[PATCH] watchdog: bcm7038_wdt: add big endian support

[PATCH] watchdog: bcm7038_wdt: add big endian support

[Álvaro Fernández Rojas]

bcm7038_wdt can be used on bmips (bcm63xx) devices too.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
 drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
index 979caa18d3c8..62494da1ac57 100644
--- a/drivers/watchdog/bcm7038_wdt.c
+++ b/drivers/watchdog/bcm7038_wdt.c
@@ -34,6 +34,24 @@ struct bcm7038_watchdog {
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
 
+static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
+{
+#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
+}
+
 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
@@ -41,15 +59,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
 
 	timeout = wdt->rate * wdog->timeout;
 
-	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
+	bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
 }
 
 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 
-	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);
 
 	return 0;
 }
@@ -66,8 +84,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 
-	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);
 
 	return 0;
 }
@@ -88,7 +106,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 	u32 time_left;
 
-	time_left = readl(wdt->base + WDT_CMD_REG);
+	time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
 
 	return time_left / wdt->rate;
 }
-- 
2.20.1

Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

[Guenter Roeck]

On 2/22/21 12:03 PM, Álvaro Fernández Rojas wrote:
> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
> 
It might make sense to actually enable it for BCM63XX.

> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
> ---
>  drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
> index 979caa18d3c8..62494da1ac57 100644
> --- a/drivers/watchdog/bcm7038_wdt.c
> +++ b/drivers/watchdog/bcm7038_wdt.c
> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                                 
>  
>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  
> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
> +{
> +#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
> +}
> +

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) ?

Thanks,
Guenter

>  static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
>  {
>  	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> @@ -41,15 +59,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
>  
>  	timeout = wdt->rate * wdog->timeout;
>  
> -	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
> +	bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
>  }
>  
>  static int bcm7038_wdt_ping(struct watchdog_device *wdog)
>  {
>  	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>  
> -	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);
>  
>  	return 0;
>  }
> @@ -66,8 +84,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdog)
>  {
>  	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>  
> -	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);
>  
>  	return 0;
>  }
> @@ -88,7 +106,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
>  	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>  	u32 time_left;
>  
> -	time_left = readl(wdt->base + WDT_CMD_REG);
> +	time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
>  
>  	return time_left / wdt->rate;
>  }
> 

Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

[Álvaro Fernández Rojas]

Hi Guenter,

> El 22 feb 2021, a las 22:24, Guenter Roeck <linux@roeck-us.net> escribió:
> 
> On 2/22/21 12:03 PM, Álvaro Fernández Rojas wrote:
>> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
>> 
> It might make sense to actually enable it for BCM63XX.

bcm63xx SoCs are supported in bcm63xx and bmips.
bcm63xx doesn’t have device tree support, but bmips does and this watchdog is already enabled for bmips.

> 
>> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
>> ---
>> drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
>> 1 file changed, 24 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
>> index 979caa18d3c8..62494da1ac57 100644
>> --- a/drivers/watchdog/bcm7038_wdt.c
>> +++ b/drivers/watchdog/bcm7038_wdt.c
>> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                                 
>> 
>> static bool nowayout = WATCHDOG_NOWAYOUT;
>> 
>> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
>> +{
>> +#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
>> +}
>> +
> 
> 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’t have memory barriers and writel() does.
Those configs use the correct endiannes, so I don’t know what you mean...

> 
> Thanks,
> Guenter
> 
>> static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
>> {
>>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>> @@ -41,15 +59,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
>> 
>>    timeout = wdt->rate * wdog->timeout;
>> 
>> -    writel(timeout, wdt->base + WDT_TIMEOUT_REG);
>> +    bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
>> }
>> 
>> static int bcm7038_wdt_ping(struct watchdog_device *wdog)
>> {
>>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>> 
>> -    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);
>> 
>>    return 0;
>> }
>> @@ -66,8 +84,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdog)
>> {
>>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>> 
>> -    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);
>> 
>>    return 0;
>> }
>> @@ -88,7 +106,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
>>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
>>    u32 time_left;
>> 
>> -    time_left = readl(wdt->base + WDT_CMD_REG);
>> +    time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
>> 
>>    return time_left / wdt->rate;
>> }
>> 
> 

Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

[Guenter Roeck]

On Mon, Feb 22, 2021 at 10:48:09PM +0100, Álvaro Fernández Rojas wrote:
> Hi Guenter,
> 
> > El 22 feb 2021, a las 22:24, Guenter Roeck <linux@roeck-us.net> escribió:
> > 
> > On 2/22/21 12:03 PM, Álvaro Fernández Rojas wrote:
> >> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
> >> 
> > It might make sense to actually enable it for BCM63XX.
> 
> bcm63xx SoCs are supported in bcm63xx and bmips.
> bcm63xx doesn’t have device tree support, but bmips does and this watchdog is already enabled for bmips.
> 

Maybe add a note saying that this will only be supported for devicetree
based systems.

