dwc3控制器是怎么处理otg-编程知识

概念

在OTG中，初始主机设备称为A设备，外设称为B设备。可用电缆的连接方式来决定初始角色。两用设备使用新型Mini-AB插座，从而使Mini-A插头、Mini-B插头和Mini-AB插座增添了第5个引脚（ID），以用于识别不同的电缆端点。Mini-A插头中的ID引脚接地，Mini-B插头中的ID引脚浮空。当OTG设备检测到接地的ID引脚时，表示默认的是A设备（主机），而检测到ID引脚浮空的设备则认为是B设备（外设）。系统一旦连接后，OTG的角色还可以更换，以采用新的HNP协议。而SRP允许B设备请求A设备打开VBUS电源并启动一次对话。

设备树

我们直接看支持otg的dwc3是怎么处理otg的，从设备开始看驱动，usb3_0的这个节点一般就是厂商自己定义的，主要包括中断，一般用于vbus检测，usb的插拔情况；dwc3_0这个子节点就是通用的dwc3核心，主要包括中断，一般用于id脚的检测，来判断当前是设备还是主机；如果dr_mode设置了模式，就会用固定的模式去初始化控制器

usb3phy: usb3phy@c0030000 {compatible = "usb3-phy";reg = <0xc0030000 0x1000>;clocks = <&soc_clocks CLK_USB>;clock-names = "usb_clk";status = "disabled";
};
usb3_0: usb3-0 {compatible = "arch,dwc3";#address-cells = <1>;#size-cells = <1>;ranges;interrupts = <53>;clocks = <&soc_clocks CLK_USB>;clock-names = "usb_clk";status = "disabled";usb_dwc3_0: dwc31@c0000000 {compatible = "snps,dwc3";reg = <0xc0000000 0x11000>;interrupts = <44>;usb-phy = <&usb3phy>;maximum-speed = "super-speed";dr_mode = "peripheral";phy_type = "utmi";lpm-qos = <PM_QOS_CPUIDLE_BLOCK_AXI>;snps,dis_u3_susphy_quirk;/* allow-suspend; */status = "okay";};
};

驱动框架

设备树跟驱动match后，会执行dwc3_probe；主要是一些初始化操作，如果设置了dr_mode为peripheral，就调用dwc_gadget_init去初始化设备控制器；dr_mode为host，就调用dwc3_host_init去初始化为主机控制器；如果dr_mode为otg，就根据id的情况去初始化为主机或设备

dwc3_probedwc3_get_dr_modedwc3_core_initdwc3_debugfs_initdwc3_core_init_mode//根据模式进入一种dwc3_gadget_initdwc->gadget.ops	= &dwc3_gadget_ops;//初始化设备控制器操作函数dwc3_gadget_init_endpoints(dwc, dwc->num_eps);dep->endpoint.ops = &dwc3_gadget_ep_ops;usb_add_gadget_udc(dwc->dev, &dwc->gadget);//注册设备控制器dwc3_host_initxhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);platform_device_add(xhci)//初始化xhci平台设备；用于匹配到usb_xhci_driver-----其probe来初始化主机控制器，填充操作函数xhci_hc_driver，并注册主机控制器dwc3_drd_initrequest_threaded_irq(dwc->otg_irq, dwc3_otg_irq,dwc3_otg_thread_irq,IRQF_SHARED, "dwc3-otg", dwc);dwc3_set_mode__dwc3_set_modedwc3_otg_update//根据模式进入一种dwc3_host_initdwc3_gadget_init

