自娱自乐1之Linux UDC驱动（形式模板）

首先，我不是做驱动的开发人员。所以只能用自娱自乐来表示我的行为。

我不知道udc和gadget驱动是不是冷门的驱动，资料真是不多。我之前买了一本书，上面说到这些，就教你如何调试已写好的驱动。这样也可以写书，太坑了吧！我随便从网上搜搜都能写的比他好。难道现在的育人机构为了钱都变成了坑人机构。

我以前就希望把自己写过的驱动总结成一个模板，让人能直观的看出linux提供的接口要我们做什么甚至怎么做。虽然做这个比较难，但我还是成功的欺骗了自己，可以做到。

这是自娱自乐第一期，可能废话多了一点，请大家原谅。现在说这个模板。这个是一个未做实际应用的模板，只是编译通过，除了没实践，还缺少DMA和USB的请求类型处理样例。后期我会用它做一个驱动，不断的完善。现在这个应该在理论和实践之间的东西。

常用结构体(别人写的，不是linux-3.2.36，不过差不多)

========================================================USB UDC与gadget驱动=========================================================
/*
 *linux内核中usb设备侧驱动程序分为3个层次：UDC驱动、Gadget API和Gadget驱动程序，UDC驱动程序直接访问硬件usb控制器OHCI/EHCI/UHCI，作为usb设备和主机间的底层通信，向上层
 *提供与硬件相关操作的回调函数。当前Gadget API是对UDC驱动程序回调函数的简单包装。Gadget驱动程序具体控制系统作为usb设备时的相关功能的实现，使设备表现出“网络连接”、“打印机”
 *或“USB Mass Storage”等特性。
 *
 *    这里的USB设备控制器（UDC）驱动指作为其他USB主机控制器外设的USB硬件设备上底层硬件控制器的驱动，该硬件和驱动负责将USB设备依附于一个USB主机控制器上：比如当某运行linux的手机作为PC
 *的U盘时，手机的底层USB控制器行使USB设备控制器的功能，这时候运行在底层的是UDC驱动，而手机成为U盘，在UDC驱动之上仍然需要另一个驱动，对于USB大容量存储器为file storage驱动，这一
 *驱动称为gadget驱动（总之是一个运行linux的系统的usb接口作为另一个linux系统的设备）。usb设备驱动调用usb核心提供的API，因此具体驱动与SOC无关。同样，usb gadget驱动调用通用的gadget API
 *因此具体gadget驱动也变得与SOC无关。
 *UDC驱动和gadget驱动都位于内核的drivers/usb/gadget目录下，S3C2410对应的UDC驱动为s3c2410_udc.c。ether.c、f_serial.c、file_storage.c等文件实现了一些gadget驱动
 */
#include 

-----------------------------------------------------------struct usb_gadget------------------------------------------------------
struct usb_gadget {   //描述USB设备控制器
	/* readonly to gadget driver */                  //针对gadget驱动只读
	const struct usb_gadget_ops	*ops;                //访问硬件函数
	struct usb_ep			*ep0;                          //端点0，setup使用
	struct list_head		ep_list;	/* of usb_ep */    //其他端点列表
	enum usb_device_speed		speed;                   
	unsigned			is_dualspeed:1;
	unsigned			is_otg:1;
	unsigned			is_a_peripheral:1;
	unsigned			b_hnp_enable:1;                    //A-HOST使能了HNP支持
	unsigned			a_hnp_support:1;                   //A-HOST支持HNP
	unsigned			a_alt_hnp_support:1;
	const char			*name;
	struct device			dev;
};

------------------------------------------------------struct usb_gadget_ops-------------------------------------------------------
struct usb_gadget_ops {  //硬件操作函数
	int	(*get_frame)(struct usb_gadget *);
	int	(*wakeup)(struct usb_gadget *);
	int	(*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
	int	(*vbus_session) (struct usb_gadget *, int is_active);
	int	(*vbus_draw) (struct usb_gadget *, unsigned mA);
	int	(*pullup) (struct usb_gadget *, int is_on);
	int	(*ioctl)(struct usb_gadget *,
				unsigned code, unsigned long param);
};

-----------------------------------------------------struct usb_gadget_driver----------------------------------------------------
struct usb_gadget_driver {  //描述gadget驱动
	char			*function;                          //描述gadget功能的字符串
	enum usb_device_speed	speed;
	int			(*bind)(struct usb_gadget *);         //当驱动和gadget绑定时调用
	void			(*unbind)(struct usb_gadget *);
	int			(*setup)(struct usb_gadget *,         //处理硬件驱动未处理的端点0请求
					const struct usb_ctrlrequest *);
	void			(*disconnect)(struct usb_gadget *);
	void			(*suspend)(struct usb_gadget *);
	void			(*resume)(struct usb_gadget *);

	/* FIXME support safe rmmod */
	struct device_driver	driver;
};

-----------------------------------------------------struct usb_request----------------------------------------------------------
struct usb_request {  //表示一个传输请求的usb_request（与从机端看到的urb相似）
	void			*buf;
	unsigned		length;
	dma_addr_t		dma;

	unsigned		no_interrupt:1;
	unsigned		zero:1;
	unsigned		short_not_ok:1;

	void			(*complete)(struct usb_ep *ep,
					struct usb_request *req);
	void			*context;
	struct list_head	list;

	int			status;
	unsigned		actual;
};

----------------------------------------------------------struct usb_ep---------------------------------------------------------
struct usb_ep {   //描述一个端点
	void			*driver_data;

	const char		*name;
	const struct usb_ep_ops	*ops;
	struct list_head	ep_list;
	unsigned		maxpacket:16;
};

