On 07/26/2013 02:49 PM, Kishon Vijay Abraham I wrote:
> The PHY framework provides a set of APIs for the PHY drivers to
> create/destroy a PHY and APIs for the PHY users to obtain a reference to the
> PHY with or without using phandle. For dt-boot, the PHY drivers should
> also register *PHY provider* with the framework.
> 
> PHY drivers should create the PHY by passing id and ops like init, exit,
> power_on and power_off. This framework is also pm runtime enabled.
> 
> The documentation for the generic PHY framework is added in
> Documentation/phy.txt and the documentation for dt binding can be found at
> Documentation/devicetree/bindings/phy/phy-bindings.txt
> 
> Cc: Tomasz Figa <t.f...@samsung.com>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Signed-off-by: Kishon Vijay Abraham I <kis...@ti.com>
> Acked-by: Felipe Balbi <ba...@ti.com>
> Tested-by: Sylwester Nawrocki <s.nawro...@samsung.com>
> ---
>  .../devicetree/bindings/phy/phy-bindings.txt       |   66 ++
>  Documentation/phy.txt                              |  166 +++++
>  MAINTAINERS                                        |    8 +
>  drivers/Kconfig                                    |    2 +
>  drivers/Makefile                                   |    2 +
>  drivers/phy/Kconfig                                |   18 +
>  drivers/phy/Makefile                               |    5 +
>  drivers/phy/phy-core.c                             |  714 
> ++++++++++++++++++++
>  include/linux/phy/phy.h                            |  270 ++++++++
>  9 files changed, 1251 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/phy-bindings.txt
>  create mode 100644 Documentation/phy.txt
>  create mode 100644 drivers/phy/Kconfig
>  create mode 100644 drivers/phy/Makefile
>  create mode 100644 drivers/phy/phy-core.c
>  create mode 100644 include/linux/phy/phy.h
> 
> diff --git a/Documentation/devicetree/bindings/phy/phy-bindings.txt 
> b/Documentation/devicetree/bindings/phy/phy-bindings.txt
> new file mode 100644
> index 0000000..8ae844f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/phy/phy-bindings.txt
> @@ -0,0 +1,66 @@
> +This document explains only the device tree data binding. For general
> +information about PHY subsystem refer to Documentation/phy.txt
[...]
> @@ -0,0 +1,166 @@
> +                         PHY SUBSYSTEM
> +               Kishon Vijay Abraham I <kis...@ti.com>
> +
> +This document explains the Generic PHY Framework along with the APIs 
> provided,
> +and how-to-use.
> +
> +1. Introduction
> +
> +*PHY* is the abbreviation for physical layer. It is used to connect a device
> +to the physical medium e.g., the USB controller has a PHY to provide 
> functions
> +such as serialization, de-serialization, encoding, decoding and is 
> responsible
> +for obtaining the required data transmission rate. Note that some USB
> +controllers have PHY functionality embedded into it and others use an 
> external
> +PHY. Other peripherals that use PHY include Wireless LAN, Ethernet,
> +SATA etc.
> +
> +The intention of creating this framework is to bring the PHY drivers spread
> +all over the Linux kernel to drivers/phy to increase code re-use and for
> +better code maintainability.
> +
> +This framework will be of use only to devices that use external PHY (PHY
> +functionality is not embedded within the controller).
> +
> +2. Registering/Unregistering the PHY provider
> +
> +PHY provider refers to an entity that implements one or more PHY instances.
> +For the simple case where the PHY provider implements only a single instance 
> of
> +the PHY, the framework provides its own implementation of of_xlate in
> +of_phy_simple_xlate. If the PHY provider implements multiple instances, it
> +should provide its own implementation of of_xlate. of_xlate is used only for
> +dt boot case.
> +
> +#define of_phy_provider_register(dev, xlate)    \
> +        __of_phy_provider_register((dev), THIS_MODULE, (xlate))
> +
> +#define devm_of_phy_provider_register(dev, xlate)       \
> +        __of_phy_provider_register((dev), THIS_MODULE, (xlate))

This needs to be:

        __devm_of_phy_provider_register((dev), THIS_MODULE, (xlate))

as Kamil pointed out. We've tested it here with v9 and it makes
Bad Things happen. ;)

