好~ 现在万事俱备,只欠uhci硬件的注册了
现在谈一下uhci硬件的组成,uhci的硬件分为两个大的部分,主机控制器和根集线器,如下图
当提交uhci硬件的注册到pci总线后,经过一轮匹配,终于找到了uhci,进入到uhci_pci_driver->probe这个函数下
usb_hcd_pci_probe在/drivers/usb/host/uhci-hcd.c中
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int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
struct hc_driver *driver;
struct usb_hcd *hcd;
int retval;
//判断内核参数是否启用USB
if (usb_disabled())
return -ENODEV;
//判断匹配表是否存在,该表为uhci_pci_driver->id_table中的内容
if (!id)
return -EINVAL;
//取得匹配表中的私有结构,为uhci_driver
driver = (struct hc_driver *)id->driver_data;
//私有结构不存在则返回错误
if (!driver)
return -EINVAL;
//使能pci设备
if (pci_enable_device(dev) < 0)
return -ENODEV;
//设置电源为正常状态
dev->current_state = PCI_D0;
//检测是否有中断号
if (!dev->irq)
{
dev_err(&dev->dev,"Found HC with no IRQ. Check BIOS/PCI %s setup!\n",pci_name(dev));
retval = -ENODEV;
goto err1;
}
//创建usb_hcd结构
hcd = usb_create_hcd(driver, &dev->dev, pci_name(dev));
//检测创建是否成功
if (!hcd)
{
retval = -ENOMEM;
goto err1;
}
//检测是否需要映射I/O内存空间,EHCI和OHCI这两个主机控制器有自己的内存空间,访问的时候需要映射到计算机的内存空间中才能对设备进行操作,而UHCI没有自己的内存空间,对UHCI的操作是对IO端口的访问,所以UHCI需要分配IO端口空间
if (driver->flags & HCD_MEMORY)
{
/* EHCI, OHCI */
//这两个设备需要映射I/O内存空间
hcd->rsrc_start = pci_resource_start(dev, 0);
hcd->rsrc_len = pci_resource_len(dev, 0);
if (!request_mem_region(hcd->rsrc_start, hcd->rsrc_len,driver->description))
{
dev_dbg(&dev->dev, "controller already in use\n");
retval = -EBUSY;
goto err2;
}
hcd->regs = ioremap_nocache(hcd->rsrc_start, hcd->rsrc_len);
if (hcd->regs == NULL)
{
dev_dbg(&dev->dev, "error mapping memory\n");
retval = -EFAULT;
goto err3;
}
}
else
{
/* UHCI */
//UHCI需要映射I/O端口
int region;
for (region = 0; region < PCI_ROM_RESOURCE; region++)
{
//获取PCI I/O区域region号资源标记并判断是否为IO接口资源
if (!(pci_resource_flags(dev, region) & IORESOURCE_IO))
continue;
//获取PCI I/O区域refion的首地址
hcd->rsrc_start = pci_resource_start(dev, region);
//计算资源长度
hcd->rsrc_len = pci_resource_len(dev, region);
//申请映射I/O端口
if (request_region(hcd->rsrc_start, hcd->rsrc_len,driver->description))
break;
}
//没有IO接口资源则返回出错
if (region == PCI_ROM_RESOURCE)
{
dev_dbg(&dev->dev, "no i/o regions available\n");
retval = -EBUSY;
goto err1;
}
}
//开始竞争总线
pci_set_master(dev);
//PCI层初始化完毕,进入Host Controller的初始化
retval = usb_add_hcd(hcd, dev->irq, IRQF_DISABLED | IRQF_SHARED);
if (retval != 0)
goto err4;
return retval;
}
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现在看看usb_create_hcd,这个函数创建每个主机控制器必备的usb_hcd结构
usb_create_hcd在/drivers/usb/core/hcd.c中
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struct usb_hcd *usb_create_hcd (const struct hc_driver *driver,
struct device *dev, char *bus_name)
{
struct usb_hcd *hcd;
//申请空间,hcd_priv_size为动态的附加结构长度, 附加在usb_hcd的尾部
// 这段空间用于主机控制器的私有结构,uhci的私有结构为uhci_hcd,用于描述uhci的属性
hcd = kzalloc(sizeof(*hcd) + driver->hcd_priv_size, GFP_KERNEL);
if (!hcd)
{
dev_dbg (dev, "hcd alloc failed\n");
return NULL;
}
//连接usb_hcd到pci_device
dev_set_drvdata(dev, hcd);
//初始化引用计数器
kref_init(&hcd->kref);
//初始化usb总线
usb_bus_init(&hcd->self);
//连接pci_device到usb_hcd的usb_bus上
hcd->self.controller = dev;
//设置usb_bus名称
hcd->self.bus_name = bus_name;
//设置是否使用dma
hcd->self.uses_dma = (dev->dma_mask != NULL);
//hcd->rh_timer的注释为drives root-hub polling
//字面意思是一个用于记时执行某函数的结构,例如5ms后执行指定函数
init_timer(&hcd->rh_timer);
hcd->rh_timer.function = rh_timer_func;
hcd->rh_timer.data = (unsigned long) hcd;
#ifdef CONFIG_PM
