基于linux 4.9内核

源码：

drivers/usb/dw3/core.c

主要完成DesignWare USB3.0 Controller phy初始化，以及模式选择。

static struct platform_driver dwc3_driver = {
    .probe        = dwc3_probe,
    .remove        = dwc3_remove,
    .driver        = {
        .name    = "dwc3",
        .of_match_table    = of_match_ptr(of_dwc3_match),
        .acpi_match_table = ACPI_PTR(dwc3_acpi_match),
        .pm    = &dwc3_dev_pm_ops,
    },
};



static int dwc3_probe(struct platform_device *pdev)
{
	struct device		*dev = &pdev->dev;
	struct resource		*res;
	struct dwc3		*dwc;
。。。



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0); //获取资源
	if (!res) {
		dev_err(dev, "missing memory resource\n");
		return -ENODEV;
	}

	dwc->xhci_resources[0].start = res->start;
	dwc->xhci_resources[0].end = dwc->xhci_resources[0].start +
					DWC3_XHCI_REGS_END;
	dwc->xhci_resources[0].flags = res->flags;
	dwc->xhci_resources[0].name = res->name;

	res->start += DWC3_GLOBALS_REGS_START;

	/*
	 * Request memory region but exclude xHCI regs,
	 * since it will be requested by the xhci-plat driver.
	 */
	regs = devm_ioremap_resource(dev, res); //获取内存空间


	dwc->regs	= regs;
	dwc->regs_size	= resource_size(res);

	/* default to highest possible threshold */
	lpm_nyet_threshold = 0xf;

	/* default to -3.5dB de-emphasis */
	tx_de_emphasis = 1;

	/*
	 * default to assert utmi_sleep_n and use maximum allowed HIRD
	 * threshold value of 0b1100
	 */
	hird_threshold = 12;
//获取默认值，有些是从dts中读取的
	dwc->maximum_speed = usb_get_maximum_speed(dev);
	dwc->dr_mode = usb_get_dr_mode(dev);
	dwc->hsphy_mode = of_usb_get_phy_mode(dev->of_node);

	dwc->has_lpm_erratum = device_property_read_bool(dev,
				"snps,has-lpm-erratum");
	device_property_read_u8(dev, "snps,lpm-nyet-threshold",
				&lpm_nyet_threshold);
	dwc->is_utmi_l1_suspend = device_property_read_bool(dev,
				"snps,is-utmi-l1-suspend");
	device_property_read_u8(dev, "snps,hird-threshold",
				&hird_threshold);
	dwc->usb3_lpm_capable = device_property_read_bool(dev,
				"snps,usb3_lpm_capable");

	dwc->disable_scramble_quirk = device_property_read_bool(dev,
				"snps,disable_scramble_quirk");
	dwc->u2exit_lfps_quirk = device_property_read_bool(dev,
				"snps,u2exit_lfps_quirk");
	dwc->u2ss_inp3_quirk = device_property_read_bool(dev,
				"snps,u2ss_inp3_quirk");
	dwc->req_p1p2p3_quirk = device_property_read_bool(dev,
				"snps,req_p1p2p3_quirk");
	dwc->del_p1p2p3_quirk = device_property_read_bool(dev,
				"snps,del_p1p2p3_quirk");
	dwc->del_phy_power_chg_quirk = device_property_read_bool(dev,
				"snps,del_phy_power_chg_quirk");
	dwc->lfps_filter_quirk = device_property_read_bool(dev,
				"snps,lfps_filter_quirk");
	dwc->rx_detect_poll_quirk = device_property_read_bool(dev,
				"snps,rx_detect_poll_quirk");
	dwc->dis_u3_susphy_quirk = device_property_read_bool(dev,
				"snps,dis_u3_susphy_quirk");
	dwc->dis_u2_susphy_quirk = device_property_read_bool(dev,
				"snps,dis_u2_susphy_quirk");
	dwc->dis_enblslpm_quirk = device_property_read_bool(dev,
				"snps,dis_enblslpm_quirk");
	dwc->dis_rxdet_inp3_quirk = device_property_read_bool(dev,
				"snps,dis_rxdet_inp3_quirk");
	dwc->dis_u2_freeclk_exists_quirk = device_property_read_bool(dev,
				"snps,dis-u2-freeclk-exists-quirk");
	dwc->dis_del_phy_power_chg_quirk = device_property_read_bool(dev,
				"snps,dis-del-phy-power-chg-quirk");

