[PATCHv5 10/20] phy: add support for USB cluster on the Armada 375 SoC

[Kishon Vijay Abraham I]

On Thursday 15 May 2014 03:05 PM, Gregory CLEMENT wrote:
> Hi Kishon,
> 
> On 15/05/2014 11:01, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Thursday 15 May 2014 12:31 PM, Gregory CLEMENT wrote:
>>> Hi Kishon,
>>>
>>> On 14/05/2014 17:35, Gregory CLEMENT wrote:
>>>> On 14/05/2014 16:27, Kishon Vijay Abraham I wrote:
>>>>> Hi,
>>>>>
>>>>> On Tuesday 13 May 2014 03:11 PM, Gregory CLEMENT wrote:
>>>>>> On 13/05/2014 10:06, Gregory CLEMENT wrote:
>>>>>>> On 13/05/2014 07:53, Kishon Vijay Abraham I wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> On Sunday 11 May 2014 11:47 PM, Thomas Petazzoni wrote:
>>>>>>>>> From: Gregory CLEMENT <gregory.clement at free-electrons.com>
>>>>>>>>>
>>>>>>>>> The Armada 375 SoC comes with an USB2 host and device controller and
>>>>>>>>> an USB3 controller. The USB cluster control register allows to manage
>>>>>>>>> common features of both USB controllers.
>>>>>>>>>
>>>>>>>>> This commit adds a driver integrated in the generic PHY framework to
>>>>>>>>> control this USB cluster feature.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
>>>>>>>>> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
>>>>>>>>> ---
>>>>>>>>>  drivers/phy/Kconfig              |   6 ++
>>>>>>>>>  drivers/phy/Makefile             |   1 +
>>>>>>>>>  drivers/phy/phy-armada375-usb2.c | 157 +++++++++++++++++++++++++++++++++++++++
>>>>>>>>>  3 files changed, 164 insertions(+)
>>>>>>>>>  create mode 100644 drivers/phy/phy-armada375-usb2.c
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
>>>>>>>>> index 3bb05f1..e63cf9d 100644
>>>>>>>>> --- a/drivers/phy/Kconfig
>>>>>>>>> +++ b/drivers/phy/Kconfig
>>>>>>>>> @@ -15,6 +15,12 @@ config GENERIC_PHY
>>>>>>>>>  	  phy users can obtain reference to the PHY. All the users of this
>>>>>>>>>  	  framework should select this config.
>>>>>>>>>  
>>>>>>>>> +config ARMADA375_USBCLUSTER_PHY
>>>>>>>>> +	def_bool y
>>>>>>>>> +	depends on MACH_ARMADA_375 || COMPILE_TEST
>>>>>>>>> +	depends on OF
>>>>>>>>> +	select GENERIC_PHY
>>>>>>>>> +
>>>>>>>>>  config PHY_EXYNOS_MIPI_VIDEO
>>>>>>>>>  	tristate "S5P/EXYNOS SoC series MIPI CSI-2/DSI PHY driver"
>>>>>>>>>  	depends on HAS_IOMEM
>>>>>>>>> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
>>>>>>>>> index 2faf78e..47d5a86 100644
>>>>>>>>> --- a/drivers/phy/Makefile
>>>>>>>>> +++ b/drivers/phy/Makefile
>>>>>>>>> @@ -3,6 +3,7 @@
>>>>>>>>>  #
>>>>>>>>>  
>>>>>>>>>  obj-$(CONFIG_GENERIC_PHY)		+= phy-core.o
>>>>>>>>> +obj-$(CONFIG_ARMADA375_USBCLUSTER_PHY)	+= phy-armada375-usb2.o
>>>>>>>>>  obj-$(CONFIG_BCM_KONA_USB2_PHY)		+= phy-bcm-kona-usb2.o
>>>>>>>>>  obj-$(CONFIG_PHY_EXYNOS_DP_VIDEO)	+= phy-exynos-dp-video.o
>>>>>>>>>  obj-$(CONFIG_PHY_EXYNOS_MIPI_VIDEO)	+= phy-exynos-mipi-video.o
>>>>>>>>> diff --git a/drivers/phy/phy-armada375-usb2.c b/drivers/phy/phy-armada375-usb2.c
>>>>>>>>> new file mode 100644
>>>>>>>>> index 0000000..a6f746d
>>>>>>>>> --- /dev/null
>>>>>>>>> +++ b/drivers/phy/phy-armada375-usb2.c
>>>>>>>>> @@ -0,0 +1,157 @@
>>>>>>>>> +/*
>>>>>>>>> + * USB cluster support for Armada 375 platform.
>>>>>>>>> + *
>>>>>>>>> + * Copyright (C) 2014 Marvell
>>>>>>>>> + *
>>>>>>>>> + * Gregory CLEMENT <gregory.clement at free-electrons.com>
>>>>>>>>> + *
>>>>>>>>> + * This file is licensed under the terms of the GNU General Public
>>>>>>>>> + * License version 2 or later. This program is licensed "as is"
