Date:   Thu, 27 Sep 2018 13:51:36 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Al Cooper <alcooperx@...il.com>
CC:     <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Mark Rutland" <mark.rutland@....com>,
        Alan Stern <stern@...land.harvard.edu>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Dmitry Osipenko <digetx@...il.com>,
        Jianguo Sun <sunjianguo1@...wei.com>,
        James Hogan <jhogan@...nel.org>, Alban Bedel <albeu@...e.fr>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Avi Fishman <avifishman70@...il.com>,
        "Alex Elder" <elder@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        <linux-usb@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH 4/5] usb: host: Add XHCI driver for Broadcom STB SoCs

Hi,

On Wed, 2018-09-26 at 18:20 -0400, Al Cooper wrote:
> This driver enables USB XHCI on Broadcom ARM STB SoCs.
> The drivers depend on a matching "brcm,brcmstb-usb-phy"
> Broadcom STB USB Phy driver.
> 
> The standard platform driver can't be used because of differences
> in PHY and Clock handling. The standard PHY handling in hcd.c will
> do a phy_exit/phy_init on suspend/resume and this will end up
> shutting down the PHYs to the point that the host controller
> registers are no longer accessible and will cause suspend to crash.
You can avoid hcd.c to do a phy_exit/phy_init on suspend/resume by
device_init_wakeup(dev, true);

> The clocks specified in device tree for these drivers are not
> available in mainline so instead of returning EPROBE_DEFER when
> the specified clock is not found and eventually failing probe,
> the clock pointer is set to NULL which disables all clock handling.
Try to use a fixed-clock as dummy clock if the clock is optional?

