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Subject: Re: [RFC PATCH v2 06/15] usb:cdns3: Adds Host support
To:     Pawel Laszczak <pawell@cadence.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
References: <1542535751-16079-1-git-send-email-pawell@cadence.com>
 <1542535751-16079-7-git-send-email-pawell@cadence.com>
 <5BF80D44.2050600@ti.com>
 <BYAPR07MB4709593D0B03399E9D35E07BDDD70@BYAPR07MB4709.namprd07.prod.outlook.com>
CC:     "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Alan Douglas <adouglas@cadence.com>,
        "jbergsagel@ti.com" <jbergsagel@ti.com>,
        "nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>,
        Suresh Punnoose <sureshp@cadence.com>,
        "peter.chen@nxp.com" <peter.chen@nxp.com>,
        Pawel Jez <pjez@cadence.com>, Rahul Kumar <kurahul@cadence.com>
From:   Roger Quadros <rogerq@ti.com>
Message-ID: <5BFBC201.4000000@ti.com>
Date:   Mon, 26 Nov 2018 11:50:57 +0200
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Sender: linux-kernel-owner@vger.kernel.org
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Hi,

On 26/11/18 10:24, Pawel Laszczak wrote:
>> EXTERNAL MAIL
>>
>>
>> On 18/11/18 12:09, Pawel Laszczak wrote:
>>> Patch adds host-export.h and host.c file and mplements functions that
>>> allow to initialize, start and stop XHCI host driver.
>>>
>>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>>> ---
>>>  drivers/usb/cdns3/Kconfig       |  10 ++
>>>  drivers/usb/cdns3/Makefile      |   1 +
>>>  drivers/usb/cdns3/core.c        |   7 +-
>>>  drivers/usb/cdns3/host-export.h |  30 ++++
>>>  drivers/usb/cdns3/host.c        | 256 ++++++++++++++++++++++++++++++++
>>>  5 files changed, 302 insertions(+), 2 deletions(-)
>>>  create mode 100644 drivers/usb/cdns3/host-export.h
>>>  create mode 100644 drivers/usb/cdns3/host.c
>>>
>>> diff --git a/drivers/usb/cdns3/Kconfig b/drivers/usb/cdns3/Kconfig
>>> index eb22a8692991..d92bc3d68eb0 100644
>>> --- a/drivers/usb/cdns3/Kconfig
>>> +++ b/drivers/usb/cdns3/Kconfig
>>> @@ -10,6 +10,16 @@ config USB_CDNS3
>>>
>>>  if USB_CDNS3
>>>
>>> +config USB_CDNS3_HOST
>>> +        bool "Cadence USB3 host controller"
>>> +        depends on USB_XHCI_HCD
>>> +        help
>>> +          Say Y here to enable host controller functionality of the
>>> +          cadence driver.
>>> +
>>> +          Host controller is compliance with XHCI so it will use
>>> +          standard XHCI driver.
>>> +
>>>  config USB_CDNS3_PCI_WRAP
>>>  	tristate "PCIe-based Platforms"
>>>  	depends on USB_PCI && ACPI
>>> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
>>> index e779b2a2f8eb..976117ba67ff 100644
>>> --- a/drivers/usb/cdns3/Makefile
>>> +++ b/drivers/usb/cdns3/Makefile
>>> @@ -2,4 +2,5 @@ obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>>>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci.o
>>>
>>>  cdns3-y					:= core.o drd.o
>>> +cdns3-$(CONFIG_USB_CDNS3_HOST)          += host.o
>>>  cdns3-pci-y		 		:= cdns3-pci-wrap.o
>>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>>> index dbee4325da7f..4cb820be9ff3 100644
>>> --- a/drivers/usb/cdns3/core.c
>>> +++ b/drivers/usb/cdns3/core.c
>>> @@ -17,6 +17,7 @@
>>>
>>>  #include "gadget.h"
>>>  #include "core.h"
>>> +#include "host-export.h"
>>>  #include "drd.h"
>>>
>>>  static inline struct cdns3_role_driver *cdns3_get_current_role_driver(struct cdns3 *cdns)
>>> @@ -98,7 +99,8 @@ static int cdns3_core_init_role(struct cdns3 *cdns)
>>>  	}
>>>
>>>  	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST) {
>>> -		//TODO: implements host initialization
>>> +		if (cdns3_host_init(cdns))
>>> +			dev_info(dev, "doesn't support host\n");
>>
>> dev_err()
>>
>> And you need to error out with error code.
> 
> ok, but I assume that even if host returns error then we can use 
> only device role. Only when both functions return errors, then it's  a critical error 
> and function return error code. 

But at this point we are in OTG or HOST dr_mode and without host functional
both will not function correctly. So we must error out so user can debug.

