Re: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

[Roger Quadros]

On 11/08/2019 14:59, Pawel Laszczak wrote:
> Hi,
> 
>>
>> On 21/07/2019 21:32, Pawel Laszczak wrote:
>>> This patch introduce new Cadence USBSS DRD driver to Linux kernel.
>>>
>>> The Cadence USBSS DRD Controller is a highly configurable IP Core which
>>> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
>>> Host Only (XHCI)configurations.
>>>
>>> The current driver has been validated with FPGA platform. We have
>>> support for PCIe bus, which is used on FPGA prototyping.
>>>
>>> The host side of USBSS-DRD controller is compliant with XHCI
>>> specification, so it works with standard XHCI Linux driver.
>>>
>>> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
>>> ---
>>>  drivers/usb/Kconfig                |    2 +
>>>  drivers/usb/Makefile               |    2 +
>>>  drivers/usb/cdns3/Kconfig          |   46 +
>>>  drivers/usb/cdns3/Makefile         |   17 +
>>>  drivers/usb/cdns3/cdns3-pci-wrap.c |  203 +++
>>>  drivers/usb/cdns3/core.c           |  554 +++++++
>>>  drivers/usb/cdns3/core.h           |  109 ++
>>>  drivers/usb/cdns3/debug.h          |  171 ++
>>>  drivers/usb/cdns3/debugfs.c        |   87 ++
>>>  drivers/usb/cdns3/drd.c            |  390 +++++
>>>  drivers/usb/cdns3/drd.h            |  166 ++
>>>  drivers/usb/cdns3/ep0.c            |  914 +++++++++++
>>>  drivers/usb/cdns3/gadget-export.h  |   28 +
>>>  drivers/usb/cdns3/gadget.c         | 2338 ++++++++++++++++++++++++++++
>>>  drivers/usb/cdns3/gadget.h         | 1321 ++++++++++++++++
>>>  drivers/usb/cdns3/host-export.h    |   28 +
>>>  drivers/usb/cdns3/host.c           |   71 +
>>>  drivers/usb/cdns3/trace.c          |   11 +
>>>  drivers/usb/cdns3/trace.h          |  493 ++++++
>>>  19 files changed, 6951 insertions(+)
>>>  create mode 100644 drivers/usb/cdns3/Kconfig
>>>  create mode 100644 drivers/usb/cdns3/Makefile
>>>  create mode 100644 drivers/usb/cdns3/cdns3-pci-wrap.c
>>>  create mode 100644 drivers/usb/cdns3/core.c
>>>  create mode 100644 drivers/usb/cdns3/core.h
>>>  create mode 100644 drivers/usb/cdns3/debug.h
>>>  create mode 100644 drivers/usb/cdns3/debugfs.c
>>>  create mode 100644 drivers/usb/cdns3/drd.c
>>>  create mode 100644 drivers/usb/cdns3/drd.h
>>>  create mode 100644 drivers/usb/cdns3/ep0.c
>>>  create mode 100644 drivers/usb/cdns3/gadget-export.h
>>>  create mode 100644 drivers/usb/cdns3/gadget.c
>>>  create mode 100644 drivers/usb/cdns3/gadget.h
>>>  create mode 100644 drivers/usb/cdns3/host-export.h
>>>  create mode 100644 drivers/usb/cdns3/host.c
>>>  create mode 100644 drivers/usb/cdns3/trace.c
>>>  create mode 100644 drivers/usb/cdns3/trace.h
>>>