> 
> Signed-off-by: Al Cooper <alcooperx@...il.com>
> ---
>  drivers/usb/host/xhci-brcm.c | 294 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 294 insertions(+)
>  create mode 100644 drivers/usb/host/xhci-brcm.c
> 
> diff --git a/drivers/usb/host/xhci-brcm.c b/drivers/usb/host/xhci-brcm.c
> new file mode 100644
> index 000000000000..1a7578b8ef6a
> --- /dev/null
> +++ b/drivers/usb/host/xhci-brcm.c
> @@ -0,0 +1,294 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018, Broadcom */
> +
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/clk.h>
> +#include <linux/phy/phy.h>
> +
> +#include "xhci.h"
> +
> +static struct hc_driver __read_mostly xhci_brcm_hc_driver;
> +
> +#define BRCM_DRIVER_DESC "xHCI Broadcom STB driver"
> +#define BRCM_DRIVER_NAME "xhci-brcm"
> +
> +#define hcd_to_xhci_priv(h) ((struct brcm_priv *)hcd_to_xhci(h)->priv)
> +
> +struct brcm_priv {
> +	struct phy *phy;
> +};
> +
> +static void xhci_brcm_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;
> +
> +	/*
> +	 * The Broadcom XHCI core does not support save/restore state
> +	 * so we need to reset on resume.
> +	 */
> +	xhci->quirks |= XHCI_RESET_ON_RESUME;
> +}
> +
> +/* called during probe() after chip reset completes */
> +static int xhci_brcm_setup(struct usb_hcd *hcd)
> +{
> +	return xhci_gen_setup(hcd, xhci_brcm_quirks);
> +}
> +
> +static const struct xhci_driver_overrides brcm_overrides __initconst = {
> +
> +	.extra_priv_size = sizeof(struct brcm_priv),
> +	.reset = xhci_brcm_setup,
> +};
> +
> +static int xhci_brcm_probe(struct platform_device *pdev)
> +{
> +	const struct hc_driver	*driver;
> +	struct brcm_priv	*priv;
> +	struct xhci_hcd		*xhci;
> +	struct resource         *res;
> +	struct usb_hcd		*hcd;
> +	int			ret;
> +	int			irq;
> +
> +	if (usb_disabled())
> +		return -ENODEV;
> +
> +	driver = &xhci_brcm_hc_driver;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return -ENODEV;
> +
> +	/* Try to set 64-bit DMA first */
> +	if (WARN_ON(!pdev->dev.dma_mask))
> +		/* Platform did not initialize dma_mask */
> +		ret = dma_coerce_mask_and_coherent(&pdev->dev,
> +						   DMA_BIT_MASK(64));
> +	else
> +		ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> +
> +	/* If seting 64-bit DMA mask fails, fall back to 32-bit DMA mask */
> +	if (ret) {
> +		ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> +		if (ret)
> +			return ret;
> +	}
> +
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_get_noresume(&pdev->dev);
> +
> +	hcd = __usb_create_hcd(driver, &pdev->dev, &pdev->dev,
> +			       dev_name(&pdev->dev), NULL);
> +	if (!hcd) {
> +		return -ENOMEM;
> +		goto disable_runtime;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	hcd->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(hcd->regs)) {
> +		ret = PTR_ERR(hcd->regs);
> +		goto put_hcd;
> +	}
> +
> +	hcd->rsrc_start = res->start;
> +	hcd->rsrc_len = resource_size(res);
> +
> +	/*
> +	 * Not all platforms have a clk so it is not an error if the
> +	 * clock does not exists.
> +	 */
> +	xhci = hcd_to_xhci(hcd);
> +	xhci->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(xhci->clk)) {
> +		dev_err(&pdev->dev, "Clock not found in Device Tree\n");
> +		xhci->clk = NULL;
> +	}
> +	device_wakeup_enable(hcd->self.controller);
> +
> +	xhci->main_hcd = hcd;
> +	xhci->shared_hcd = __usb_create_hcd(driver, &pdev->dev, &pdev->dev,
> +					    dev_name(&pdev->dev), hcd);
> +	if (!xhci->shared_hcd) {
> +		ret = -ENOMEM;
> +		goto disable_clk;
> +	}
> +
> +	if (device_property_read_bool(&pdev->dev, "usb3-lpm-capable"))
> +		xhci->quirks |= XHCI_LPM_SUPPORT;
> +
> +	priv = hcd_to_xhci_priv(hcd);
> +	priv->phy = devm_of_phy_get_by_index(&pdev->dev, pdev->dev.of_node, 0);
> +	if (IS_ERR(priv->phy)) {
> +		dev_err(&pdev->dev, "USB Phy not found.\n");
> +		ret = PTR_ERR(priv->phy);
> +		goto put_usb3_hcd;
> +	}
> +	ret = phy_init(priv->phy);
> +	if (ret)
> +		goto put_usb3_hcd;
> +
> +	hcd->skip_phy_initialization = 1;
> +	ret = usb_add_hcd(hcd, irq, IRQF_SHARED);
> +	if (ret)
> +		goto disable_usb_phy;
> +
> +	if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
> +		xhci->shared_hcd->can_do_streams = 1;
> +
> +	ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
> +	if (ret)
> +		goto dealloc_usb2_hcd;
> +
> +	device_enable_async_suspend(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
> +
> +	/*
> +	 * Prevent runtime pm from being on as default, users should enable
> +	 * runtime pm using power/control in sysfs.
> +	 */
> +	pm_runtime_forbid(&pdev->dev);
> +
> +	return 0;
> +
> +dealloc_usb2_hcd:
> +	usb_remove_hcd(hcd);
> +
> +disable_usb_phy:
> +	phy_exit(priv->phy);
> +
> +put_usb3_hcd:
> +	usb_put_hcd(xhci->shared_hcd);
> +
> +disable_clk:
> +	if (!IS_ERR(xhci->clk))
> +		clk_disable_unprepare(xhci->clk);
> +
> +put_hcd:
> +	usb_put_hcd(hcd);
> +
> +disable_runtime:
> +	pm_runtime_put_noidle(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
> +
> +	return ret;
> +}
> +
> +static int xhci_brcm_remove(struct platform_device *dev)
> +{
> +	struct usb_hcd	*hcd = platform_get_drvdata(dev);
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +	struct brcm_priv *priv = hcd_to_xhci_priv(hcd);
> +
> +	xhci->xhc_state |= XHCI_STATE_REMOVING;
> +
> +	usb_remove_hcd(xhci->shared_hcd);
> +	usb_remove_hcd(hcd);
> +	usb_put_hcd(xhci->shared_hcd);
> +	phy_exit(priv->phy);
> +	clk_disable_unprepare(xhci->clk);
> +	usb_put_hcd(hcd);
> +
> +	pm_runtime_set_suspended(&dev->dev);
> +	pm_runtime_disable(&dev->dev);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int xhci_brcm_suspend(struct device *dev)
> +{
> +	int ret;
> +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +
> +	ret = xhci_suspend(xhci, device_may_wakeup(dev));
> +	clk_disable_unprepare(xhci->clk);
> +	return ret;
> +}
> +
> +static int xhci_brcm_resume(struct device *dev)
> +{
> +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +	int err;
> +
> +	err = clk_prepare_enable(xhci->clk);
> +	if (err)
> +		return err;
> +	return xhci_resume(xhci, 0);
> +}
> +
> +static int xhci_brcm_runtime_suspend(struct device *dev)
> +{
> +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +
> +	return xhci_suspend(xhci, true);
> +}
> +
> +static int xhci_brcm_runtime_resume(struct device *dev)
> +{
> +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +
> +	return xhci_resume(xhci, 0);
> +}
> +
> +#endif /* CONFIG_PM_SLEEP */
> +
> +
> +static const struct dev_pm_ops xhci_brcm_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(xhci_brcm_suspend, xhci_brcm_resume)
> +
> +	SET_RUNTIME_PM_OPS(xhci_brcm_runtime_suspend,
> +			   xhci_brcm_runtime_resume,
> +			   NULL)
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id brcm_xhci_of_match[] = {
> +	{ .compatible = "brcm,xhci-brcm-v2" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, brcm_xhci_of_match);
> +#endif
> +
> +static struct platform_driver xhci_brcm_driver = {
> +	.probe	= xhci_brcm_probe,
> +	.remove	= xhci_brcm_remove,
> +	.driver	= {
> +		.name = BRCM_DRIVER_NAME,
> +		.pm = &xhci_brcm_pm_ops,
> +		.of_match_table = of_match_ptr(brcm_xhci_of_match),
> +	},
> +};
> +
> +static int __init xhci_brcm_init(void)
> +{
> +	pr_info("%s: " BRCM_DRIVER_DESC "\n", BRCM_DRIVER_NAME);
> +	xhci_init_driver(&xhci_brcm_hc_driver, &brcm_overrides);
> +	return platform_driver_register(&xhci_brcm_driver);
> +}
> +module_init(xhci_brcm_init);
> +
> +static void __exit xhci_brcm_exit(void)
> +{
> +	platform_driver_unregister(&xhci_brcm_driver);
> +}
> +module_exit(xhci_brcm_exit);
> +
> +MODULE_ALIAS("platform:xhci-brcm");
> +MODULE_DESCRIPTION(BRCM_DRIVER_DESC);
> +MODULE_AUTHOR("Al Cooper");
> +MODULE_LICENSE("GPL");

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