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SubjectRe: [v3 PATCH 4/6] usb: roles: add API to get usb_role_switch by node
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On Wed, 2019-04-10 at 13:22 +0300, Heikki Krogerus wrote:
> On Wed, Apr 03, 2019 at 10:09:12AM +0800, Chunfeng Yun wrote:
> > Add fwnode_usb_role_switch_get() to make easier to get
> > usb_role_switch by fwnode which register it.
> > It's useful when there is not device_connection registered
> > between two drivers and only knows the fwnode which register
> > usb_role_switch.
> >
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > ---
> > v3 changes:
> > 1. use fwnodes instead of node suggested by Andy
> > 2. rebuild the API suggested by Heikki
> >
> > v2 no changes
> > ---
> > drivers/usb/roles/class.c | 31 +++++++++++++++++++++++++++++++
> > include/linux/usb/role.h | 2 ++
> > 2 files changed, 33 insertions(+)
> >
> > diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> > index f45d8df5cfb8..5ecb57f8960b 100644
> > --- a/drivers/usb/roles/class.c
> > +++ b/drivers/usb/roles/class.c
> > @@ -12,6 +12,7 @@
> > #include <linux/device.h>
> > #include <linux/module.h>
> > #include <linux/mutex.h>
> > +#include <linux/of.h>
> > #include <linux/slab.h>
> >
> > static struct class *role_class;
> > @@ -135,6 +136,36 @@ struct usb_role_switch *usb_role_switch_get(struct device *dev)
> > }
> > EXPORT_SYMBOL_GPL(usb_role_switch_get);
> >
> > +static int __switch_match_fwnode(struct device *dev, const void *fwnode)
> > +{
> > + return dev_fwnode(dev->parent) == (const struct fwnode_handle *)fwnode;
> > +}
>
> I don't think this is actually needed.
Yes, you are right

> Why not just assign the
> parent's fwnode for the mux as well?
will do it in next version

>
> I'll add an example to the patch 6/6 in this series.
>
> > +/**
> > + * fwnode_usb_role_switch_get - Find USB role switch by it's parent fwnode
> > + * @fwnode: The fwnode that register USB role switch
> > + *
> > + * Finds and returns role switch registered by @fwnode. The reference count
> > + * for the found switch is incremented.
> > + */
> > +struct usb_role_switch *
> > +fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
> > +{
> > + struct usb_role_switch *sw;
> > + struct device *dev;
> > +
> > + dev = class_find_device(role_class, NULL, fwnode,
> > + __switch_match_fwnode);
>
> So here you can then reuse switch_fwnode_match():
>
> dev = class_find_device(role_class, NULL, fwnode, switch_fwnode_match);
I make a fast test, it works, thanks a lot Heikki

>
> > + if (!dev)
> > + return ERR_PTR(-EPROBE_DEFER);
> > +
> > + sw = to_role_switch(dev);
> > + WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
> > +
> > + return sw;
> > +}
> > +EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get);
> > +
> > /**
> > * usb_role_switch_put - Release handle to a switch
> > * @sw: USB Role Switch
> > diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h
> > index c05ffa6abda9..d21cd55d9e45 100644
> > --- a/include/linux/usb/role.h
> > +++ b/include/linux/usb/role.h
> > @@ -46,6 +46,8 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role);
> > enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw);
> > struct usb_role_switch *usb_role_switch_get(struct device *dev);
> > void usb_role_switch_put(struct usb_role_switch *sw);
> > +struct usb_role_switch *
> > +fwnode_usb_role_switch_get(struct fwnode_handle *fwnode);
> >
> > struct usb_role_switch *
> > usb_role_switch_register(struct device *parent,
> > --
> > 2.20.1
>
> thanks,
>


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