------------------------------------------------------struct usb_ep_ops---------------------------------------------------------
struct usb_ep_ops {   //描述端点操作
	int (*enable) (struct usb_ep *ep,
		const struct usb_endpoint_descriptor *desc);
	int (*disable) (struct usb_ep *ep);

	struct usb_request *(*alloc_request) (struct usb_ep *ep,
		gfp_t gfp_flags);
	void (*free_request) (struct usb_ep *ep, struct usb_request *req);

	int (*queue) (struct usb_ep *ep, struct usb_request *req,
		gfp_t gfp_flags);
	int (*dequeue) (struct usb_ep *ep, struct usb_request *req);

	int (*set_halt) (struct usb_ep *ep, int value);
	int (*set_wedge) (struct usb_ep *ep);

	int (*fifo_status) (struct usb_ep *ep);
	void (*fifo_flush) (struct usb_ep *ep);
};
--------------------------------------------------------------------------------------------------------------------------------
/*
 *UDC和gadget驱动围绕上述数据结构及其成员函数而展开。 
 *在具体的UDC驱动中，需要封装usb_gadget和每个端点usb_ep，实现端点usb_ep_ops，完成usb_request。另外usb_gadget_register_driver和usb_gadget_unregister_driver这两个API需要由UDC
 *驱动提供，gadget驱动会调用它们。
 */
int usb_gadget_register_driver(struct usb_gadget_driver *driver); //注册，在加载模块中调用，该函数中会调用driver->bind()函数，将usb_gadget_driver与具体的gadget绑定
int usb_gadget_unregister_driver(struct usb_gadget_driver *driver); //注销，在卸载模块中调用，告诉UDC驱动不再投入工作，如果UDC正在和USB主机连接，会先调用driver->disconnect()
                                                                    //函数，而后会调用unbind()函数
//在linux/usb/gadget.h中，封装了一些常用的API：                                                                    
int usb_ep_enable(struct usb_ep *ep,const struct usb_endpoint_descriptor *desc);  //使能端点 ，该函数会调用struct usb_ep_ops->enable()
int usb_ep_disable(struct usb_ep *ep);  //禁止端点,该函数会调用struct usb_ep_ops->disable()

struct usb_request *usb_ep_alloc_request(struct usb_ep *ep,gfp_t gfp_flags);    //分配一个依附于某端点的 usb_request,该函数会调用struct usb_ep_ops->usb_request()
void usb_ep_free_request(struct usb_ep *ep,struct usb_request *req);            //释放一个依附于某端点的 usb_request,该函数会调用struct usb_ep_ops->free_request()

int usb_ep_queue(struct usb_ep *ep, struct usb_request *req, gfp_t gfp_flags);//提交usb_request,该函数告诉UDC完成usb_request（读写buffer），当请求被完成后，该请求对应的completion函数会被调用，
                                                                              //该函数会调用struct usb_ep_ops->queue()，该函数告诉UDC完成usb_request(读写buffer)，当请求完成后，该请求对应的completion函数会被调用
int usb_ep_dequeue(struct usb_ep *ep, struct usb_request *req);  //取消usb_request,该函数会调用struct usb_ep_ops->dequeue()

端点FIFO管理：
int usb_ep_fifo_status(struct usb_ep *ep);  //该函数会调用truct usb_ep_ops->fifo_status返回目前FIFO中的字节数
void usb_ep_fifo_flush(struct usb_ep *ep);  //该函数会调用truct usb_ep_ops->fifo_flush,以flush（冲洗）掉FIFO中的数据

int usb_gadget_frame_number(struct usb_gadget *gadget); //它调用gadget->ops->get_frame(gadget)返回目前的帧号

/*
 *S3C2410的UDC驱动在 /driver/usb/gadget/s3c2410_udc.c
 */
/-----------------------------------------------------------------------------------------------------------------------------/

看请求队列的处理

struct xxxxx_request

{

    structlist_head        queue;       /* ep'srequests */

    structusb_request        req;       //对应主机端看到的urb

};

struct xxxxx_ep

{

    struct usb_ep ep; //描述一个端点

   struct list_head queue;

   …

}

 

    /*device/ep0 records init */

    INIT_LIST_HEAD(&dev->gadget.ep_list);

    INIT_LIST_HEAD(&dev->gadget.ep0->ep_list);

   

…

/* basic endpoint recordsinit */

    for(i = 0; i < XXXXX_ENDPOINTS; i++) {

        structxxxxx_ep *ep = &dev->ep[i];

 

        if(i != 0)//除了ep0

            list_add_tail(&ep->ep.ep_list, &dev->gadget.ep_list);

        …

        INIT_LIST_HEAD(&ep->queue);

 }

ep0就用gadget里面的，这个在上层的gadget驱动才能看到。Udc只要这样做就可以了

 

gadget驱动会调用xxxxx_udc_queue把请求插入ep->queue

udc在端点中断时会从对应的queue取出处理，我的模板没体现这点。

下面说udc驱动大概包涵哪些。

1.       struct usb_ep_ops

2.       struct usb_gadget_ops xxxxx_ops

3.       有一个中断来处理对应的事件，请求一般包涵在次。（目前的模板没有体现）。

事实上现在的模板就是告诉你上面两个要实现什么，及怎么实现。代码中有详细解释。我不多说了。

.H

/***********************************
 Copyright(C), 2013 LDP
 FileName:  xxxxx_udc.h
 Author:    wwxxxxll
 Date:          
 Description:  
 History:       
 Author       Date            Desc
************************************/
#ifndef __XXXXX_UDC_H__
#define __XXXXX_UDC_H__
/*************配置选项**************/
#define XXXXX_DEBUG_FS  //使用debugfs

//struct usb_ep_ops
#define XXXXX_NEWSTYLE  //使用udc_start
#define XXXXX_SETWEDHE  //实现set_weght方法
#define XXXXX_FIFO_STATUS //支持fifo_status方法
#define XXXXX_FIFO_FLUSH //支持fifo_flush方法

//struct usb_gadget_ops
#define XXXXX_XXXXX_GET_FRAME //支持get_frame
#define XXXXX_WAKEUP //支持wakeup功能
#define XXXXX_SELFPOWERED //selfpowered支持
#define XXXXX_VBUS_SESSION //vbus连接控制支持
#define XXXXXX_PULLUP //usb连接控制支持

#define XXXXX_HAVE_CLK  //有专用的CLK
#ifdef XXXXX_HAVE_CLK
#define CLK_DELAY_TIME 10 //ms
#endif

