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Message-ID: <DB3PR0402MB3916A54972EE7887FCB18A23F5F90@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Date: Mon, 1 Jul 2019 09:04:14 +0000
From: Anson Huang <anson.huang@....com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
Leonard Crestez <leonard.crestez@....com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
Daniel Baluta <daniel.baluta@....com>,
Jacky Bai <ping.bai@....com>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
Abel Vesa <abel.vesa@....com>,
"andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
"ccaione@...libre.com" <ccaione@...libre.com>,
"angus@...ea.ca" <angus@...ea.ca>,
"agx@...xcpu.org" <agx@...xcpu.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
CC: dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V3 1/5] clocksource: timer-of: Support getting clock
frequency from DT
Hi, Daniel
> Subject: Re: [PATCH V3 1/5] clocksource: timer-of: Support getting clock
> frequency from DT
>
>
> Hi Anson,
>
> thanks for taking care of adding the clock-frequency handling in the timer-of.
Sure.
>
> On 28/06/2019 05:30, Anson.Huang@....com wrote:
> > From: Anson Huang <Anson.Huang@....com>
> >
> > More and more platforms use platform driver model for clock driver, so
> > the clock driver is NOT ready during timer initialization phase, it
> > will cause timer initialization failed.
> >
> > To support those platforms with upper scenario, introducing a new flag
> > TIMER_OF_CLOCK_FREQUENCY which is mutually exclusive with
> > TIMER_OF_CLOCK flag to support getting timer clock frequency from DT,
> > then of_clk operations can be skipped.
> >
> > User needs to select either TIMER_OF_CLOCK_FREQUENCY or
> TIMER_OF_CLOCK
> > flag if want to use timer-of driver to initialize the clock rate, and
> > the corresponding clock name or property name needs to be specified.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@....com>
> > ---
> > New patch:
> > - Add new flag of TIMER_OF_CLOCK_FREQUENCY, mutually exclusive
> with TIMER_OF_CLOCK, to support
> > getting clock frequency from DT directly;
> > - Add prop_name to of_timer_clk structure, if using
> TIMER_OF_CLOCK_FREQUENCY flag, user needs
> > to pass the property name for timer-of driver to get clock frequency
> from DT, this is to avoid
> > the couple of timer-of driver and DT, so timer-of driver does NOT
> use a fixed property name.
> > ---
> > drivers/clocksource/timer-of.c | 23 +++++++++++++++++++++++
> > drivers/clocksource/timer-of.h | 8 +++++---
> > 2 files changed, 28 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/clocksource/timer-of.c
> > b/drivers/clocksource/timer-of.c index 8054228..c91a8b6 100644
> > --- a/drivers/clocksource/timer-of.c
> > +++ b/drivers/clocksource/timer-of.c
> > @@ -161,6 +161,21 @@ static __init int timer_of_base_init(struct
> device_node *np,
> > return 0;
> > }
> >
> > +static __init int timer_of_clk_frequency_init(struct device_node *np,
> > + struct of_timer_clk *of_clk) {
> > + int ret;
> > + u32 rate;
> > +
> > + ret = of_property_read_u32(np, of_clk->prop_name, &rate);
> > + if (!ret) {
> > + of_clk->rate = rate;
> > + of_clk->period = DIV_ROUND_UP(rate, HZ);
> > + }
> > +
> > + return ret;
> > +}
> > +
> > int __init timer_of_init(struct device_node *np, struct timer_of *to)
> > {
> > int ret = -EINVAL;
> > @@ -178,6 +193,11 @@ int __init timer_of_init(struct device_node *np,
> struct timer_of *to)
> > if (ret)
> > goto out_fail;
> > flags |= TIMER_OF_CLOCK;
> > + } else if (to->flags & TIMER_OF_CLOCK_FREQUENCY) {
> > + ret = timer_of_clk_frequency_init(np, &to->of_clk);
> > + if (ret)
> > + goto out_fail;
> > + flags |= TIMER_OF_CLOCK_FREQUENCY;
> > }
>
> /* Pre-condition */
>
> if (to->flags & (TIMER_OF_CLOCK | TIMER_OF_CLOCK_FREQUENCY))
> return -EINVAL;
>
> [ ... ]
>
> if (to->flags & TIMER_OF_CLOCK) {
> }
>
> if (to->flags & TIMER_OF_CLOCK_FREQUENCY) { }
>
Ah, make sense, they are exclusive, will add it in next version.
> > if (to->flags & TIMER_OF_IRQ) {
> > @@ -201,6 +221,9 @@ int __init timer_of_init(struct device_node *np,
> struct timer_of *to)
> > if (flags & TIMER_OF_CLOCK)
> > timer_of_clk_exit(&to->of_clk);
> >
> > + if (flags & TIMER_OF_CLOCK_FREQUENCY)
> > + to->of_clk.rate = 0;
> > +
> > if (flags & TIMER_OF_BASE)
> > timer_of_base_exit(&to->of_base);
> > return ret;
> > diff --git a/drivers/clocksource/timer-of.h
> > b/drivers/clocksource/timer-of.h index a5478f3..f1a083e 100644
> > --- a/drivers/clocksource/timer-of.h
> > +++ b/drivers/clocksource/timer-of.h
> > @@ -4,9 +4,10 @@
> >
> > #include <linux/clockchips.h>
> >
> > -#define TIMER_OF_BASE 0x1
> > -#define TIMER_OF_CLOCK 0x2
> > -#define TIMER_OF_IRQ 0x4
> > +#define TIMER_OF_BASE 0x1
> > +#define TIMER_OF_CLOCK 0x2
> > +#define TIMER_OF_IRQ 0x4
> > +#define TIMER_OF_CLOCK_FREQUENCY 0x8
> >
> > struct of_timer_irq {
> > int irq;
> > @@ -26,6 +27,7 @@ struct of_timer_base { struct of_timer_clk {
> > struct clk *clk;
> > const char *name;
> > + const char *prop_name;
>
> For the moment, keep it hardcoded with "clock-frequency" directly in the
> function.
OK, then I will NOT add any dt-binding for this property. The reason to use prop_name
instead of hardcode is I don't want to create a binding doc just for this property.
Thanks,
Anson.
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