[PATCH v10 1/5] serdev: Make .remove in struct serdev_device_driver optional

[PATCH v10 1/5] serdev: Make .remove in struct serdev_device_driver optional

[Andrey Smirnov]

Using devres infrastructure it is possible to write a serdev driver
that doesn't have any code that needs to be called as a part of
.remove. Add code to make .remove optional.

Cc: linux-kernel@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: cphealy@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 drivers/tty/serdev/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index c68fb3a8ea1c..f500f6a2ca88 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -252,8 +252,8 @@ static int serdev_drv_probe(struct device *dev)
 static int serdev_drv_remove(struct device *dev)
 {
 	const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
-
-	sdrv->remove(to_serdev_device(dev));
+	if (sdrv->remove)
+		sdrv->remove(to_serdev_device(dev));
 	return 0;
 }
 
-- 
2.13.6

Re: [PATCH v10 1/5] serdev: Make .remove in struct serdev_device_driver optional

[Rob Herring]

On Tue, Oct 31, 2017 at 11:36 AM, Andrey Smirnov
<andrew.smirnov@gmail.com> wrote:
> Using devres infrastructure it is possible to write a serdev driver
> that doesn't have any code that needs to be called as a part of
> .remove. Add code to make .remove optional.
>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-serial@vger.kernel.org
> Cc: Rob Herring <robh@kernel.org>
> Cc: cphealy@gmail.com
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  drivers/tty/serdev/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v10 1/5] serdev: Make .remove in struct serdev_device_driver optional

[Greg Kroah-Hartman]

On Tue, Oct 31, 2017 at 09:36:52AM -0700, Andrey Smirnov wrote:
> Using devres infrastructure it is possible to write a serdev driver
> that doesn't have any code that needs to be called as a part of
> .remove. Add code to make .remove optional.

What about manual unbind from userspace through sysfs?  You need to have
a remove function.  All drivers need that, to not have it is pretty lazy :)

thanks,

greg k-h

Re: [PATCH v10 1/5] serdev: Make .remove in struct serdev_device_driver optional

[Sebastian Reichel]

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Hi Greg,

On Sat, Nov 04, 2017 at 12:24:31PM +0100, Greg Kroah-Hartman wrote:
> On Tue, Oct 31, 2017 at 09:36:52AM -0700, Andrey Smirnov wrote:
> > Using devres infrastructure it is possible to write a serdev driver
> > that doesn't have any code that needs to be called as a part of
> > .remove. Add code to make .remove optional.
> 
> What about manual unbind from userspace through sysfs?  You need to have
> a remove function.  All drivers need that, to not have it is pretty lazy :)

Resources,that have been requested via devres are free'd by the
devres framework after the driver specific remove function. This
also works for manual unbind.

If *all* driver resources are allocated using devres, you will end
up with an empty remove function. In that case it makes sense to
remove it completly. This is what quite a few (mainline) i2c and
spi drivers actually do.

-- Sebastian

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[PATCH v10 2/5] serdev: Introduce devm_serdev_device_open()

[Andrey Smirnov]

Add code implementing managed version of serdev_device_open() for
serdev device drivers that "open" the device during driver's lifecycle
only once (e.g. opened in .probe() and closed in .remove()).

Cc: linux-kernel@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: cphealy@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 Documentation/driver-model/devres.txt |  3 +++
 drivers/tty/serdev/core.c             | 27 +++++++++++++++++++++++++++
 include/linux/serdev.h                |  1 +
 3 files changed, 31 insertions(+)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 69f08c0f23a8..e9c6b5cfeec1 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -383,6 +383,9 @@ RESET
   devm_reset_control_get()
   devm_reset_controller_register()
 
+SERDEV
+  devm_serdev_device_open()
+
 SLAVE DMA ENGINE
   devm_acpi_dma_controller_register()
 
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index f500f6a2ca88..b3a785665c6f 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -116,6 +116,33 @@ void serdev_device_close(struct serdev_device *serdev)
 }
 EXPORT_SYMBOL_GPL(serdev_device_close);
 
