Re: [RFC PATCH 5/6] usb: otg: add device tree support to otg library

[kishon]

On Monday 21 January 2013 06:51 PM, Roger Quadros wrote:
> On 01/16/2013 05:01 PM, Kishon Vijay Abraham I wrote:
> > Added an API devm_usb_get_phy_by_phandle(), to get usb phy by passing a
> > device node phandle value. This function will return a pointer to
> > the phy on success, -EPROBE_DEFER if there is a device_node for the phandle,
> > but the phy has not been added, or a ERR_PTR() otherwise.
> >
> > Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> > Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> > ---
> >   drivers/usb/otg/otg.c   |   77 +++++++++++++++++++++++++++++++++++++++++++++++
> >   include/linux/usb/phy.h |    8 +++++
> >   2 files changed, 85 insertions(+)
> >
> > diff --git a/drivers/usb/otg/otg.c b/drivers/usb/otg/otg.c
> > index dbf2043..e9799bb 100644
> > --- a/drivers/usb/otg/otg.c
> > +++ b/drivers/usb/otg/otg.c
> > @@ -13,7 +13,9 @@
> >   #include <linux/export.h>
> >   #include <linux/err.h>
> >   #include <linux/device.h>
> > +#include <linux/module.h>
> >   #include <linux/slab.h>
> > +#include <linux/of.h>
> >
> >   #include <linux/usb/otg.h>
> >
> > @@ -34,6 +36,20 @@ static struct usb_phy *__usb_find_phy(struct device *dev, u8 index)
> >   	return ERR_PTR(-ENODEV);
> >   }
> >
> > +static struct usb_phy *__of_usb_find_phy(struct device_node *node)
> > +{
> > +	struct usb_phy  *phy;
> > +
> > +	list_for_each_entry(phy, &phy_list, head) {
> > +		if (node != phy->dev->of_node)
> > +			continue;
> > +
> > +		return phy;
> > +	}
> > +
> > +	return ERR_PTR(-ENODEV);
> > +}
> > +
> >   static void devm_usb_phy_release(struct device *dev, void *res)
> >   {
> >   	struct usb_phy *phy = *(struct usb_phy **)res;
> > @@ -109,6 +125,67 @@ err0:
> >   }
> >   EXPORT_SYMBOL(usb_get_phy);
> >
> > + /**
> > + * devm_usb_get_phy_by_phandle - find the USB PHY by phandle
> > + * @dev - device that requests this phy
> > + * @phandle - name of the property holding the phy phandle value
> > + * @index - the index of the phy
> > + *
> > + * Returns the phy driver associated with the given phandle value,
> > + * after getting a refcount to it, -ENODEV if there is no such phy or
> > + * -EPROBE_DEFER if there is a phandle to the phy, but the device is
> > + * not yet loaded. While at that, it also associates the device with
> > + * the phy using devres. On driver detach, release function is invoked
> > + * on the devres data, then, devres data is freed.
> > + *
> > + * For use by USB host and peripheral drivers.
> > + */
> > +struct usb_phy *devm_usb_get_phy_by_phandle(struct device *dev,
> > +	const char *phandle, u8 index)
> > +{
> > +	struct usb_phy	*phy = NULL, **ptr;
> > +	unsigned long	flags;
> > +	struct device_node *node;
> > +
> > +	if (!dev->of_node) {
> > +		dev_dbg(dev, "device does not have a device node entry\n");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	node = of_parse_phandle(dev->of_node, phandle, index);
> > +	if (!node) {
> > +		dev_dbg(dev, "failed to get %s phandle in %s node\n", phandle,
> > +			dev->of_node->full_name);
> > +		return ERR_PTR(-ENODEV);
> > +	}
> > +
> > +	ptr = devres_alloc(devm_usb_phy_release, sizeof(*ptr), GFP_KERNEL);
> > +	if (!ptr) {
> > +		dev_dbg(dev, "failed to allocate memory for devres\n");
> > +		return ERR_PTR(-ENOMEM);
> > +	}
>
> I fail to understand why you need ptr at all and why do devres_alloc()
> for it.

Thats how we create a "managed device resource". You can have a look at 
Documentation/driver-model/devres.txt and drivers/base/devres.c.

I'm not sure if that is what you are looking for :-P

Thanks
Kishon
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