<snip>

>>
>>> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
>>> new file mode 100644
>>> index 000000000000..291f08be56fe
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/gadget.c
>>> @@ -0,0 +1,2338 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Cadence USBSS DRD Driver - gadget side.
>>> + *
>>> + * Copyright (C) 2018-2019 Cadence Design Systems.
>>> + * Copyright (C) 2017-2018 NXP
>>> + *
>>> + * Authors: Pawel Jez <pjez@xxxxxxxxxxx>,
>>> + *          Pawel Laszczak <pawell@xxxxxxxxxxx>
>>> + *          Peter Chen <peter.chen@xxxxxxx>
>>> + */
>>> +
>>
>> <snip>
>>
>>> +/**
>>> + * cdns3_device_irq_handler- interrupt handler for device part of controller
>>> + *
>>> + * @irq: irq number for cdns3 core device
>>> + * @data: structure of cdns3
>>> + *
>>> + * Returns IRQ_HANDLED or IRQ_NONE
>>> + */
>>> +static irqreturn_t cdns3_device_irq_handler(int irq, void *data)
>>> +{
>>> +	struct cdns3_device *priv_dev;
>>> +	struct cdns3 *cdns = data;
>>> +	irqreturn_t ret = IRQ_NONE;
>>> +	unsigned long flags;
>>> +	u32 reg;
>>> +
>>> +	priv_dev = cdns->gadget_dev;
>>> +	spin_lock_irqsave(&priv_dev->lock, flags);
>>> +
>>> +	/* check USB device interrupt */
>>> +	reg = readl(&priv_dev->regs->usb_ists);
>>> +
>>> +	if (reg) {
>>> +		writel(reg, &priv_dev->regs->usb_ists);
>>
>> Do we need to mask device interrupts till thread handler has done processing
>> current set of events?
> 
> Yes, we need do this to avoid raising the next the same interrupts. 
> If we return back from hard irq handler without clearing reported interrupts,
> then system report them again. The solution for this is to use IRQF_ONESHOT
> flag during registering interrupt, but I can't use this flag 
> because I have shared interrupt line with other component. 
> 
> In this version these (usb_ists) interrupts are handled in hard irq, but in next version
> will be moved to thread handler. 
> 
>>> +		cdns3_check_usb_interrupt_proceed(priv_dev, reg);
>>> +		ret = IRQ_HANDLED;
>>> +	}
>>> +
>>> +	/* check endpoint interrupt */
>>> +	reg = readl(&priv_dev->regs->ep_ists);
>>> +
>>> +	if (reg) {
>>> +		priv_dev->shadow_ep_en |= reg;
>>> +		reg = ~reg & readl(&priv_dev->regs->ep_ien);
>>> +		/* mask deferred interrupt. */
>>> +		writel(reg, &priv_dev->regs->ep_ien);
>>> +		ret = IRQ_WAKE_THREAD;
>>> +	}
>>> +
>>> +	spin_unlock_irqrestore(&priv_dev->lock, flags);
>>> +	return ret;
>>> +}
>>> +
>>
>> <snip>
>>
>>> +
>>> +static int cdns3_gadget_start(struct cdns3 *cdns)
>>> +{
>>> +	struct cdns3_device *priv_dev;
>>> +	u32 max_speed;
>>> +	int ret;
>>> +
>>> +	priv_dev = kzalloc(sizeof(*priv_dev), GFP_KERNEL);
>>> +	if (!priv_dev)
>>> +		return -ENOMEM;
>>> +
>>> +	cdns->gadget_dev = priv_dev;
>>> +	priv_dev->sysdev = cdns->dev;
>>> +	priv_dev->dev = cdns->dev;
>>> +	priv_dev->regs = cdns->dev_regs;
>>> +
>>> +	device_property_read_u16(priv_dev->dev, "cdns,on-chip-buff-size",
>>> +				 &priv_dev->onchip_buffers);
>>> +
>>> +	if (priv_dev->onchip_buffers <=  0) {
>>> +		u32 reg = readl(&priv_dev->regs->usb_cap2);
>>> +
>>> +		priv_dev->onchip_buffers = USB_CAP2_ACTUAL_MEM_SIZE(reg);
>>> +	}
>>> +
>>> +	if (!priv_dev->onchip_buffers)
>>> +		priv_dev->onchip_buffers = 256;
>>> +
>>> +	max_speed = usb_get_maximum_speed(cdns->dev);
>>> +
>>> +	/* Check the maximum_speed parameter */
>>> +	switch (max_speed) {
>>> +	case USB_SPEED_FULL:
>>
>> In this case we need to limit controller max speed to full-speed as system
>> integrator would expect that. e.g. in DT node, maximum-speed = "full-speed";
>>
>> I suppose we need to set the force Full-speed bit here?
>>
>>> +	case USB_SPEED_HIGH:
>>
>> Here we need to restrict device controller max-speed to high-speed.
>>
> 
> Why system integrator would limit the speed of controller? 