主机控制器的初始化

上面的代码分析到：dwc3_host_init会通过 platform_device_add(xhci)//初始化xhci平台设备；用于匹配到usb_xhci_driver-----其probe来初始化主机控制器，填充操作函数xhci_hc_driver，并注册主机控制器

drivers/usb/host/xhci-plat.c中的usb_xhci_driver通过name(xhci-hcd)匹配上;xhci_init_driver将通用的xhci_hc_driver，赋值给xhci_plat_hc_driver；过程跟ehci_init_driver一致

static int xhci_plat_probe(struct platform_device *pdev)
{const struct xhci_plat_priv *priv_match;const struct hc_driver	*driver;struct device		*sysdev, *tmpdev;struct xhci_hcd		*xhci;struct resource         *res;struct usb_hcd		*hcd;int			ret;int			irq;struct xhci_plat_priv	*priv = NULL;if (usb_disabled())return -ENODEV;driver = &xhci_plat_hc_driver;irq = platform_get_irq(pdev, 0);if (irq < 0)return irq;/** sysdev must point to a device that is known to the system firmware* or PCI hardware. We handle these three cases here:* 1. xhci_plat comes from firmware* 2. xhci_plat is child of a device from firmware (dwc3-plat)* 3. xhci_plat is grandchild of a pci device (dwc3-pci)*/for (sysdev = &pdev->dev; sysdev; sysdev = sysdev->parent) {if (is_of_node(sysdev->fwnode) ||is_acpi_device_node(sysdev->fwnode))break;
#ifdef CONFIG_PCIelse if (sysdev->bus == &pci_bus_type)break;
#endif}if (!sysdev)sysdev = &pdev->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));elseret = dma_set_mask_and_coherent(sysdev, 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(sysdev, 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, sysdev, &pdev->dev,dev_name(&pdev->dev), NULL);if (!hcd) {ret = -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);xhci = hcd_to_xhci(hcd);/** Not all platforms have clks so it is not an error if the* clock do not exist.*/xhci->reg_clk = devm_clk_get_optional(&pdev->dev, "reg");if (IS_ERR(xhci->reg_clk)) {ret = PTR_ERR(xhci->reg_clk);goto put_hcd;}ret = clk_prepare_enable(xhci->reg_clk);if (ret)goto put_hcd;xhci->clk = devm_clk_get_optional(&pdev->dev, NULL);if (IS_ERR(xhci->clk)) {ret = PTR_ERR(xhci->clk);goto disable_reg_clk;}ret = clk_prepare_enable(xhci->clk);if (ret)goto disable_reg_clk;priv_match = of_device_get_match_data(&pdev->dev);if (priv_match) {priv = hcd_to_xhci_priv(hcd);/* Just copy data for now */if (priv_match)*priv = *priv_match;}device_wakeup_enable(hcd->self.controller);xhci->main_hcd = hcd;xhci->shared_hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,dev_name(&pdev->dev), hcd);if (!xhci->shared_hcd) {ret = -ENOMEM;goto disable_clk;}/* imod_interval is the interrupt moderation value in nanoseconds. */xhci->imod_interval = 40000;/* Iterate over all parent nodes for finding quirks */for (tmpdev = &pdev->dev; tmpdev; tmpdev = tmpdev->parent) {if (device_property_read_bool(tmpdev, "usb2-lpm-disable"))xhci->quirks |= XHCI_HW_LPM_DISABLE;if (device_property_read_bool(tmpdev, "usb3-lpm-capable"))xhci->quirks |= XHCI_LPM_SUPPORT;if (device_property_read_bool(tmpdev, "quirk-broken-port-ped"))xhci->quirks |= XHCI_BROKEN_PORT_PED;device_property_read_u32(tmpdev, "imod-interval-ns",&xhci->imod_interval);}hcd->usb_phy = devm_usb_get_phy_by_phandle(sysdev, "usb-phy", 0);if (IS_ERR(hcd->usb_phy)) {ret = PTR_ERR(hcd->usb_phy);if (ret == -EPROBE_DEFER)goto put_usb3_hcd;hcd->usb_phy = NULL;} else {ret = usb_phy_init(hcd->usb_phy);if (ret)goto put_usb3_hcd;}hcd->tpl_support = of_usb_host_tpl_support(sysdev->of_node);xhci->shared_hcd->tpl_support = hcd->tpl_support;if (priv) {ret = xhci_priv_plat_setup(hcd);if (ret)goto disable_usb_phy;}if ((xhci->quirks & XHCI_SKIP_PHY_INIT) || (priv && (priv->quirks & XHCI_SKIP_PHY_INIT)))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;
....
}
static struct platform_driver usb_xhci_driver = {.probe	= xhci_plat_probe,.remove	= xhci_plat_remove,.shutdown = usb_hcd_platform_shutdown,.driver	= {.name = "xhci-hcd",.pm = &xhci_plat_pm_ops,.of_match_table = of_match_ptr(usb_xhci_of_match),.acpi_match_table = ACPI_PTR(usb_xhci_acpi_match),},
};
MODULE_ALIAS("platform:xhci-hcd");static int __init xhci_plat_init(void)
{xhci_init_driver(&xhci_plat_hc_driver, &xhci_plat_overrides);return platform_driver_register(&usb_xhci_driver);
}
module_init(xhci_plat_init);static void __exit xhci_plat_exit(void)
{platform_driver_unregister(&usb_xhci_driver);
}
module_exit(xhci_plat_exit);