INIT_WORK(&hcd->wakeup_work, hcd_resume_work);
#endif
//连接hc_driver到usb_hcd上
hcd->driver = driver;
//设置设备名称
hcd->product_desc = (driver->product_desc) ? driver->product_desc : "USB Host Controller";
return hcd;
}
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分配并初始化好的usb_hcd结构如下,其中bus_name和uses_dma因为我还没看pci,所以这两个值不清楚,不过在uhci中dma是肯定会用到的
为什么会有个白框呢?还记得hcd = kzalloc(sizeof(*hcd) + driver->hcd_priv_size, GFP_KERNEL);
这句么,这个白框就是所申请的hcd_priv_size大小的空间,里面是什么我们还不知道,所以是一片白的,等用到的时候我再把它画出来
hcd准备好之后,就要进入更深一个层次的初始化了, usb_add_hcd负责这部分的工作
usb_add_hcd在/drivers/usb/core/hcd.c中
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int usb_add_hcd(struct usb_hcd *hcd,
unsigned int irqnum, unsigned long irqflags)
{
int retval;
struct usb_device *rhdev;
dev_info(hcd->self.controller, "%s\n", hcd->product_desc);
//设置默认的批准标志,为无线设备设0,否则设1
hcd->authorized_default = hcd->wireless? 0 : 1;
//设置主机控制器的状态为硬件可用
set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
/* HC is in reset state, but accessible. Now do the one-time init,
* bottom up so that hcds can customize the root hubs before khubd
* starts talking to them. (Note, bus id is assigned early too.)
*/
//初始化缓冲池
if ((retval = hcd_buffer_create(hcd)) != 0)
{
dev_dbg(hcd->self.controller, "pool alloc failed\n");
return retval;
}
//注册USB host controller
if ((retval = usb_register_bus(&hcd->self)) < 0)
goto err_register_bus;
//分配一个设备描述符用于根设备
if ((rhdev = usb_alloc_dev(NULL, &hcd->self, 0)) == NULL)
{
dev_err(hcd->self.controller, "unable to allocate root hub\n");
retval = -ENOMEM;
goto err_allocate_root_hub;
}
//设置最高速度
rhdev->speed = (hcd->driver->flags & HCD_USB2) ? USB_SPEED_HIGH : USB_SPEED_FULL;
//连接根集线设备到usb_bus上
hcd->self.root_hub = rhdev;
/* wakeup flag init defaults to "everything works" for root hubs,
* but drivers can override it in reset() if needed, along with
* recording the overall controller's system wakeup capability.
*/
//打开ROOT HUB的WAKEUP
device_init_wakeup(&rhdev->dev, 1);
/* "reset" is misnamed; its role is now one-time init. the controller
* should already have been reset (and boot firmware kicked off etc).
*/
//复位设备
if (hcd->driver->reset && (retval = hcd->driver->reset(hcd)) < 0)
{
dev_err(hcd->self.controller, "can't setup\n");
goto err_hcd_driver_setup;
}
/* NOTE: root hub and controller capabilities may not be the same */
if (device_can_wakeup(hcd->self.controller) && device_can_wakeup(&hcd->self.root_hub->dev))
dev_dbg(hcd->self.controller, "supports USB remote wakeup\n");
/* enable irqs just before we start the controller */
//判断是否有中断处理函数
if (hcd->driver->irq)
{
/* IRQF_DISABLED doesn't work as advertised when used together
* with IRQF_SHARED. As usb_hcd_irq() will always disable
* interrupts we can remove it here.
*/
irqflags &= ~IRQF_DISABLED;
//设置中断描述串
snprintf(hcd->irq_descr, sizeof(hcd->irq_descr), "%s:usb%d",
hcd->driver->description, hcd->self.busnum);
//安装中断处理函数
if ((retval = request_irq(irqnum, &usb_hcd_irq, irqflags,hcd->irq_descr, hcd)) != 0)
{
dev_err(hcd->self.controller,"request interrupt %d failed\n", irqnum);
goto err_request_irq;
}
hcd->irq = irqnum;
dev_info(hcd->self.controller, "irq %d, %s 0x%08llx\n", irqnum,
(hcd->driver->flags & HCD_MEMORY) ?"io mem" : "io base",
(unsigned long long)hcd->rsrc_start);
}
else
{
hcd->irq = -1;
if (hcd->rsrc_start)
dev_info(hcd->self.controller, "%s 0x%08llx\n",
(hcd->driver->flags & HCD_MEMORY) ?
