Re: [linux-sunxi] [PATCH 2/3] rtc: sun6i: Add support for H6 RTC
From: OndÅej Jirman
Date: Mon Aug 05 2019 - 06:20:05 EST
On Mon, Aug 05, 2019 at 06:16:14PM +0800, Chen-Yu Tsai wrote:
> On Fri, Apr 12, 2019 at 8:07 PM megous via linux-sunxi
> <linux-sunxi@xxxxxxxxxxxxxxxx> wrote:
> > From: Ondrej Jirman <megous@xxxxxxxxxx>
> > 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@xxxxxxxxxx>
> > ---
> > 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 11f56de52179..7375a530c565 100644
> > --- a/drivers/rtc/rtc-sun6i.c
> > +++ b/drivers/rtc/rtc-sun6i.c
> > @@ -41,9 +41,11 @@
> > /* Control register */
> > #define SUN6I_LOSC_CTRL 0x0000
> > #define SUN6I_LOSC_CTRL_KEY (0x16aa << 16)
> > +#define SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS BIT(15)
> Manual says bit 14? Or is this different from LOSC_AUTO_SWT_EN?
> The rest looks ok.
Yes, see H6 BSP:
20 #define REG_CLK32K_AUTO_SWT_EN BIT(14)
21 #define REG_CLK32K_AUTO_SWT_BYPASS BIT(15)