>>>>>>>>> + * without any warranty of any kind, whether express or implied.
>>>>>>>>> + *
>>>>>>>>> + * Armada 375 comes with an USB2 host and device controller and an
>>>>>>>>> + * USB3 controller. The USB cluster control register allows to manage
>>>>>>>>> + * common features of both USB controllers.
>>>>>>>>> + */
>>>>>>>>> +
>>>>>>>>> +#include <linux/init.h>
>>>>>>>>> +#include <linux/io.h>
>>>>>>>>> +#include <linux/kernel.h>
>>>>>>>>> +#include <linux/module.h>
>>>>>>>>> +#include <linux/of_address.h>
>>>>>>>>> +#include <linux/phy/phy.h>
>>>>>>>>> +#include <linux/platform_device.h>
>>>>>>>>> +#include <linux/slab.h>
>>>>>>>>> +
>>>>>>>>> +#define USB2_PHY_CONFIG_DISABLE BIT(0)
>>>>>>>>> +
>>>>>>>>> +/* The USB cluster allows to choose between two PHYs */
>>>>>>>>> +#define NB_PHY 2
>>>>>>>>> +
>>>>>>>>> +enum {
>>>>>>>>> +	PHY_USB2 = 0,
>>>>>>>>> +	PHY_USB3 = 1,
>>>>>>>>> +};
>>>>>>>>> +
>>>>>>>>> +struct armada375_cluster_phy {
>>>>>>>>> +	struct phy *phy;
>>>>>>>>> +	void __iomem *reg;
>>>>>>>>> +	bool enable;
>>>>>>>>> +	bool use_usb3;
>>>>>>>>> +};
>>>>>>>>> +
>>>>>>>>> +struct armada375_cluster_phy usb_cluster_phy[NB_PHY];
>>>>>>>>> +
>>>>>>>>> +static int armada375_usb_phy_init(struct phy *phy)
>>>>>>>>> +{
>>>>>>>>> +	struct armada375_cluster_phy *cluster_phy = phy_get_drvdata(phy);
>>>>>>>>> +	u32 reg;
>>>>>>>>
>>>>>>>> This function should be protected since both your PHYs use this ops.
>>>>>>>
>>>>>>> Right
>>>>>>
>>>>>> Actually only one PHY can access this register. See the probe function,
>>>>>> cluster_phy->enable is only set to true for one PHY.
>>>>>>
>>>>>>>
>>>>>>>>> +
>>>>>>>>> +	if (!cluster_phy->enable)
>>>>>>>>> +		return -ENODEV;
>>>>>>>>> +
>>>>>>>>> +	reg = readl(cluster_phy->reg);
>>>>>>>>> +	if (cluster_phy->use_usb3)
>>>>>>>>> +		reg |= USB2_PHY_CONFIG_DISABLE;
>>>>>>>>> +	else
>>>>>>>>> +		reg &= ~USB2_PHY_CONFIG_DISABLE;
>>>>>>>>> +	writel(reg, cluster_phy->reg);
>>>>>>>>
>>>>>>>> This is confusing since both your PHYs control the same bit?
>>>>>>
>>>>>> Same here at the end the bit is accessed by only one PHY.
>>>>>>
>>>>>>>>> +
>>>>>>>>> +	return 0;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +static struct phy_ops armada375_usb_phy_ops = {
>>>>>>>>> +	.init = armada375_usb_phy_init,
>>>>>>>>> +	.owner		= THIS_MODULE,
>>>>>>>>> +};
>>>>>>>>> +
>>>>>>>>> +static struct phy *armada375_usb_phy_xlate(struct device *dev,
>>>>>>>>> +					struct of_phandle_args *args)
>>>>>>>>> +{
>>>>>>>>> +	if (WARN_ON(args->args[0] >= NB_PHY))
>>>>>>>>> +		return ERR_PTR(-ENODEV);
>>>>>>>>> +
>>>>>>>>> +	return usb_cluster_phy[args->args[0]].phy;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +static int armada375_usb_phy_probe(struct platform_device *pdev)
>>>>>>>>> +{
>>>>>>>>> +	struct device *dev = &pdev->dev;
>>>>>>>>> +	struct phy *phy;
>>>>>>>>> +	struct phy_provider *phy_provider;
>>>>>>>>> +	void __iomem *usb_cluster_base;
>>>>>>>>> +	struct device_node *xhci_node;
>>>>>>>>> +	struct resource *res;
>>>>>>>>> +	int i;
>>>>>>>>> +
>>>>>>>>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>>>>>>> +	usb_cluster_base = devm_ioremap_resource(&pdev->dev, res);
>>>>>>>>> +	if (!usb_cluster_base)
>>>>>>>>> +		return -ENOMEM;
>>>>>>>>> +
>>>>>>>>> +	for (i = 0; i < NB_PHY; i++) {
>>>>>>>>
>>>>>>>> For devices which have multiple PHYs, each PHY should be modelled as the
>>>>>>>> sub-node of the *PHY provider* device node.
>>>>>>>
