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

From: [email-masked] (Kishon Vijay Abraham I)
Date: Wed, 14 May 2014 19:57:26 +0530

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?

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?

Thanks
Kishon