[net-next v7 0/8] net: wwan: add NMEA port type support

[net-next v7 0/8] net: wwan: add NMEA port type support

[Slark Xiao]

The series introduces a long discussed NMEA port type support for the
WWAN subsystem. There are two goals. From the WWAN driver perspective,
NMEA exported as any other port type (e.g. AT, MBIM, QMI, etc.). From
user space software perspective, the exported chardev belongs to the
GNSS class what makes it easy to distinguish desired port and the WWAN
device common to both NMEA and control (AT, MBIM, etc.) ports makes it
easy to locate a control port for the GNSS receiver activation.

Done by exporting the NMEA port via the GNSS subsystem with the WWAN
core acting as proxy between the WWAN modem driver and the GNSS
subsystem.

The series starts from a cleanup patch. Then three patches prepares the
WWAN core for the proxy style operation. Followed by a patch introding a
new WWNA port type, integration with the GNSS subsystem and demux. The
series ends with a couple of patches that introduce emulated EMEA port
to the WWAN HW simulator.

The series is the product of the discussion with Loic about the pros and
cons of possible models and implementation. Also Muhammad and Slark did
a great job defining the problem, sharing the code and pushing me to
finish the implementation. Daniele has caught an issue on driver
unloading and suggested an investigation direction. What was concluded
by Loic. Many thanks.

Changes RFCv1->RFCv2:
* Uniformly use put_device() to release port memory. This made code less
  weird and way more clear. Thank you, Loic, for noticing and the fix
  discussion!
Changes RFCv2->RFCv5:
* Fix premature WWAN device unregister; new patch 2/7, thus, all
  subsequent patches have been renumbered
* Minor adjustments here and there
Changes v6->V7:
* Fix typo and others which lead to build error

Sergey Ryazanov (7):
  net: wwan: core: remove unused port_id field
  net: wwan: core: explicit WWAN device reference counting
  net: wwan: core: split port creation and registration
  net: wwan: core: split port unregister and stop
  net: wwan: add NMEA port support
  net: wwan: hwsim: refactor to support more port types
  net: wwan: hwsim: support NMEA port emulation

Slark Xiao (1):
  net: wwan: mhi_wwan_ctrl: Add NMEA channel support

 drivers/net/wwan/Kconfig         |   1 +
 drivers/net/wwan/mhi_wwan_ctrl.c |   1 +
 drivers/net/wwan/wwan_core.c     | 277 +++++++++++++++++++++++++------
 drivers/net/wwan/wwan_hwsim.c    | 201 ++++++++++++++++++----
 include/linux/wwan.h             |   2 +
 5 files changed, 394 insertions(+), 88 deletions(-)

-- 
2.25.1

[net-next v7 1/8] net: wwan: core: remove unused port_id field

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

It was used initially for a port id allocation, then removed, and then
accidently introduced again, but it is still unused. Drop it again to
keep code clean.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/wwan_core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 63a47d420bc5..ade8bbffc93e 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -43,7 +43,6 @@ static struct dentry *wwan_debugfs_dir;
  *
  * @id: WWAN device unique ID.
  * @dev: Underlying device.
- * @port_id: Current available port ID to pick.
  * @ops: wwan device ops
  * @ops_ctxt: context to pass to ops
  * @debugfs_dir:  WWAN device debugfs dir
@@ -51,7 +50,6 @@ static struct dentry *wwan_debugfs_dir;
 struct wwan_device {
 	unsigned int id;
 	struct device dev;
-	atomic_t port_id;
 	const struct wwan_ops *ops;
 	void *ops_ctxt;
 #ifdef CONFIG_WWAN_DEBUGFS
-- 
2.25.1

[net-next v7 2/8] net: wwan: core: explicit WWAN device reference counting

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

We need information about existing WWAN device children since we remove
the device after removing the last child. Previously, we tracked users
implicitly by checking whether ops was registered and existence of a
child device of the wwan_class class. Upcoming GNSS (NMEA) port type
support breaks this approach by introducing a child device of the
gnss_class class.

And a modem driver can easily trigger a kernel Oops by removing regular
(e.g., MBIM, AT) ports first and then removing a GNSS port. The WWAN
device will be unregistered on removal of a last regular WWAN port. And
subsequent GNSS port removal will cause NULL pointer dereference in
simple_recursive_removal().

In order to support ports of classes other than wwan_class, switch to
explicit references counting. Introduce a dedicated counter to the WWAN
device struct, increment it on every wwan_create_dev() call, decrement
on wwan_remove_dev(), and actually unregister the WWAN device when there
are no more references.

Run tested with wwan_hwsim with NMEA support patches applied and
different port removing sequences.

Reported-by: Daniele Palmas <dnlplm@gmail.com>
Closes: https://lore.kernel.org/netdev/CAGRyCJE28yf-rrfkFbzu44ygLEvoUM7fecK1vnrghjG_e9UaRA@mail.gmail.com/
Suggested-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
 drivers/net/wwan/wwan_core.c | 34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index ade8bbffc93e..1da935e84008 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -42,6 +42,9 @@ static struct dentry *wwan_debugfs_dir;
  * struct wwan_device - The structure that defines a WWAN device
  *
  * @id: WWAN device unique ID.
+ * @refcount: Reference count of this WWAN device. When this refcount reaches
+ * zero, the device is deleted. NB: access is protected by global
+ * wwan_register_lock mutex.
  * @dev: Underlying device.
  * @ops: wwan device ops
  * @ops_ctxt: context to pass to ops
@@ -49,6 +52,7 @@ static struct dentry *wwan_debugfs_dir;
  */
 struct wwan_device {
 	unsigned int id;
+	int refcount;
 	struct device dev;
 	const struct wwan_ops *ops;
 	void *ops_ctxt;
@@ -222,8 +226,10 @@ static struct wwan_device *wwan_create_dev(struct device *parent)
 
 	/* If wwandev already exists, return it */
 	wwandev = wwan_dev_get_by_parent(parent);
-	if (!IS_ERR(wwandev))
+	if (!IS_ERR(wwandev)) {
+		wwandev->refcount++;
 		goto done_unlock;
+	}
 
 	id = ida_alloc(&wwan_dev_ids, GFP_KERNEL);
 	if (id < 0) {
@@ -242,6 +248,7 @@ static struct wwan_device *wwan_create_dev(struct device *parent)
 	wwandev->dev.class = &wwan_class;
 	wwandev->dev.type = &wwan_dev_type;
 	wwandev->id = id;
+	wwandev->refcount = 1;
 	dev_set_name(&wwandev->dev, "wwan%d", wwandev->id);
 
 	err = device_register(&wwandev->dev);
@@ -263,30 +270,18 @@ static struct wwan_device *wwan_create_dev(struct device *parent)
 	return wwandev;
 }
 
-static int is_wwan_child(struct device *dev, void *data)
-{
-	return dev->class == &wwan_class;
-}
-
 static void wwan_remove_dev(struct wwan_device *wwandev)
 {
-	int ret;
-
 	/* Prevent concurrent picking from wwan_create_dev */
 	mutex_lock(&wwan_register_lock);
 
-	/* WWAN device is created and registered (get+add) along with its first
-	 * child port, and subsequent port registrations only grab a reference
-	 * (get). The WWAN device must then be unregistered (del+put) along with
-	 * its last port, and reference simply dropped (put) otherwise. In the
-	 * same fashion, we must not unregister it when the ops are still there.
-	 */
-	if (wwandev->ops)
-		ret = 1;
-	else
-		ret = device_for_each_child(&wwandev->dev, NULL, is_wwan_child);
+	if (--wwandev->refcount <= 0) {
+		struct device *child = device_find_any_child(&wwandev->dev);
+
+		put_device(child);
+		if (WARN_ON(wwandev->ops || child))	/* Paranoid */
+			goto out_unlock;
 
-	if (!ret) {
 #ifdef CONFIG_WWAN_DEBUGFS
 		debugfs_remove_recursive(wwandev->debugfs_dir);
 #endif
@@ -295,6 +290,7 @@ static void wwan_remove_dev(struct wwan_device *wwandev)
 		put_device(&wwandev->dev);
 	}
 
+out_unlock:
 	mutex_unlock(&wwan_register_lock);
 }
 
-- 
2.25.1

[net-next v7 3/8] net: wwan: core: split port creation and registration

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Upcoming GNSS (NMEA) port type support requires exporting it via the
GNSS subsystem. On another hand, we still need to do basic WWAN core
work: find or allocate the WWAN device, make it the port parent, etc. To
reuse as much code as possible, split the port creation function into
the registration of a regular WWAN port device, and basic port struct
initialization.

To be able to use put_device() uniformly, break the device_register()
call into device_initialize() and device_add() and call device
initialization earlier.