dwc3_core_init_mode

dwc3_core_init_mode根据设备树获得的模式，初始化控制器为对应模式，初始化控制器的操作函数：主机有主机的操作函数；设备有设备的操作函数

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:dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, false);phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_DEVICE);phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_DEVICE);ret = dwc3_gadget_init(dwc);if (ret) {if (ret != -EPROBE_DEFER)dev_err(dev, "failed to initialize gadget\n");return ret;}break;case USB_DR_MODE_HOST:dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, true);phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);ret = dwc3_host_init(dwc);if (ret) {if (ret != -EPROBE_DEFER)dev_err(dev, "failed to initialize host\n");return ret;}break;case USB_DR_MODE_OTG:INIT_WORK(&dwc->drd_work, __dwc3_set_mode);ret = dwc3_drd_init(dwc);if (ret) {if (ret != -EPROBE_DEFER)dev_err(dev, "failed to initialize dual-role\n");return ret;}break;default:dev_err(dev, "Unsupported mode of operation %d\n", dwc->dr_mode);return -EINVAL;}return 0;
}

OTG模式

注册中断

一般是通过id脚注册中断：use OTG block to get ID event

int dwc3_drd_init(struct dwc3 *dwc)
{int ret, irq;dwc->edev = dwc3_get_extcon(dwc);if (IS_ERR(dwc->edev))return PTR_ERR(dwc->edev);if (ROLE_SWITCH &&device_property_read_bool(dwc->dev, "usb-role-switch")) {ret = dwc3_setup_role_switch(dwc);if (ret < 0)return ret;} else if (dwc->edev) {dwc->edev_nb.notifier_call = dwc3_drd_notifier;ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,&dwc->edev_nb);if (ret < 0) {dev_err(dwc->dev, "couldn't register cable notifier\n");return ret;}dwc3_drd_update(dwc);} else {dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_OTG);dwc->current_dr_role = DWC3_GCTL_PRTCAP_OTG;/* use OTG block to get ID event */irq = dwc3_otg_get_irq(dwc);if (irq < 0)return irq;dwc->otg_irq = irq;/* disable all OTG IRQs */dwc3_otg_disable_events(dwc, DWC3_OTG_ALL_EVENTS);/* clear all events */dwc3_otg_clear_events(dwc);ret = request_threaded_irq(dwc->otg_irq, dwc3_otg_irq,dwc3_otg_thread_irq,IRQF_SHARED, "dwc3-otg", dwc);if (ret) {dev_err(dwc->dev, "failed to request irq #%d --> %d\n",dwc->otg_irq, ret);ret = -ENODEV;return ret;}dwc3_otg_init(dwc);dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);}return 0;
}