>>
>>>  	}
>>>
>>>  	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_PERIPHERAL) {
>>> @@ -142,7 +144,7 @@ static irqreturn_t cdns3_irq(int irq, void *data)
>>>
>>>  static void cdns3_remove_roles(struct cdns3 *cdns)
>>>  {
>>> -	//TODO: implements this function
>>
>> if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST)
>>
>>> +	cdns3_host_remove(cdns);
>>
>> How about calling it cdns3_host_exit() to complement cdns3_host_init().
>>
>>>  }
>>>
>>>  static int cdns3_do_role_switch(struct cdns3 *cdns, enum cdns3_roles role)
>>> @@ -410,6 +412,7 @@ static struct platform_driver cdns3_driver = {
>>>
>>>  static int __init cdns3_driver_platform_register(void)
>>>  {
>>> +	cdns3_host_driver_init();
>>>  	return platform_driver_register(&cdns3_driver);
>>>  }
>>>  module_init(cdns3_driver_platform_register);
>>> diff --git a/drivers/usb/cdns3/host-export.h b/drivers/usb/cdns3/host-export.h
>>> new file mode 100644
>>> index 000000000000..f8f3b230b472
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/host-export.h
>>> @@ -0,0 +1,30 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>> +/*
>>> + * Cadence USBSS DRD Driver -Host Export APIs
>>> + *
>>> + * Copyright (C) 2017 NXP
>>> + *
>>> + * Authors: Peter Chen <peter.chen@nxp.com>
>>> + */
>>> +#ifndef __LINUX_CDNS3_HOST_EXPORT
>>> +#define __LINUX_CDNS3_HOST_EXPORT
>>> +
>>> +#ifdef CONFIG_USB_CDNS3_HOST
>>> +
>>> +int cdns3_host_init(struct cdns3 *cdns);
>>> +void cdns3_host_remove(struct cdns3 *cdns);
>>> +void cdns3_host_driver_init(void);
>>> +
>>> +#else
>>> +
>>> +static inline int cdns3_host_init(struct cdns3 *cdns)
>>> +{
>>> +	return -ENXIO;
>>> +}
>>> +
>>> +static inline void cdns3_host_remove(struct cdns3 *cdns) { }
>>> +static inline void cdns3_host_driver_init(void) {}
>>> +
>>> +#endif /* CONFIG_USB_CDNS3_HOST */
>>> +
>>> +#endif /* __LINUX_CDNS3_HOST_EXPORT */
>>> diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
>>> new file mode 100644
>>> index 000000000000..0dd47976cb28
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/host.c
>>> @@ -0,0 +1,256 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Cadence USBSS DRD Driver - host side
>>> + *
>>> + * Copyright (C) 2018 Cadence Design Systems.
>>> + * Copyright (C) 2018 NXP
>>> + *
>>> + * Authors: Peter Chen <peter.chen@nxp.com>
>>> + *	    Pawel Laszczak <pawell@cadence.com>
>>> + */
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/device.h>
>>> +#include <linux/io.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/dma-mapping.h>
>>> +#include <linux/usb.h>
>>> +#include <linux/usb/hcd.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/usb/of.h>
>>> +
>>> +#include "../host/xhci.h"
>>> +#include "core.h"
>>> +#include "host-export.h"
>>> +
>>> +static struct hc_driver __read_mostly xhci_cdns3_hc_driver;
>>> +
>>> +static void xhci_cdns3_quirks(struct device *dev, struct xhci_hcd *xhci)
>>> +{
>>> +	/*
>>> +	 * As of now platform drivers don't provide MSI support so we ensure
>>> +	 * here that the generic code does not try to make a pci_dev from our
>>> +	 * dev struct in order to setup MSI
>>> +	 */
>>> +	xhci->quirks |= XHCI_PLAT;
>>> +}
>>> +
>>> +static int xhci_cdns3_setup(struct usb_hcd *hcd)
>>> +{
>>> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
>>> +	u32 command;
>>> +	int ret;
>>> +
>>> +	ret = xhci_gen_setup(hcd, xhci_cdns3_quirks);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	/* set usbcmd.EU3S */
>>> +	command = readl(&xhci->op_regs->command);
>>> +	command |= CMD_PM_INDEX;
>>> +	writel(command, &xhci->op_regs->command);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static const struct xhci_driver_overrides xhci_cdns3_overrides __initconst = {
>>> +	.extra_priv_size = sizeof(struct xhci_hcd),
>>> +	.reset = xhci_cdns3_setup,
>>> +};
>>> +
>>> +struct cdns3_host {
>>> +	struct device dev;
>>> +	struct usb_hcd *hcd;
>>> +};
>>> +
>>> +static irqreturn_t cdns3_host_irq(struct cdns3 *cdns)
>>> +{
>>> +	struct device *dev = cdns->host_dev;
>>> +	struct usb_hcd	*hcd;
>>> +
>>> +	if (dev)
>>> +		hcd = dev_get_drvdata(dev);
>>> +	else
>>> +		return IRQ_NONE;
>>> +
>>> +	if (hcd)
>>> +		return usb_hcd_irq(cdns->irq, hcd);
>>> +	else
>>> +		return IRQ_NONE;
>>
>> Why can't you just reuse the xhci-platform driver and let it manage the IRQ?
>> Since it is a shared IRQ, different drivers can request the same IRQ and return IRQ_NONE
>> if the IRQ wasn't from their device.
> 
> In device role the host part of controller is kept in reset, so driver can't read the host register. 
> Such solution allows driver to control access to host register. 
> So if driver has shared separate interrupt for host role then it has to check if controller work in 
> Host role.  

