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

From: [email-masked] (Gregory CLEMENT)
Date: Thu, 15 May 2014 09:01:58 +0200

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 <[email-masked]>
>>>>>>
>>>>>> 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 <[email-masked]>
>>>>>> Signed-off-by: Thomas Petazzoni <[email-masked]>
>>>>>> ---
>>>>>>  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 <[email-masked]>
>>>>>> + *
>>>>>> + * 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?

Note that in both case the binding will be the same.

I would prefer the first solution because hacking the init_count (or
the power_count) don't seem to me the right thing to do.

Thanks,

Gregory

> Thanks,
> Gregory
>> Thanks
>> Kishon

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com