中断处理

根据id脚的状态,判断是做主机还是设备

static irqreturn_t dwc3_otg_irq(int irq, void *_dwc)
{u32 reg;struct dwc3 *dwc = _dwc;irqreturn_t ret = IRQ_NONE;reg = dwc3_readl(dwc->regs, DWC3_OEVT);if (reg) {/* ignore non OTG events, we can't disable them in OEVTEN */if (!(reg & DWC3_OTG_ALL_EVENTS)) {dwc3_writel(dwc->regs, DWC3_OEVT, reg);return IRQ_NONE;}if (dwc->current_otg_role == DWC3_OTG_ROLE_HOST &&!(reg & DWC3_OEVT_DEVICEMODE))dwc->otg_restart_host = 1;dwc3_writel(dwc->regs, DWC3_OEVT, reg);ret = IRQ_WAKE_THREAD;}return ret;
}

可以看作中断下半部，来通过dwc3_set_mode将控制器初始化为主机或者设备

static irqreturn_t dwc3_otg_thread_irq(int irq, void *_dwc)
{struct dwc3 *dwc = _dwc;spin_lock(&dwc->lock);if (dwc->otg_restart_host) {dwc3_otg_host_init(dwc);dwc->otg_restart_host = 0;}spin_unlock(&dwc->lock);dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);return IRQ_HANDLED;
}void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
{unsigned long flags;spin_lock_irqsave(&dwc->lock, flags);dwc->desired_dr_role = mode;spin_unlock_irqrestore(&dwc->lock, flags);queue_work(system_freezable_wq, &dwc->drd_work);
}

设置模式

模式设置的是设备或者主机，就直接调用dwc3_gadget_init或者dwc3_host_init初始化控制器；如果是otg模式，就要根据dwc3_otg_update去判断id脚的情况来更新为设备或者主机

static void __dwc3_set_mode(struct work_struct *work)
{struct dwc3 *dwc = work_to_dwc(work);unsigned long flags;int ret;u32 reg;if (dwc->dr_mode != USB_DR_MODE_OTG)return;if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG)dwc3_otg_update(dwc, 0);if (!dwc->desired_dr_role)return;if (dwc->desired_dr_role == dwc->current_dr_role)return;if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev)return;switch (dwc->current_dr_role) {case DWC3_GCTL_PRTCAP_HOST:dwc3_host_exit(dwc);break;case DWC3_GCTL_PRTCAP_DEVICE:dwc3_gadget_exit(dwc);dwc3_event_buffers_cleanup(dwc);break;case DWC3_GCTL_PRTCAP_OTG:dwc3_otg_exit(dwc);spin_lock_irqsave(&dwc->lock, flags);dwc->desired_otg_role = DWC3_OTG_ROLE_IDLE;spin_unlock_irqrestore(&dwc->lock, flags);dwc3_otg_update(dwc, 1);break;default:break;}spin_lock_irqsave(&dwc->lock, flags);dwc3_set_prtcap(dwc, dwc->desired_dr_role);spin_unlock_irqrestore(&dwc->lock, flags);switch (dwc->desired_dr_role) {case DWC3_GCTL_PRTCAP_HOST:ret = dwc3_host_init(dwc);if (ret) {dev_err(dwc->dev, "failed to initialize host\n");} else {if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, true);phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);if (dwc->dis_split_quirk) {reg = dwc3_readl(dwc->regs, DWC3_GUCTL3);reg |= DWC3_GUCTL3_SPLITDISABLE;dwc3_writel(dwc->regs, DWC3_GUCTL3, reg);dwc3_save_controller_regs(DWC3_GUCTL3, reg);}}break;case DWC3_GCTL_PRTCAP_DEVICE:dwc3_event_buffers_setup(dwc);if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, false);phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_DEVICE);phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_DEVICE);ret = dwc3_gadget_init(dwc);if (ret)dev_err(dwc->dev, "failed to initialize peripheral\n");break;case DWC3_GCTL_PRTCAP_OTG:dwc3_otg_init(dwc);dwc3_otg_update(dwc, 0);break;default:break;}
}