I understand what you mean. I think the issue here is that you are having the host ISR active
even when host role is stopped. This is the root cause of the problem.

When you stop host role, the host driver *must* unregister the ISR
and then place the host in reset.

This will happen correctly if you use platform_unregister_device() to unregister the
XHCI device in cdns3_host_stop().

> 
>>> +}
>>> +
>>> +static void cdns3_host_release(struct device *dev)
>>> +{
>>> +	struct cdns3_host *host = container_of(dev, struct cdns3_host, dev);
>>> +
>>> +	kfree(host);
>>> +}
>>> +
>>> +static int cdns3_host_start(struct cdns3 *cdns)
>>> +{
>>> +	struct cdns3_host *host;
>>> +	struct device *dev;
>>> +	struct device *sysdev;
>>> +	struct xhci_hcd	*xhci;
>>> +	int ret;
>>> +
>>> +	host = kzalloc(sizeof(*host), GFP_KERNEL);
>>> +	if (!host)
>>> +		return -ENOMEM;
>>> +
>>> +	dev = &host->dev;
>>> +	dev->release = cdns3_host_release;
>>> +	dev->parent = cdns->dev;
>>> +	dev_set_name(dev, "xhci-cdns3");
>>> +	cdns->host_dev = dev;
>>> +	ret = device_register(dev);
>>> +	if (ret)
>>> +		goto err1;
>>> +
>>> +	sysdev = cdns->dev;
>>> +	/* Try to set 64-bit DMA first */
>>> +	if (WARN_ON(!sysdev->dma_mask))
>>> +		/* Platform did not initialize dma_mask */
>>> +		ret = dma_coerce_mask_and_coherent(sysdev,
>>> +						   DMA_BIT_MASK(64));
>>> +	else
>>> +		ret = dma_set_mask_and_coherent(sysdev, DMA_BIT_MASK(64));
>>> +
>>> +	/* If setting 64-bit DMA mask fails, fall back to 32-bit DMA mask */
>>> +	if (ret) {
>>> +		ret = dma_set_mask_and_coherent(sysdev, DMA_BIT_MASK(32));
>>> +		if (ret)
>>> +			return ret;
>>> +	}
>>> +
>>> +	pm_runtime_set_active(dev);
>>> +	pm_runtime_no_callbacks(dev);
>>> +	pm_runtime_enable(dev);
>>> +	host->hcd = __usb_create_hcd(&xhci_cdns3_hc_driver, sysdev, dev,
>>> +				     dev_name(dev), NULL);
>>> +	if (!host->hcd) {
>>> +		ret = -ENOMEM;
>>> +		goto err2;
>>> +	}
>>> +
>>> +	host->hcd->regs = cdns->xhci_regs;
>>> +	host->hcd->rsrc_start = cdns->xhci_res->start;
>>> +	host->hcd->rsrc_len = resource_size(cdns->xhci_res);
>>> +
>>> +	device_wakeup_enable(host->hcd->self.controller);
>>> +	xhci = hcd_to_xhci(host->hcd);
>>> +
>>> +	xhci->main_hcd = host->hcd;
>>> +	xhci->shared_hcd = __usb_create_hcd(&xhci_cdns3_hc_driver, sysdev, dev,
>>> +					    dev_name(dev), host->hcd);
>>> +	if (!xhci->shared_hcd) {
>>> +		ret = -ENOMEM;
>>> +		goto err3;
>>> +	}
>>> +
>>> +	host->hcd->tpl_support = of_usb_host_tpl_support(sysdev->of_node);
>>> +	xhci->shared_hcd->tpl_support = host->hcd->tpl_support;
>>> +	ret = usb_add_hcd(host->hcd, 0, IRQF_SHARED);
>>> +	if (ret)
>>> +		goto err4;
>>> +
>>> +	ret = usb_add_hcd(xhci->shared_hcd, 0, IRQF_SHARED);
>>> +	if (ret)
>>> +		goto err5;
>>> +
>>> +	device_set_wakeup_capable(dev, true);
>>
>> All this is being done by the xhci-plat.c
>>
>> You can make use of it by just creating a xhci-hcd platform device.
>>
>> e.g.
>> platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
>> platform_device_add_resources() to add IRQ and memory resource.
>> platform_device_add_properties() to add any quirks.
>> platform_device_add()
>>
> 
> If we do this in this way driver will not control the interrupt. 