>>>>>>> Actually it is the opposite the same PHY is shared between the EHCI
>>>>>>> and the xHCI controllers. It is more a PHY muxer than a PHY itself.
>>>>>>>
>>>>>>> I had to create 2 logical PHYs because once the phy_init() is called
>>>>>>> by a USB driver then the .init ops is not called anymore by the next
>>>>>>> call to phy_init(). One of the goal of this is to disable a port for
>>>>>>> the USB controller which can't use it due to the configuration of the
>>>>>>> USB cluster.
>>>>>>>
>>>>>>> But I can see how to make this two "pseudo" PHYs sub-node of the *PHY
>>>>>>> provider* device node. It shouldn't change the internal logic of this
>>>>>>> driver.
>>>>>>
>>>>>> I need to make a distinction when the PHY access by the xHCI or when
>>>>>> it was access by the EHCI. If I create two new sub-node then I will
>>>>>> also need to add a property to make this distinction. It seems a little
>>>>>> overkill for the need.
>>>>>
>>>>> Alright, so you have a single PHY that can be used by either XHCI or EHCI? And
>>>>> the use of PHY is mutually exclusive? How should it behave if you have both
>>>>> XHCI and EHCI?
>>>>
>>>> if we have both XHCI and EHCI then it is the USB2_PHY_CONFIG_DISABLE which
>>>> determine which one is used. By default we decide to select the XHCI.
>>>>
>>>>>
>>>>> One way to configure the PHY to a particular mode is by passing it as phandle
>>>>> arguments. I think you can use that to enable or disable USB2_PHY_CONFIG_DISABLE?
>>>>
>>>> actually it was more or less what I do:
>>>> for the XHCI I use:
>>>> phys = <&usbcluster 1>;
>>>> which enable the USB2_PHY_CONFIG_DISABLE
>>>>
>>>> for the EHCI I use phys = <&usbcluster 0>;
>>>> which disable the USB2_PHY_CONFIG_DISABLE
>>>>
>>>> If I had to create two PHY it was because of the behavior of
>>>> phy_init(). I need to be able to disable a controller if it can't use
>>>> the PHY. For this purpose my ops->init() exits in error. However
>>>> phy_init() will call ops->init() only one time, then the internal
>>>> counter init_count will be incremented, and the next call to phy_init
>>>> will skip the call to ops->init. And the behavior is the same for
>>>> phy_power_on().
>>>>
>>>> So given this I don't see how to do in an other way except by
>>>> modifying the value of the counter in my ops.
>>>
>>> What do you prefer here? Keep the current implementation or using
>>> only one PHY by passing a argument through the phandle and in the
>>> same time hacking the init_count?
>>
>> I clearly don't prefer having of_find_compatible_node in PHY driver code. If
>> you can find something without using that, it would be good.
>>
>> Maybe create an API in phy-core that invokes the call-backs without caring
>> about the ref count and implement some sort of mutual exclusivity in your
>> driver? However this needs to be reviewed and discussed.
> 
> Thanks for your feedback. This feature (usb cluster) is a nice to have
> for the Armada 375 SoC, but is not mandatory for the USB support on
> this SoC.
> 
> As I don't want to postpone the merge of the USB support for this. I
> will resend a new patch series, without the usb-cluster support, to be
> merged in 3.16 kernel. And in the same time I will submit a new series
> with an extension of the phy-core API. if everything goes well, then
> it will be also merged in 3.16, else it will be in the next release.

Thanks for doing that.
> 
> 
> Thanks again for your time,

No problem.

Cheers
Kishon