While at it, fix a minor number leak upon WWAN port registration
failure.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
 drivers/net/wwan/wwan_core.c | 68 ++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 26 deletions(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 1da935e84008..1a9a77d597e6 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -357,7 +357,8 @@ static void wwan_port_destroy(struct device *dev)
 {
 	struct wwan_port *port = to_wwan_port(dev);
 
-	ida_free(&minors, MINOR(port->dev.devt));
+	if (dev->class == &wwan_class)
+		ida_free(&minors, MINOR(dev->devt));
 	mutex_destroy(&port->data_lock);
 	mutex_destroy(&port->ops_lock);
 	kfree(port);
@@ -436,6 +437,43 @@ static int __wwan_port_dev_assign_name(struct wwan_port *port, const char *fmt)
 	return dev_set_name(&port->dev, "%s", buf);
 }
 
+/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */
+static int wwan_port_register_wwan(struct wwan_port *port)
+{
+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+	char namefmt[0x20];
+	int minor, err;
+
+	/* A port is exposed as character device, get a minor */
+	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
+	if (minor < 0)
+		return minor;
+
+	port->dev.class = &wwan_class;
+	port->dev.devt = MKDEV(wwan_major, minor);
+
+	/* allocate unique name based on wwan device id, port type and number */
+	snprintf(namefmt, sizeof(namefmt), "wwan%u%s%%d", wwandev->id,
+		 wwan_port_types[port->type].devsuf);
+
+	/* Serialize ports registration */
+	mutex_lock(&wwan_register_lock);
+
+	__wwan_port_dev_assign_name(port, namefmt);
+	err = device_add(&port->dev);
+
+	mutex_unlock(&wwan_register_lock);
+
+	if (err) {
+		ida_free(&minors, minor);
+		return err;
+	}
+
+	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port->dev));
+
+	return 0;
+}
+
 struct wwan_port *wwan_create_port(struct device *parent,
 				   enum wwan_port_type type,
 				   const struct wwan_port_ops *ops,
@@ -444,8 +482,7 @@ struct wwan_port *wwan_create_port(struct device *parent,
 {
 	struct wwan_device *wwandev;
 	struct wwan_port *port;
-	char namefmt[0x20];
-	int minor, err;
+	int err;
 
 	if (type > WWAN_PORT_MAX || !ops)
 		return ERR_PTR(-EINVAL);
@@ -457,17 +494,9 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	if (IS_ERR(wwandev))
 		return ERR_CAST(wwandev);
 
-	/* A port is exposed as character device, get a minor */
-	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
-	if (minor < 0) {
-		err = minor;
-		goto error_wwandev_remove;
-	}
-
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
 	if (!port) {
 		err = -ENOMEM;
-		ida_free(&minors, minor);
 		goto error_wwandev_remove;
 	}
 
@@ -481,27 +510,14 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	mutex_init(&port->data_lock);
 
 	port->dev.parent = &wwandev->dev;
-	port->dev.class = &wwan_class;
 	port->dev.type = &wwan_port_dev_type;
-	port->dev.devt = MKDEV(wwan_major, minor);
 	dev_set_drvdata(&port->dev, drvdata);
+	device_initialize(&port->dev);
 
-	/* allocate unique name based on wwan device id, port type and number */
-	snprintf(namefmt, sizeof(namefmt), "wwan%u%s%%d", wwandev->id,
-		 wwan_port_types[port->type].devsuf);
-
-	/* Serialize ports registration */
-	mutex_lock(&wwan_register_lock);
-
-	__wwan_port_dev_assign_name(port, namefmt);
-	err = device_register(&port->dev);
-
-	mutex_unlock(&wwan_register_lock);
-
+	err = wwan_port_register_wwan(port);
 	if (err)
 		goto error_put_device;
 
-	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port->dev));
 	return port;
 
 error_put_device:
-- 
2.25.1

Re: [net-next,v7,3/8] net: wwan: core: split port creation and registration

[Jakub Kicinski]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net: wwan: core: split port creation and registration

This patch splits the port creation function to prepare for upcoming GNSS
port type support. It separates device_register() into device_initialize()
and device_add(), and moves minor number allocation into the new
wwan_port_register_wwan() function.

> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
> index 1da935e84008..1a9a77d597e6 100644
> --- a/drivers/net/wwan/wwan_core.c
> +++ b/drivers/net/wwan/wwan_core.c
> @@ -357,7 +357,8 @@ static void wwan_port_destroy(struct device *dev)
>  {
>  	struct wwan_port *port = to_wwan_port(dev);
>
> -	ida_free(&minors, MINOR(port->dev.devt));
> +	if (dev->class == &wwan_class)
> +		ida_free(&minors, MINOR(dev->devt));
>  	mutex_destroy(&port->data_lock);
>  	mutex_destroy(&port->ops_lock);
>  	kfree(port);

[ ... ]

> +/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */
> +static int wwan_port_register_wwan(struct wwan_port *port)
> +{
> +	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
> +	char namefmt[0x20];
> +	int minor, err;
> +
> +	/* A port is exposed as character device, get a minor */
> +	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
> +	if (minor < 0)
> +		return minor;
> +
> +	port->dev.class = &wwan_class;
> +	port->dev.devt = MKDEV(wwan_major, minor);

[ ... ]

> +	err = device_add(&port->dev);
> +
> +	mutex_unlock(&wwan_register_lock);
> +
> +	if (err) {
> +		ida_free(&minors, minor);
                ^^^^^^^^^^^^^^^^^^^^^^^^

When device_add() fails, this frees the minor. However, port->dev.class
was already set to wwan_class above, and port->dev.devt contains the minor
number. The caller (wwan_create_port) then calls put_device() which
triggers wwan_port_destroy(). Since dev->class == &wwan_class is true,
wwan_port_destroy() calls ida_free() again on the same minor.

Wouldn't this cause a double ida_free when device_add() fails? The call
chain is: wwan_port_register_wwan() fails -> ida_free(minor) -> return
error -> wwan_create_port() -> put_device() -> wwan_port_destroy() ->
ida_free(minor) again.

Maybe the class should be cleared on error before returning, or the
ida_free in the error path should be removed since wwan_port_destroy()
will handle it?

> +		return err;
> +	}
> +
> +	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port->dev));
> +
> +	return 0;
> +}

[ ... ]

> +	device_initialize(&port->dev);
> +
> +	err = wwan_port_register_wwan(port);
>  	if (err)
>  		goto error_put_device;
> +
>  	return port;
>
>  error_put_device:
> +	put_device(&port->dev);
-- 
pw-bot: cr

Re:Re: [net-next,v7,3/8] net: wwan: core: split port creation and registration

[Slark Xiao]

At 2026-01-16 10:44:35, "Jakub Kicinski" <kuba@kernel.org> wrote:
>This is an AI-generated review of your patch. The human sending this
>email has considered the AI review valid, or at least plausible.
>
>For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
>---
>net: wwan: core: split port creation and registration
>
>This patch splits the port creation function to prepare for upcoming GNSS
>port type support. It separates device_register() into device_initialize()
>and device_add(), and moves minor number allocation into the new
>wwan_port_register_wwan() function.
>
>> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
>> index 1da935e84008..1a9a77d597e6 100644
>> --- a/drivers/net/wwan/wwan_core.c
>> +++ b/drivers/net/wwan/wwan_core.c
>> @@ -357,7 +357,8 @@ static void wwan_port_destroy(struct device *dev)
>>  {
>>  	struct wwan_port *port = to_wwan_port(dev);
>>
>> -	ida_free(&minors, MINOR(port->dev.devt));
>> +	if (dev->class == &wwan_class)
>> +		ida_free(&minors, MINOR(dev->devt));
>>  	mutex_destroy(&port->data_lock);
>>  	mutex_destroy(&port->ops_lock);
>>  	kfree(port);
>
>[ ... ]
>
>> +/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */
>> +static int wwan_port_register_wwan(struct wwan_port *port)
>> +{
>> +	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
>> +	char namefmt[0x20];
>> +	int minor, err;
>> +
>> +	/* A port is exposed as character device, get a minor */
>> +	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
>> +	if (minor < 0)
>> +		return minor;
>> +
>> +	port->dev.class = &wwan_class;
>> +	port->dev.devt = MKDEV(wwan_major, minor);
>
>[ ... ]
>
>> +	err = device_add(&port->dev);
>> +
>> +	mutex_unlock(&wwan_register_lock);
>> +
>> +	if (err) {
>> +		ida_free(&minors, minor);
>                ^^^^^^^^^^^^^^^^^^^^^^^^
>
>When device_add() fails, this frees the minor. However, port->dev.class
>was already set to wwan_class above, and port->dev.devt contains the minor
>number. The caller (wwan_create_port) then calls put_device() which
>triggers wwan_port_destroy(). Since dev->class == &wwan_class is true,
>wwan_port_destroy() calls ida_free() again on the same minor.
>
>Wouldn't this cause a double ida_free when device_add() fails? The call
>chain is: wwan_port_register_wwan() fails -> ida_free(minor) -> return
>error -> wwan_create_port() -> put_device() -> wwan_port_destroy() ->
>ida_free(minor) again.
>
>Maybe the class should be cleared on error before returning, or the
>ida_free in the error path should be removed since wwan_port_destroy()
>will handle it?
>
Hi Sergey,
We need to review this changes again.

