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[0/6] usb: Linking ports to their Type-C connectors

Message ID 20210325122926.58392-1-heikki.krogerus@linux.intel.com
Headers show
Series usb: Linking ports to their Type-C connectors | expand

Message

Heikki Krogerus March 25, 2021, 12:29 p.m. UTC 
Hi,

Adding a simple function typec_link_port() that can be used to create
a symlink "connector" that points to the USB Type-C connector of a
port. It is used with USB ports initially, but hopefully later also
with other things like DisplayPorts.

Being able to see which connector is connected to a port is important
in general, but it is really important when for example the data or
power role of a device needs to swapped. The user probable wants to
know which USB device is disconnected if role swap on a USB Type-C
connector is executed.

Hope these are OK.

thanks,

Heikki Krogerus (6):
  usb: Iterator for ports
  usb: typec: Organize the private headers properly
  usb: typec: Declare the typec_class static
  usb: typec: Port mapping utility
  usb: Link the ports to the connectors they are attached to
  usb: typec: Link all ports during connector registration

 Documentation/ABI/testing/sysfs-bus-usb |   9 +
 drivers/usb/core/port.c                 |   3 +
 drivers/usb/core/usb.c                  |  43 ++++
 drivers/usb/typec/Makefile              |   1 +
 drivers/usb/typec/bus.c                 |   2 +
 drivers/usb/typec/bus.h                 |  19 +-
 drivers/usb/typec/class.c               | 101 +++------
 drivers/usb/typec/class.h               |  94 ++++++++
 drivers/usb/typec/mux.c                 |   4 +-
 drivers/usb/typec/mux.h                 |  21 ++
 drivers/usb/typec/port-mapper.c         | 283 ++++++++++++++++++++++++
 include/linux/usb.h                     |   1 +
 include/linux/usb/typec.h               |  13 ++
 13 files changed, 499 insertions(+), 95 deletions(-)
 create mode 100644 drivers/usb/typec/class.h
 create mode 100644 drivers/usb/typec/mux.h
 create mode 100644 drivers/usb/typec/port-mapper.c

Comments

Alan Stern March 25, 2021, 2:41 p.m. UTC | #1 
On Thu, Mar 25, 2021 at 03:29:21PM +0300, Heikki Krogerus wrote:
> Introducing usb_for_each_port(). It works the same way as
> usb_for_each_dev(), but instead of going through every USB
> device in the system, it walks through the USB ports in the
> system.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

This has a couple of nasty errors.

> ---
>  drivers/usb/core/usb.c | 43 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/usb.h    |  1 +
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> index 2ce3667ec6fae..6d49db9a1b208 100644
> --- a/drivers/usb/core/usb.c
> +++ b/drivers/usb/core/usb.c
> @@ -398,6 +398,49 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
>  }
>  EXPORT_SYMBOL_GPL(usb_for_each_dev);
>  
> +struct each_hub_arg {
> +	void *data;
> +	int (*fn)(struct device *, void *);
> +};
> +
> +static int __each_hub(struct device *dev, void *data)
> +{
> +	struct each_hub_arg *arg = (struct each_hub_arg *)data;
> +	struct usb_device *hdev = to_usb_device(dev);

to_usb_device() won't work properly if the struct device isn't embedded 
in an actual usb_device structure.  And that will happen, since the USB 
bus type holds usb_interface structures as well as usb_devices.

In fact, you should use usb_for_each_dev here; it already does what you 
want.

> +	struct usb_hub *hub;
> +	int ret;
> +	int i;
> +
> +	hub = usb_hub_to_struct_hub(hdev);
> +	if (!hub)
> +		return 0;
> +
> +	for (i = 0; i < hdev->maxchild; i++) {
> +		ret = arg->fn(&hub->ports[i]->dev, arg->data);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}

Don't you need some sort of locking or refcounting here?  What would 
happen if this hub got removed while the routine was running?