#define XXXXX_USE_IRQ

//端口信息
#define XXXXX_ENDPOINTS 2 //端口数
#define EP0_FIFO_SIZE 8
#define EP1_FIFO_SIZE 64
#define EP1_ADDRESS 1
#define EP1_ATTR USB_ENDPOINT_XFER_BULK
#define XXXXX_EP_FILO_SIZE 128
/***********************************/

/*************寄存器定义************/

/***********************************/


struct xxxxx_ep 
{
    struct usb_ep ep; //描述一个端点
    struct list_head queue;
    struct xxxxx_udc *dev;
    const struct usb_endpoint_descriptor *desc;

    unsigned char fifosize;
    unsigned char bEndpointAddress;
    unsigned char bmAttributes;

    u16 fifo_size;
    u8 num;

    unsigned stopped :1;//维护一个端口停止标志

#ifdef XXXXX_SETWEDHE
    unsigned wedged :1;
#endif
};

#define to_xxxxx_ep(ep_p) container_of(ep_p, struct xxxxx_ep, ep)

struct xxxxx_request 
{
    struct list_head        queue;        /* ep's requests */
    struct usb_request        req;        //对应主机端看到的urb
};

#define to_xxxxx_req(req_p) container_of(req_p, struct xxxxx_request, req)

//根据实际要求定义，这个不能当做模板，主要是便于软件管理
//一般有下面几个，有的驱动不用这些定义去管理
enum ep0state {
    EP0_IDLE,
    EP0_IN, 
    EP0_OUT,    
    EP0_STALL,        
};
    
struct xxxxx_udc 
{
    spinlock_t lock;

    void __iomem *virl_addr;
    u32 phy_addr;
    u32 reg_size;

    struct usb_gadget gadget;
    struct usb_gadget_driver *driver;

    enum ep0state ep0state;
    struct xxxxx_ep ep[XXXXX_ENDPOINTS];
    struct xxxxx_request fifo_req;

#ifdef XXXXX_DEBUG_FS
    struct dentry *debug_info;
#endif 

#ifdef XXXXX_HAVE_CLK
    struct clk *xxxxx_clk;
#endif

#ifdef XXXXX_USE_IRQ
    unsigned int irq_num;
#endif

    u16    devstatus;
};

#define to_xxxxx_udc(gadget_p) container_of(gadget_p, struct xxxxx_udc, gadget)

#endif//__XXXXX_UDC_H__

.c

/***********************************
 Copyright(C), 2013 LDP
 FileName:  xxxxx_udc.c
 Author:    wwxxxxll
 Date:          
 Description: linux-3.2-36
 History:       
 Author       Date            Desc
************************************/

#include //MODULE_*
#include //printk
#include //kzalloc() kfree()
#include //struct usb_gadget等
#include //struct clk
#include //platform
#include 
#include 
#include 

#include 
#include //ioremap

#include "xxxxx_udc.h"

#ifdef XXXXX_DEBUG_FS
#include 
#include //seq_printf seq_read
#endif

#define DRIVER_DESC    "XXXXX USB Device Controller Gadget"
#define DRIVER_VERSION    "2013"
#define DRIVER_AUTHOR    "wwxxxxll"

static const char        gadget_name[] = "xxxxx_udc";
static const char        driver_desc[] = DRIVER_DESC;



//根据实际情况修改
static const char ep0name[] = "ep0";
static const char * const ep_name[] = {
    ep0name,
    "ep1",
};

#ifdef XXXXX_DEBUG_FS
static struct dentry *xxxxx_udc_debugfs_root;

static int xxxxx_udc_debugfs_seq_show(struct seq_file *m, void *p)
{
    seq_printf(m, "My name is %s\n", gadget_name);

    return 0;
}

static int xxxxx_udc_debugfs_fops_open(struct inode *inode,
                     struct file *file)
{
    return single_open(file, xxxxx_udc_debugfs_seq_show, NULL);
}

static const struct file_operations xxxxx_udc_debugfs_fops = 
{
    .open        = xxxxx_udc_debugfs_fops_open,
    .read        = seq_read,
    .llseek        = seq_lseek,
    .release    = single_release,
    .owner        = THIS_MODULE,
};
#endif

/***********************hardware_handler************************/
static void xxxxx_usb_reset(struct xxxxx_udc *dev)
{
    //硬件操作
}

//udc的这个中断，真是包罗万象，各硬件差别比较大
//简单一点说，就是清楚中断标致位，再根据中断标志位对应处理
//实际要复杂的多，如果是ep0，还会从fifo中取得usb_ctrlrequest
//进行对应的处理，我们在实现具体的实现时再说吧
static irqreturn_t xxxxx_udc_irq(int dummy, void *_dev)
{
    return IRQ_HANDLED;
}
/***************************************************************/

/***********************queue***********************************/
//对于usb请求，一般都要维护一个list去管理请求

//端点list初始化，存入gadget里
static void xxxxx_usb_reinit(struct xxxxx_udc *dev)
{
    u32 i;

    /* device/ep0 records init */
    INIT_LIST_HEAD (&dev->gadget.ep_list);
    dev->gadget.ep0 = &dev->ep[0].ep;//ep0单独存放
    dev->gadget.speed = USB_SPEED_UNKNOWN;
    dev->ep0state = EP0_IDLE;
    INIT_LIST_HEAD (&dev->gadget.ep0->ep_list);

    for (i = 0; i < XXXXX_ENDPOINTS; i++) {
        struct xxxxx_ep *ep = &dev->ep[i];

        if (i != 0)
            list_add_tail (&ep->ep.ep_list, &dev->gadget.ep_list);

        ep->dev = dev;
        ep->desc = NULL;
        ep->stopped = 0;
        INIT_LIST_HEAD (&ep->queue);
    }
}

static void xxxxx_udc_done(struct xxxxx_ep *ep, struct xxxxx_request *req, int status)
{
    struct xxxxx_udc *dev;
    unsigned stopped = ep->stopped;

    list_del_init(&req->queue);

    if (likely (req->req.status == -EINPROGRESS))//正在进行中
        req->req.status = status;
    else
        status = req->req.status;

    dev = ep->dev;