>> +		return err;
>> +	}
>> +
>> +	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port->dev));
>> +
>> +	return 0;
>> +}
>
>[ ... ]
>
>> +	device_initialize(&port->dev);
>> +
>> +	err = wwan_port_register_wwan(port);
>>  	if (err)
>>  		goto error_put_device;
>> +
>>  	return port;
>>
>>  error_put_device:
>> +	put_device(&port->dev);
>-- 
>pw-bot: cr

Re:Re:Re: [net-next,v7,3/8] net: wwan: core: split port creation and registration

[Slark Xiao]

At 2026-01-16 11:24:54, "Slark Xiao" <slark_xiao@163.com> wrote:
>
>
>At 2026-01-16 10:44:35, "Jakub Kicinski" <kuba@kernel.org> wrote:
>>This is an AI-generated review of your patch. The human sending this
>>email has considered the AI review valid, or at least plausible.
>>
>>For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
>>---
>>net: wwan: core: split port creation and registration
>>
>>This patch splits the port creation function to prepare for upcoming GNSS
>>port type support. It separates device_register() into device_initialize()
>>and device_add(), and moves minor number allocation into the new
>>wwan_port_register_wwan() function.
>>
>>> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
>>> index 1da935e84008..1a9a77d597e6 100644
>>> --- a/drivers/net/wwan/wwan_core.c
>>> +++ b/drivers/net/wwan/wwan_core.c
>>> @@ -357,7 +357,8 @@ static void wwan_port_destroy(struct device *dev)
>>>  {
>>>  	struct wwan_port *port = to_wwan_port(dev);
>>>
>>> -	ida_free(&minors, MINOR(port->dev.devt));
>>> +	if (dev->class == &wwan_class)
>>> +		ida_free(&minors, MINOR(dev->devt));
>>>  	mutex_destroy(&port->data_lock);
>>>  	mutex_destroy(&port->ops_lock);
>>>  	kfree(port);
>>
>>[ ... ]
>>
>>> +/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */
>>> +static int wwan_port_register_wwan(struct wwan_port *port)
>>> +{
>>> +	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
>>> +	char namefmt[0x20];
>>> +	int minor, err;
>>> +
>>> +	/* A port is exposed as character device, get a minor */
>>> +	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
>>> +	if (minor < 0)
>>> +		return minor;
>>> +
>>> +	port->dev.class = &wwan_class;
>>> +	port->dev.devt = MKDEV(wwan_major, minor);
>>
>>[ ... ]
>>
>>> +	err = device_add(&port->dev);
>>> +
>>> +	mutex_unlock(&wwan_register_lock);
>>> +
>>> +	if (err) {
>>> +		ida_free(&minors, minor);
>>                ^^^^^^^^^^^^^^^^^^^^^^^^

>>
Hi Sergey,
Can we modify it like this?

+	if (err) {
+		ida_free(&minors, minor);
+		port->dev.class = NULL;

This shall be able to avoid the double free issue.

>>When device_add() fails, this frees the minor. However, port->dev.class
>>was already set to wwan_class above, and port->dev.devt contains the minor
>>number. The caller (wwan_create_port) then calls put_device() which
>>triggers wwan_port_destroy(). Since dev->class == &wwan_class is true,
>>wwan_port_destroy() calls ida_free() again on the same minor.
>>
>>Wouldn't this cause a double ida_free when device_add() fails? The call
>>chain is: wwan_port_register_wwan() fails -> ida_free(minor) -> return
>>error -> wwan_create_port() -> put_device() -> wwan_port_destroy() ->
>>ida_free(minor) again.
>>
>>Maybe the class should be cleared on error before returning, or the
>>ida_free in the error path should be removed since wwan_port_destroy()
>>will handle it?
>>
>Hi Sergey,
>We need to review this changes again.
>
>>> +		return err;
>>> +	}
>>> +
>>> +	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port->dev));
>>> +
>>> +	return 0;
>>> +}
>>
>>[ ... ]
>>
>>> +	device_initialize(&port->dev);
>>> +
>>> +	err = wwan_port_register_wwan(port);
>>>  	if (err)
>>>  		goto error_put_device;
>>> +
>>>  	return port;
>>>
>>>  error_put_device:
>>> +	put_device(&port->dev);
>>-- 
>>pw-bot: cr

Re: Re:Re: [net-next,v7,3/8] net: wwan: core: split port creation and registration

[Loic Poulain]

On Thu, Jan 22, 2026 at 3:32 AM Slark Xiao <slark_xiao@163.com> wrote:
>
>
>
> At 2026-01-16 11:24:54, "Slark Xiao" <slark_xiao@163.com> wrote:
> >
> >
> >At 2026-01-16 10:44:35, "Jakub Kicinski" <kuba@kernel.org> wrote:
> >>This is an AI-generated review of your patch. The human sending this
> >>email has considered the AI review valid, or at least plausible.
> >>
> >>For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
> >>---
> >>net: wwan: core: split port creation and registration
> >>
> >>This patch splits the port creation function to prepare for upcoming GNSS
> >>port type support. It separates device_register() into device_initialize()
> >>and device_add(), and moves minor number allocation into the new
> >>wwan_port_register_wwan() function.
> >>
> >>> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
> >>> index 1da935e84008..1a9a77d597e6 100644
> >>> --- a/drivers/net/wwan/wwan_core.c
> >>> +++ b/drivers/net/wwan/wwan_core.c
> >>> @@ -357,7 +357,8 @@ static void wwan_port_destroy(struct device *dev)
> >>>  {
> >>>     struct wwan_port *port = to_wwan_port(dev);
> >>>
> >>> -   ida_free(&minors, MINOR(port->dev.devt));
> >>> +   if (dev->class == &wwan_class)
> >>> +           ida_free(&minors, MINOR(dev->devt));
> >>>     mutex_destroy(&port->data_lock);
> >>>     mutex_destroy(&port->ops_lock);
> >>>     kfree(port);
> >>
> >>[ ... ]
> >>
> >>> +/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */
> >>> +static int wwan_port_register_wwan(struct wwan_port *port)
> >>> +{
> >>> +   struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
> >>> +   char namefmt[0x20];
> >>> +   int minor, err;
> >>> +
> >>> +   /* A port is exposed as character device, get a minor */
> >>> +   minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
> >>> +   if (minor < 0)
> >>> +           return minor;
> >>> +
> >>> +   port->dev.class = &wwan_class;
> >>> +   port->dev.devt = MKDEV(wwan_major, minor);
> >>
> >>[ ... ]
> >>
> >>> +   err = device_add(&port->dev);
> >>> +
> >>> +   mutex_unlock(&wwan_register_lock);
> >>> +
> >>> +   if (err) {
> >>> +           ida_free(&minors, minor);
> >>                ^^^^^^^^^^^^^^^^^^^^^^^^
>
> >>
> Hi Sergey,
> Can we modify it like this?
>
> +       if (err) {
> +               ida_free(&minors, minor);
> +               port->dev.class = NULL;
>
> This shall be able to avoid the double free issue.

I would prefer to let wwan_port_destroy() handle this, meaning we
shouldn’t free the IDA here and should simply return the error code,
but your approach is also acceptable.

Regards,
Loic

[net-next v7 4/8] net: wwan: core: split port unregister and stop

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Upcoming GNSS (NMEA) port type support requires exporting it via the
GNSS subsystem. On another hand, we still need to do basic WWAN core
work: call the port stop operation, purge queues, release the parent
WWAN device, etc. To reuse as much code as possible, split the port
unregistering function into the deregistration of a regular WWAN port
device, and the common port tearing down code.

