linux-kernel - Re: [PATCH v6 2/4] rtc: goldfish: use __raw_writel()/__raw

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Message-Id: <90a1b3b0-97d7-4880-a42f-44c450cbc2fb@www.fastmail.com>
Date:   Thu, 13 Jan 2022 21:18:53 +0000
From:   "Jiaxun Yang" <jiaxun.yang@...goat.com>
To:     "Laurent Vivier" <laurent@...ier.eu>, linux-kernel@...r.kernel.org
Cc:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Alessandro Zummo" <a.zummo@...ertech.it>,
        linux-m68k@...ts.linux-m68k.org,
        "John Stultz" <john.stultz@...aro.org>, linux-rtc@...r.kernel.org,
        "Arnd Bergmann" <arnd@...db.de>,
        "Daniel Lezcano" <daniel.lezcano@...aro.org>,
        "Geert Uytterhoeven" <geert@...ux-m68k.org>,
        "Stephen Boyd" <sboyd@...nel.org>,
        "Alexandre Belloni" <alexandre.belloni@...tlin.com>
Subject: Re: [PATCH v6 2/4] rtc: goldfish: use __raw_writel()/__raw_readl()



在2022年1月13日一月 下午8:19，Laurent Vivier写道：
> As android implementation defines the endianness of the device is the one
> of the architecture replace all writel()/readl() by
> __raw_writel()/__raw_readl()
>
> https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-master-dev/hw/timer/goldfish_timer.c#177
>
> The same change has been done for goldfish-tty:
>
>   commit da31de35cd2f ("tty: goldfish: use __raw_writel()/__raw_readl()")
>
> Signed-off-by: Laurent Vivier <laurent@...ier.eu>

Acked-by: Jiauxn Yang <jiaxun.yang@...goat.com>

Well I do think it's a mistake by Android. They only considered little endian as they only have little endian devices.

But given that the implementation is already a part of QEMU, we must live with that :-)

Thanks.

> ---
>  drivers/rtc/rtc-goldfish.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
> index 7ab95d052644..3e76160d40b9 100644
> --- a/drivers/rtc/rtc-goldfish.c
> +++ b/drivers/rtc/rtc-goldfish.c
> @@ -41,8 +41,8 @@ static int goldfish_rtc_read_alarm(struct device *dev,
>  	rtcdrv = dev_get_drvdata(dev);
>  	base = rtcdrv->base;
> 
> -	rtc_alarm_low = readl(base + TIMER_ALARM_LOW);
> -	rtc_alarm_high = readl(base + TIMER_ALARM_HIGH);
> +	rtc_alarm_low = __raw_readl(base + TIMER_ALARM_LOW);
> +	rtc_alarm_high = __raw_readl(base + TIMER_ALARM_HIGH);
>  	rtc_alarm = (rtc_alarm_high << 32) | rtc_alarm_low;
> 
>  	do_div(rtc_alarm, NSEC_PER_SEC);
> @@ -50,7 +50,7 @@ static int goldfish_rtc_read_alarm(struct device *dev,
> 
>  	rtc_time64_to_tm(rtc_alarm, &alrm->time);
> 
> -	if (readl(base + TIMER_ALARM_STATUS))
> +	if (__raw_readl(base + TIMER_ALARM_STATUS))
>  		alrm->enabled = 1;
>  	else
>  		alrm->enabled = 0;
> @@ -71,18 +71,18 @@ static int goldfish_rtc_set_alarm(struct device *dev,
> 
>  	if (alrm->enabled) {
>  		rtc_alarm64 = rtc_tm_to_time64(&alrm->time) * NSEC_PER_SEC;
> -		writel((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
> -		writel(rtc_alarm64, base + TIMER_ALARM_LOW);
> -		writel(1, base + TIMER_IRQ_ENABLED);
> +		__raw_writel((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
> +		__raw_writel(rtc_alarm64, base + TIMER_ALARM_LOW);
> +		__raw_writel(1, base + TIMER_IRQ_ENABLED);
>  	} else {
>  		/*
>  		 * if this function was called with enabled=0
>  		 * then it could mean that the application is
>  		 * trying to cancel an ongoing alarm
>  		 */
> -		rtc_status_reg = readl(base + TIMER_ALARM_STATUS);
> +		rtc_status_reg = __raw_readl(base + TIMER_ALARM_STATUS);
>  		if (rtc_status_reg)
> -			writel(1, base + TIMER_CLEAR_ALARM);
> +			__raw_writel(1, base + TIMER_CLEAR_ALARM);
>  	}
> 
>  	return 0;
> @@ -98,9 +98,9 @@ static int goldfish_rtc_alarm_irq_enable(struct device *dev,
>  	base = rtcdrv->base;
> 
>  	if (enabled)
> -		writel(1, base + TIMER_IRQ_ENABLED);
> +		__raw_writel(1, base + TIMER_IRQ_ENABLED);
>  	else
> -		writel(0, base + TIMER_IRQ_ENABLED);
> +		__raw_writel(0, base + TIMER_IRQ_ENABLED);
> 
>  	return 0;
>  }
> @@ -110,7 +110,7 @@ static irqreturn_t goldfish_rtc_interrupt(int irq, 
> void *dev_id)
>  	struct goldfish_rtc *rtcdrv = dev_id;
>  	void __iomem *base = rtcdrv->base;
> 
> -	writel(1, base + TIMER_CLEAR_INTERRUPT);
> +	__raw_writel(1, base + TIMER_CLEAR_INTERRUPT);
> 
>  	rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);
> 
> @@ -128,8 +128,8 @@ static int goldfish_rtc_read_time(struct device 
> *dev, struct rtc_time *tm)
>  	rtcdrv = dev_get_drvdata(dev);
>  	base = rtcdrv->base;
> 
> -	time_low = readl(base + TIMER_TIME_LOW);
> -	time_high = readl(base + TIMER_TIME_HIGH);
> +	time_low = __raw_readl(base + TIMER_TIME_LOW);
> +	time_high = __raw_readl(base + TIMER_TIME_HIGH);
>  	time = (time_high << 32) | time_low;
> 
>  	do_div(time, NSEC_PER_SEC);
> @@ -149,8 +149,8 @@ static int goldfish_rtc_set_time(struct device 
> *dev, struct rtc_time *tm)
>  	base = rtcdrv->base;
> 
>  	now64 = rtc_tm_to_time64(tm) * NSEC_PER_SEC;
> -	writel((now64 >> 32), base + TIMER_TIME_HIGH);
> -	writel(now64, base + TIMER_TIME_LOW);
> +	__raw_writel((now64 >> 32), base + TIMER_TIME_HIGH);
> +	__raw_writel(now64, base + TIMER_TIME_LOW);
> 
>  	return 0;
>  }
> -- 
> 2.34.1

-- 
- Jiaxun