Alan Stern
Heikki Krogerus March 25, 2021, 3:14 p.m. UTC | #2 
On Thu, Mar 25, 2021 at 10:41:09AM -0400, Alan Stern wrote:
> On Thu, Mar 25, 2021 at 03:29:21PM +0300, Heikki Krogerus wrote:
> > Introducing usb_for_each_port(). It works the same way as
> > usb_for_each_dev(), but instead of going through every USB
> > device in the system, it walks through the USB ports in the
> > system.
> > 
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> 
> This has a couple of nasty errors.
> 
> > ---
> >  drivers/usb/core/usb.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/usb.h    |  1 +
> >  2 files changed, 44 insertions(+)
> > 
> > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> > index 2ce3667ec6fae..6d49db9a1b208 100644
> > --- a/drivers/usb/core/usb.c
> > +++ b/drivers/usb/core/usb.c
> > @@ -398,6 +398,49 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
> >  }
> >  EXPORT_SYMBOL_GPL(usb_for_each_dev);
> >  
> > +struct each_hub_arg {
> > +	void *data;
> > +	int (*fn)(struct device *, void *);
> > +};
> > +
> > +static int __each_hub(struct device *dev, void *data)
> > +{
> > +	struct each_hub_arg *arg = (struct each_hub_arg *)data;
> > +	struct usb_device *hdev = to_usb_device(dev);
> 
> to_usb_device() won't work properly if the struct device isn't embedded 
> in an actual usb_device structure.  And that will happen, since the USB 
> bus type holds usb_interface structures as well as usb_devices.

OK, so I need to filter them out.

> In fact, you should use usb_for_each_dev here; it already does what you 
> want.

Unfortunately I can't use usb_for_each_dev here, because it deals with
struct usb_device while I need to deal with struct device in the
callback.

> > +	struct usb_hub *hub;
> > +	int ret;
> > +	int i;
> > +
> > +	hub = usb_hub_to_struct_hub(hdev);
> > +	if (!hub)
> > +		return 0;
> > +
> > +	for (i = 0; i < hdev->maxchild; i++) {
> > +		ret = arg->fn(&hub->ports[i]->dev, arg->data);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> 
> Don't you need some sort of locking or refcounting here?  What would 
> happen if this hub got removed while the routine was running?

I'll use a lock then.

thanks,
Heikki Krogerus March 25, 2021, 3:23 p.m. UTC | #3 
On Thu, Mar 25, 2021 at 05:14:45PM +0200, Heikki Krogerus wrote:
> On Thu, Mar 25, 2021 at 10:41:09AM -0400, Alan Stern wrote:
> > On Thu, Mar 25, 2021 at 03:29:21PM +0300, Heikki Krogerus wrote:
> > > Introducing usb_for_each_port(). It works the same way as
> > > usb_for_each_dev(), but instead of going through every USB
> > > device in the system, it walks through the USB ports in the
> > > system.
> > > 
> > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > 
> > This has a couple of nasty errors.
> > 
> > > ---
> > >  drivers/usb/core/usb.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> > >  include/linux/usb.h    |  1 +
> > >  2 files changed, 44 insertions(+)
> > > 
> > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> > > index 2ce3667ec6fae..6d49db9a1b208 100644
> > > --- a/drivers/usb/core/usb.c
> > > +++ b/drivers/usb/core/usb.c
> > > @@ -398,6 +398,49 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
> > >  }
> > >  EXPORT_SYMBOL_GPL(usb_for_each_dev);
> > >  
> > > +struct each_hub_arg {
> > > +	void *data;
> > > +	int (*fn)(struct device *, void *);
> > > +};
> > > +
> > > +static int __each_hub(struct device *dev, void *data)
> > > +{
> > > +	struct each_hub_arg *arg = (struct each_hub_arg *)data;
> > > +	struct usb_device *hdev = to_usb_device(dev);
> > 
> > to_usb_device() won't work properly if the struct device isn't embedded 
> > in an actual usb_device structure.  And that will happen, since the USB 
> > bus type holds usb_interface structures as well as usb_devices.
> 
> OK, so I need to filter them out.
> 
> > In fact, you should use usb_for_each_dev here; it already does what you 
> > want.
> 
> Unfortunately I can't use usb_for_each_dev here, because it deals with
> struct usb_device while I need to deal with struct device in the
> callback.

