Re: [PATCH V4 1/5] phy: Add new Exynos5 USB 3.0 PHY driver

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

On Monday 14 April 2014 06:50 PM, Vivek Gautam wrote:
> On Mon, Apr 14, 2014 at 6:29 PM, Kishon Vijay Abraham I <kishon@ti.com> wrote:
>>
>>
>> On Monday 14 April 2014 06:12 PM, Vivek Gautam wrote:
>>> Hi,
>>>
>>>
>>> On Mon, Apr 14, 2014 at 5:57 PM, Kishon Vijay Abraham I <kishon@ti.com> wrote:
>>>> Hi,
>>>>
>>>> On Tuesday 08 April 2014 08:06 PM, Vivek Gautam wrote:
>>>>> Add a new driver for the USB 3.0 PHY on Exynos5 series of SoCs.
>>>>> The new driver uses the generic PHY framework and will interact
>>>>> with DWC3 controller present on Exynos5 series of SoCs.
>>>>> Thereby, removing old phy-samsung-usb3 driver and related code
>>>>> used untill now which was based on usb/phy framework.
>>>>>
>>>>> Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
>>>>> ---
>>>>>  .../devicetree/bindings/phy/samsung-phy.txt        |   42 ++
>>>>>  drivers/phy/Kconfig                                |   11 +
>>>>>  drivers/phy/Makefile                               |    1 +
>>>>>  drivers/phy/phy-exynos5-usbdrd.c                   |  668 ++++++++++++++++++++
>>>>>  4 files changed, 722 insertions(+)
>>>>>  create mode 100644 drivers/phy/phy-exynos5-usbdrd.c
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/phy/samsung-phy.txt b/Documentation/devicetree/bindings/phy/samsung-phy.txt
>>>>> index 28f9edb..6d99ba9 100644
>>>>> --- a/Documentation/devicetree/bindings/phy/samsung-phy.txt
>>>>> +++ b/Documentation/devicetree/bindings/phy/samsung-phy.txt
>>>>> @@ -74,3 +74,45 @@ phy-consumer@12340000 {
>>>>>
>>>>>  Refer to DT bindings documentation of particular PHY consumer devices for more
>>>>>  information about required PHYs and the way of specification.
>>>>> +
>>>>> +Samsung Exynos5 SoC series USB DRD PHY controller
>>>>> +--------------------------------------------------
>>>>> +
>>>>> +Required properties:
>>>>> +- compatible : Should be set to one of the following supported values:
>>>>> +     - "samsung,exynos5250-usbdrd-phy" - for exynos5250 SoC,
>>>>> +     - "samsung,exynos5420-usbdrd-phy" - for exynos5420 SoC.
>>>>> +- reg : Register offset and length of USB DRD PHY register set;
>>>>> +- clocks: Clock IDs array as required by the controller
>>>>> +- clock-names: names of clocks correseponding to IDs in the clock property;
>>>>> +            Required clocks:
>>>>> +     - phy: main PHY clock (same as USB DRD controller i.e. DWC3 IP clock),
>>>>> +            used for register access.
>>>>> +     - ref: PHY's reference clock (usually crystal clock), associated by
>>>>> +            phy name, used to determine bit values for clock settings
>>>>> +            register.
>>>>> +     Additional clock required for Exynos5420:
>>>>> +     - usb30_sclk_100m: Additional special clock used for PHY operation
>>>>> +                        depicted as 'sclk_usbphy30' in CMU of Exynos5420.
>>>>> +- samsung,syscon-phandle: phandle for syscon interface, which is used to
>>>>> +                       control pmu registers for power isolation.
>>>>> +- samsung,pmu-offset: phy power control register offset to pmu-system-controller
>>>>> +                   base.
>>>>> +- #phy-cells : from the generic PHY bindings, must be 1;
>>>>> +
>>>>> +For "samsung,exynos5250-usbdrd-phy" and "samsung,exynos5420-usbdrd-phy"
>>>>> +compatible PHYs, the second cell in the PHY specifier identifies the
>>>>> +PHY id, which is interpreted as follows:
>>>>> +  0 - UTMI+ type phy,
>>>>> +  1 - PIPE3 type phy,
>>>>> +
>>>>> +Example:
>>>>> +     usb3_phy: usbphy@12100000 {
>>>>> +             compatible = "samsung,exynos5250-usbdrd-phy";
>>>>> +             reg = <0x12100000 0x100>;
>>>>> +             clocks = <&clock 286>, <&clock 1>;
>>>>> +             clock-names = "phy", "usb3phy_refclk";
>>>>> +             samsung,syscon-phandle = <&pmu_syscon>;
>>>>> +             samsung,pmu-offset = <0x704>;
>>>>> +             #phy-cells = <1>;
>>>>> +     };
>>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
>>>>> index 8d3c49c..d955a05 100644
>>>>> --- a/drivers/phy/Kconfig
>>>>> +++ b/drivers/phy/Kconfig
>>>>> @@ -166,4 +166,15 @@ config PHY_XGENE
>>>>>       help
>>>>>         This option enables support for APM X-Gene SoC multi-purpose PHY.
>>>>>
>>>>> +config PHY_EXYNOS5_USBDRD
>>>>> +     tristate "Exynos5 SoC series USB DRD PHY driver"
>>>>> +     depends on ARCH_EXYNOS5 && OF
>>>>> +     depends on HAS_IOMEM
>>>>> +     select GENERIC_PHY
>>>>> +     select MFD_SYSCON
>>>>
>>>> Lets try to avoid select in Kconfig. We've got enough problems with that.
>>>
>>> I hope you meant with "select MFD_SYSCON".
>>> We are referencing the syscon for accessing pmu reg, for which we need
>>> this config to be selected.
>>> Other Exynos phy drivers also need this config and for that they have
>>> selected this.
>>>
>>> Do you want me to do it any other way ?
>>
>> depends on is one option.
> 
> Ok, i can see there are places where depends_on MFD_SYSCON is used.
> "drivers/gpu/drm/exynos/Kconfig:60"
> 
> so, do you want me to fix at other places too ?
> 
> But i also have a question here.
> MFD_SYSCON is a subsystem that's facilitating us in getting our work
> done here by giving an access to pmu_system_controller.
> So unless MFD_SYSCON is exposed, the phy driver will not be exposed to us.
> So is that valid enough really ?

maybe in the Kconfig for MFD_SYSCON, we can select it if PHY_EXYNOS5_USBDRD is
enabled?

config MFD_SYSCON
default y if PHY_EXYNOS5_USBDRD

Thanks
Kishon