Subject: [RESEND PATCH v10 1/8] drivers: phy: add generic PHY framework

From: [email-masked] (Kishon Vijay Abraham I)
Date: Tue, 30 Jul 2013 10:42:00 +0530

Hi,

On Monday 29 July 2013 09:21 PM, Sylwester Nawrocki wrote:
> 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 <[email-masked]>
>> Cc: Greg Kroah-Hartman <[email-masked]>
>> Signed-off-by: Kishon Vijay Abraham I <[email-masked]>
>> Acked-by: Felipe Balbi <[email-masked]>
>> Tested-by: Sylwester Nawrocki <[email-masked]>
>> ---
>>  .../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 <[email-masked]>
>> +
>> +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 ?

hmm.. perhaps a dev_WARN too..
> 
>> +	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 ?
That's just to signify an error path.. it doesn't affect anyways ;-)

Thanks
Kishon