linux-kernel - Re: [PATCH] watchdog: bcm7038

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Date:   Mon, 22 Feb 2021 13:24:04 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Álvaro Fernández Rojas <noltari@...il.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: bcm7038_wdt: add big endian support

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@...il.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;
>  }
>