linux-kernel - Re: [PATCH v2] watchdog: Add a device managed API for watchdog_register

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Message-ID: <57490281.50000@roeck-us.net>
Date:	Fri, 27 May 2016 19:29:21 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Neil Armstrong <narmstrong@...libre.com>,
	linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
	Wim Van Sebroeck <wim@...ana.be>
Subject: Re: [PATCH v2] watchdog: Add a device managed API for
 watchdog_register_device()

On 05/27/2016 08:33 AM, Neil Armstrong wrote:
> This helps in reducing code in .remove callbacks and sometimes
> dropping .remove callbacks entirely.
>
> Changes since v1 at http://lkml.kernel.org/r/1464251510-15554-1-git-send-email-narmstrong@baylibre.com :
> - Fix brackets in devm_watchdog_register_device()
>
Hi Neil,

For future patches: Change log after '---', please.

> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>

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

Thanks,
Guenter

> ---
>   Documentation/driver-model/devres.txt |  3 +++
>   drivers/watchdog/watchdog_core.c      | 37 +++++++++++++++++++++++++++++++++++
>   include/linux/watchdog.h              |  3 +++
>   3 files changed, 43 insertions(+)
>
> diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
> index c63eea0..589296b 100644
> --- a/Documentation/driver-model/devres.txt
> +++ b/Documentation/driver-model/devres.txt
> @@ -357,3 +357,6 @@ SLAVE DMA ENGINE
>
>   SPI
>     devm_spi_register_master()
> +
> +WATCHDOG
> +  devm_watchdog_register_device()
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index 981a668..7c5e3dc 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -329,6 +329,43 @@ void watchdog_unregister_device(struct watchdog_device *wdd)
>
>   EXPORT_SYMBOL_GPL(watchdog_unregister_device);
>
> +static void devm_watchdog_unregister_device(struct device *dev, void *res)
> +{
> +	watchdog_unregister_device(*(struct watchdog_device **)res);
> +}
> +
> +/**
> + * devm_watchdog_register_device() - resource managed watchdog_register_device()
> + * @dev: device that is registering this watchdog device
> + * @wdd: watchdog device
> + *
> + * Managed watchdog_register_device(). For watchdog device registered by this
> + * function,  watchdog_unregister_device() is automatically called on driver
> + * detach. See watchdog_register_device() for more information.
> + */
> +int devm_watchdog_register_device(struct device *dev,
> +				struct watchdog_device *wdd)
> +{
> +	struct watchdog_device **rcwdd;
> +	int ret;
> +
> +	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*wdd),
> +			     GFP_KERNEL);
> +	if (!rcwdd)
> +		return -ENOMEM;
> +
> +	ret = watchdog_register_device(wdd);
> +	if (!ret) {
> +		*rcwdd = wdd;
> +		devres_add(dev, rcwdd);
> +	} else {
> +		devres_free(rcwdd);
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
> +
>   static int __init watchdog_deferred_registration(void)
>   {
>   	mutex_lock(&wtd_deferred_reg_mutex);
> diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
> index 51732d6c..6b75e38 100644
> --- a/include/linux/watchdog.h
> +++ b/include/linux/watchdog.h
> @@ -180,4 +180,7 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd,
>   extern int watchdog_register_device(struct watchdog_device *);
>   extern void watchdog_unregister_device(struct watchdog_device *);
>
> +/* devres register variant */
> +int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);
> +
>   #endif  /* ifndef _LINUX_WATCHDOG_H */
>