    /* don't modify queue heads during completion callback */
    ep->stopped = 1;
    //先解锁再加锁，加锁是在dequeue_all调用前做的
    spin_unlock(&dev->lock);
    req->req.complete(&ep->ep, &req->req);
    spin_lock(&dev->lock);
    ep->stopped = stopped;
}

static void xxxxx_dequeue_all(struct xxxxx_ep *ep, int status)
{
    struct xxxxx_request *req;

    if (&ep->queue == NULL)
        return;

    while (!list_empty(&ep->queue)) //list_del_init会删除链表中的元素
    {
        req = list_entry(ep->queue.next, struct xxxxx_request, queue);
        xxxxx_udc_done(ep, req, status);
    }
}


/***************************************************************/
//may not be the endpoint named "ep0".这是gadget.h的源话
/**************************ep_ops*******************************/
//描述端点操作

//当设备配置或接口设置改变时，驱动会enable或disable端口
static int xxxxx_udc_ep_enable(struct usb_ep *_ep, const struct usb_endpoint_descriptor *desc)
{
    struct xxxxx_udc    *dev;
    struct xxxxx_ep    *ep;
    u32 max;
    unsigned long    flags;

    ep = to_xxxxx_ep(_ep);
    if (!_ep || !desc || ep->desc
            || (desc->bDescriptorType != USB_DT_ENDPOINT)
            || (_ep->name == ep0name))
        return -EINVAL;
    dev = ep->dev;
    if (!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)
        return -ESHUTDOWN;

    max = usb_endpoint_maxp(desc) & 0x1fff;

    spin_lock_irqsave(&dev->lock, flags);

    _ep->maxpacket = max & 0x7fff;
    ep->desc = desc;

    ep->stopped = 0;
#ifdef XXXXX_SETWEDHE
    ep->wedged = 0;
#endif
    ep->bEndpointAddress = desc->bEndpointAddress;

    //寄存器操作
    spin_unlock_irqrestore(&dev->lock, flags);

    return 0;
}

static int xxxxx_udc_ep_disable(struct usb_ep *_ep)
{
    struct xxxxx_ep *ep = to_xxxxx_ep(_ep);
    unsigned long flags;

    if (!_ep || !ep->desc) {
        return -EINVAL;
    }

    local_irq_save(flags);

    ep->desc = NULL;
    ep->stopped = 1;

    //清除请求list和关闭ep
    xxxxx_dequeue_all(ep, -ESHUTDOWN);//关机后将无法传输端点

    local_irq_restore(flags);

    return 0;
}

//动态分配请求
static struct usb_request *xxxxx_udc_alloc_request(struct usb_ep *_ep, gfp_t gfp_flags)
{
    struct xxxxx_request *req;

    if (!_ep)
        return NULL;

    req = kzalloc (sizeof(struct xxxxx_request), gfp_flags);
    if (!req)
        return NULL;

    INIT_LIST_HEAD (&req->queue);

    return &req->req;
}

//释放请求
static void xxxxx_udc_free_request(struct usb_ep *_ep, struct usb_request *_req)
{
    //struct xxxxx_ep    *ep = to_xxxxx_ep(_ep);
    struct xxxxx_request *req = to_xxxxx_req(_req);

    if (!_ep || !_req)
        return;

    WARN_ON (!list_empty (&req->queue));
    kfree(req);
}

//下面的queue是插入一个请求
//dequeue删除一个请求
static int xxxxx_udc_queue(struct usb_ep *_ep, struct usb_request *_req, gfp_t gfp_flags)
{
    struct xxxxx_udc    *dev;
    unsigned long        flags;
    struct xxxxx_request    *req = to_xxxxx_req(_req);
    struct xxxxx_ep        *ep = to_xxxxx_ep(_ep);

    if (unlikely (!_ep || (!ep->desc && ep->num != 0))) //这个逻辑下面会看到很多（_ep为空或[ep->desc为空且不是0端点]）
    {
        return -EINVAL;
    }

    dev = ep->dev;
    if (unlikely (!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)) 
    {
        return -ESHUTDOWN;
    }

    if (unlikely(!_req || !_req->complete
            || !_req->buf || !list_empty(&req->queue))) //_req或_req->buf为空、complete执行错误、req->queue不为空
    {
        return -EINVAL;
    }

    local_irq_save (flags);

    //硬件操作

    if (likely(req != 0))
        list_add_tail(&req->queue, &ep->queue);//请求入list

    local_irq_restore(flags);

    return 0;
}

static int xxxxx_udc_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
    struct xxxxx_ep        *ep = to_xxxxx_ep(_ep);
    struct xxxxx_udc    *dev;
    int            retval = -EINVAL;
    unsigned long        flags;
    struct xxxxx_request    *req = NULL;


    if (!_ep || !_req)
        return retval;

    dev = ep->dev;

    if (!dev->driver)
        return -ESHUTDOWN;

    local_irq_save (flags);

    list_for_each_entry (req, &ep->queue, queue) 
    {
        if (&req->req == _req) 
        {
            list_del_init (&req->queue);
            _req->status = -ECONNRESET;//Connection reset by peer
            retval = 0;
            break;
        }
    }

    if (retval == 0) 
    {
        xxxxx_udc_done(ep, req, -ECONNRESET);
    }

    local_irq_restore (flags);
    return retval;
}

#ifdef XXXXX_FIFO_STATUS
//fifo状态，返回fifo中的字节数。
//在上层的调用usb_ep_fifo_statu()如果不用fifo或不支持这个操作返回错误-EOPNOTSUPP
//net2272就有寄存器EP_AVAIL记录fifo中的字节数。
//s3c2440硬件不支持，没实现，上层调用会得到-EOPNOTSUPP
static int xxxxx_udc_fifo_status(struct usb_ep *_ep)
{
    struct xxxxx_ep *ep;
    u16 retval = 0;

    ep = to_xxxxx_ep(_ep);
    if (!_ep || (!ep->desc && ep->num != 0))
        return -ENODEV;
    if (!ep->dev->driver || ep->dev->gadget.speed == USB_SPEED_UNKNOWN)
        return -ESHUTDOWN;