In order to keep more code generic, break the device_unregister() call
into device_del() and put_device(), which release the port memory
uniformly.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/wwan_core.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 1a9a77d597e6..ae91b1cd7142 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -474,6 +474,18 @@ static int wwan_port_register_wwan(struct wwan_port *port)
 	return 0;
 }
 
+/* Unregister a regular WWAN port (e.g. AT, MBIM, etc) */
+static void wwan_port_unregister_wwan(struct wwan_port *port)
+{
+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+
+	dev_set_drvdata(&port->dev, NULL);
+
+	dev_info(&wwandev->dev, "port %s disconnected\n", dev_name(&port->dev));
+
+	device_del(&port->dev);
+}
+
 struct wwan_port *wwan_create_port(struct device *parent,
 				   enum wwan_port_type type,
 				   const struct wwan_port_ops *ops,
@@ -534,18 +546,19 @@ void wwan_remove_port(struct wwan_port *port)
 	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
 
 	mutex_lock(&port->ops_lock);
-	if (port->start_count)
+	if (port->start_count) {
 		port->ops->stop(port);
+		port->start_count = 0;
+	}
 	port->ops = NULL; /* Prevent any new port operations (e.g. from fops) */
 	mutex_unlock(&port->ops_lock);
 
 	wake_up_interruptible(&port->waitqueue);
-
 	skb_queue_purge(&port->rxq);
-	dev_set_drvdata(&port->dev, NULL);
 
-	dev_info(&wwandev->dev, "port %s disconnected\n", dev_name(&port->dev));
-	device_unregister(&port->dev);
+	wwan_port_unregister_wwan(port);
+
+	put_device(&port->dev);
 
 	/* Release related wwan device */
 	wwan_remove_dev(wwandev);
-- 
2.25.1

[net-next v7 5/8] net: wwan: add NMEA port support

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Many WWAN modems come with embedded GNSS receiver inside and have a
dedicated port to output geopositioning data. On the one hand, the
GNSS receiver has little in common with WWAN modem and just shares a
host interface and should be exported using the GNSS subsystem. On the
other hand, GNSS receiver is not automatically activated and needs a
generic WWAN control port (AT, MBIM, etc.) to be turned on. And a user
space software needs extra information to find the control port.

Introduce the new type of WWAN port - NMEA. When driver asks to register
a NMEA port, the core allocates common parent WWAN device as usual, but
exports the NMEA port via the GNSS subsystem and acts as a proxy between
the device driver and the GNSS subsystem.

>From the WWAN device driver perspective, a NMEA port is registered as a
regular WWAN port without any difference. And the driver interacts only
with the WWAN core. From the user space perspective, the NMEA port is a
GNSS device which parent can be used to enumerate and select the proper
control port for the GNSS receiver management.

CC: Slark Xiao <slark_xiao@163.com>
CC: Muhammad Nuzaihan <zaihan@unrealasia.net>
CC: Qiang Yu <quic_qianyu@quicinc.com>
CC: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
CC: Johan Hovold <johan@kernel.org>
Suggested-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/Kconfig     |   1 +
 drivers/net/wwan/wwan_core.c | 156 +++++++++++++++++++++++++++++++++--
 include/linux/wwan.h         |   2 +
 3 files changed, 154 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig
index 410b0245114e..88df55d78d90 100644
--- a/drivers/net/wwan/Kconfig
+++ b/drivers/net/wwan/Kconfig
@@ -7,6 +7,7 @@ menu "Wireless WAN"
 
 config WWAN
 	tristate "WWAN Driver Core"
+	depends on GNSS || GNSS = n
 	help
 	  Say Y here if you want to use the WWAN driver core. This driver
 	  provides a common framework for WWAN drivers.
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index ae91b1cd7142..c50f1fad17a5 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -1,5 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2021, Linaro Ltd <loic.poulain@linaro.org> */
+/* WWAN Driver Core
+ *
+ * Copyright (c) 2021, Linaro Ltd <loic.poulain@linaro.org>
+ * Copyright (c) 2025, Sergey Ryazanov <ryazanov.s.a@gmail.com>
+ */
 
 #include <linux/bitmap.h>
 #include <linux/err.h>
@@ -16,6 +20,7 @@
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/termios.h>
+#include <linux/gnss.h>
 #include <linux/wwan.h>
 #include <net/rtnetlink.h>
 #include <uapi/linux/wwan.h>
@@ -75,6 +80,7 @@ struct wwan_device {
  * @headroom_len: SKB reserved headroom size
  * @frag_len: Length to fragment packet
  * @at_data: AT port specific data
+ * @gnss: Pointer to GNSS device associated with this port
  */
 struct wwan_port {
 	enum wwan_port_type type;
@@ -93,9 +99,16 @@ struct wwan_port {
 			struct ktermios termios;
 			int mdmbits;
 		} at_data;
+		struct gnss_device *gnss;
 	};
 };
 
+static int wwan_port_op_start(struct wwan_port *port);
+static void wwan_port_op_stop(struct wwan_port *port);
+static int wwan_port_op_tx(struct wwan_port *port, struct sk_buff *skb,
+			   bool nonblock);
+static int wwan_wait_tx(struct wwan_port *port, bool nonblock);
+
 static ssize_t index_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct wwan_device *wwan = to_wwan_dev(dev);
@@ -336,6 +349,7 @@ static const struct {
 		.name = "MIPC",
 		.devsuf = "mipc",
 	},
+	/* WWAN_PORT_NMEA is exported via the GNSS subsystem */
 };
 
 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
@@ -486,6 +500,124 @@ static void wwan_port_unregister_wwan(struct wwan_port *port)
 	device_del(&port->dev);
 }
 
+#if IS_ENABLED(CONFIG_GNSS)
+static int wwan_gnss_open(struct gnss_device *gdev)
+{
+	return wwan_port_op_start(gnss_get_drvdata(gdev));
+}
+
+static void wwan_gnss_close(struct gnss_device *gdev)
+{
+	wwan_port_op_stop(gnss_get_drvdata(gdev));
+}
+
+static int wwan_gnss_write(struct gnss_device *gdev, const unsigned char *buf,
+			   size_t count)
+{
+	struct wwan_port *port = gnss_get_drvdata(gdev);
+	struct sk_buff *skb, *head = NULL, *tail = NULL;
+	size_t frag_len, remain = count;
+	int ret;
+
+	ret = wwan_wait_tx(port, false);
+	if (ret)
+		return ret;
+
+	do {
+		frag_len = min(remain, port->frag_len);
+		skb = alloc_skb(frag_len + port->headroom_len, GFP_KERNEL);
+		if (!skb) {
+			ret = -ENOMEM;
+			goto freeskb;
+		}
+		skb_reserve(skb, port->headroom_len);
+		memcpy(skb_put(skb, frag_len), buf + count - remain, frag_len);
+
+		if (!head) {
+			head = skb;
+		} else {
+			if (!tail)
+				skb_shinfo(head)->frag_list = skb;
+			else
+				tail->next = skb;
+
+			tail = skb;
+			head->data_len += skb->len;
+			head->len += skb->len;
+			head->truesize += skb->truesize;
+		}
+	} while (remain -= frag_len);
+
+	ret = wwan_port_op_tx(port, head, false);
+	if (!ret)
+		return count;
+
+freeskb:
+	kfree_skb(head);
+	return ret;
+}
+
+static struct gnss_operations wwan_gnss_ops = {
+	.open = wwan_gnss_open,
+	.close = wwan_gnss_close,
+	.write_raw = wwan_gnss_write,
+};
+
+/* GNSS port specific device registration */
+static int wwan_port_register_gnss(struct wwan_port *port)
+{
+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+	struct gnss_device *gdev;
+	int err;
+
+	gdev = gnss_allocate_device(&wwandev->dev);
+	if (!gdev)
+		return -ENOMEM;
+
+	/* NB: for now we support only NMEA WWAN port type, so hardcode
+	 * the GNSS port type. If more GNSS WWAN port types will be added,
+	 * then we should dynamically map WWAN port type to GNSS type.
+	 */
+	gdev->type = GNSS_TYPE_NMEA;
+	gdev->ops = &wwan_gnss_ops;
+	gnss_set_drvdata(gdev, port);
+
+	port->gnss = gdev;
+
+	err = gnss_register_device(gdev);
+	if (err) {
+		gnss_put_device(gdev);
+		return err;
+	}
+
+	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&gdev->dev));
+
+	return 0;
+}
+
+/* GNSS port specific device unregistration */
+static void wwan_port_unregister_gnss(struct wwan_port *port)
+{
+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+	struct gnss_device *gdev = port->gnss;
+
+	dev_info(&wwandev->dev, "port %s disconnected\n", dev_name(&gdev->dev));
+
+	gnss_deregister_device(gdev);
+	gnss_put_device(gdev);
+}
+#else
+static inline int wwan_port_register_gnss(struct wwan_port *port)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void wwan_port_unregister_gnss(struct wwan_port *port)
+{
+	WARN_ON(1);	/* This handler cannot be called */
+}
+#endif
+
 struct wwan_port *wwan_create_port(struct device *parent,
 				   enum wwan_port_type type,
 				   const struct wwan_port_ops *ops,
@@ -526,7 +658,11 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	dev_set_drvdata(&port->dev, drvdata);
 	device_initialize(&port->dev);
 
-	err = wwan_port_register_wwan(port);
+	if (port->type == WWAN_PORT_NMEA)
+		err = wwan_port_register_gnss(port);
+	else
+		err = wwan_port_register_wwan(port);
+
 	if (err)
 		goto error_put_device;
 
