linux-kernel - Re: [PATCH RESEND V2 2/3] clocksource: imx-sysctr: Make timer work with clock driver using platform driver model

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Date:   Thu, 27 Jun 2019 14:36:27 +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, l.stach@...gutronix.de,
        abel.vesa@....com, ccaione@...libre.com, angus@...ea.ca,
        andrew.smirnov@...il.com, 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 V2 2/3] clocksource: imx-sysctr: Make timer work
 with clock driver using platform driver model

On 23/06/2019 14:38, Anson.Huang@....com wrote:
> From: Anson Huang <Anson.Huang@....com>
> 
> On some i.MX8M platforms, clock driver uses platform driver
> model and it is NOT ready during timer initialization phase,
> the clock operations will fail and system counter driver will
> fail too. As all the i.MX8M platforms' system counter clock
> are from OSC which is always enabled, so it is no need to enable
> clock for system counter driver, the ONLY thing is to pass
> clock frequence to driver.
> 
> To make system counter driver work for upper scenario, add an
> option of skipping of_clk operation for system counter driver,
> an optional property "clock-frequency" is introduced to pass
> the frequency value to system counter driver and indicate driver
> to skip of_clk operations.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>
> ---
> Changes since V1:
> 	- improve commit log, no content change.
> ---
>  drivers/clocksource/timer-imx-sysctr.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/clocksource/timer-imx-sysctr.c b/drivers/clocksource/timer-imx-sysctr.c
> index fd7d680..8ff3d7e 100644
> --- a/drivers/clocksource/timer-imx-sysctr.c
> +++ b/drivers/clocksource/timer-imx-sysctr.c
> @@ -129,6 +129,14 @@ static void __init sysctr_clockevent_init(void)
>  static int __init sysctr_timer_init(struct device_node *np)
>  {
>  	int ret = 0;
> +	u32 rate;
> +
> +	if (!of_property_read_u32(np, "clock-frequency",
> +				  &rate)) {
> +		to_sysctr.of_clk.rate = rate;
> +		to_sysctr.of_clk.period = DIV_ROUND_UP(rate, HZ);
> +		to_sysctr.flags &= ~TIMER_OF_CLOCK;
> +	}

Please take the opportunity to add the TIMER_OF_CLOCK_FREQUENCY flag in
timer-of and the corresponding code above.

Then check the clock-frequency presence and add TIMER_OF_CLOCK or
TIMER_OF_CLOCK_FREQUENCY flag to the timer-of structure.

eg:

    to_sysctr.flags |= of_find_property(np, "clock-frequency", NULL) ?
		TIMER_OF_CLOCK_FREQUENCY : TIMER_OF_CLOCK;
	



>  	ret = timer_of_init(np, &to_sysctr);
>  	if (ret)
> 


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