    //retval = 读寄存器

    return retval;
}
#endif

#ifdef XXXXX_FIFO_FLUSH
//冲掉fifo的不明确数据，这个决不用除非端点不能用于任何协议传输，这是上层调用的事
static void xxxxx_udc_fifo_flush(struct usb_ep *_ep)
{
    struct xxxxx_ep *ep;

    ep = to_xxxxx_ep(_ep);
    if (!_ep || (!ep->desc && ep->num != 0))
        return;
    if (!ep->dev->driver || ep->dev->gadget.speed == USB_SPEED_UNKNOWN)
        return;

    //寄存器操作
}
#endif

/*
上层调用usb_ep_set_wedge
停止一个端点并忽略CLEAR_FEATURE请求。如果Gadget驱动清除停止状态，它将自动Unwedge端点
一般用一个位wedge表示
如果没有实现set_wedge方法。就用set_halt(ep, 1);代替
我们看个例子（在file_storage.c中）
Bulk-only
当出现无效的CBW时
Bulk-only Spec说我们必须停止IN 端点。还说必须保持这个状态知道下一次的reset，但是没有办法
告诉控制器忽略CLEAR_FEATURE请求。所以我们用一个位来记录，搞定！
下面是参考net2272的代码，
value=1:set_halt
= 0:clear_halt
*/
static int xxxxx_set_halt_and_wedge(struct usb_ep *_ep, int value, int wedged)
{
    struct xxxxx_ep *ep;
    unsigned long flags;
    int ret = 0;

    ep = container_of(_ep, struct xxxxx_ep, ep);
    if (!_ep || (!ep->desc && ep->num != 0))
        return -EINVAL;
    if (!ep->dev->driver || ep->dev->gadget.speed == USB_SPEED_UNKNOWN)
        return -ESHUTDOWN;
    if (ep->desc /* not ep0 */ && usb_endpoint_xfer_isoc(ep->desc))//判断是不是同步端点，见下面
        return -EINVAL;

    spin_lock_irqsave(&ep->dev->lock, flags);



    if (!list_empty(&ep->queue))
        ret = -EAGAIN;
#ifdef XXXXX_FIFO_STATUS
    else if ((ep->bEndpointAddress & USB_DIR_IN) && value && xxxxx_udc_fifo_status(_ep) != 0)//fifo_status是上面实现的
        ret = -EAGAIN;
#endif
    else {
        /* set/clear */
        if (value) {
            if (ep->num == 0)
            {
                 ep->dev->ep0state = EP0_STALL;
                 ep->stopped = 1;
                //net2272的端点0在setup时自动复位，没有什么操作。s3c2440就不是了
                //ep->dev->protocol_stall = 1;
                //ep0 set_halt
            }
            else
                //epx(x != 0) set_halt
            if (wedged)//维护wedged
                ep->wedged = 1;
        } else {
            //ep clear_halt
            ep->wedged = 0;
        }
    }
    spin_unlock_irqrestore(&ep->dev->lock, flags);

    return ret;
}
//_ep 不能是同步端点，同步端点不支持错误重发机制。在上面判断
static int xxxxx_udc_set_halt(struct usb_ep *_ep, int value)
{
    return xxxxx_set_halt_and_wedge(_ep, value, 0);
}

#ifdef XXXXX_SETWEDHE

static int xxxxx_udc_set_wedge(struct usb_ep *_ep)
{
    if (!_ep || _ep->name == ep0name)//一般都是端点0请求复位
        return -EINVAL;

    return xxxxx_set_halt_and_wedge(_ep, 1, 1);
}
#endif

static const struct usb_ep_ops xxxxx_ep_ops = 
{
    .enable        = xxxxx_udc_ep_enable,
    .disable    = xxxxx_udc_ep_disable,

    .alloc_request    = xxxxx_udc_alloc_request,
    .free_request    = xxxxx_udc_free_request,

    .queue        = xxxxx_udc_queue,
    .dequeue    = xxxxx_udc_dequeue,
 
    .set_halt    = xxxxx_udc_set_halt,

#ifdef XXXXX_SETWEDHE
    .set_wedge  = xxxxx_udc_set_wedge,
#endif

#ifdef XXXXX_FIFO_STATUS
    .fifo_status = xxxxx_udc_fifo_status,
#endif

#ifdef XXXXX_FIFO_FLUSH
    .fifo_flush = xxxxx_udc_fifo_flush,
#endif
};

/***************************************************************/
//USB 设备的常用操作包括：设备连接、设备移除、设备配置、地址分配、数据传输、 
//设备挂起、设备唤醒等。
/**************************usb_gadget_ops***********************/
//硬件操作函数

//获取帧号，当主机发送USB 数据包时，每个帧的开始（SOF）包包含一个帧号。
//这个帧号一般自动加载到对应寄存器，此函数主要就是读这些寄存器
//如果设备不支持返回负
static int xxxxx_udc_get_frame(struct usb_gadget *usb_gdt_p)
{
#ifdef XXXXX_GET_FRAME
    struct xxxxx_udc *dev = to_xxxxx_udc(usb_gdt_p);
    int retval = 0;
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);

    //retval = 读寄存器

    spin_unlock_irqrestore(&dev->lock, flags);

    return retval;
#else
    return -EOPNOTSUPP;
#endif
}

#ifdef XXXXX_WAKEUP
//唤醒，举个例子net2272。它的寄存器usbctl0的第五位控制唤醒功能使能
//寄存器usbctl1的第三位通过写1去resume，s3c2440在PWR_REG也有类似
static int xxxxx_udc_wakeup(struct usb_gadget *usb_gdt_p)
{
    struct xxxxx_udc *dev = to_xxxxx_udc(usb_gdt_p);
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);