"io mem" : "io base",
(unsigned long long)hcd->rsrc_start);
}
//启动设备
if ((retval = hcd->driver->start(hcd)) < 0)
{
dev_err(hcd->self.controller, "startup error %d\n", retval);
goto err_hcd_driver_start;
}
/* starting here, usbcore will pay attention to this root hub */
rhdev->bus_mA = min(500u, hcd->power_budget);
//注册根集线器
if ((retval = register_root_hub(hcd)) != 0)
goto err_register_root_hub;
//添加设备属性文件
retval = sysfs_create_group(&rhdev->dev.kobj, &usb_bus_attr_group);
if (retval < 0)
{
printk(KERN_ERR "Cannot register USB bus sysfs attributes: %d\n",
retval);
goto error_create_attr_group;
}
if (hcd->uses_new_polling && hcd->poll_rh)
//查询设备状态
usb_hcd_poll_rh_status(hcd);
return retval;
}
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首先是hcd_buffer_create,这个函数用于初始化主机控制器的dma内存池,为以后的dma内存分配做准备
hcd_buffer_create在/drivers/usb/core/buffer.c中
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int hcd_buffer_create(struct usb_hcd *hcd)
{
char name[16];
int i, size;
if (!hcd->self.controller->dma_mask && !(hcd->driver->flags & HCD_LOCAL_MEM))
return 0;
//创建4个不同大小的缓冲池,为不同大小的dma请求分配合适的dma内存
for (i = 0; i < HCD_BUFFER_POOLS; i++)
{
size = pool_max[i];
if (!size)
continue;
snprintf(name, sizeof name, "buffer-%d", size);
//创建DMA内存池,此时还没有真正分配空间
hcd->pool[i] = dma_pool_create(name, hcd->self.controller,size, size, 0);
if (!hcd->pool [i])
{
hcd_buffer_destroy(hcd);
return -ENOMEM;
}
}
return 0;
}
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usb_register_bus用于注册uhci自己的总线,管理连接到uhci的所有设备
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static int usb_register_bus(struct usb_bus *bus)
{
int result = -E2BIG;
int busnum;
mutex_lock(&usb_bus_list_lock);
//在usbmap位图中寻找未占用的位
busnum = find_next_zero_bit (busmap.busmap, USB_MAXBUS, 1);
//大于限制则返回错误
if (busnum >= USB_MAXBUS)
{
printk (KERN_ERR "%s: too many buses\n", usbcore_name);
goto error_find_busnum;
}
//置相应位为已经使用
set_bit (busnum, busmap.busmap);
//设置uhci总线的地址号
bus->busnum = busnum;
//创建一个usb_host%目录,用于表达该设备为主机控制器
bus->dev = device_create_drvdata(usb_host_class, bus->controller,
MKDEV(0, 0), bus,"usb_host%d", busnum);
result = PTR_ERR(bus->dev);
if (IS_ERR(bus->dev))
goto error_create_class_dev;
/* Add it to the local list of buses */
//添加到usb_bus_list的链表中
list_add (&bus->bus_list, &usb_bus_list);
mutex_unlock(&usb_bus_list_lock);
//新型的总线通知机制,我还没研究,放着等我弄懂先吧
usb_notify_add_bus(bus);
dev_info (bus->controller, "new USB bus registered, assigned bus "
"number %d\n", bus->busnum);
return 0;
}
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这个函数执行完后的结构图如下
然后到usb_alloc_dev,这个函数负责分配一个usb设备数据结构,在这里,这个usb数据结构用于描述主机控制器的根集线器,这个根集线器也是usb设备的一种
usb_alloc_dev在/drivers/usb/core/usb.c中
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struct usb_device *usb_alloc_dev(struct usb_device *parent,
struct usb_bus *bus, unsigned port1)
{
struct usb_device *dev;
//取得设备所连接的主机控制器结构
struct usb_hcd *usb_hcd = container_of(bus, struct usb_hcd, self);
unsigned root_hub = 0;
//分配usb_device结构
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return NULL;
//增加主机控制器的设备计数器
if (!usb_get_hcd(bus_to_hcd(bus)))
{
kfree(dev);
return NULL;
}
//初始化设备
device_initialize(&dev->dev);
//设置所属总线类型,这里是重点,为什么匹配的时候不是匹配pci总线或者其它总线,因为在这里设置了这个设备属于usb总线
dev->dev.bus = &usb_bus_type;
//设置设备自身类型,这里也是重点,这里设置了设备的类型,是设备还是接口,对于usb驱动来说分两类,设备驱动和接口驱动, usb_generic_driver为usb设备驱动,hub为usb接口驱动
dev->dev.type = &usb_device_type;
//设置属性组,也就是目录下的描述文件
dev->dev.groups = usb_device_groups;
//设置是否使用dma
dev->dev.dma_mask = bus->controller->dma_mask;
set_dev_node(&dev->dev, dev_to_node(bus->controller));
//设置设备状态为连接
dev->state = USB_STATE_ATTACHED;
atomic_set(&dev->urbnum, 0)
INIT_LIST_HEAD(&dev->ep0.urb_list);
//初始化端点0
dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
/* ep0 maxpacket comes later, from device descriptor */
usb_enable_endpoint(dev, &dev->ep0);
//设置URB发送允许位
dev->can_submit = 1;
/* Save readable and stable topology id, distinguishing devices
* by location for diagnostics, tools, driver model, etc. The
* string is a path along hub ports, from the root. Each device's
* dev->devpath will be stable until USB is re-cabled, and hubs
* are often labeled with these port numbers. The bus_id isn't
* as stable: bus->busnum changes easily from modprobe order,
* cardbus or pci hotplugging, and so on.
