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

[Pawel Laszczak <pawell@cadence.com>]

>
>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@cadence.com>
>>>> ---
>>>>  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@cadence.com>,
>>>> + *          Pawel Laszczak <pawell@cadence.com>
>>>> + *          Peter Chen <peter.chen@nxp.com>
>>>> + */
>>>> +
>>>
>>> <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.
>

I think I know what you mean. 

I've add such functionality to next version.
  

>> 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;
>>>> +}
>>>> +
>>>
>
--
pawell