    //寄存器操作

    spin_unlock_irqrestore(&dev->lock, flags);

    return 0;
}
#endif

#ifdef XXXXX_SELFPOWERED
//设置自供电标志(selfpowered feature)，一般就用一个变量位或一个位记录一下。USB_RECIP_DEVICE时返回状态
static int xxxxx_udc_set_selfpowered (struct usb_gadget *usb_gdt_p, int is_selfpowered)
{
    struct xxxxx_udc *dev = to_xxxxx_udc(usb_gdt_p);

    if (is_selfpowered)
        dev->devstatus |= (1 << USB_DEVICE_SELF_POWERED);
    else
        dev->devstatus &= ~(1 << USB_DEVICE_SELF_POWERED);

    return 0;
}
#endif

#ifdef XXXXX_VBUS_SESSION
//vbus在硬件上就是usb的电源脚，这个函数就是来控制它。一般通过一个gpio拉高拉底
//这个vbus会话，实际的我看了s3c2410和at91的处理，就是让usb的D+线与一个gpio口连接
//通过置1置0来控制usb
static int xxxxx_udc_vbus_session (struct usb_gadget *usb_gdt_p, int is_active)
{
    struct xxxxx_udc *dev = to_xxxxx_udc(usb_gdt_p);
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);

    //寄存器操作

    spin_unlock_irqrestore(&dev->lock, flags);

    return 0;
}
#endif

#ifdef XXXXX_VBBUS_DRAW
//强制vbus电源控制器行为，在SET_CONFIGRATION时，设置vbus的电流量
//vbus应该是表示总线电压，在硬件上是一个脚
//主要是对usb电流的设置，看一下gta02平台，这个函数会操作pcf50633(一种移动设备的电源管理芯片）
static int xxxxx_udc_vbus_draw (struct usb_gadget *usb_gdt_p, unsigned mA)
{
    return 0;
}
#endif

#ifdef XXXXXX_PULLUP
//这个和上面的vbus_session区别是
//vbus_session是控制vbus的连接
//pullup是控制usb模块的连接
//在udc-core.c中newstyle的驱动probe函数时才调用它，所以你要实现udc_start和udc_stop，
//当然除了注册，也可以通过sysfs调用它。和newstyle无关。
//composite.c也有一些调用
//这个就是根据is_on来connect或disconnect usb
//net2272就是由USBCTL0的第三位控制的，s3c2440还是通过gpio和vbus_session没
//区别
static int xxxxx_udc_pullup (struct usb_gadget *usb_gdt_p, int is_on)
{
    struct xxxxx_udc *dev = to_xxxxx_udc(usb_gdt_p);
    unsigned long flags;

    spin_lock_irqsave(&dev->lock, flags);

    if (is_on)
    {
        //enable
    }
    else
    {
        //disable
    }

    spin_unlock_irqrestore(&dev->lock, flags);

    return 0;
}
#endif

//不好意思，我看了linux-3.2.36的/gadget的目录没发现有实现这个的硬件
static int xxxxx_udc_ioctl(struct usb_gadget *usb_gdt_p, unsigned code, unsigned long param)
{
    return 0;
}

//这个也没看驱动实现它，从名字就是获取配置参数，就简单看看struct usb_dcd_config_params
/*
struct usb_dcd_config_params {
        __u8  bU1devExitLat;    // U1 Device exit Latency  u1设备等待时间
#define USB_DEFAULT_U1_DEV_EXIT_LAT     0x01    // Less then 1 microsec 至少1微秒
        __le16 bU2DevExitLat;   // U2 Device exit Latency 
#define USB_DEFAULT_U2_DEV_EXIT_LAT     0x1F4   // Less then 500 microsec 
};
对应struct usb_ss_cap_descriptor 中的成员
每一个I/O请求包延迟时间限制
*/
static void xxxxx_udc_get_config_params(struct usb_dcd_config_params *usb_dc_cfg_pm)
{
}

//在udc-core.c中start和udc_start的解释一样，在bind()之前调用，只要实现一个就行了
//我知道start主要有bind回调
//udc_start主要是设备执行了non-control请求后，要重新连接，net2272和r8a66597实现的就是它
#ifdef XXXXX_NEWSTYLE
static int xxxxx_udc_start(struct usb_gadget *usb_gdt_p, struct usb_gadget_driver *driver);
static int xxxxx_udc_stop(struct usb_gadget *usb_gdt_p, struct usb_gadget_driver *driver);
#else
//s3c2410 xxxxx 实现它
static int xxxxx_start(struct usb_gadget_driver *driver, int (*bind)(struct usb_gadget *));
static int xxxxx_stop(struct usb_gadget_driver *driver);
#endif

static const struct usb_gadget_ops xxxxx_ops = 
{
    .get_frame        = xxxxx_udc_get_frame,
#ifdef XXXXX_WAKEUP
    .wakeup            = xxxxx_udc_wakeup,
#endif

#ifdef XXXXX_SELFPOWERED
    .set_selfpowered = xxxxx_udc_set_selfpowered,
#endif

#ifdef XXXXX_VBUS_SESSION
    .vbus_session    = xxxxx_udc_vbus_session,
#endif

#ifdef XXXXX_VBBUS_DRAW
    .vbus_draw        = xxxxx_udc_vbus_draw,
#endif

#ifdef XXXXXX_PULLUP
    .pullup            = xxxxx_udc_pullup,
#endif

    .ioctl          = xxxxx_udc_ioctl,
    .get_config_params = xxxxx_udc_get_config_params,
#ifdef XXXXX_NEWSTYLE
    .udc_start         = xxxxx_udc_start,
    .udc_stop       = xxxxx_udc_stop,
#else
    .start            = xxxxx_start,
    .stop            = xxxxx_stop,
#endif
};

/***************************************************************/


/***************************************************************/

static struct xxxxx_udc udc_info = {
    .gadget = {
        .ops        = &xxxxx_ops,
        .ep0        = &udc_info.ep[0].ep,
        .name        = gadget_name,
        .dev = {
            .init_name    = "gadget",
        },
/*
根据自己的硬件选择
unsigned is_dualspeed:1;
unsigned is_otg:1;
unsigned is_a_peripheral:1;
unsigned b_hnp_enable:1; //hnp:主机协商协议 otg特有的
unsigned a_hnp_support:1;
unsigned a_alt_hnp_support:1;
*/
    },

    /* control endpoint */
    .ep[0] = {
        .num = 0,
        .ep =
        {
            .name        = "ep0",
            .ops        = &xxxxx_ep_ops,
            .maxpacket    = EP0_FIFO_SIZE,
        },
        .dev        = &udc_info,
    },

