Re: [PATCH v6 2/3] usb: cdns3: add runtime PM support

[Chunfeng Yun <chunfeng.yun@mediatek.com>]

On Fri, 2020-08-21 at 10:48 +0800, Peter Chen wrote:
> Introduce runtime PM and wakeup interrupt handler for cdns3,
> the runtime PM is default off since other cdns3 may not
> implement glue layer support for runtime PM.
> 
> One typical wakeup event use case is xHCI runtime suspend will clear
> USBCMD.RS bit, after that the xHCI will not trigger any interrupts,
> so its parent (cdns core device) needs to resume xHCI device when
> any (wakeup) events occurs at host port.
> 
> When the controller is in low power mode, the lpm flag will be set.
> The interrupt triggered later than lpm flag is set considers as
> wakeup interrupt and handled at cdns_wakeup_irq. Once the wakeup
> occurs, it first disables interrupt to avoid later interrupt
> occurrence since the controller is in low power mode at that
> time, and access registers may be invalid at that time. At wakeup
> handler, it will call pm_request_resume to wakeup xHCI device, and
> at runtime resume handler, it will enable interrupt again.
> 
> The API platform_suspend is introduced for glue layer to implement
> platform specific PM sequence.
> 
> Reviewed-by: Pawel Laszczak <pawell@cadence.com>
> Signed-off-by: Peter Chen <peter.chen@nxp.com>
> ---
>  drivers/usb/cdns3/core.c   | 153 ++++++++++++++++++++++++++++++++-----
>  drivers/usb/cdns3/core.h   |  16 ++++
>  drivers/usb/cdns3/drd.c    |   3 +
>  drivers/usb/cdns3/gadget.c |   4 +
>  drivers/usb/cdns3/host.c   |   7 ++
>  5 files changed, 166 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index e56dbb6a898c..8e588eef38df 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -392,6 +392,30 @@ static void set_phy_power_off(struct cdns3 *cdns)
>  	phy_power_off(cdns->usb2_phy);
>  }
>  
> +/**
> + * cdns3_wakeup_irq - interrupt handler for wakeup events
> + *
remove blank line?
"Do not leave a blank line between the function description and the
arguments, nor between the arguments"
see kernel-doc.rst, Function parameters

> + * @irq: irq number for cdns3 core device
> + * @data: structure of cdns3
> + *
> + * Returns IRQ_HANDLED or IRQ_NONE
> + */
> +static irqreturn_t cdns3_wakeup_irq(int irq, void *data)
> +{
> +	struct cdns3 *cdns = data;
> +
> +	if (cdns->in_lpm) {
> +		disable_irq_nosync(irq);
> +		cdns->wakeup_pending = true;
> +		if ((cdns->role == USB_ROLE_HOST) && cdns->host_dev)
> +			pm_request_resume(&cdns->host_dev->dev);
> +
> +		return IRQ_HANDLED;
> +	}
> +
> +	return IRQ_NONE;
> +}
> +
>  /**
>   * cdns3_probe - probe for cdns3 core device
>   * @pdev: Pointer to cdns3 core platform device
> @@ -418,6 +442,7 @@ static int cdns3_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	cdns->dev = dev;
> +	cdns->pdata = dev_get_platdata(dev);
>  
>  	platform_set_drvdata(pdev, cdns);
>  
> @@ -466,6 +491,15 @@ static int cdns3_probe(struct platform_device *pdev)
>  
>  	cdns->otg_res = *res;
>  
> +	cdns->wakeup_irq = platform_get_irq_byname_optional(pdev, "wakeup");
> +	if (cdns->wakeup_irq == -EPROBE_DEFER)
> +		return cdns->wakeup_irq;
> +
> +	if (cdns->wakeup_irq < 0) {
> +		dev_dbg(dev, "couldn't get wakeup irq\n");
> +		cdns->wakeup_irq = 0x0;
> +	}
> +
>  	mutex_init(&cdns->mutex);
>  
>  	cdns->usb2_phy = devm_phy_optional_get(dev, "cdns3,usb2-phy");
> @@ -502,6 +536,19 @@ static int cdns3_probe(struct platform_device *pdev)
>  		goto err3;
>  	}
>  
> +	if (cdns->wakeup_irq) {
> +		ret = devm_request_threaded_irq(cdns->dev, cdns->wakeup_irq,
> +						cdns3_wakeup_irq,
> +						NULL,
> +						IRQF_SHARED,
> +						dev_name(cdns->dev), cdns);
> +
> +		if (ret) {
> +			dev_err(cdns->dev, "couldn't register wakeup irq handler\n");
> +			goto err3;
> +		}
> +	}
> +
>  	ret = cdns3_drd_init(cdns);
>  	if (ret)
>  		goto err4;
> @@ -510,9 +557,11 @@ static int cdns3_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err4;
>  
> +	spin_lock_init(&cdns->lock);
>  	device_set_wakeup_capable(dev, true);
>  	pm_runtime_set_active(dev);
>  	pm_runtime_enable(dev);
> +	pm_runtime_forbid(dev);
>  
>  	/*
>  	 * The controller needs less time between bus and controller suspend,
> @@ -559,52 +608,122 @@ static int cdns3_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -#ifdef CONFIG_PM_SLEEP
> +#ifdef CONFIG_PM
What about using __maybe_unused instead of #ifdef ?