*/
//检测是否为根集线器,分配不同的名字
if (unlikely(!parent))
{
//设置设备的层次为0
dev->devpath[0] = '0';
//设置父设备,这是根集线器,没有父设备,所以为NULL
dev->dev.parent = bus->controller;
sprintf(&dev->dev.bus_id[0], "usb%d", bus->busnum);
root_hub = 1;
}
else
{
/* match any labeling on the hubs; it's one-based */
if (parent->devpath[0] == '0')
snprintf(dev->devpath, sizeof dev->devpath,"%d", port1);
else
snprintf(dev->devpath, sizeof dev->devpath,"%s.%d", parent->devpath, port1);
dev->dev.parent = &parent->dev;
sprintf(&dev->dev.bus_id[0], "%d-%s",bus->busnum, dev->devpath);
/* hub driver sets up TT records */
}
//设置usb设备的节点号
dev->portnum = port1;
//设置usb设备的usb总线
dev->bus = bus;
//设置上层hub
dev->parent = parent;
INIT_LIST_HEAD(&dev->filelist);
//这部分为电源管理机制,我们不关心这部分内容
#ifdef CONFIG_PM
mutex_init(&dev->pm_mutex);
INIT_DELAYED_WORK(&dev->autosuspend, usb_autosuspend_work);
dev->autosuspend_delay = usb_autosuspend_delay * HZ;
dev->connect_time = jiffies;
dev->active_duration = -jiffies;
#endif
//检测是否为根集线器,这里为根集线器
if (root_hub) /* Root hub always ok [and always wired] */
//设置设备的批准标志为1
dev->authorized = 1;
else
{
dev->authorized = usb_hcd->authorized_default;
dev->wusb = usb_bus_is_wusb(bus)? 1 : 0;
}
return dev;
}
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执行完后的结构图如下
现在到hcd->driver->reset,这个函数为uhci_init
uhci_init在/drivers/usb/host/uhci-hcd.c中
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static int uhci_init(struct usb_hcd *hcd)
{
//这里解开白框的秘密了,原来是一个uhci_hcd结构,如果大家仔细的话,其实这个结构很早就出现了,在uhci_driver中,hcd_priv_size = sizeof(struct uhci_hcd), hcd_priv_size的值正是uhci_hcd的大小
struct uhci_hcd *uhci = hcd_to_uhci(hcd);
int port;
//取得IO端口资源区长度
unsigned io_size = (unsigned) hcd->rsrc_len;
//取得IO端口资源区起始地址
uhci->io_addr = (unsigned long) hcd->rsrc_start;
/* The UHCI spec says devices must have 2 ports, and goes on to say
* they may have more but gives no way to determine how many there
* are. However according to the UHCI spec, Bit 7 of the port
* status and control register is always set to 1. So we try to
* use this to our advantage. Another common failure mode when
* a nonexistent register is addressed is to return all ones, so
* we test for that also.
*/
//判断根集线器有几个端口
for (port = 0; port < (io_size - USBPORTSC1) / 2; port++)
{
unsigned int portstatus;
//inw - 读IO端口
portstatus = inw(uhci->io_addr + USBPORTSC1 + (port * 2));
//第7位不为1或者全为1则说明端口寄存器,判断完毕
if (!(portstatus & 0x0080) || portstatus == 0xffff)
break;
}
if (debug)
dev_info(uhci_dev(uhci), "detected %d ports\n", port);
/* Anything greater than 7 is weird so we'll ignore it. */
//多于7个端口则强制设置为2个
if (port > UHCI_RH_MAXCHILD)
{
dev_info(uhci_dev(uhci), "port count misdetected? ""forcing to 2 ports\n");
port = 2;
}
//记录端口数
uhci->rh_numports = port;
/* Kick BIOS off this hardware and reset if the controller
* isn't already safely quiescent.
*/
//判断UHCI是否需要重置
check_and_reset_hc(uhci);
return 0;
}
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