    /* first group of endpoints */
    .ep[1] = {
        .num = 1,
        .ep = 
        {
            .name        = "ep1",
            .ops        = &xxxxx_ep_ops,
            .maxpacket    = EP1_FIFO_SIZE,
        },
        .dev        = &udc_info,
        .fifo_size    = EP1_FIFO_SIZE,
        .bEndpointAddress = EP1_ADDRESS,
        .bmAttributes    = EP1_ATTR,
    },
};

static void stop_activity(struct xxxxx_udc *dev, struct usb_gadget_driver *driver)
{
    unsigned i;

    if (dev->gadget.speed == USB_SPEED_UNKNOWN)
        driver = NULL;

    /* disconnect gadget driver after quiesceing hw and the driver */

    xxxxx_usb_reset(dev);//复位或disable
    for (i = 0; i < XXXXX_ENDPOINTS; i++)
    {
        xxxxx_dequeue_all(&dev->ep[i], -ECONNABORTED);
    }

#ifndef XXXXX_NEWSTYLE
/*
if (udc_is_newstyle(udc)) {
        udc->driver->disconnect(udc->gadget);
        udc->driver->unbind(udc->gadget);
        usb_gadget_udc_stop(udc->gadget, udc->driver);
        usb_gadget_disconnect(udc->gadget);//对应pull_up
} else {
        usb_gadget_stop(udc->gadget, udc->driver);//所以非newstyle要disconnect
}
*/
    if (driver) 
    {
        spin_unlock(&dev->lock);
        driver->disconnect(&dev->gadget);
        spin_lock(&dev->lock);
    }
#endif

    if (dev->driver)
    {
        xxxxx_usb_reinit(dev);//重初始化
    }
}

#ifdef XXXXX_NEWSTYLE
/*
udc 的probe函数
if (udc_is_newstyle(udc)) {//是否实现udc_start and udc_stop
        ret = bind(udc->gadget);
        if (ret)
                goto err1;
        ret = usb_gadget_udc_start(udc->gadget, driver);//已绑定,bind是gadget实现的
        if (ret) {
                driver->unbind(udc->gadget);
                goto err1;
        }
        usb_gadget_connect(udc->gadget);//上面的pullup
} else {

        ret = usb_gadget_start(udc->gadget, driver, bind);
        if (ret)
                goto err1;

}
*/
//net2272和r8a66597实现的就是它
//下面参考net2272
static int xxxxx_udc_start(struct usb_gadget *usb_gdt_p, struct usb_gadget_driver *driver)
{
    struct xxxxx_udc *dev;

    if (!driver || !driver->unbind || !driver->setup ||
        driver->speed != USB_SPEED_HIGH)
        return -EINVAL;

    dev = container_of(usb_gdt_p, struct xxxxx_udc, gadget);

    /* hook up the driver ... */
    driver->driver.bus = NULL;
    dev->driver = driver;
    dev->gadget.dev.driver = &driver->driver;

    //使能udc，硬件操作

    return 0;
}

static int xxxxx_udc_stop(struct usb_gadget *usb_gdt_p, struct usb_gadget_driver *driver)
{
    struct xxxxx_udc *dev;
    unsigned long flags;

    dev = container_of(usb_gdt_p, struct xxxxx_udc, gadget);

    spin_lock_irqsave(&dev->lock, flags);
    stop_activity(dev, driver);
    spin_unlock_irqrestore(&dev->lock, flags);

    dev->gadget.dev.driver = NULL;
    dev->driver = NULL;

    return 0;
}

#else
//s3c2410 goku实现它，参考goku
static int xxxxx_start(struct usb_gadget_driver *driver, int (*bind)(struct usb_gadget *usb_gdt_p))
{
    struct xxxxx_udc *dev = &udc_info;
    int    retval = 0;

    if (!driver
            || driver->speed < USB_SPEED_FULL
            || !bind
            || !driver->disconnect
            || !driver->setup)
        return -EINVAL;
    if (!dev)
        return -ENODEV;
    if (dev->driver)
        return -EBUSY;

    /* hook up the driver */
    driver->driver.bus = NULL;
    dev->driver = driver;
    dev->gadget.dev.driver = &driver->driver;

    if ((retval = device_add(&dev->gadget.dev)) != 0) 
    {
        goto register_error;
    }

    retval = bind(&dev->gadget);
    if (retval) 
    {
        device_del(&dev->gadget.dev);
        goto register_error;
    }

    //使能udc，硬件操作

register_error:
    dev->driver = NULL;
    dev->gadget.dev.driver = NULL;
    return retval;
}

static int xxxxx_stop(struct usb_gadget_driver *driver)
{
    struct xxxxx_udc *dev = &udc_info;
    unsigned long    flags;

    if (!dev)
        return -ENODEV;
    if (!driver || driver != dev->driver || !driver->unbind)
        return -EINVAL;

    spin_lock_irqsave(&dev->lock, flags);
    dev->driver = NULL;
    stop_activity(dev, driver);
    spin_unlock_irqrestore(&dev->lock, flags);

    driver->unbind(&dev->gadget);
    dev->gadget.dev.driver = NULL;
    dev->driver = NULL;

    device_del(&dev->gadget.dev);
    
    return 0;
}
#endif

/***************************************************************/
static int xxxxx_udc_probe(struct platform_device *pdev)
{

    struct xxxxx_udc *udc = &udc_info;
    struct device *dev = &pdev->dev;
    int retval;
    struct resource *res;
#ifdef XXXXX_USE_IRQ
    struct resource *resirq;
#endif
    resource_size_t res_size;

    dev_dbg(dev, "%s()\n", __func__);

#ifdef XXXXX_HAVE_CLK
    udc->xxxxx_clk = clk_get(NULL, "xxxxx");
    if (IS_ERR(udc->xxxxx_clk)) 
    {
        dev_err(dev, "failed to get usb bus clock source\n");
        return PTR_ERR(udc->xxxxx_clk);
    }

    clk_enable(udc->xxxxx_clk);

#if (CLK_DELAY_TIME != 0)
    mdelay(CLK_DELAY_TIME);
#endif

    dev_dbg(dev, "got and enabled clocks\n");
#endif //XXXXX_HAVE_CLK

    if (strncmp(pdev->name, "xxxxx", 7) == 0) {
        dev_info(dev, "xxxxx: increasing FIFO to %d bytes\n", XXXXX_EP_FILO_SIZE);
        udc_info.ep[1].fifo_size = XXXXX_EP_FILO_SIZE;
    }

    spin_lock_init (&udc->lock);

