[PATCH v3 2/3] watchdog: dw_wdt: get reset lines from dt

[p.zabel@pengutronix.de (Philipp Zabel)]

On Thu, 2017-05-18 at 10:42 +0200, Steffen Trumtrar wrote:
> The dw_wdt has an external reset line, that can keep the device in reset
> and therefore rendering it useless and also is the only way of stopping
> the watchdog once it was started.
> 
> Get the reset lines for this core from the devicetree. As these lines are
> optional, use devm_reset_control_get_optional_shared. If the reset line
> is not specified in the devicetree, the reset framework will just skip
> deasserting and continue.
> This way all users of the driver will continue to function without
> any harm, even if the reset line is not specified in the devicetree.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: linux-watchdog at vger.kernel.org
> ---
>  drivers/watchdog/dw_wdt.c |  9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 914da3a4d334..61cbae3a9331 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -29,6 +29,7 @@
>  #include <linux/of.h>
>  #include <linux/pm.h>
>  #include <linux/platform_device.h>
> +#include <linux/reset.h>
>  #include <linux/watchdog.h>
>  
>  #define WDOG_CONTROL_REG_OFFSET		    0x00
> @@ -54,6 +55,7 @@ struct dw_wdt {
>  	struct clk		*clk;
>  	unsigned long		rate;
>  	struct watchdog_device	wdd;
> +	struct reset_control	*rst;
>  };
>  
>  #define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)
> @@ -234,6 +236,12 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
>  		goto out_disable_clk;

Sorry, I didn't notice this before.

>  	}
>  
> +	dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> +	if (IS_ERR(dw_wdt->rst))
> +		return PTR_ERR(dw_wdt->rst);

This should either goto out_disable_clk, or the reset_control could be
acquired a bit earlier before enabling the clock.

> +
> +	reset_control_deassert(dw_wdt->rst);
> +
>  	wdd = &dw_wdt->wdd;
>  	wdd->info = &dw_wdt_ident;
>  	wdd->ops = &dw_wdt_ops;
> @@ -278,6 +286,7 @@ static int dw_wdt_drv_remove(struct platform_device *pdev)
>  {
>  	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
>  
> +	reset_control_assert(dw_wdt->rst);

And I'd move this ...

>  	watchdog_unregister_device(&dw_wdt->wdd);

... here for symmetry.

>  	clk_disable_unprepare(dw_wdt->clk);
>  

Otherwise,
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp