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

From: [email-masked] (Kishon Vijay Abraham I)
Date: Thu, 15 May 2014 14:31:33 +0530

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 <[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?

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
Kishon