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) 
    {
        dev_err(&pdev->dev, "can't get device resources\n");
        retval = -ENODEV;
        goto err_clk;
    }
/*
    pdata = pdev->dev.platform_data;
    if (!pdata) {
        dev_err(&pdev->dev, "driver needs platform data\n");
        return -ENODEV;
    }
*/
    res_size = resource_size(res);
    if (!request_mem_region(res->start, res_size, res->name)) 
    {
        dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
            res_size, res->start);
        retval = -ENOMEM;

        goto err_clk;
    }

    udc->virl_addr = ioremap(res->start, res_size);
    if (!udc->virl_addr) 
    {
        retval = -ENOMEM;
        goto err_mem;
    }
    udc->phy_addr = res->start;
    udc->reg_size = res_size;

    device_initialize(&udc->gadget.dev);
    udc->gadget.dev.parent = &pdev->dev;
    udc->gadget.dev.dma_mask = pdev->dev.dma_mask;

    platform_set_drvdata(pdev, udc);

    //少不了硬件初始化
    xxxxx_usb_reset(udc);
    xxxxx_usb_reinit(udc);

#ifdef XXXXX_USE_IRQ
    resirq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (!resirq) 
    {
        dev_err(&pdev->dev, "can't get device irq resources\n");
        retval = -ENODEV;
        goto err_map;
    }

    udc->irq_num = resirq->start;

    /* irq setup after old hardware state is cleaned up */
    retval = request_irq(udc->irq_num, xxxxx_udc_irq, 0, gadget_name, udc);
    if (retval != 0) 
    {
        dev_err(dev, "cannot get irq %i, err %d\n", udc->irq_num, retval);
        retval = -EBUSY;
        goto err_map;
    }

    dev_dbg(dev, "got irq %i\n", udc->irq_num);

#endif

    retval = usb_add_gadget_udc(&pdev->dev, &udc->gadget);
    if (retval)
        goto err_int;

#ifdef XXXXX_DEBUG_FS
    if (xxxxx_udc_debugfs_root) 
    {
        udc->debug_info = debugfs_create_file("registers", S_IRUGO, xxxxx_udc_debugfs_root,
                udc, &xxxxx_udc_debugfs_fops);
        if (!udc->debug_info)
            dev_warn(dev, "debugfs file creation failed\n");
    }
#endif

    dev_dbg(dev, "probe ok\n");

    return 0;

err_int:
#ifdef XXXXX_USE_IRQ
    free_irq(udc->irq_num, udc);
#endif
err_map:
    iounmap(udc->virl_addr);
err_mem:
    release_mem_region(res->start, res_size);
err_clk:
#ifdef XXXXX_HAVE_CLK
    clk_put(udc->xxxxx_clk);
    clk_disable(udc->xxxxx_clk);
#endif

    return retval;
}

static int xxxxx_udc_remove(struct platform_device *pdev)
{
    struct xxxxx_udc *udc = platform_get_drvdata(pdev);

    dev_dbg(&pdev->dev, "%s()\n", __func__);

    usb_del_gadget_udc(&udc->gadget);
    if (udc->driver)
        return -EBUSY;

#ifdef XXXXX_DEBUG_FS
    debugfs_remove(udc->debug_info);
#endif

#ifdef XXXXX_USE_IRQ
    free_irq(udc->irq_num, udc);
#endif

    iounmap(udc->virl_addr);
    release_mem_region(udc->phy_addr, udc->reg_size);

    platform_set_drvdata(pdev, NULL);

#ifdef XXXXX_HAVE_CLK
    if (!IS_ERR(udc->xxxxx_clk) && udc->xxxxx_clk != NULL) {
        clk_disable(udc->xxxxx_clk);
        clk_put(udc->xxxxx_clk);
        udc->xxxxx_clk = NULL;
    }
#endif

    dev_dbg(&pdev->dev, "%s: remove ok\n", __func__);

    return 0;
}

#ifdef CONFIG_PM
static int xxxxx_udc_suspend(struct platform_device *pdev, pm_message_t message)
{
    return 0;
}

static int xxxxx_udc_resume(struct platform_device *pdev)
{
    return 0;
}
#else
#define xxxxx_udc_suspend    NULL
#define xxxxx_udc_resume    NULL
#endif

/***************************************************************/

static const struct platform_device_id xxxxx_udc_ids[] = {
    { "xxxxx-usbgadget", },
    { }
};

MODULE_DEVICE_TABLE(platform, xxxxx_udc_ids);

//有些设备可能用struct pci_driver，我就不考虑这么多了。
static struct platform_driver udc_driver_xxxxx = {
    .driver        = {
        .name    = "xxxxx-usbgadget",
        .owner    = THIS_MODULE,
    },
    .probe        = xxxxx_udc_probe,
    .remove        = __exit_p(xxxxx_udc_remove),
    .suspend    = xxxxx_udc_suspend,
    .resume        = xxxxx_udc_resume,
    .id_table    = xxxxx_udc_ids,
};


static int __init udc_init(void)
{
    int retval;

    xxxxx_udc_debugfs_root = debugfs_create_dir(gadget_name, NULL);
    if (IS_ERR(xxxxx_udc_debugfs_root)) {
        printk(KERN_ERR "%s: debugfs dir creation failed %ld\n",
            gadget_name, PTR_ERR(xxxxx_udc_debugfs_root));
        xxxxx_udc_debugfs_root = NULL;
    }

    retval = platform_driver_register(&udc_driver_xxxxx);
    if (retval)
        goto err;

    return 0;

err:
    debugfs_remove(xxxxx_udc_debugfs_root);
    return retval;
}

static void __exit udc_exit(void)
{
    platform_driver_unregister(&udc_driver_xxxxx);
    debugfs_remove(xxxxx_udc_debugfs_root);
}

module_init(udc_init);
module_exit(udc_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");

下期预告：

基于模板实现一个实际的udc驱动。