+static void devm_serdev_device_release(struct device *dev, void *dr)
+{
+	serdev_device_close(*(struct serdev_device **)dr);
+}
+
+int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
+{
+	struct serdev_device **dr;
+	int ret;
+
+	dr = devres_alloc(devm_serdev_device_release, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
+
+	ret = serdev_device_open(serdev);
+	if (ret) {
+		devres_free(dr);
+		return ret;
+	}
+
+	*dr = serdev;
+	devres_add(dev, dr);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_serdev_device_open);
+
 void serdev_device_write_wakeup(struct serdev_device *serdev)
 {
 	complete(&serdev->write_comp);
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index e69402d4a8ae..9929063bd45d 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -193,6 +193,7 @@ static inline int serdev_controller_receive_buf(struct serdev_controller *ctrl,
 
 int serdev_device_open(struct serdev_device *);
 void serdev_device_close(struct serdev_device *);
+int devm_serdev_device_open(struct device *, struct serdev_device *);
 unsigned int serdev_device_set_baudrate(struct serdev_device *, unsigned int);
 void serdev_device_set_flow_control(struct serdev_device *, bool);
 int serdev_device_write_buf(struct serdev_device *, const unsigned char *, size_t);
-- 
2.13.6

Re: [PATCH v10 2/5] serdev: Introduce devm_serdev_device_open()

[Rob Herring]

On Tue, Oct 31, 2017 at 11:36 AM, Andrey Smirnov
<andrew.smirnov@gmail.com> wrote:
> Add code implementing managed version of serdev_device_open() for
> serdev device drivers that "open" the device during driver's lifecycle
> only once (e.g. opened in .probe() and closed in .remove()).
>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-serial@vger.kernel.org
> Cc: Rob Herring <robh@kernel.org>
> Cc: cphealy@gmail.com
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  Documentation/driver-model/devres.txt |  3 +++
>  drivers/tty/serdev/core.c             | 27 +++++++++++++++++++++++++++
>  include/linux/serdev.h                |  1 +
>  3 files changed, 31 insertions(+)

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v10 2/5] serdev: Introduce devm_serdev_device_open()

[Johan Hovold]

On Tue, Oct 31, 2017 at 09:36:53AM -0700, Andrey Smirnov wrote:
> Add code implementing managed version of serdev_device_open() for
> serdev device drivers that "open" the device during driver's lifecycle
> only once (e.g. opened in .probe() and closed in .remove()).
> 
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-serial@vger.kernel.org
> Cc: Rob Herring <robh@kernel.org>
> Cc: cphealy@gmail.com
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  Documentation/driver-model/devres.txt |  3 +++
>  drivers/tty/serdev/core.c             | 27 +++++++++++++++++++++++++++
>  include/linux/serdev.h                |  1 +
>  3 files changed, 31 insertions(+)

> +int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
> +{
> +	struct serdev_device **dr;
> +	int ret;
> +
> +	dr = devres_alloc(devm_serdev_device_release, sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return -ENOMEM;
> +
> +	ret = serdev_device_open(serdev);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	*dr = serdev;
> +	devres_add(dev, dr);
> +
> +	return ret;

This would be more readable as return 0.

> +}
> +EXPORT_SYMBOL_GPL(devm_serdev_device_open);

Johan

Re: [PATCH v10 2/5] serdev: Introduce devm_serdev_device_open()

[Andrey Smirnov]

On Sun, Nov 5, 2017 at 7:38 AM, Johan Hovold <johan@kernel.org> wrote:
> On Tue, Oct 31, 2017 at 09:36:53AM -0700, Andrey Smirnov wrote:
>> Add code implementing managed version of serdev_device_open() for
>> serdev device drivers that "open" the device during driver's lifecycle
>> only once (e.g. opened in .probe() and closed in .remove()).
>>
>> Cc: linux-kernel@vger.kernel.org
>> Cc: linux-serial@vger.kernel.org
>> Cc: Rob Herring <robh@kernel.org>
>> Cc: cphealy@gmail.com
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Cc: Lucas Stach <l.stach@pengutronix.de>
>> Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
>> Cc: Lee Jones <lee.jones@linaro.org>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: Pavel Machek <pavel@ucw.cz>
>> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
>> Cc: Johan Hovold <johan@kernel.org>
>> Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
>> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
>> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
>> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
>> ---
>>  Documentation/driver-model/devres.txt |  3 +++
>>  drivers/tty/serdev/core.c             | 27 +++++++++++++++++++++++++++
>>  include/linux/serdev.h                |  1 +
>>  3 files changed, 31 insertions(+)
>
>> +int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
>> +{
>> +     struct serdev_device **dr;
>> +     int ret;
>> +
>> +     dr = devres_alloc(devm_serdev_device_release, sizeof(*dr), GFP_KERNEL);
>> +     if (!dr)
>> +             return -ENOMEM;
>> +
>> +     ret = serdev_device_open(serdev);
>> +     if (ret) {
>> +             devres_free(dr);
>> +             return ret;
>> +     }
>> +
>> +     *dr = serdev;
>> +     devres_add(dev, dr);
>> +
>> +     return ret;
>
> This would be more readable as return 0.

Sure, I'll change that in v11.

Thanks,
Andrey Smrinov