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From:   =?utf-8?Q?=C3=81lvaro_Fern=C3=A1ndez_Rojas?= <noltari@gmail.com>
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Subject: Re: [PATCH] watchdog: bcm7038_wdt: add big endian support
Date:   Mon, 22 Feb 2021 22:48:09 +0100
Message-Id: <80DB1B7E-D719-4597-A2B7-7CAD592E1B19@gmail.com>
References: <9381ef9e-a569-9bcd-5546-a48922e4961d@roeck-us.net>
Cc:     Wim Van Sebroeck <wim@linux-watchdog.org>,
        linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
In-Reply-To: <9381ef9e-a569-9bcd-5546-a48922e4961d@roeck-us.net>
To:     Guenter Roeck <linux@roeck-us.net>
Precedence: bulk

Hi Guenter,

> El 22 feb 2021, a las 22:24, Guenter Roeck <linux@roeck-us.net> escribi=C3=
=B3:
>=20
> =EF=BB=BFOn 2/22/21 12:03 PM, =C3=81lvaro Fern=C3=A1ndez Rojas wrote:
>> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
>>=20
> It might make sense to actually enable it for BCM63XX.

bcm63xx SoCs are supported in bcm63xx and bmips.
bcm63xx doesn=E2=80=99t have device tree support, but bmips does and this wa=
tchdog is already enabled for bmips.

>=20
>> Signed-off-by: =C3=81lvaro Fern=C3=A1ndez Rojas <noltari@gmail.com>
>> ---
>> drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
>> 1 file changed, 24 insertions(+), 6 deletions(-)
>>=20
>> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wd=
t.c
>> index 979caa18d3c8..62494da1ac57 100644
>> --- a/drivers/watchdog/bcm7038_wdt.c
>> +++ b/drivers/watchdog/bcm7038_wdt.c
>> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                             =
   =20
>>=20
>> static bool nowayout =3D WATCHDOG_NOWAYOUT;
>>=20
>> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *r=
eg)
>> +{
>> +#ifdef CONFIG_CPU_BIG_ENDIAN
>> +    __raw_writel(data, reg);
>> +#else
>> +    writel(data, reg);
>> +#endif
>> +}
>> +
>> +static inline unsigned long bcm7038_wdt_read(void __iomem *reg)
>> +{
>> +#ifdef CONFIG_CPU_BIG_ENDIAN
>> +    return __raw_readl(reg);
>> +#else
>> +    return readl(reg);
>> +#endif
>> +}
>> +
>=20
> This needs further explanation. Why not just use __raw_writel() and
> __raw_readl() unconditionally ? Also, is it known for sure that,
> say, bmips_be_defconfig otherwise uses the wrong endianness
> (vs. bmips_stb_defconfig which is a little endian configuration) ?

Because __raw_writel() doesn=E2=80=99t have memory barriers and writel() doe=
s.
Those configs use the correct endiannes, so I don=E2=80=99t know what you me=
an...

>=20
> Thanks,
> Guenter
>=20
>> static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
>> {
>>    struct bcm7038_watchdog *wdt =3D watchdog_get_drvdata(wdog);
>> @@ -41,15 +59,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchd=
og_device *wdog)
>>=20
>>    timeout =3D wdt->rate * wdog->timeout;
>>=20
>> -    writel(timeout, wdt->base + WDT_TIMEOUT_REG);
>> +    bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
>> }
>>=20
>> static int bcm7038_wdt_ping(struct watchdog_device *wdog)
>> {
>>    struct bcm7038_watchdog *wdt =3D watchdog_get_drvdata(wdog);
>>=20
>> -    writel(WDT_START_1, wdt->base + WDT_CMD_REG);
>> -    writel(WDT_START_2, wdt->base + WDT_CMD_REG);
>> +    bcm7038_wdt_write(WDT_START_1, wdt->base + WDT_CMD_REG);
>> +    bcm7038_wdt_write(WDT_START_2, wdt->base + WDT_CMD_REG);
>>=20
>>    return 0;
>> }
>> @@ -66,8 +84,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdo=
g)
>> {
>>    struct bcm7038_watchdog *wdt =3D watchdog_get_drvdata(wdog);
>>=20
>> -    writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
>> -    writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
>> +    bcm7038_wdt_write(WDT_STOP_1, wdt->base + WDT_CMD_REG);
>> +    bcm7038_wdt_write(WDT_STOP_2, wdt->base + WDT_CMD_REG);
>>=20
>>    return 0;
>> }
>> @@ -88,7 +106,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct wa=
tchdog_device *wdog)
>>    struct bcm7038_watchdog *wdt =3D watchdog_get_drvdata(wdog);
>>    u32 time_left;
>>=20
>> -    time_left =3D readl(wdt->base + WDT_CMD_REG);
>> +    time_left =3D bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
>>=20
>>    return time_left / wdt->rate;
>> }
>>=20
>=20