Why should this driver control host interrupt when it doesn't
have access to HOST registers.

> This code  has written by Peter Chan and I am convinced 
> that this concept is only correct one.
> 
>>> +
>>> +	return 0;
>>> +
>>> +err5:
>>> +	usb_remove_hcd(host->hcd);
>>> +err4:
>>> +	usb_put_hcd(xhci->shared_hcd);
>>> +err3:
>>> +	usb_put_hcd(host->hcd);
>>> +err2:
>>> +	device_del(dev);
>>> +err1:
>>> +	put_device(dev);
>>> +	cdns->host_dev = NULL;
>>> +	return ret;
>>> +}
>>> +
>>> +static void cdns3_host_stop(struct cdns3 *cdns)
>>> +{
>>> +	struct device *dev = cdns->host_dev;
>>> +	struct xhci_hcd	*xhci;
>>> +	struct usb_hcd	*hcd;
>>> +
>>> +	if (dev) {
>>> +		hcd = dev_get_drvdata(dev);
>>> +		xhci = hcd_to_xhci(hcd);
>>> +		usb_remove_hcd(xhci->shared_hcd);
>>> +		usb_remove_hcd(hcd);
>>> +		synchronize_irq(cdns->irq);
>>> +		usb_put_hcd(xhci->shared_hcd);
>>> +		usb_put_hcd(hcd);
>>> +		cdns->host_dev = NULL;
>>> +		pm_runtime_set_suspended(dev);
>>> +		pm_runtime_disable(dev);
>>> +		device_del(dev);
>>> +		put_device(dev);
>>> +	}
>>
>> You can replace this with just
>> 	platform_device_unregister(xhci_dev);
>>
>>> +}
>>> +
>>> +#if CONFIG_PM
>>> +static int cdns3_host_suspend(struct cdns3 *cdns, bool do_wakeup)
>>> +{
>>> +	struct device *dev = cdns->host_dev;
>>> +	struct xhci_hcd	*xhci;
>>> +
>>> +	if (!dev)
>>> +		return 0;
>>> +
>>> +	xhci = hcd_to_xhci(dev_get_drvdata(dev));
>>> +	return xhci_suspend(xhci, do_wakeup);
>>> +}
>>> +
>>> +static int cdns3_host_resume(struct cdns3 *cdns, bool hibernated)
>>> +{
>>> +	struct device *dev = cdns->host_dev;
>>> +	struct xhci_hcd	*xhci;
>>> +
>>> +	if (!dev)
>>> +		return 0;
>>> +
>>> +	xhci = hcd_to_xhci(dev_get_drvdata(dev));
>>> +	return xhci_resume(xhci, hibernated);
>>> +}
>>
>> These won't be required any more as xhci-plat is doing this.
>>
>>> +#endif /* CONFIG_PM */
>>> +
>>> +int cdns3_host_init(struct cdns3 *cdns)
>>> +{
>>> +	struct cdns3_role_driver *rdrv;
>>> +
>>> +	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
>>> +	if (!rdrv)
>>> +		return -ENOMEM;
>>> +
>>> +	rdrv->start	= cdns3_host_start;
>>> +	rdrv->stop	= cdns3_host_stop;
>>> +	rdrv->irq	= cdns3_host_irq;
>>> +#if CONFIG_PM
>>> +	rdrv->suspend	= cdns3_host_suspend;
>>> +	rdrv->resume	= cdns3_host_resume;
>>> +#endif /* CONFIG_PM */
>>> +	rdrv->name	= "host";
>>> +	cdns->roles[CDNS3_ROLE_HOST] = rdrv;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +void cdns3_host_remove(struct cdns3 *cdns)
>>> +{
>>> +	cdns3_host_stop(cdns);
>>
>> calling cdns3_host_stop() here can lead to problems as Controller might be in
>> peripheral mode at this point. The core driver needs to ensure that relevant role
>> is stopped before calling cdns3_host_remove().
>>
>> Here you need to unregister the role driver though.
>>
>> cdns->roles[CDNS3_ROLE_HOST] = NULL;
>>
> This function can be called only in host mode/role. It operate on host registers. 
> This checking is provided in core.c file. 
>>> +}
>>> +
>>> +void __init cdns3_host_driver_init(void)
>>> +{
>>> +	xhci_init_driver(&xhci_cdns3_hc_driver, &xhci_cdns3_overrides);
>>> +}
>>>
>>

cheers,
-roger

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