Ah, I can use it instead of bus_for_each_dev() in usb_for_each_port().
I'll fix these in v2.

For the lock I guess I can just use the peer lock (usb_port_peer_mutex)?

thanks,
Heikki Krogerus March 25, 2021, 3:33 p.m. UTC | #4 
On Thu, Mar 25, 2021 at 04:20:15PM +0100, Greg Kroah-Hartman wrote:
> On Thu, Mar 25, 2021 at 05:14:42PM +0200, Heikki Krogerus wrote:
> > On Thu, Mar 25, 2021 at 10:41:09AM -0400, Alan Stern wrote:
> > > On Thu, Mar 25, 2021 at 03:29:21PM +0300, Heikki Krogerus wrote:
> > > > Introducing usb_for_each_port(). It works the same way as
> > > > usb_for_each_dev(), but instead of going through every USB
> > > > device in the system, it walks through the USB ports in the
> > > > system.
> > > > 
> > > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > > 
> > > This has a couple of nasty errors.
> > > 
> > > > ---
> > > >  drivers/usb/core/usb.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> > > >  include/linux/usb.h    |  1 +
> > > >  2 files changed, 44 insertions(+)
> > > > 
> > > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
> > > > index 2ce3667ec6fae..6d49db9a1b208 100644
> > > > --- a/drivers/usb/core/usb.c
> > > > +++ b/drivers/usb/core/usb.c
> > > > @@ -398,6 +398,49 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(usb_for_each_dev);
> > > >  
> > > > +struct each_hub_arg {
> > > > +	void *data;
> > > > +	int (*fn)(struct device *, void *);
> > > > +};
> > > > +
> > > > +static int __each_hub(struct device *dev, void *data)
> > > > +{
> > > > +	struct each_hub_arg *arg = (struct each_hub_arg *)data;
> > > > +	struct usb_device *hdev = to_usb_device(dev);
> > > 
> > > to_usb_device() won't work properly if the struct device isn't embedded 
> > > in an actual usb_device structure.  And that will happen, since the USB 
> > > bus type holds usb_interface structures as well as usb_devices.
> > 
> > OK, so I need to filter them out.
> > 
> > > In fact, you should use usb_for_each_dev here; it already does what you 
> > > want.
> > 
> > Unfortunately I can't use usb_for_each_dev here, because it deals with
> > struct usb_device while I need to deal with struct device in the
> > callback.
> 
> Why do you need 'struct device' in the callback?  All you really want is
> the hub devices, right?

I need the ports, not the hubs.

> > > > +	struct usb_hub *hub;
> > > > +	int ret;
> > > > +	int i;
> > > > +
> > > > +	hub = usb_hub_to_struct_hub(hdev);
> > > > +	if (!hub)
> > > > +		return 0;
> > > > +
> > > > +	for (i = 0; i < hdev->maxchild; i++) {
> > > > +		ret = arg->fn(&hub->ports[i]->dev, arg->data);
> > > > +		if (ret)
> > > > +			return ret;
> > > > +	}
> > > > +
> > > > +	return 0;
> > > > +}
> > > 
> > > Don't you need some sort of locking or refcounting here?  What would 
> > > happen if this hub got removed while the routine was running?
> > 
> > I'll use a lock then.
> 
> That's not going to work to be held over a callback.  Just properly
> increment the reference count.

I though we have done that already. Does bus_for_each_dev() do that
for the device that it passes to the callback until that callback
returns?

thanks,