> > 
> >> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
> >> ---
> >> drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
> >> 1 file changed, 24 insertions(+), 6 deletions(-)
> >> 
> >> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
> >> index 979caa18d3c8..62494da1ac57 100644
> >> --- a/drivers/watchdog/bcm7038_wdt.c
> >> +++ b/drivers/watchdog/bcm7038_wdt.c
> >> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                                 
> >> 
> >> static bool nowayout = WATCHDOG_NOWAYOUT;
> >> 
> >> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
> >> +{
> >> +#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
> >> +}
> >> +
> > 
> > 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’t have memory barriers and writel() does.
> Those configs use the correct endiannes, so I don’t know what you mean...
> 
So are you saying that it already works with bmips_stb_defconfig 
(because it is little endian), that bmips_stb_defconfig needs memory
barriers, and that bmips_be_defconfig doesn't need memory barriers ?
Odd, but I'll take you by your word. And other code does something
similar, so I guess there must be a reason for it.

Anyway, after looking into that other code, please use something like

        if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
                __raw_writel(value, reg);
        else
                writel(value, reg);

Thanks,
Guenter

> > 
> > Thanks,
> > Guenter
> > 
> >> static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
> >> {
> >>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> >> @@ -41,15 +59,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
> >> 
> >>    timeout = wdt->rate * wdog->timeout;
> >> 
> >> -    writel(timeout, wdt->base + WDT_TIMEOUT_REG);
> >> +    bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
> >> }
> >> 
> >> static int bcm7038_wdt_ping(struct watchdog_device *wdog)
> >> {
> >>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> >> 
> >> -    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);
> >> 
> >>    return 0;
> >> }
> >> @@ -66,8 +84,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdog)
> >> {
> >>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> >> 
> >> -    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);
> >> 
> >>    return 0;
> >> }
> >> @@ -88,7 +106,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
> >>    struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
> >>    u32 time_left;
> >> 
> >> -    time_left = readl(wdt->base + WDT_CMD_REG);
> >> +    time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
> >> 
> >>    return time_left / wdt->rate;
> >> }
> >> 
> > 

Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

[Florian Fainelli]

On 2/22/2021 2:24 PM, Guenter Roeck wrote:
> On Mon, Feb 22, 2021 at 10:48:09PM +0100, Álvaro Fernández Rojas wrote:
>> Hi Guenter,
>>
>>> El 22 feb 2021, a las 22:24, Guenter Roeck <linux@roeck-us.net> escribió:
>>>
>>> On 2/22/21 12:03 PM, Álvaro Fernández Rojas wrote:
>>>> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
>>>>
>>> It might make sense to actually enable it for BCM63XX.
>>
>> bcm63xx SoCs are supported in bcm63xx and bmips.
>> bcm63xx doesn’t have device tree support, but bmips does and this watchdog is already enabled for bmips.
>>
> 
> Maybe add a note saying that this will only be supported for devicetree
> based systems.
> 
>>>
>>>> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
>>>> ---
>>>> drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
>>>> 1 file changed, 24 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
>>>> index 979caa18d3c8..62494da1ac57 100644
>>>> --- a/drivers/watchdog/bcm7038_wdt.c
>>>> +++ b/drivers/watchdog/bcm7038_wdt.c
>>>> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                                 
>>>>
>>>> static bool nowayout = WATCHDOG_NOWAYOUT;
>>>>
>>>> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
>>>> +{
>>>> +#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
>>>> +}
>>>> +
>>>
>>> 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’t have memory barriers and writel() does.
>> Those configs use the correct endiannes, so I don’t know what you mean...
>>
> So are you saying that it already works with bmips_stb_defconfig 
> (because it is little endian), that bmips_stb_defconfig needs memory
> barriers, and that bmips_be_defconfig doesn't need memory barriers ?
> Odd, but I'll take you by your word. And other code does something
> similar, so I guess there must be a reason for it.

It would be so nice to copy people, and the author of that driver who
could give you such an answer. Neither bmips_be_defconfig nor
bmips_stb_defconfig require barrier because the bus interface towards
registers that is used on those SoCs is non-reordering non-buffered.