>  
> -static int cdns3_suspend(struct device *dev)
> +static int cdns3_set_platform_suspend(struct device *dev,
> +		bool suspend, bool wakeup)
> +{
> +	struct cdns3 *cdns = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	if (cdns->pdata && cdns->pdata->platform_suspend)
> +		ret = cdns->pdata->platform_suspend(dev, suspend, wakeup);
> +
> +	return ret;
> +}
> +
> +static int cdns3_controller_suspend(struct device *dev, pm_message_t msg)
>  {
>  	struct cdns3 *cdns = dev_get_drvdata(dev);
> +	bool wakeup;
>  	unsigned long flags;
>  
> -	if (cdns->role == USB_ROLE_HOST)
> +	if (cdns->in_lpm)
>  		return 0;
>  
> -	if (pm_runtime_status_suspended(dev))
> -		pm_runtime_resume(dev);
> +	if (PMSG_IS_AUTO(msg))
> +		wakeup = true;
> +	else
> +		wakeup = device_may_wakeup(dev);
>  
> -	if (cdns->roles[cdns->role]->suspend) {
> -		spin_lock_irqsave(&cdns->gadget_dev->lock, flags);
> -		cdns->roles[cdns->role]->suspend(cdns, false);
> -		spin_unlock_irqrestore(&cdns->gadget_dev->lock, flags);
> -	}
> +	cdns3_set_platform_suspend(cdns->dev, true, wakeup);
> +	set_phy_power_off(cdns);
> +	spin_lock_irqsave(&cdns->lock, flags);
> +	cdns->in_lpm = true;
> +	spin_unlock_irqrestore(&cdns->lock, flags);
> +	dev_dbg(cdns->dev, "%s ends\n", __func__);
>  
>  	return 0;
>  }
>  
> -static int cdns3_resume(struct device *dev)
> +static int cdns3_controller_resume(struct device *dev, pm_message_t msg)
>  {
>  	struct cdns3 *cdns = dev_get_drvdata(dev);
> +	int ret;
>  	unsigned long flags;
>  
> -	if (cdns->role == USB_ROLE_HOST)
> +	if (!cdns->in_lpm)
>  		return 0;
>  
> -	if (cdns->roles[cdns->role]->resume) {
> -		spin_lock_irqsave(&cdns->gadget_dev->lock, flags);
> +	ret = set_phy_power_on(cdns);
> +	if (ret)
> +		return ret;
> +
> +	cdns3_set_platform_suspend(cdns->dev, false, false);
> +
> +	spin_lock_irqsave(&cdns->lock, flags);
> +	if (cdns->roles[cdns->role]->resume && !PMSG_IS_AUTO(msg))
>  		cdns->roles[cdns->role]->resume(cdns, false);
> -		spin_unlock_irqrestore(&cdns->gadget_dev->lock, flags);
> +
> +	cdns->in_lpm = false;
> +	spin_unlock_irqrestore(&cdns->lock, flags);
> +	if (cdns->wakeup_pending) {
> +		cdns->wakeup_pending = false;
> +		enable_irq(cdns->wakeup_irq);
> +	}
> +	dev_dbg(cdns->dev, "%s ends\n", __func__);
> +
> +	return ret;
> +}
> +
> +static int cdns3_runtime_suspend(struct device *dev)
> +{
> +	return cdns3_controller_suspend(dev, PMSG_AUTO_SUSPEND);
> +}
> +
> +static int cdns3_runtime_resume(struct device *dev)
> +{
> +	return cdns3_controller_resume(dev, PMSG_AUTO_RESUME);
> +}
> +#ifdef CONFIG_PM_SLEEP
> +
> +static int cdns3_suspend(struct device *dev)
> +{
> +	struct cdns3 *cdns = dev_get_drvdata(dev);
> +	unsigned long flags;
> +
> +	if (pm_runtime_status_suspended(dev))
> +		pm_runtime_resume(dev);
> +
> +	if (cdns->roles[cdns->role]->suspend) {
> +		spin_lock_irqsave(&cdns->lock, flags);
> +		cdns->roles[cdns->role]->suspend(cdns, false);
> +		spin_unlock_irqrestore(&cdns->lock, flags);
>  	}
>  
> +	return cdns3_controller_suspend(dev, PMSG_SUSPEND);
> +}
> +
> +static int cdns3_resume(struct device *dev)
> +{
> +	int ret;
> +
> +	ret = cdns3_controller_resume(dev, PMSG_RESUME);
> +	if (ret)
> +		return ret;
> +
>  	pm_runtime_disable(dev);
>  	pm_runtime_set_active(dev);
>  	pm_runtime_enable(dev);
>  
> -	return 0;
> +	return ret;
>  }
> -#endif
> +#endif /* CONFIG_PM_SLEEP */
> +#endif /* CONFIG_PM */
>  
>  static const struct dev_pm_ops cdns3_pm_ops = {
>  	SET_SYSTEM_SLEEP_PM_OPS(cdns3_suspend, cdns3_resume)
> +	SET_RUNTIME_PM_OPS(cdns3_runtime_suspend, cdns3_runtime_resume, NULL)
>  };
>  
>  #ifdef CONFIG_OF
> diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
> index 1ad1f1fe61e9..1b1707796db2 100644
> --- a/drivers/usb/cdns3/core.h
> +++ b/drivers/usb/cdns3/core.h
> @@ -38,6 +38,12 @@ struct cdns3_role_driver {
>  };
>  
>  #define CDNS3_XHCI_RESOURCES_NUM	2
> +
> +struct cdns3_platform_data {
> +	int (*platform_suspend)(struct device *dev,
> +			bool suspend, bool wakeup);
> +};
> +
>  /**
>   * struct cdns3 - Representation of Cadence USB3 DRD controller.
