > oscillator fails. This is enabled by default. Disable it during
> > > > > probe.
> > > > > 
> > > > > Signed-off-by: Ondrej Jirman <megous@...ous.com>
> > > > > Reviewed-by: Chen-Yu Tsai <wens@...e.org>
> > > > > ---
> > > > > 
> > > > >  drivers/rtc/rtc-sun6i.c | 40
> > > > >  ++++++++++++++++++++++++++++++++++++++--
> > > > >  1 file changed, 38 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> > > > > index d50ee023b559..b0c3752bed3f 100644
> > > > > --- a/drivers/rtc/rtc-sun6i.c
> > > > > +++ b/drivers/rtc/rtc-sun6i.c
> > > > > @@ -32,9 +32,11 @@
> > > > > 
> > > > >  /* Control register */
> > > > >  #define SUN6I_LOSC_CTRL				0x0000
> > > > >  #define SUN6I_LOSC_CTRL_KEY			(0x16aa 
<< 16)
> > > > > 
> > > > > +#define SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS		BIT(15)
> > > > 
> > > > User manual says that above field is bit 14.
> > > 
> > > See the previous discussion, this is from BSP.
> > 
> > I have two versions of BSP (don't ask me which) which have this set as bit
> > 14 and changing this to 14 actually solves all my problems with LOSC (no
> > more issues with setting RTC and HDMI-CEC works now - it uses LOSC as
> > parent) on Tanix TX6 box.
> 
> Interesting. Is LOSC fed externally generated clock, or is it setup as a
> crystal oscillator on your board?

I really don't know, but here is DT: http://ix.io/1ThI

> 
> Anyway, see here:
> 
> https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.h?h=h6-4.9-bsp#n649
> https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n652

Interesting, 4.9 BSP has additional bit definition, which is not documented in 
manual and 3.10 BSP to which I refer.

I was referring to 3.10 BSP, which uses only bit 14. I thought that you named 
it differently.

> 
> It would be nice to know what's really happening.
> 
> My output is:
> 
> [    0.832252] sun6i-rtc 7000000.rtc: registered as rtc0
> [    0.832257] sun6i-rtc 7000000.rtc: RTC enabled
> [    1.728968] sun6i-rtc 7000000.rtc: setting system clock to
> 1970-01-01T00:00:07 UTC (7)

With change, I get same output.

> 
> I think, you may have just enabled the auto switch feature, and running the
> clock from low precision RC oscillator with your patch.

True, now I think there is no external crystal, but I'm still not sure how to 
confirm that.

> 
> The real issue probably is that the mainline driver is missing this:
> 
> https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n650
> 

Not sure what you mean by that. ext vs. int source selection?