> +of_phy_provider_register and devm_of_phy_provider_register macros can be 
> used to
> +register the phy_provider and it takes device and of_xlate as
> +arguments. For the dt boot case, all PHY providers should use one of the 
> above
> +2 macros to register the PHY provider.
> +
> +void devm_of_phy_provider_unregister(struct device *dev,
> +     struct phy_provider *phy_provider);
> +void of_phy_provider_unregister(struct phy_provider *phy_provider);
> +
> +devm_of_phy_provider_unregister and of_phy_provider_unregister can be used to
> +unregister the PHY.
> +
[...]
> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> new file mode 100644
> index 0000000..f1d15e5
> --- /dev/null
> +++ b/drivers/phy/phy-core.c
> @@ -0,0 +1,714 @@
[...]
> +static struct phy *phy_lookup(struct device *device, const char *port)
> +{
> +     unsigned int count;
> +     struct phy *phy;
> +     struct device *dev;
> +     struct phy_consumer *consumers;
> +     struct class_dev_iter iter;
        
Don't you need something like

        if (phy->init_data == NULL)     
                return ERR_PTR(-EINVAL);

to ensure there is no attempt to dereference NULL platform data ?

> +     class_dev_iter_init(&iter, phy_class, NULL, NULL);
> +     while ((dev = class_dev_iter_next(&iter))) {
> +             phy = to_phy(dev);
> +             count = phy->init_data->num_consumers;
> +             consumers = phy->init_data->consumers;
> +             while (count--) {
> +                     if (!strcmp(consumers->dev_name, dev_name(device)) &&
> +                                     !strcmp(consumers->port, port)) {
> +                             class_dev_iter_exit(&iter);
> +                             return phy;
> +                     }
> +                     consumers++;
> +             }
> +     }
> +
> +     class_dev_iter_exit(&iter);
> +     return ERR_PTR(-ENODEV);
> +}
> +
[...]
> +int phy_init(struct phy *phy)
> +{
> +     int ret;
> +
> +     ret = phy_pm_runtime_get_sync(phy);
> +     if (ret < 0 && ret != -ENOTSUPP)
> +             return ret;
> +
> +     mutex_lock(&phy->mutex);
> +     if (phy->init_count++ == 0 && phy->ops->init) {
> +             ret = phy->ops->init(phy);
> +             if (ret < 0) {
> +                     dev_err(&phy->dev, "phy init failed --> %d\n", ret);
> +                     goto out;

Is this 'goto' and similar ones below really needed ?

> +             }
> +     }
> +
> +out:
> +     mutex_unlock(&phy->mutex);
> +     phy_pm_runtime_put(phy);
> +     return ret;
> +}
> +EXPORT_SYMBOL_GPL(phy_init);
> +
> +int phy_exit(struct phy *phy)
> +{
> +     int ret;
> +
> +     ret = phy_pm_runtime_get_sync(phy);
> +     if (ret < 0 && ret != -ENOTSUPP)
> +             return ret;
> +
> +     mutex_lock(&phy->mutex);
> +     if (--phy->init_count == 0 && phy->ops->exit) {
> +             ret = phy->ops->exit(phy);
> +             if (ret < 0) {
> +                     dev_err(&phy->dev, "phy exit failed --> %d\n", ret);
> +                     goto out;
> +             }
> +     }
> +
> +out:
> +     mutex_unlock(&phy->mutex);
> +     phy_pm_runtime_put(phy);
> +     return ret;
> +}
> +EXPORT_SYMBOL_GPL(phy_exit);
> +
> +int phy_power_on(struct phy *phy)
> +{
> +     int ret = -ENOTSUPP;
> +
> +     ret = phy_pm_runtime_get_sync(phy);
> +     if (ret < 0 && ret != -ENOTSUPP)
> +             return ret;
> +
> +     mutex_lock(&phy->mutex);
> +     if (phy->power_count++ == 0 && phy->ops->power_on) {
> +             ret = phy->ops->power_on(phy);
> +             if (ret < 0) {
> +                     dev_err(&phy->dev, "phy poweron failed --> %d\n", ret);
> +                     goto out;
> +             }
> +     }
> +
> +out:
> +     mutex_unlock(&phy->mutex);
> +
> +     return ret;
> +}
> +EXPORT_SYMBOL_GPL(phy_power_on);
> +
> +int phy_power_off(struct phy *phy)
> +{
> +     int ret = -ENOTSUPP;
> +
> +     mutex_lock(&phy->mutex);
> +     if (--phy->power_count == 0 && phy->ops->power_off) {
> +             ret =  phy->ops->power_off(phy);
> +             if (ret < 0) {
> +                     dev_err(&phy->dev, "phy poweroff failed --> %d\n", ret);
> +                     goto out;
> +             }
> +     }
> +
> +out:
> +     mutex_unlock(&phy->mutex);
> +     phy_pm_runtime_put(phy);
> +
> +     return ret;
> +}
> +EXPORT_SYMBOL_GPL(phy_power_off);

--
Thanks,
Sylwester
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