Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
User-Agent: Cyrus-JMAP/3.5.0-alpha0-4569-g891f756243-fm-20220111.001-g891f7562
Mime-Version: 1.0
Message-Id: <f6e1858c-a31f-4f07-96ed-fb1d792dab49@www.fastmail.com>
In-Reply-To: <20220115193245.3777833-3-laurent@vivier.eu>
References: <20220115193245.3777833-1-laurent@vivier.eu>
 <20220115193245.3777833-3-laurent@vivier.eu>
Date:   Sat, 15 Jan 2022 22:25:58 +0000
From:   "Jiaxun Yang" <jiaxun.yang@flygoat.com>
To:     "Laurent Vivier" <laurent@vivier.eu>, linux-kernel@vger.kernel.org
Cc:     "John Stultz" <john.stultz@linaro.org>, linux-rtc@vger.kernel.org,
        "Daniel Lezcano" <daniel.lezcano@linaro.org>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        "Alessandro Zummo" <a.zummo@towertech.it>,
        "Alexandre Belloni" <alexandre.belloni@bootlin.com>,
        "Stephen Boyd" <sboyd@kernel.org>,
        "Geert Uytterhoeven" <geert@linux-m68k.org>,
        "Arnd Bergmann" <arnd@arndb.de>, linux-m68k@lists.linux-m68k.org
Subject: Re: [PATCH v8 2/4] rtc: goldfish: introduce
 goldfish_ioread32()/goldfish_iowrite32()
Content-Type: text/plain;charset=utf-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk


=E5=9C=A82022=E5=B9=B41=E6=9C=8815=E6=97=A5=E4=B8=80=E6=9C=88 =E4=B8=8B=E5=
=8D=887:32=EF=BC=8CLaurent Vivier=E5=86=99=E9=81=93=EF=BC=9A
> The goldfish device always uses the same endianness as the architecture
> using it:
> https://android.googlesource.com/platform/external/qemu/+/refs/heads/e=
mu-master-dev/hw/timer/goldfish_timer.c#177
>
> On a big-endian machine, the device is also big-endian, on a
> little-endian machine the device is little-endian.
>
> So we need to use the right accessor to read/write values to the goldf=
ish
> registers: ioread32()/iowrite32() on a little-endian machine,
> ioread32be()/iowrite32be() on a big-endian machine.
>
> This patch introduces goldfish_ioread32()/goldfish_iowrite32() that us=
es
> the expected accessor according to the machine endianness.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>

Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

> ---
>  drivers/rtc/rtc-goldfish.c | 39 +++++++++++++++++++++++---------------
>  1 file changed, 24 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
> index 7ab95d052644..b0cae4729b03 100644
> --- a/drivers/rtc/rtc-goldfish.c
> +++ b/drivers/rtc/rtc-goldfish.c
> @@ -23,6 +23,15 @@
>  #define TIMER_ALARM_STATUS	0x18
>  #define TIMER_CLEAR_INTERRUPT	0x1c
>=20
> +/* goldfish endianness depends on CPU endianness */
> +#ifdef CONFIG_CPU_BIG_ENDIAN
> +#define goldfish_ioread32 ioread32be
> +#define goldfish_iowrite32 iowrite32be
> +#else
> +#define goldfish_ioread32 ioread32
> +#define goldfish_iowrite32 iowrite32
> +#endif
> +
>  struct goldfish_rtc {
>  	void __iomem *base;
>  	int irq;
> @@ -41,8 +50,8 @@ static int goldfish_rtc_read_alarm(struct device *de=
v,
>  	rtcdrv =3D dev_get_drvdata(dev);
>  	base =3D rtcdrv->base;
>=20
> -	rtc_alarm_low =3D readl(base + TIMER_ALARM_LOW);
> -	rtc_alarm_high =3D readl(base + TIMER_ALARM_HIGH);
> +	rtc_alarm_low =3D goldfish_ioread32(base + TIMER_ALARM_LOW);
> +	rtc_alarm_high =3D goldfish_ioread32(base + TIMER_ALARM_HIGH);
>  	rtc_alarm =3D (rtc_alarm_high << 32) | rtc_alarm_low;
>=20
>  	do_div(rtc_alarm, NSEC_PER_SEC);
> @@ -50,7 +59,7 @@ static int goldfish_rtc_read_alarm(struct device *de=
v,
>=20
>  	rtc_time64_to_tm(rtc_alarm, &alrm->time);
>=20
> -	if (readl(base + TIMER_ALARM_STATUS))
> +	if (goldfish_ioread32(base + TIMER_ALARM_STATUS))
>  		alrm->enabled =3D 1;
>  	else
>  		alrm->enabled =3D 0;
> @@ -71,18 +80,18 @@ static int goldfish_rtc_set_alarm(struct device *d=
ev,
>=20
>  	if (alrm->enabled) {
>  		rtc_alarm64 =3D 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);
> +		goldfish_iowrite32((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
> +		goldfish_iowrite32(rtc_alarm64, base + TIMER_ALARM_LOW);
> +		goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
>  	} else {
>  		/*
>  		 * if this function was called with enabled=3D0
>  		 * then it could mean that the application is
>  		 * trying to cancel an ongoing alarm
>  		 */
> -		rtc_status_reg =3D readl(base + TIMER_ALARM_STATUS);
> +		rtc_status_reg =3D goldfish_ioread32(base + TIMER_ALARM_STATUS);
>  		if (rtc_status_reg)
> -			writel(1, base + TIMER_CLEAR_ALARM);
> +			goldfish_iowrite32(1, base + TIMER_CLEAR_ALARM);
>  	}
>=20
>  	return 0;
> @@ -98,9 +107,9 @@ static int goldfish_rtc_alarm_irq_enable(struct dev=
ice *dev,
>  	base =3D rtcdrv->base;
>=20
>  	if (enabled)
> -		writel(1, base + TIMER_IRQ_ENABLED);
> +		goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
>  	else
> -		writel(0, base + TIMER_IRQ_ENABLED);
> +		goldfish_iowrite32(0, base + TIMER_IRQ_ENABLED);
>=20
>  	return 0;
>  }
> @@ -110,7 +119,7 @@ static irqreturn_t goldfish_rtc_interrupt(int irq,=20
> void *dev_id)
>  	struct goldfish_rtc *rtcdrv =3D dev_id;
>  	void __iomem *base =3D rtcdrv->base;
>=20
> -	writel(1, base + TIMER_CLEAR_INTERRUPT);
> +	goldfish_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);
>=20
>  	rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);
>=20
> @@ -128,8 +137,8 @@ static int goldfish_rtc_read_time(struct device=20
> *dev, struct rtc_time *tm)
>  	rtcdrv =3D dev_get_drvdata(dev);
>  	base =3D rtcdrv->base;
>=20
> -	time_low =3D readl(base + TIMER_TIME_LOW);
> -	time_high =3D readl(base + TIMER_TIME_HIGH);
> +	time_low =3D goldfish_ioread32(base + TIMER_TIME_LOW);
> +	time_high =3D goldfish_ioread32(base + TIMER_TIME_HIGH);
>  	time =3D (time_high << 32) | time_low;
>=20
>  	do_div(time, NSEC_PER_SEC);
> @@ -149,8 +158,8 @@ static int goldfish_rtc_set_time(struct device=20
> *dev, struct rtc_time *tm)
>  	base =3D rtcdrv->base;
>=20
>  	now64 =3D rtc_tm_to_time64(tm) * NSEC_PER_SEC;
> -	writel((now64 >> 32), base + TIMER_TIME_HIGH);
> -	writel(now64, base + TIMER_TIME_LOW);
> +	goldfish_iowrite32((now64 >> 32), base + TIMER_TIME_HIGH);
> +	goldfish_iowrite32(now64, base + TIMER_TIME_LOW);
>=20
>  	return 0;
>  }
> --=20
> 2.34.1

--=20
- Jiaxun