Best regards,
Jernej

> regards,
> 	o.
> 
> > Best regards,
> > Jernej
> > 
> > > regards,
> > > 
> > > 	o.
> > > 	
> > > > Best regards,
> > > > Jernej
> > > > 
> > > > >  #define SUN6I_LOSC_CTRL_ALM_DHMS_ACC		BIT(9)
> > > > >  #define SUN6I_LOSC_CTRL_RTC_HMS_ACC		BIT(8)
> > > > >  #define SUN6I_LOSC_CTRL_RTC_YMD_ACC		BIT(7)
> > > > > 
> > > > > +#define SUN6I_LOSC_CTRL_EXT_LOSC_EN		BIT(4)
> > > > > 
> > > > >  #define SUN6I_LOSC_CTRL_EXT_OSC			BIT(0)
> > > > >  #define SUN6I_LOSC_CTRL_ACC_MASK		GENMASK(9, 7)
> > > > > 
> > > > > @@ -128,6 +130,8 @@ struct sun6i_rtc_clk_data {
> > > > > 
> > > > >  	unsigned int has_prescaler : 1;
> > > > >  	unsigned int has_out_clk : 1;
> > > > >  	unsigned int export_iosc : 1;
> > > > > 
> > > > > +	unsigned int has_losc_en : 1;
> > > > > +	unsigned int has_auto_swt : 1;
> > > > > 
> > > > >  };
> > > > >  
> > > > >  struct sun6i_rtc_dev {
> > > > > 
> > > > > @@ -190,6 +194,10 @@ static int sun6i_rtc_osc_set_parent(struct
> > > > > clk_hw
> > > > > *hw,
> > > > > u8 index) val &= ~SUN6I_LOSC_CTRL_EXT_OSC;
> > > > > 
> > > > >  	val |= SUN6I_LOSC_CTRL_KEY;
> > > > >  	val |= index ? SUN6I_LOSC_CTRL_EXT_OSC : 0;
> > > > > 
> > > > > +	if (rtc->data->has_losc_en) {
> > > > > +		val &= ~SUN6I_LOSC_CTRL_EXT_LOSC_EN;
> > > > > +		val |= index ? SUN6I_LOSC_CTRL_EXT_LOSC_EN : 0;
> > > > > +	}
> > > > > 
> > > > >  	writel(val, rtc->base + SUN6I_LOSC_CTRL);
> > > > >  	spin_unlock_irqrestore(&rtc->lock, flags);
> > > > > 
> > > > > @@ -215,6 +223,7 @@ static void __init sun6i_rtc_clk_init(struct
> > > > > device_node *node, const char *iosc_name = "rtc-int-osc";
> > > > > 
> > > > >  	const char *clkout_name = "osc32k-out";
> > > > >  	const char *parents[2];
> > > > > 
> > > > > +	u32 reg;
> > > > > 
> > > > >  	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
> > > > >  	if (!rtc)
> > > > > 
> > > > > @@ -235,9 +244,18 @@ static void __init sun6i_rtc_clk_init(struct
> > > > > device_node *node, goto err;
> > > > > 
> > > > >  	}
> > > > > 
> > > > > +	reg = SUN6I_LOSC_CTRL_KEY;
> > > > > +	if (rtc->data->has_auto_swt) {
> > > > > +		/* Bypass auto-switch to int osc, on ext losc failure
> > 
> > */
> > 
> > > > > +		reg |= SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS;
> > > > > +		writel(reg, rtc->base + SUN6I_LOSC_CTRL);
> > > > > +	}
> > > > > +
> > > > > 
> > > > >  	/* Switch to the external, more precise, oscillator */
> > > > > 
> > > > > -	writel(SUN6I_LOSC_CTRL_KEY | SUN6I_LOSC_CTRL_EXT_OSC,
> > > > > -	       rtc->base + SUN6I_LOSC_CTRL);
> > > > > +	reg |= SUN6I_LOSC_CTRL_EXT_OSC;
> > > > > +	if (rtc->data->has_losc_en)
> > > > > +		reg |= SUN6I_LOSC_CTRL_EXT_LOSC_EN;
> > > > > +	writel(reg, rtc->base + SUN6I_LOSC_CTRL);
> > > > > 
> > > > >  	/* Yes, I know, this is ugly. */
> > > > >  	sun6i_rtc = rtc;
> > > > > 
> > > > > @@ -345,6 +363,23 @@ CLK_OF_DECLARE_DRIVER(sun8i_h3_rtc_clk,
> > > > > "allwinner,sun8i-h3-rtc", CLK_OF_DECLARE_DRIVER(sun50i_h5_rtc_clk,
> > > > > "allwinner,sun50i-h5-rtc", sun8i_h3_rtc_clk_init);
> > > > > 
> > > > > +static const struct sun6i_rtc_clk_data sun50i_h6_rtc_data = {
> > > > > +	.rc_osc_rate = 16000000,
> > > > > +	.fixed_prescaler = 32,
> > > > > +	.has_prescaler = 1,
> > > > > +	.has_out_clk = 1,
> > > > > +	.export_iosc = 1,
> > > > > +	.has_losc_en = 1,
> > > > > +	.has_auto_swt = 1,
> > > > > +};
> > > > > +
> > > > > +static void __init sun50i_h6_rtc_clk_init(struct device_node *node)
> > > > > +{
> > > > > +	sun6i_rtc_clk_init(node, &sun50i_h6_rtc_data);
> > > > > +}
> > > > > +CLK_OF_DECLARE_DRIVER(sun50i_h6_rtc_clk, "allwinner,sun50i-h6-rtc",
> > > > > +		      sun50i_h6_rtc_clk_init);
> > > > > +
> > > > > 
> > > > >  static const struct sun6i_rtc_clk_data sun8i_v3_rtc_data = {
> > > > >  
> > > > >  	.rc_osc_rate = 32000,
> > > > >  	.has_out_clk = 1,
> > > > > 
> > > > > @@ -675,6 +710,7 @@ static const struct of_device_id
> > > > > sun6i_rtc_dt_ids[]
> > > > > = {
> > > > > 
> > > > >  	{ .compatible = "allwinner,sun8i-r40-rtc" },
> > > > >  	{ .compatible = "allwinner,sun8i-v3-rtc" },
> > > > >  	{ .compatible = "allwinner,sun50i-h5-rtc" },
> > > > > 
> > > > > +	{ .compatible = "allwinner,sun50i-h6-rtc" },
> > > > > 
> > > > >  	{ /* sentinel */ },
> > > > >  
> > > > >  };
> > > > >  MODULE_DEVICE_TABLE(of, sun6i_rtc_dt_ids);
> > > > 
> > > > _______________________________________________
> > > > linux-arm-kernel mailing list
> > > > linux-arm-kernel@...ts.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > 
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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