linux-kernel - Re: [PATCH RESEND V4 1/5] clocksource: timer-of: Support getting clock frequency from DT

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Message-ID: <c7ff76e5-d73d-e71e-c3f4-445bdd2c5b93@linaro.org>
Date:   Tue, 2 Jul 2019 10:06:44 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Anson.Huang@....com, tglx@...utronix.de, robh+dt@...nel.org,
        mark.rutland@....com, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, leonard.crestez@....com,
        viresh.kumar@...aro.org, daniel.baluta@....com, ping.bai@....com,
        l.stach@...gutronix.de, abel.vesa@....com,
        andrew.smirnov@...il.com, ccaione@...libre.com, angus@...ea.ca,
        agx@...xcpu.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Linux-imx@....com
Subject: Re: [PATCH RESEND V4 1/5] clocksource: timer-of: Support getting
 clock frequency from DT

Hi Anson,

why did you resend the series?


On 02/07/2019 09:55, 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's timer node, the property name should be "clock-frequency",
> 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.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> ---
> Changes since V3:
> 	- use hardcoded "clock-frequency" instead of adding new variable prop_name;
> 	- add pre-condition check for TIMER_OF_CLOCK and TIMER_OF_CLOCK_FREQUENCY, they MUST be exclusive.
> ---
>  drivers/clocksource/timer-of.c | 29 +++++++++++++++++++++++++++++
>  drivers/clocksource/timer-of.h |  7 ++++---
>  2 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-of.c b/drivers/clocksource/timer-of.c
> index 8054228..858f684 100644
> --- a/drivers/clocksource/timer-of.c
> +++ b/drivers/clocksource/timer-of.c
> @@ -161,11 +161,30 @@ 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, "clock-frequency", &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)
>  {
> +	unsigned long clock_flags = TIMER_OF_CLOCK | TIMER_OF_CLOCK_FREQUENCY;
>  	int ret = -EINVAL;
>  	int flags = 0;
>  
> +	if ((to->flags & clock_flags) == clock_flags)
> +		return ret;
> +
>  	if (to->flags & TIMER_OF_BASE) {
>  		ret = timer_of_base_init(np, &to->of_base);
>  		if (ret)
> @@ -180,6 +199,13 @@ int __init timer_of_init(struct device_node *np, struct timer_of *to)
>  		flags |= TIMER_OF_CLOCK;
>  	}
>  
> +	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;
> +	}
> +
>  	if (to->flags & TIMER_OF_IRQ) {
>  		ret = timer_of_irq_init(np, &to->of_irq);
>  		if (ret)
> @@ -201,6 +227,9 @@ 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..a08e108 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;
> 


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