@@ -556,7 +692,10 @@ void wwan_remove_port(struct wwan_port *port)
 	wake_up_interruptible(&port->waitqueue);
 	skb_queue_purge(&port->rxq);
 
-	wwan_port_unregister_wwan(port);
+	if (port->type == WWAN_PORT_NMEA)
+		wwan_port_unregister_gnss(port);
+	else
+		wwan_port_unregister_wwan(port);
 
 	put_device(&port->dev);
 
@@ -567,8 +706,15 @@ EXPORT_SYMBOL_GPL(wwan_remove_port);
 
 void wwan_port_rx(struct wwan_port *port, struct sk_buff *skb)
 {
-	skb_queue_tail(&port->rxq, skb);
-	wake_up_interruptible(&port->waitqueue);
+	if (port->type == WWAN_PORT_NMEA) {
+#if IS_ENABLED(CONFIG_GNSS)
+		gnss_insert_raw(port->gnss, skb->data, skb->len);
+#endif
+		consume_skb(skb);
+	} else {
+		skb_queue_tail(&port->rxq, skb);
+		wake_up_interruptible(&port->waitqueue);
+	}
 }
 EXPORT_SYMBOL_GPL(wwan_port_rx);
 
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index a4d6cc0c9f68..1e0e2cb53579 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -19,6 +19,7 @@
  * @WWAN_PORT_FASTBOOT: Fastboot protocol control
  * @WWAN_PORT_ADB: ADB protocol control
  * @WWAN_PORT_MIPC: MTK MIPC diagnostic interface
+ * @WWAN_PORT_NMEA: embedded GNSS receiver with NMEA output
  *
  * @WWAN_PORT_MAX: Highest supported port types
  * @WWAN_PORT_UNKNOWN: Special value to indicate an unknown port type
@@ -34,6 +35,7 @@ enum wwan_port_type {
 	WWAN_PORT_FASTBOOT,
 	WWAN_PORT_ADB,
 	WWAN_PORT_MIPC,
+	WWAN_PORT_NMEA,
 
 	/* Add new port types above this line */
 
-- 
2.25.1

Re: [net-next v7 5/8] net: wwan: add NMEA port support

[Simon Horman]

On Thu, Jan 15, 2026 at 07:46:22PM +0800, Slark Xiao wrote:

...

> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c

...

> +#else
> +static inline int wwan_port_register_gnss(struct wwan_port *port)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline void wwan_port_unregister_gnss(struct wwan_port *port)
> +{
> +	WARN_ON(1);	/* This handler cannot be called */
> +}

Please don't use the inline keyword in .c files unless there is a
demonstrable - usually performance - reason to do so. Rather, let the
compiler inline code as it sees fit.

Using the inline keyword in .h is of course fine.

> +#endif
> +

...

Re:Re: [net-next v7 5/8] net: wwan: add NMEA port support

[Slark Xiao]

At 2026-01-20 20:30:37, "Simon Horman" <horms@kernel.org> wrote:
>On Thu, Jan 15, 2026 at 07:46:22PM +0800, Slark Xiao wrote:
>
>...
>
>> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
>
>...
>
>> +#else
>> +static inline int wwan_port_register_gnss(struct wwan_port *port)
>> +{
>> +	return -EOPNOTSUPP;
>> +}
>> +
>> +static inline void wwan_port_unregister_gnss(struct wwan_port *port)
>> +{
>> +	WARN_ON(1);	/* This handler cannot be called */
>> +}
>
>Please don't use the inline keyword in .c files unless there is a
>demonstrable - usually performance - reason to do so. Rather, let the
>compiler inline code as it sees fit.
>
>Using the inline keyword in .h is of course fine.
>
I think this shall be a mistake.
For a GNSS device, these 2 API shall not be called frequently.
So there is no necessary to add "inline" to improve performance.
How do you think, Sergey?

>> +#endif
>> +
>
>...

Re: Re: [net-next v7 5/8] net: wwan: add NMEA port support

[Loic Poulain]

On Wed, Jan 21, 2026 at 3:09 AM Slark Xiao <slark_xiao@163.com> wrote:
>
>
>
> At 2026-01-20 20:30:37, "Simon Horman" <horms@kernel.org> wrote:
> >On Thu, Jan 15, 2026 at 07:46:22PM +0800, Slark Xiao wrote:
> >
> >...
> >
> >> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
> >
> >...
> >
> >> +#else
> >> +static inline int wwan_port_register_gnss(struct wwan_port *port)
> >> +{
> >> +    return -EOPNOTSUPP;
> >> +}
> >> +
> >> +static inline void wwan_port_unregister_gnss(struct wwan_port *port)
> >> +{
> >> +    WARN_ON(1);     /* This handler cannot be called */
> >> +}
> >
> >Please don't use the inline keyword in .c files unless there is a
> >demonstrable - usually performance - reason to do so. Rather, let the
> >compiler inline code as it sees fit.
> >
> >Using the inline keyword in .h is of course fine.
> >
> I think this shall be a mistake.
> For a GNSS device, these 2 API shall not be called frequently.
> So there is no necessary to add "inline" to improve performance.

Indeed, it's fine to remove that explicit inlines here.

Regards,
Loic

Re: Re: [net-next v7 5/8] net: wwan: add NMEA port support

[Simon Horman]

On Wed, Jan 21, 2026 at 03:16:33PM +0100, Loic Poulain wrote:
> On Wed, Jan 21, 2026 at 3:09 AM Slark Xiao <slark_xiao@163.com> wrote:
> >
> >
> >
> > At 2026-01-20 20:30:37, "Simon Horman" <horms@kernel.org> wrote:
> > >On Thu, Jan 15, 2026 at 07:46:22PM +0800, Slark Xiao wrote:
> > >
> > >...
> > >
> > >> diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
> > >
> > >...
> > >
> > >> +#else
> > >> +static inline int wwan_port_register_gnss(struct wwan_port *port)
> > >> +{
> > >> +    return -EOPNOTSUPP;
> > >> +}
> > >> +
> > >> +static inline void wwan_port_unregister_gnss(struct wwan_port *port)
> > >> +{
> > >> +    WARN_ON(1);     /* This handler cannot be called */
> > >> +}
> > >
> > >Please don't use the inline keyword in .c files unless there is a
> > >demonstrable - usually performance - reason to do so. Rather, let the
> > >compiler inline code as it sees fit.
> > >
> > >Using the inline keyword in .h is of course fine.
> > >
> > I think this shall be a mistake.
> > For a GNSS device, these 2 API shall not be called frequently.
> > So there is no necessary to add "inline" to improve performance.
> 
> Indeed, it's fine to remove that explicit inlines here.

Thanks!

[net-next v7 6/8] net: wwan: hwsim: refactor to support more port types

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Just introduced WWAN NMEA port type needs a testing option. The WWAN HW
simulator was developed with the AT port type in mind and cannot be
easily extended. Refactor it now to make it capable to support more port
types.

No big functional changes, mostly renaming with a little code
rearrangement.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/wwan_hwsim.c | 73 ++++++++++++++++++++---------------
 1 file changed, 41 insertions(+), 32 deletions(-)

diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
index 733688cd4607..11d15dc39041 100644
--- a/drivers/net/wwan/wwan_hwsim.c
+++ b/drivers/net/wwan/wwan_hwsim.c
@@ -56,12 +56,16 @@ struct wwan_hwsim_port {
 	struct wwan_port *wwan;
 	struct work_struct del_work;
 	struct dentry *debugfs_topdir;
-	enum {			/* AT command parser state */
-		AT_PARSER_WAIT_A,
-		AT_PARSER_WAIT_T,
-		AT_PARSER_WAIT_TERM,
-		AT_PARSER_SKIP_LINE,
-	} pstate;
+	union {
+		struct {
+			enum {	/* AT command parser state */
+				AT_PARSER_WAIT_A,
+				AT_PARSER_WAIT_T,
+				AT_PARSER_WAIT_TERM,
+				AT_PARSER_SKIP_LINE,
+			} pstate;
+		} at_emul;
+	};
 };
 
 static const struct file_operations wwan_hwsim_debugfs_portdestroy_fops;
@@ -101,16 +105,16 @@ static const struct wwan_ops wwan_hwsim_wwan_rtnl_ops = {
 	.setup = wwan_hwsim_netdev_setup,
 };
 
-static int wwan_hwsim_port_start(struct wwan_port *wport)
+static int wwan_hwsim_at_emul_start(struct wwan_port *wport)
 {
 	struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
 
-	port->pstate = AT_PARSER_WAIT_A;
+	port->at_emul.pstate = AT_PARSER_WAIT_A;
 
 	return 0;
 }
 
-static void wwan_hwsim_port_stop(struct wwan_port *wport)
+static void wwan_hwsim_at_emul_stop(struct wwan_port *wport)
 {
 }
 