	dwc->tx_de_emphasis_quirk = device_property_read_bool(dev,
				"snps,tx_de_emphasis_quirk");
	device_property_read_u8(dev, "snps,tx_de_emphasis",
				&tx_de_emphasis);
	device_property_read_string(dev, "snps,hsphy_interface",
				    &dwc->hsphy_interface);
	device_property_read_u32(dev, "snps,quirk-frame-length-adjustment",
				 &dwc->fladj);

	dwc->lpm_nyet_threshold = lpm_nyet_threshold;
	dwc->tx_de_emphasis = tx_de_emphasis;

	dwc->hird_threshold = hird_threshold
		| (dwc->is_utmi_l1_suspend << 4);

	platform_set_drvdata(pdev, dwc);
	dwc3_cache_hwparams(dwc);

	ret = dwc3_core_get_phy(dwc);


	pm_runtime_set_active(dev);
	pm_runtime_use_autosuspend(dev);
	pm_runtime_set_autosuspend_delay(dev, DWC3_DEFAULT_AUTOSUSPEND_DELAY);
	pm_runtime_enable(dev);
	ret = pm_runtime_get_sync(dev);


	pm_runtime_forbid(dev);

	ret = dwc3_alloc_event_buffers(dwc, DWC3_EVENT_BUFFERS_SIZE); //分配event buf空间
//获取usb mode(dr_mode),otg、host或者device

	ret = dwc3_get_dr_mode(dwc);


	ret = dwc3_alloc_scratch_buffers(dwc); //分配暂存缓冲区

	ret = dwc3_core_init(dwc); //初始化PHY，获取模式

。。。

	ret = dwc3_core_init_mode(dwc); //根据mode，分别初始化gadget,host和otg


	dwc3_debugfs_init(dwc);
	pm_runtime_put(dev);

。。。。。。

	return ret;
}

我们看看dwc3_core_init@core.c做了什么？

static int dwc3_core_init(struct dwc3 *dwc)
{
	u32			hwparams4 = dwc->hwparams.hwparams4;
	u32			reg;
	int			ret;

。。。。。。

	/* issue device SoftReset too */
    //软复位
	ret = dwc3_soft_reset(dwc);

   //初始化phy后如果是device设备再次软复位，host设置直接返回
	ret = dwc3_core_soft_reset(dwc);


	ret = dwc3_phy_setup(dwc); //PHY接口初始化

。。。

	dwc3_core_num_eps(dwc); //获取in,out端点数

	ret = dwc3_setup_scratch_buffers(dwc);
	if (ret)
		goto err1;

	/* Adjust Frame Length */
	dwc3_frame_length_adjustment(dwc);

	usb_phy_set_suspend(dwc->usb2_phy, 0);
	usb_phy_set_suspend(dwc->usb3_phy, 0);
	ret = phy_power_on(dwc->usb2_generic_phy);

	ret = phy_power_on(dwc->usb3_generic_phy); //phy 上电

	ret = dwc3_event_buffers_setup(dwc);
	if (ret) {
		dev_err(dwc->dev, "failed to setup event buffers\n");
		goto err4;
	}

	switch (dwc->dr_mode) { //设置dr模式
	case USB_DR_MODE_PERIPHERAL:
		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
		break;
	case USB_DR_MODE_HOST:
		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_HOST);
		break;
	case USB_DR_MODE_OTG:
		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
		break;
	default:
		dev_warn(dwc->dev, "Unsupported mode %d\n", dwc->dr_mode);
		break;
	}

。。。


	return ret;
}

 dwc3_core_init_mode分别根据不同的模式，调用不同的初始化函数：

static int dwc3_core_init_mode(struct dwc3 *dwc)
{
	struct device *dev = dwc->dev;
	int ret;

	switch (dwc->dr_mode) {
	case USB_DR_MODE_PERIPHERAL: //gadget模式
		ret = dwc3_gadget_init(dwc);
		break;
	case USB_DR_MODE_HOST: //主机模式
		ret = dwc3_host_init(dwc);
		break;
	case USB_DR_MODE_OTG: //otg模式
		ret = dwc3_host_init(dwc);
		ret = dwc3_gadget_init(dwc);

		break;

	}

	return 0;
}