>   * @dev: pointer to Cadence device struct
> @@ -50,6 +56,7 @@ struct cdns3_role_driver {
>   * @otg_regs: pointer to base of otg registers
>   * @otg_irq: irq number for otg controller
>   * @dev_irq: irq number for device controller
> + * @wakeup_irq: irq number for wakeup event, it is optional
>   * @roles: array of supported roles for this controller
>   * @role: current role
>   * @host_dev: the child host device pointer for cdns3 core
> @@ -62,6 +69,10 @@ struct cdns3_role_driver {
>   *           This field based on firmware setting, kernel configuration
>   *           and hardware configuration.
>   * @role_sw: pointer to role switch object.
> + * @in_lpm: indicate the controller is in low power mode
> + * @wakeup_pending: wakeup interrupt pending
> + * @pdata: platform data from glue layer
> + * @lock: spinlock structure
>   */
>  struct cdns3 {
>  	struct device			*dev;
> @@ -79,6 +90,7 @@ struct cdns3 {
>  
>  	int				otg_irq;
>  	int				dev_irq;
> +	int				wakeup_irq;
>  	struct cdns3_role_driver	*roles[USB_ROLE_DEVICE + 1];
>  	enum usb_role			role;
>  	struct platform_device		*host_dev;
> @@ -89,6 +101,10 @@ struct cdns3 {
>  	struct mutex			mutex;
>  	enum usb_dr_mode		dr_mode;
>  	struct usb_role_switch		*role_sw;
> +	bool				in_lpm;
> +	bool				wakeup_pending;
> +	struct cdns3_platform_data	*pdata;
> +	spinlock_t			lock;
>  };
>  
>  int cdns3_hw_role_switch(struct cdns3 *cdns);
> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
> index 6234bcd6158a..5f2685cadf5e 100644
> --- a/drivers/usb/cdns3/drd.c
> +++ b/drivers/usb/cdns3/drd.c
> @@ -293,6 +293,9 @@ static irqreturn_t cdns3_drd_irq(int irq, void *data)
>  	if (cdns->dr_mode != USB_DR_MODE_OTG)
>  		return IRQ_NONE;
>  
> +	if (cdns->in_lpm)
> +		return ret;
> +
>  	reg = readl(&cdns->otg_regs->ivect);
>  
>  	if (!reg)
> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> index dea649ee173b..8bbb38cd560b 100644
> --- a/drivers/usb/cdns3/gadget.c
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -1769,9 +1769,13 @@ static void cdns3_check_usb_interrupt_proceed(struct cdns3_device *priv_dev,
>  static irqreturn_t cdns3_device_irq_handler(int irq, void *data)
>  {
>  	struct cdns3_device *priv_dev = data;
> +	struct cdns3 *cdns = dev_get_drvdata(priv_dev->dev);
>  	irqreturn_t ret = IRQ_NONE;
>  	u32 reg;
>  
> +	if (cdns->in_lpm)
> +		return ret;
> +
>  	/* check USB device interrupt */
>  	reg = readl(&priv_dev->regs->usb_ists);
>  	if (reg) {
> diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
> index 36c63d9ecd37..b3e2cb69762c 100644
> --- a/drivers/usb/cdns3/host.c
> +++ b/drivers/usb/cdns3/host.c
> @@ -13,11 +13,13 @@
>  #include "core.h"
>  #include "drd.h"
>  #include "host-export.h"
> +#include <linux/usb/hcd.h>
>  
>  static int __cdns3_host_init(struct cdns3 *cdns)
>  {
>  	struct platform_device *xhci;
>  	int ret;
> +	struct usb_hcd *hcd;
>  
>  	cdns3_drd_host_on(cdns);
>  
> @@ -43,6 +45,11 @@ static int __cdns3_host_init(struct cdns3 *cdns)
>  		goto err1;
>  	}
>  
> +	/* Glue needs to access xHCI region register for Power management */
> +	hcd = platform_get_drvdata(xhci);
> +	if (hcd)
> +		cdns->xhci_regs = hcd->regs;
> +
>  	return 0;
>  err1:
>  	platform_device_put(xhci);