@@ -120,7 +124,7 @@ static void wwan_hwsim_port_stop(struct wwan_port *wport)
  *
  * Be aware that this processor is not fully V.250 compliant.
  */
-static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
+static int wwan_hwsim_at_emul_tx(struct wwan_port *wport, struct sk_buff *in)
 {
 	struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
 	struct sk_buff *out;
@@ -142,17 +146,17 @@ static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
 	for (i = 0, s = 0; i < in->len; ++i) {
 		char c = in->data[i];
 
-		if (port->pstate == AT_PARSER_WAIT_A) {
+		if (port->at_emul.pstate == AT_PARSER_WAIT_A) {
 			if (c == 'A' || c == 'a')
-				port->pstate = AT_PARSER_WAIT_T;
+				port->at_emul.pstate = AT_PARSER_WAIT_T;
 			else if (c != '\n')	/* Ignore formating char */
-				port->pstate = AT_PARSER_SKIP_LINE;
-		} else if (port->pstate == AT_PARSER_WAIT_T) {
+				port->at_emul.pstate = AT_PARSER_SKIP_LINE;
+		} else if (port->at_emul.pstate == AT_PARSER_WAIT_T) {
 			if (c == 'T' || c == 't')
-				port->pstate = AT_PARSER_WAIT_TERM;
+				port->at_emul.pstate = AT_PARSER_WAIT_TERM;
 			else
-				port->pstate = AT_PARSER_SKIP_LINE;
-		} else if (port->pstate == AT_PARSER_WAIT_TERM) {
+				port->at_emul.pstate = AT_PARSER_SKIP_LINE;
+		} else if (port->at_emul.pstate == AT_PARSER_WAIT_TERM) {
 			if (c != '\r')
 				continue;
 			/* Consume the trailing formatting char as well */
@@ -162,11 +166,11 @@ static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
 			skb_put_data(out, &in->data[s], n);/* Echo */
 			skb_put_data(out, "\r\nOK\r\n", 6);
 			s = i + 1;
-			port->pstate = AT_PARSER_WAIT_A;
-		} else if (port->pstate == AT_PARSER_SKIP_LINE) {
+			port->at_emul.pstate = AT_PARSER_WAIT_A;
+		} else if (port->at_emul.pstate == AT_PARSER_SKIP_LINE) {
 			if (c != '\r')
 				continue;
-			port->pstate = AT_PARSER_WAIT_A;
+			port->at_emul.pstate = AT_PARSER_WAIT_A;
 		}
 	}
 
@@ -183,18 +187,25 @@ static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
 	return 0;
 }
 
-static const struct wwan_port_ops wwan_hwsim_port_ops = {
-	.start = wwan_hwsim_port_start,
-	.stop = wwan_hwsim_port_stop,
-	.tx = wwan_hwsim_port_tx,
+static const struct wwan_port_ops wwan_hwsim_at_emul_port_ops = {
+	.start = wwan_hwsim_at_emul_start,
+	.stop = wwan_hwsim_at_emul_stop,
+	.tx = wwan_hwsim_at_emul_tx,
 };
 
-static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev)
+static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev,
+						   enum wwan_port_type type)
 {
+	const struct wwan_port_ops *ops;
 	struct wwan_hwsim_port *port;
 	char name[0x10];
 	int err;
 
+	if (type == WWAN_PORT_AT)
+		ops = &wwan_hwsim_at_emul_port_ops;
+	else
+		return ERR_PTR(-EINVAL);
+
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
 	if (!port)
 		return ERR_PTR(-ENOMEM);
@@ -205,9 +216,7 @@ static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev)
 	port->id = dev->port_idx++;
 	spin_unlock(&dev->ports_lock);
 
-	port->wwan = wwan_create_port(&dev->dev, WWAN_PORT_AT,
-				      &wwan_hwsim_port_ops,
-				      NULL, port);
+	port->wwan = wwan_create_port(&dev->dev, type, ops, NULL, port);
 	if (IS_ERR(port->wwan)) {
 		err = PTR_ERR(port->wwan);
 		goto err_free_port;
@@ -392,7 +401,7 @@ static ssize_t wwan_hwsim_debugfs_portcreate_write(struct file *file,
 	struct wwan_hwsim_dev *dev = file->private_data;
 	struct wwan_hwsim_port *port;
 
-	port = wwan_hwsim_port_new(dev);
+	port = wwan_hwsim_port_new(dev, WWAN_PORT_AT);
 	if (IS_ERR(port))
 		return PTR_ERR(port);
 
@@ -459,6 +468,8 @@ static int __init wwan_hwsim_init_devs(void)
 	int i, j;
 
 	for (i = 0; i < wwan_hwsim_devsnum; ++i) {
+		struct wwan_hwsim_port *port;
+
 		dev = wwan_hwsim_dev_new();
 		if (IS_ERR(dev))
 			return PTR_ERR(dev);
@@ -471,9 +482,7 @@ static int __init wwan_hwsim_init_devs(void)
 		 * the simulator readiness time.
 		 */
 		for (j = 0; j < 2; ++j) {
-			struct wwan_hwsim_port *port;
-
-			port = wwan_hwsim_port_new(dev);
+			port = wwan_hwsim_port_new(dev, WWAN_PORT_AT);
 			if (IS_ERR(port))
 				return PTR_ERR(port);
 
-- 
2.25.1

[net-next v7 7/8] net: wwan: hwsim: support NMEA port emulation

[Slark Xiao]

From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Support NMEA port emulation for the WWAN core GNSS port testing purpose.
Emulator produces pair of GGA + RMC sentences every second what should
be enough to fool gpsd into believing it is working with a NMEA GNSS
receiver.

If the GNSS system is enabled then one NMEA port will be created
automatically for the simulated WWAN device. Manual NMEA port creation
is not supported at the moment.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/wwan_hwsim.c | 128 +++++++++++++++++++++++++++++++++-
 1 file changed, 126 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
index 11d15dc39041..e4b1bbff9af2 100644
--- a/drivers/net/wwan/wwan_hwsim.c
+++ b/drivers/net/wwan/wwan_hwsim.c
@@ -2,7 +2,7 @@
 /*
  * WWAN device simulator for WWAN framework testing.
  *
- * Copyright (c) 2021, Sergey Ryazanov <ryazanov.s.a@gmail.com>
+ * Copyright (c) 2021, 2025, Sergey Ryazanov <ryazanov.s.a@gmail.com>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -12,8 +12,10 @@
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/spinlock.h>
+#include <linux/time.h>
 #include <linux/list.h>
 #include <linux/skbuff.h>
+#include <linux/timer.h>
 #include <linux/netdevice.h>
 #include <linux/wwan.h>
 #include <linux/debugfs.h>
@@ -65,6 +67,9 @@ struct wwan_hwsim_port {
 				AT_PARSER_SKIP_LINE,
 			} pstate;
 		} at_emul;
+		struct {
+			struct timer_list timer;
+		} nmea_emul;
 	};
 };
 
@@ -193,6 +198,108 @@ static const struct wwan_port_ops wwan_hwsim_at_emul_port_ops = {
 	.tx = wwan_hwsim_at_emul_tx,
 };
 
