linux-kernel - Re: [PATCH V5 1/5] clocksource: imx-sysctr: Add internal clock divider handle

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Message-ID: <7edad4d7-5ba2-d710-eb8d-b3ff97051a41@linaro.org>
Date:   Tue, 6 Aug 2019 12:27:51 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Anson Huang <anson.huang@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "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>,
        dl-linux-imx <linux-imx@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        Leonard Crestez <leonard.crestez@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        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-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH V5 1/5] clocksource: imx-sysctr: Add internal clock
 divider handle

On 06/08/2019 03:55, Anson Huang wrote:
> Gentle ping...

Coming back from vacation. It is in the pipe ... :)

>> From: Anson Huang <Anson.Huang@....com>
>>
>> The system counter block guide states that the base clock is internally divided
>> by 3 before use, that means the clock input of system counter defined in DT
>> should be base clock which is normally from OSC, and then internally divided
>> by 3 before use.
>>
>> Signed-off-by: Anson Huang <Anson.Huang@....com>
>> ---
>> Changes since V4:
>> 	- to solve the clock driver probed after system counter driver issue,
>> now we can easily switch to
>> 	  use fixed clock defined in DT and get its rate, then divided by 3 to
>> get real clock rate for
>> 	  system counter driver, no need to add "clock-frequency" property in
>> DT.
>> ---
>>  drivers/clocksource/timer-imx-sysctr.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/clocksource/timer-imx-sysctr.c
>> b/drivers/clocksource/timer-imx-sysctr.c
>> index fd7d680..b7c80a3 100644
>> --- a/drivers/clocksource/timer-imx-sysctr.c
>> +++ b/drivers/clocksource/timer-imx-sysctr.c
>> @@ -20,6 +20,8 @@
>>  #define SYS_CTR_EN		0x1
>>  #define SYS_CTR_IRQ_MASK	0x2
>>
>> +#define SYS_CTR_CLK_DIV		0x3
>> +
>>  static void __iomem *sys_ctr_base;
>>  static u32 cmpcr;
>>
>> @@ -134,6 +136,9 @@ static int __init sysctr_timer_init(struct device_node
>> *np)
>>  	if (ret)
>>  		return ret;
>>
>> +	/* system counter clock is divided by 3 internally */
>> +	to_sysctr.of_clk.rate /= SYS_CTR_CLK_DIV;
>> +
>>  	sys_ctr_base = timer_of_base(&to_sysctr);
>>  	cmpcr = readl(sys_ctr_base + CMPCR);
>>  	cmpcr &= ~SYS_CTR_EN;
>> --
>> 2.7.4
> 


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