更新模式

ignore_idstatus为0，就回去读id相关寄存器，获取id脚的状态desired_otg_role；为高就是DWC3_OTG_ROLE_DEVICE，为低就是DWC3_OTG_ROLE_HOST；跟current_otg_role一样就返回，不一样就关掉当前的控制器，初始化为desired_otg_role的控制器模式

void dwc3_otg_update(struct dwc3 *dwc, bool ignore_idstatus)
{int ret;u32 reg;int id;unsigned long flags;if (dwc->dr_mode != USB_DR_MODE_OTG)return;/* don't do anything if debug user changed role to not OTG */if (dwc->current_dr_role != DWC3_GCTL_PRTCAP_OTG)return;if (!ignore_idstatus) {reg = dwc3_readl(dwc->regs, DWC3_OSTS);id = !!(reg & DWC3_OSTS_CONIDSTS);dwc->desired_otg_role = id ? DWC3_OTG_ROLE_DEVICE :DWC3_OTG_ROLE_HOST;}if (dwc->desired_otg_role == dwc->current_otg_role)return;switch (dwc->current_otg_role) {case DWC3_OTG_ROLE_HOST:dwc3_host_exit(dwc);spin_lock_irqsave(&dwc->lock, flags);dwc3_otg_host_exit(dwc);spin_unlock_irqrestore(&dwc->lock, flags);break;case DWC3_OTG_ROLE_DEVICE:dwc3_gadget_exit(dwc);spin_lock_irqsave(&dwc->lock, flags);dwc3_event_buffers_cleanup(dwc);dwc3_otg_device_exit(dwc);spin_unlock_irqrestore(&dwc->lock, flags);break;default:break;}spin_lock_irqsave(&dwc->lock, flags);dwc->current_otg_role = dwc->desired_otg_role;spin_unlock_irqrestore(&dwc->lock, flags);switch (dwc->desired_otg_role) {case DWC3_OTG_ROLE_HOST:spin_lock_irqsave(&dwc->lock, flags);dwc3_otgregs_init(dwc);dwc3_otg_host_init(dwc);spin_unlock_irqrestore(&dwc->lock, flags);ret = dwc3_host_init(dwc);if (ret) {dev_err(dwc->dev, "failed to initialize host\n");} else {if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, true);if (dwc->usb2_generic_phy)phy_set_mode(dwc->usb2_generic_phy,PHY_MODE_USB_HOST);}break;case DWC3_OTG_ROLE_DEVICE:spin_lock_irqsave(&dwc->lock, flags);dwc3_otgregs_init(dwc);dwc3_otg_device_init(dwc);dwc3_event_buffers_setup(dwc);spin_unlock_irqrestore(&dwc->lock, flags);if (dwc->usb2_phy)otg_set_vbus(dwc->usb2_phy->otg, false);if (dwc->usb2_generic_phy)phy_set_mode(dwc->usb2_generic_phy,PHY_MODE_USB_DEVICE);ret = dwc3_gadget_init(dwc);if (ret)dev_err(dwc->dev, "failed to initialize peripheral\n");break;default:break;}
}

debugfs

drivers/usb/dwc3/debugfs.c通过应用层写模式到属性文件中，也能直接切换模式

static ssize_t dwc3_mode_write(struct file *file,const char __user *ubuf, size_t count, loff_t *ppos)
{struct seq_file         *s = file->private_data;struct dwc3             *dwc = s->private;u32                     mode = 0;char                    buf[32];if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))return -EFAULT;if (!strncmp(buf, "host", 4))mode = DWC3_GCTL_PRTCAP_HOST;if (!strncmp(buf, "device", 6))mode = DWC3_GCTL_PRTCAP_DEVICE;if (!strncmp(buf, "otg", 3))mode = DWC3_GCTL_PRTCAP_OTG;dwc3_set_mode(dwc, mode);return count;
}