> 
> Anyway, after looking into that other code, please use something like
> 
>         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
>                 __raw_writel(value, reg);
>         else
>                 writel(value, reg);

Yes please.
-- 
Florian

Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

[Florian Fainelli]

On 2/22/2021 7:41 PM, Florian Fainelli wrote:
> 
> 
> On 2/22/2021 2:24 PM, Guenter Roeck wrote:
>> On Mon, Feb 22, 2021 at 10:48:09PM +0100, Álvaro Fernández Rojas wrote:
>>> Hi Guenter,
>>>
>>>> El 22 feb 2021, a las 22:24, Guenter Roeck <linux@roeck-us.net> escribió:
>>>>
>>>> On 2/22/21 12:03 PM, Álvaro Fernández Rojas wrote:
>>>>> bcm7038_wdt can be used on bmips (bcm63xx) devices too.
>>>>>
>>>> It might make sense to actually enable it for BCM63XX.
>>>
>>> bcm63xx SoCs are supported in bcm63xx and bmips.
>>> bcm63xx doesn’t have device tree support, but bmips does and this watchdog is already enabled for bmips.
>>>
>>
>> Maybe add a note saying that this will only be supported for devicetree
>> based systems.
>>
>>>>
>>>>> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
>>>>> ---
>>>>> drivers/watchdog/bcm7038_wdt.c | 30 ++++++++++++++++++++++++------
>>>>> 1 file changed, 24 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
>>>>> index 979caa18d3c8..62494da1ac57 100644
>>>>> --- a/drivers/watchdog/bcm7038_wdt.c
>>>>> +++ b/drivers/watchdog/bcm7038_wdt.c
>>>>> @@ -34,6 +34,24 @@ struct bcm7038_watchdog {                                 
>>>>>
>>>>> static bool nowayout = WATCHDOG_NOWAYOUT;
>>>>>
>>>>> +static inline void bcm7038_wdt_write(unsigned long data, void __iomem *reg)
>>>>> +{
>>>>> +#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
>>>>> +}
>>>>> +
>>>>
>>>> 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’t have memory barriers and writel() does.
>>> Those configs use the correct endiannes, so I don’t know what you mean...
>>>
>> So are you saying that it already works with bmips_stb_defconfig 
>> (because it is little endian), that bmips_stb_defconfig needs memory
>> barriers, and that bmips_be_defconfig doesn't need memory barriers ?
>> Odd, but I'll take you by your word. And other code does something
>> similar, so I guess there must be a reason for it.
> 
> It would be so nice to copy people, and the author of that driver who
> could give you such an answer. Neither bmips_be_defconfig nor
> bmips_stb_defconfig require barrier because the bus interface towards
> registers that is used on those SoCs is non-reordering non-buffered.

I should mention though that using __raw_writel() with an ARM big-endian
would not work which is why {read,write}l_relaxed() should be preferred
such that all combinations work. A good example that has been proven to
work on BMIPS BE/LE and ARM BE/LE is bcmgenet.c
-- 
Florian

[PATCH v2] watchdog: bcm7038_wdt: add big endian support

[Álvaro Fernández Rojas]

bcm7038_wdt can be used on bmips big endian (bcm63xx) devices too.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
 v2: use approach indicated by Florian (same as bcmgenet.c)

 drivers/watchdog/bcm7038_wdt.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/watchdog/bcm7038_wdt.c b/drivers/watchdog/bcm7038_wdt.c
index 979caa18d3c8..acaaa0005d5b 100644
--- a/drivers/watchdog/bcm7038_wdt.c
+++ b/drivers/watchdog/bcm7038_wdt.c
@@ -34,6 +34,25 @@ struct bcm7038_watchdog {
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
 
+static inline void bcm7038_wdt_write(u32 value, void __iomem *addr)
+{
+	/* MIPS chips strapped for BE will automagically configure the
+	 * peripheral registers for CPU-native byte order.
+	 */
+	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+		__raw_writel(value, addr);
+	else
+		writel_relaxed(value, addr);
+}
+
+static inline u32 bcm7038_wdt_read(void __iomem *addr)
+{
+	if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+		return __raw_readl(addr);
+	else
+		return readl_relaxed(addr);
+}
+
 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
@@ -41,15 +60,15 @@ static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
 
 	timeout = wdt->rate * wdog->timeout;
 
-	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
+	bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
 }
 
 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 
-	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);
 
 	return 0;
 }
@@ -66,8 +85,8 @@ static int bcm7038_wdt_stop(struct watchdog_device *wdog)
 {
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 
-	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);
 
 	return 0;
 }
@@ -88,7 +107,7 @@ static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
 	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 	u32 time_left;
 
-	time_left = readl(wdt->base + WDT_CMD_REG);
+	time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
 
 	return time_left / wdt->rate;
 }
-- 
2.20.1

Re: [PATCH v2] watchdog: bcm7038_wdt: add big endian support

[Guenter Roeck]

On 2/23/21 12:00 AM, Álvaro Fernández Rojas wrote:
> bcm7038_wdt can be used on bmips big endian (bcm63xx) devices too.
> 
> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

With the assumption that the driver indeed does not need memory
barriers,

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Thanks,
Guenter