To save cost? For many use cases, high-speed is more then sufficient.

> For debugging purpose it's  ok, but in production system it's better 
> to use higher speed.
> Do we relay need such functionality ?

Mostly for testing purpose. I can just change the DT node's speed property
to the lower speed to limit the controller to that speed.

If we can achieve that with a few lines of code, why not support it?

> 
>>> +	case USB_SPEED_SUPER:
>>> +		break;
>>> +	default:
>>> +		dev_err(cdns->dev, "invalid maximum_speed parameter %d\n",
>>> +			max_speed);
>>> +		/* fall through */
>>> +	case USB_SPEED_UNKNOWN:
>>> +		/* default to superspeed */
>>> +		max_speed = USB_SPEED_SUPER;
>>> +		break;
>>> +	}
>>> +
>>> +	/* fill gadget fields */
>>> +	priv_dev->gadget.max_speed = max_speed;
>>> +	priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
>>> +	priv_dev->gadget.ops = &cdns3_gadget_ops;
>>> +	priv_dev->gadget.name = "usb-ss-gadget";
>>> +	priv_dev->gadget.sg_supported = 1;
>>> +
>>> +	spin_lock_init(&priv_dev->lock);
>>> +	INIT_WORK(&priv_dev->pending_status_wq,
>>> +		  cdns3_pending_setup_status_handler);
>>> +
>>> +	/* initialize endpoint container */
>>> +	INIT_LIST_HEAD(&priv_dev->gadget.ep_list);
>>> +	INIT_LIST_HEAD(&priv_dev->aligned_buf_list);
>>> +
>>> +	ret = cdns3_init_eps(priv_dev);
>>> +	if (ret) {
>>> +		dev_err(priv_dev->dev, "Failed to create endpoints\n");
>>> +		goto err1;
>>> +	}
>>> +
>>> +	/* allocate memory for setup packet buffer */
>>> +	priv_dev->setup_buf = dma_alloc_coherent(priv_dev->sysdev, 8,
>>> +						 &priv_dev->setup_dma, GFP_DMA);
>>> +	if (!priv_dev->setup_buf) {
>>> +		ret = -ENOMEM;
>>> +		goto err2;
>>> +	}
>>> +
>>> +	priv_dev->dev_ver = readl(&priv_dev->regs->usb_cap6);
>>> +
>>> +	dev_dbg(priv_dev->dev, "Device Controller version: %08x\n",
>>> +		readl(&priv_dev->regs->usb_cap6));
>>> +	dev_dbg(priv_dev->dev, "USB Capabilities:: %08x\n",
>>> +		readl(&priv_dev->regs->usb_cap1));
>>> +	dev_dbg(priv_dev->dev, "On-Chip memory cnfiguration: %08x\n",
>>> +		readl(&priv_dev->regs->usb_cap2));
>>> +
>>> +	priv_dev->dev_ver = GET_DEV_BASE_VERSION(priv_dev->dev_ver);
>>> +
>>> +	priv_dev->zlp_buf = kzalloc(CDNS3_EP_ZLP_BUF_SIZE, GFP_KERNEL);
>>> +	if (!priv_dev->zlp_buf) {
>>> +		ret = -ENOMEM;
>>> +		goto err3;
>>> +	}
>>> +
>>> +	/* add USB gadget device */
>>> +	ret = usb_add_gadget_udc(priv_dev->dev, &priv_dev->gadget);
>>> +	if (ret < 0) {
>>> +		dev_err(priv_dev->dev,
>>> +			"Failed to register USB device controller\n");
>>> +		goto err4;
>>> +	}
>>> +
>>> +	return 0;
>>> +err4:
>>> +	kfree(priv_dev->zlp_buf);
>>> +err3:
>>> +	dma_free_coherent(priv_dev->sysdev, 8, priv_dev->setup_buf,
>>> +			  priv_dev->setup_dma);
>>> +err2:
>>> +	cdns3_free_all_eps(priv_dev);
>>> +err1:
>>> +	cdns->gadget_dev = NULL;
>>> +	return ret;
>>> +}
>>> +
>>

cheers,
-roger
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