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

From: Roger Quadros <[email-masked]>
Date: Mon, 21 Jan 2013 15:21:21 +0200

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 <[email-masked]>
> Signed-off-by: Kishon Vijay Abraham I <[email-masked]>
> ---
>  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.

> +
> +	spin_lock_irqsave(&phy_lock, flags);
> +
> +	phy = __of_usb_find_phy(node);
> +	if (IS_ERR(phy) || !try_module_get(phy->dev->driver->owner)) {
> +		phy = ERR_PTR(-EPROBE_DEFER);
> +		devres_free(ptr);
> +		goto err0;
> +	}
> +
> +	*ptr = phy;
> +	devres_add(dev, ptr);
> +
> +	get_device(phy->dev);
> +
> +err0:
> +	spin_unlock_irqrestore(&phy_lock, flags);
> +
> +	return phy;
> +}
> +EXPORT_SYMBOL(devm_usb_get_phy_by_phandle);
> +

--
cheers,
-roger