Re: [Patch v4 2/3] drivers: phy: Add support for optional phys

[Kishon Vijay Abraham I <kishon@ti.com>]

On Tuesday 04 February 2014 11:03 PM, Andrew Lunn wrote:
> Add devm_phy_optional_get and phy_optioanl_get, which should be used
> when the phy is optional. They does not return an error when the phy
> does not exist, rather they returns NULL, which is considered as a valid
> phy, but results in NOPs when used with the consumer API.
> 
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
> Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
> v2
>  Add phy_optional_get()
>  Improve the comments about the optional functions.
>  Drop the dev_err()->dev_dbg() changes.
> v4
>  Add Tested-by
> ---
>  Documentation/phy.txt   | 20 +++++++++++++-------
>  drivers/phy/phy-core.c  | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/phy/phy.h | 14 ++++++++++++++
>  3 files changed, 72 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/phy.txt b/Documentation/phy.txt
> index 2e24b993e95f..ebff6ee52441 100644
> --- a/Documentation/phy.txt
> +++ b/Documentation/phy.txt
> @@ -75,14 +75,20 @@ Before the controller can make use of the PHY, it has to get a reference to
>  it. This framework provides the following APIs to get a reference to the PHY.
>  
>  struct phy *phy_get(struct device *dev, const char *string);
> +struct phy *phy_optional_get(struct device *dev, const char *string);
>  struct phy *devm_phy_get(struct device *dev, const char *string);
> -
> -phy_get and devm_phy_get can be used to get the PHY. In the case of dt boot,
> -the string arguments should contain the phy name as given in the dt data and
> -in the case of non-dt boot, it should contain the label of the PHY.
> -The only difference between the two APIs is that devm_phy_get associates the
> -device with the PHY using devres on successful PHY get. On driver detach,
> -release function is invoked on the the devres data and devres data is freed.
> +struct phy *devm_phy_optional_get(struct device *dev, const char *string);
> +
> +phy_get, phy_optional_get, devm_phy_get and devm_phy_optional_get can
> +be used to get the PHY. In the case of dt boot, the string arguments
> +should contain the phy name as given in the dt data and in the case of
> +non-dt boot, it should contain the label of the PHY.  The two
> +devm_phy_get associates the device with the PHY using devres on
> +successful PHY get. On driver detach, release function is invoked on
> +the the devres data and devres data is freed. phy_optional_get and
> +devm_phy_optional_get should be used when the phy is optional. These
> +two functions will never return -ENODEV, but instead returns NULL when
> +the phy cannot be found.
>  
>  It should be noted that NULL is a valid phy reference. All phy
>  consumer calls on the NULL phy become NOPs. That is the release calls,
> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> index a9cdeee20d91..5f5b0f4be5be 100644
> --- a/drivers/phy/phy-core.c
> +++ b/drivers/phy/phy-core.c
> @@ -426,6 +426,27 @@ struct phy *phy_get(struct device *dev, const char *string)
>  EXPORT_SYMBOL_GPL(phy_get);
>  
>  /**
> + * phy_optional_get() - lookup and obtain a reference to an optional phy.
> + * @dev: device that requests this phy
> + * @string: the phy name as given in the dt data or the name of the controller
> + * port for non-dt case
> + *
> + * Returns the phy driver, after getting a refcount to it; or
> + * NULL if there is no such phy.  The caller is responsible for
> + * calling phy_put() to release that count.
> + */
> +struct phy *phy_optional_get(struct device *dev, const char *string)
> +{
> +	struct phy *phy = phy_get(dev, string);
> +
> +	if (PTR_ERR(phy) == -ENODEV)
> +		phy = NULL;
> +
> +	return phy;
> +}
> +EXPORT_SYMBOL_GPL(phy_optional_get);
> +
> +/**
>   * devm_phy_get() - lookup and obtain a reference to a phy.
>   * @dev: device that requests this phy
>   * @string: the phy name as given in the dt data or phy device name
> @@ -456,6 +477,30 @@ struct phy *devm_phy_get(struct device *dev, const char *string)
>  EXPORT_SYMBOL_GPL(devm_phy_get);
>  
>  /**
> + * devm_phy_optional_get() - lookup and obtain a reference to an optional phy.
> + * @dev: device that requests this phy
> + * @string: the phy name as given in the dt data or phy device name
> + * for non-dt case
> + *
> + * Gets the phy using phy_get(), and associates a device with it using
> + * devres. On driver detach, release function is invoked on the devres
> + * data, then, devres data is freed. This differs to devm_phy_get() in
> + * that if the phy does not exist, it is not considered an error and
> + * -ENODEV will not be returned. Instead the NULL phy is returned,
> + * which can be passed to all other phy consumer calls.
> + */
> +struct phy *devm_phy_optional_get(struct device *dev, const char *string)
> +{
> +	struct phy *phy = devm_phy_get(dev, string);
> +
> +	if (PTR_ERR(phy) == -ENODEV)
> +		phy = NULL;
> +
> +	return phy;
> +}
> +EXPORT_SYMBOL_GPL(devm_phy_optional_get);
> +
> +/**
>   * phy_create() - create a new phy
>   * @dev: device that is creating the new phy
>   * @ops: function pointers for performing phy operations
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index e273e5ac19c9..3f83459dbb20 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -146,7 +146,9 @@ static inline void phy_set_bus_width(struct phy *phy, int bus_width)
>  	phy->attrs.bus_width = bus_width;
>  }
>  struct phy *phy_get(struct device *dev, const char *string);
> +struct phy *phy_optional_get(struct device *dev, const char *string);
>  struct phy *devm_phy_get(struct device *dev, const char *string);
> +struct phy *devm_phy_optional_get(struct device *dev, const char *string);
>  void phy_put(struct phy *phy);
>  void devm_phy_put(struct device *dev, struct phy *phy);
>  struct phy *of_phy_simple_xlate(struct device *dev,
> @@ -232,11 +234,23 @@ static inline struct phy *phy_get(struct device *dev, const char *string)
>  	return ERR_PTR(-ENOSYS);
>  }
>  
> +static inline struct phy *phy_optional_get(struct device *dev,
> +					   const char *string)
> +{
> +	return ERR_PTR(-ENOSYS);
> +}
> +
>  static inline struct phy *devm_phy_get(struct device *dev, const char *string)
>  {
>  	return ERR_PTR(-ENOSYS);
>  }
>  
> +static inline struct phy *devm_phy_optional_get(struct device *dev,
> +						const char *string)
> +{
> +	return ERR_PTR(-ENOSYS);
> +}
> +
>  static inline void phy_put(struct phy *phy)
>  {
>  }
>