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@xxxxxxxxxxxxxx>
> Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: linux-watchdog@xxxxxxxxxxxxxxx
> ---
> 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@xxxxxxxxxxxxxx>
regards
Philipp
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