+#if IS_ENABLED(CONFIG_GNSS)
+#define NMEA_MAX_LEN		82	/* Max sentence length */
+#define NMEA_TRAIL_LEN		5	/* '*' + Checksum + <CR><LF> */
+#define NMEA_MAX_DATA_LEN	(NMEA_MAX_LEN - NMEA_TRAIL_LEN)
+
+static __printf(2, 3)
+void wwan_hwsim_nmea_skb_push_sentence(struct sk_buff *skb,
+				       const char *fmt, ...)
+{
+	unsigned char *s, *p;
+	va_list ap;
+	u8 cs = 0;
+	int len;
+
+	s = skb_put(skb, NMEA_MAX_LEN + 1);	/* +'\0' */
+	if (!s)
+		return;
+
+	va_start(ap, fmt);
+	len = vsnprintf(s, NMEA_MAX_DATA_LEN + 1, fmt, ap);
+	va_end(ap);
+	if (WARN_ON_ONCE(len > NMEA_MAX_DATA_LEN))/* No space for trailer */
+		return;
+
+	for (p = s + 1; *p != '\0'; ++p)/* Skip leading '$' or '!' */
+		cs ^= *p;
+	p += snprintf(p, 5 + 1, "*%02X\r\n", cs);
+
+	len = (p - s) - (NMEA_MAX_LEN + 1);	/* exp. vs real length diff */
+	skb->tail += len;			/* Adjust tail to real length */
+	skb->len += len;
+}
+
+static void wwan_hwsim_nmea_emul_timer(struct timer_list *t)
+{
+	/* 43.74754722298909 N 11.25759835922875 E in DMM format */
+	static const unsigned int coord[4 * 2] = { 43, 44, 8528, 0,
+						   11, 15, 4559, 0 };
+	struct wwan_hwsim_port *port = timer_container_of(port, t, nmea_emul.timer);
+	struct sk_buff *skb;
+	struct tm tm;
+
+	time64_to_tm(ktime_get_real_seconds(), 0, &tm);
+
+	mod_timer(&port->nmea_emul.timer, jiffies + HZ);	/* 1 second */
+
+	skb = alloc_skb(NMEA_MAX_LEN * 2, GFP_KERNEL);	/* GGA + RMC */
+	if (!skb)
+		return;
+
+	wwan_hwsim_nmea_skb_push_sentence(skb,
+					  "$GPGGA,%02u%02u%02u.000,%02u%02u.%04u,%c,%03u%02u.%04u,%c,1,7,1.03,176.2,M,55.2,M,,",
+					  tm.tm_hour, tm.tm_min, tm.tm_sec,
+					  coord[0], coord[1], coord[2],
+					  coord[3] ? 'S' : 'N',
+					  coord[4], coord[5], coord[6],
+					  coord[7] ? 'W' : 'E');
+
+	wwan_hwsim_nmea_skb_push_sentence(skb,
+					  "$GPRMC,%02u%02u%02u.000,A,%02u%02u.%04u,%c,%03u%02u.%04u,%c,0.02,31.66,%02u%02u%02u,,,A",
+					  tm.tm_hour, tm.tm_min, tm.tm_sec,
+					  coord[0], coord[1], coord[2],
+					  coord[3] ? 'S' : 'N',
+					  coord[4], coord[5], coord[6],
+					  coord[7] ? 'W' : 'E',
+					  tm.tm_mday, tm.tm_mon + 1,
+					  (unsigned int)tm.tm_year - 100);
+
+	wwan_port_rx(port->wwan, skb);
+}
+
+static int wwan_hwsim_nmea_emul_start(struct wwan_port *wport)
+{
+	struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
+
+	timer_setup(&port->nmea_emul.timer, wwan_hwsim_nmea_emul_timer, 0);
+	wwan_hwsim_nmea_emul_timer(&port->nmea_emul.timer);
+
+	return 0;
+}
+
+static void wwan_hwsim_nmea_emul_stop(struct wwan_port *wport)
+{
+	struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
+
+	timer_delete_sync(&port->nmea_emul.timer);
+}
+
+static int wwan_hwsim_nmea_emul_tx(struct wwan_port *wport, struct sk_buff *in)
+{
+	consume_skb(in);
+
+	return 0;
+}
+
+static const struct wwan_port_ops wwan_hwsim_nmea_emul_port_ops = {
+	.start = wwan_hwsim_nmea_emul_start,
+	.stop = wwan_hwsim_nmea_emul_stop,
+	.tx = wwan_hwsim_nmea_emul_tx,
+};
+#endif
+
 static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev,
 						   enum wwan_port_type type)
 {
@@ -203,6 +310,10 @@ static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev,
 
 	if (type == WWAN_PORT_AT)
 		ops = &wwan_hwsim_at_emul_port_ops;
+#if IS_ENABLED(CONFIG_GNSS)
+	else if (type == WWAN_PORT_NMEA)
+		ops = &wwan_hwsim_nmea_emul_port_ops;
+#endif
 	else
 		return ERR_PTR(-EINVAL);
 
@@ -478,9 +589,10 @@ static int __init wwan_hwsim_init_devs(void)
 		list_add_tail(&dev->list, &wwan_hwsim_devs);
 		spin_unlock(&wwan_hwsim_devs_lock);
 
-		/* Create a couple of ports per each device to accelerate
+		/* Create a few various ports per each device to accelerate
 		 * the simulator readiness time.
 		 */
+
 		for (j = 0; j < 2; ++j) {
 			port = wwan_hwsim_port_new(dev, WWAN_PORT_AT);
 			if (IS_ERR(port))
@@ -490,6 +602,18 @@ static int __init wwan_hwsim_init_devs(void)
 			list_add_tail(&port->list, &dev->ports);
 			spin_unlock(&dev->ports_lock);
 		}
+
+#if IS_ENABLED(CONFIG_GNSS)
+		port = wwan_hwsim_port_new(dev, WWAN_PORT_NMEA);
+		if (IS_ERR(port)) {
+			dev_warn(&dev->dev, "failed to create initial NMEA port: %d\n",
+				 (int)PTR_ERR(port));
+		} else {
+			spin_lock(&dev->ports_lock);
+			list_add_tail(&port->list, &dev->ports);
+			spin_unlock(&dev->ports_lock);
+		}
+#endif
 	}
 
 	return 0;
-- 
2.25.1

Re: [net-next,v7,7/8] net: wwan: hwsim: support NMEA port emulation

[Jakub Kicinski]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net: wwan: hwsim: support NMEA port emulation

This commit adds NMEA port emulation to the WWAN hardware simulator for
GNSS port testing. The emulator generates GGA and RMC sentences every
second via a timer callback.

> diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
> index 11d15dc39041..e4b1bbff9af2 100644
> --- a/drivers/net/wwan/wwan_hwsim.c
> +++ b/drivers/net/wwan/wwan_hwsim.c

[ ... ]

> +#if IS_ENABLED(CONFIG_GNSS)
> +#define NMEA_MAX_LEN		82	/* Max sentence length */
> +#define NMEA_TRAIL_LEN		5	/* '*' + Checksum + <CR><LF> */
> +#define NMEA_MAX_DATA_LEN	(NMEA_MAX_LEN - NMEA_TRAIL_LEN)
> +
> +static __printf(2, 3)
> +void wwan_hwsim_nmea_skb_push_sentence(struct sk_buff *skb,
> +				       const char *fmt, ...)
> +{
> +	unsigned char *s, *p;
> +	va_list ap;
> +	u8 cs = 0;
> +	int len;
> +
> +	s = skb_put(skb, NMEA_MAX_LEN + 1);	/* +'\0' */

[ ... ]

> +static void wwan_hwsim_nmea_emul_timer(struct timer_list *t)
> +{
> +	/* 43.74754722298909 N 11.25759835922875 E in DMM format */
> +	static const unsigned int coord[4 * 2] = { 43, 44, 8528, 0,
> +						   11, 15, 4559, 0 };
> +	struct wwan_hwsim_port *port = timer_container_of(port, t, nmea_emul.timer);
> +	struct sk_buff *skb;
> +	struct tm tm;
> +
> +	time64_to_tm(ktime_get_real_seconds(), 0, &tm);
> +
> +	mod_timer(&port->nmea_emul.timer, jiffies + HZ);	/* 1 second */
> +
> +	skb = alloc_skb(NMEA_MAX_LEN * 2, GFP_KERNEL);	/* GGA + RMC */
                       ^^^^^^^^^^^^^^     ^^^^^^^^^^

Two questions about this allocation:

1. The buffer size appears to be insufficient. The allocation requests
NMEA_MAX_LEN * 2 = 164 bytes, but wwan_hwsim_nmea_skb_push_sentence()
is called twice and each call uses skb_put(skb, NMEA_MAX_LEN + 1) which
reserves 83 bytes per sentence. The total needed is 166 bytes, which
exceeds the 164 bytes allocated. Would this cause skb_over_panic() to
trigger on the second skb_put() call?

2. This function is a timer callback registered via timer_setup() in
wwan_hwsim_nmea_emul_start(). Timer callbacks run in softirq context
where sleeping is not permitted. GFP_KERNEL allocations can sleep when
memory pressure triggers reclaim. Should this be GFP_ATOMIC instead to
avoid "scheduling while atomic" warnings?

> +	if (!skb)
> +		return;
> +
> +	wwan_hwsim_nmea_skb_push_sentence(skb,
> +					  "$GPGGA,%02u%02u%02u.000,%02u%02u.%04u,%c,%03u%02u.%04u,%c,1,7,1.03,176.2,M,55.2,M,,",
> +					  tm.tm_hour, tm.tm_min, tm.tm_sec,
> +					  coord[0], coord[1], coord[2],
> +					  coord[3] ? 'S' : 'N',
> +					  coord[4], coord[5], coord[6],
> +					  coord[7] ? 'W' : 'E');
> +
> +	wwan_hwsim_nmea_skb_push_sentence(skb,
> +					  "$GPRMC,%02u%02u%02u.000,A,%02u%02u.%04u,%c,%03u%02u.%04u,%c,0.02,31.66,%02u%02u%02u,,,A",
> +					  tm.tm_hour, tm.tm_min, tm.tm_sec,
> +					  coord[0], coord[1], coord[2],
> +					  coord[3] ? 'S' : 'N',
> +					  coord[4], coord[5], coord[6],
> +					  coord[7] ? 'W' : 'E',
> +					  tm.tm_mday, tm.tm_mon + 1,
> +					  (unsigned int)tm.tm_year - 100);
> +
> +	wwan_port_rx(port->wwan, skb);
> +}

[ ... ]

Re:Re: [net-next,v7,7/8] net: wwan: hwsim: support NMEA port emulation

[Slark Xiao]

At 2026-01-16 10:44:41, "Jakub Kicinski" <kuba@kernel.org> wrote:
>This is an AI-generated review of your patch. The human sending this
>email has considered the AI review valid, or at least plausible.
>
>For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
>---
>net: wwan: hwsim: support NMEA port emulation
>
>This commit adds NMEA port emulation to the WWAN hardware simulator for
>GNSS port testing. The emulator generates GGA and RMC sentences every
>second via a timer callback.
>
>> diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
>> index 11d15dc39041..e4b1bbff9af2 100644
>> --- a/drivers/net/wwan/wwan_hwsim.c
>> +++ b/drivers/net/wwan/wwan_hwsim.c
>
>[ ... ]
>
>> +#if IS_ENABLED(CONFIG_GNSS)
>> +#define NMEA_MAX_LEN		82	/* Max sentence length */
>> +#define NMEA_TRAIL_LEN		5	/* '*' + Checksum + <CR><LF> */
>> +#define NMEA_MAX_DATA_LEN	(NMEA_MAX_LEN - NMEA_TRAIL_LEN)
>> +
>> +static __printf(2, 3)
>> +void wwan_hwsim_nmea_skb_push_sentence(struct sk_buff *skb,
>> +				       const char *fmt, ...)
>> +{
>> +	unsigned char *s, *p;
>> +	va_list ap;
>> +	u8 cs = 0;
>> +	int len;
>> +
>> +	s = skb_put(skb, NMEA_MAX_LEN + 1);	/* +'\0' */
>
>[ ... ]
>
>> +static void wwan_hwsim_nmea_emul_timer(struct timer_list *t)
>> +{
>> +	/* 43.74754722298909 N 11.25759835922875 E in DMM format */
>> +	static const unsigned int coord[4 * 2] = { 43, 44, 8528, 0,
>> +						   11, 15, 4559, 0 };
>> +	struct wwan_hwsim_port *port = timer_container_of(port, t, nmea_emul.timer);
>> +	struct sk_buff *skb;
>> +	struct tm tm;
>> +
>> +	time64_to_tm(ktime_get_real_seconds(), 0, &tm);
>> +
>> +	mod_timer(&port->nmea_emul.timer, jiffies + HZ);	/* 1 second */
>> +
>> +	skb = alloc_skb(NMEA_MAX_LEN * 2, GFP_KERNEL);	/* GGA + RMC */
>                       ^^^^^^^^^^^^^^     ^^^^^^^^^^
>
Hi Sergey, Loic,
Let's update it as :
+	skb = alloc_skb(NMEA_MAX_LEN * 2+2, GFP_ATOMIC);	/* GGA + RMC */

How do you think?


>Two questions about this allocation:
>
>1. The buffer size appears to be insufficient. The allocation requests
>NMEA_MAX_LEN * 2 = 164 bytes, but wwan_hwsim_nmea_skb_push_sentence()
>is called twice and each call uses skb_put(skb, NMEA_MAX_LEN + 1) which
>reserves 83 bytes per sentence. The total needed is 166 bytes, which
>exceeds the 164 bytes allocated. Would this cause skb_over_panic() to
>trigger on the second skb_put() call?
>
>2. This function is a timer callback registered via timer_setup() in
>wwan_hwsim_nmea_emul_start(). Timer callbacks run in softirq context
>where sleeping is not permitted. GFP_KERNEL allocations can sleep when
>memory pressure triggers reclaim. Should this be GFP_ATOMIC instead to
>avoid "scheduling while atomic" warnings?
>
>> +	if (!skb)
>> +		return;
>> +
>> +	wwan_hwsim_nmea_skb_push_sentence(skb,
>> +					  "$GPGGA,%02u%02u%02u.000,%02u%02u.%04u,%c,%03u%02u.%04u,%c,1,7,1.03,176.2,M,55.2,M,,",
>> +					  tm.tm_hour, tm.tm_min, tm.tm_sec,
>> +					  coord[0], coord[1], coord[2],
>> +					  coord[3] ? 'S' : 'N',
>> +					  coord[4], coord[5], coord[6],
>> +					  coord[7] ? 'W' : 'E');
>> +
>> +	wwan_hwsim_nmea_skb_push_sentence(skb,
>> +					  "$GPRMC,%02u%02u%02u.000,A,%02u%02u.%04u,%c,%03u%02u.%04u,%c,0.02,31.66,%02u%02u%02u,,,A",
>> +					  tm.tm_hour, tm.tm_min, tm.tm_sec,
>> +					  coord[0], coord[1], coord[2],
>> +					  coord[3] ? 'S' : 'N',
>> +					  coord[4], coord[5], coord[6],
>> +					  coord[7] ? 'W' : 'E',
>> +					  tm.tm_mday, tm.tm_mon + 1,
>> +					  (unsigned int)tm.tm_year - 100);
>> +
>> +	wwan_port_rx(port->wwan, skb);
>> +}
>
>[ ... ]

[net-next v7 8/8] net: wwan: mhi_wwan_ctrl: Add NMEA channel support

[Slark Xiao]

For MHI WWAN device, we need a match between NMEA channel and
WWAN_PORT_NMEA type. Then the GNSS subsystem could create the
gnss device succssfully.

Signed-off-by: Slark Xiao <slark_xiao@163.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/net/wwan/mhi_wwan_ctrl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wwan/mhi_wwan_ctrl.c b/drivers/net/wwan/mhi_wwan_ctrl.c
index e9f979d2d851..e13c0b078175 100644
--- a/drivers/net/wwan/mhi_wwan_ctrl.c
+++ b/drivers/net/wwan/mhi_wwan_ctrl.c
@@ -263,6 +263,7 @@ static const struct mhi_device_id mhi_wwan_ctrl_match_table[] = {
 	{ .chan = "QMI", .driver_data = WWAN_PORT_QMI },
 	{ .chan = "DIAG", .driver_data = WWAN_PORT_QCDM },
 	{ .chan = "FIREHOSE", .driver_data = WWAN_PORT_FIREHOSE },
+	{ .chan = "NMEA", .driver_data = WWAN_PORT_NMEA },
 	{},
 };
 MODULE_DEVICE_TABLE(mhi, mhi_wwan_ctrl_match_table);
-- 
2.25.1

Re: [net-next v7 8/8] net: wwan: mhi_wwan_ctrl: Add NMEA channel support

[Sergey Ryazanov]

On 1/15/26 13:46, Slark Xiao wrote:
> For MHI WWAN device, we need a match between NMEA channel and
> WWAN_PORT_NMEA type. Then the GNSS subsystem could create the
> gnss device succssfully.
> 
> Signed-off-by: Slark Xiao <slark_xiao@163.com>
> Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>

Acked-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Re: [net-next v7 0/8] net: wwan: add NMEA port type support

[Jakub Kicinski]

On Thu, 15 Jan 2026 19:46:17 +0800 Slark Xiao wrote:
> The series introduces a long discussed NMEA port type support for the
> WWAN subsystem. There are two goals. From the WWAN driver perspective,
> NMEA exported as any other port type (e.g. AT, MBIM, QMI, etc.). From
> user space software perspective, the exported chardev belongs to the
> GNSS class what makes it easy to distinguish desired port and the WWAN
> device common to both NMEA and control (AT, MBIM, etc.) ports makes it
> easy to locate a control port for the GNSS receiver activation.

I'm going to release the results of AI code review. Since you ignored
the reposting period with this version please do not post v8 until
next week.

Re:Re: [net-next v7 0/8] net: wwan: add NMEA port type support

[Slark Xiao]

At 2026-01-16 10:43:52, "Jakub Kicinski" <kuba@kernel.org> wrote:
>On Thu, 15 Jan 2026 19:46:17 +0800 Slark Xiao wrote:
>> The series introduces a long discussed NMEA port type support for the
>> WWAN subsystem. There are two goals. From the WWAN driver perspective,
>> NMEA exported as any other port type (e.g. AT, MBIM, QMI, etc.). From
>> user space software perspective, the exported chardev belongs to the
>> GNSS class what makes it easy to distinguish desired port and the WWAN
>> device common to both NMEA and control (AT, MBIM, etc.) ports makes it
>> easy to locate a control port for the GNSS receiver activation.
>
>I'm going to release the results of AI code review. Since you ignored
>the reposting period with this version please do not post v8 until
>next week.

Sorry, I didn't mean to break these rules. And I sent v7 before you previous warm notice in v6.
Anyway, I will follow it in future.