Linux USB裝置驅動程式設計 和 USB下載線驅動設計

USB裝置驅動模型

USB裝置包括配置(configuration)、介面（interface）和端點(endpoint)，一個USB裝置驅動程式對應一個USB介面，而非整個USB裝置。

在Linux核心中，使用 struct usb_driver結構體 描述一個USB驅動。

struct usb_driver {
    const char *name; /*驅動程式名*/
    /* 當USB核心發現了該驅動能夠處理的USB介面時，呼叫該函式 */
    int (*probe) (struct usb_interface *intf, const struct usb_device_id *id);
    /* 當相應的USB介面被移除時，呼叫該函式 */
    void (*disconnect) (struct usb_interface *intf);
    /* USB驅動能夠處理的裝置列表 */
    const struct usb_device_id *id_table;
}
 

URB通訊模型

USB請求塊（USB request block-URB）是USB裝置驅動中用來與USB裝置通訊所用的基本載體和核心資料結構，非常類似於網路裝置驅動中的sk_buff結構體，是USB主機與裝置通訊的“電波”。

struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
//引數：
//iso_packets：urb所包含的等時資料包的個數。
//mem_flags：記憶體分配標識(如GFP_KERNEL)，參考kmalloc。

static inline void usb_fill_int_urb(
    struct urb *urb, //待初始化的urb
    struct usb_device *dev, //urb所要訪問的裝置
    unsigned int pipe, //要訪問的端點所對應的管道，
    void *transfer_buffer, //儲存傳輸資料的buffer
    int buffer_length, //buffer長度
    usb_complete_t complete_fn, //urb完成時呼叫的函式
    void *context, //賦值到urb->context的資料
    int interval //urb被排程的時間間隔
)
 

在完成urb的建立和初始化後，USB驅動需要將urb提交 
給USB核心。

int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
//引數：
//urb：要提交urb的指標
//mem_flags: 記憶體分配標識(如GFP_KERNEL)，參考kmalloc

URB被提交到USB核心後，USB核心指定usb主控制器驅動 
程式來處理該urb，處理完之後，urb完成函式將被呼叫。

HID協議

HID(Human Interface Device)， 屬於人機互動類的裝置，如USB滑鼠，USB鍵盤，USB遊戲操縱桿等。該類裝置必須遵循HID設計規範。

滑鼠裝置驅動程式

從硬體結構上看，滑鼠是URB匯流排裝置，從功能上看，滑鼠是輸入型裝置。因此滑鼠驅動由兩部分組成，分別是URB驅動和輸入裝置驅動。

程式碼舉例：

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/usb/input.h>
#include <linux/hid.h>

/* for apple IDs */
#ifdef CONFIG_USB_HID_MODULE
#include "../hid-ids.h"
#endif

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.6"
#define DRIVER_AUTHOR "Vojtech Pavlik <[email protected]>"
#define DRIVER_DESC "USB HID Boot Protocol mouse driver"
#define DRIVER_LICENSE "GPL"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE(DRIVER_LICENSE);

struct usb_mouse {
    char name[128];
    char phys[64];
    struct usb_device *usbdev;
    struct input_dev *dev;
    struct urb *irq;

    signed char *data;
    dma_addr_t data_dma;
};

static void usb_mouse_irq(struct urb *urb)
{
    struct usb_mouse *mouse = urb->context;
    signed char *data = mouse->data;
    struct input_dev *dev = mouse->dev;
    int status;

    /* 檢測urb傳輸是否成功 */
    switch (urb->status) {
    case 0:         /* success */
        break;
    case -ECONNRESET:   /* unlink */
    case -ENOENT:
    case -ESHUTDOWN:
        return;
    /* -EPIPE:  should clear the halt */
    default:        /* error */
        goto resubmit;
    }

    /* 報告按鍵狀態 */
    input_report_key(dev, BTN_LEFT,   data[0] & 0x01);
    input_report_key(dev, BTN_RIGHT,  data[0] & 0x02);
    input_report_key(dev, BTN_MIDDLE, data[0] & 0x04);
    input_report_key(dev, BTN_SIDE,   data[0] & 0x08);
    input_report_key(dev, BTN_EXTRA,  data[0] & 0x10);

    input_report_rel(dev, REL_X,     data[1]);
    input_report_rel(dev, REL_Y,     data[2]);
    input_report_rel(dev, REL_WHEEL, data[3]);

    input_sync(dev);
resubmit:
    /* 提交下次傳輸 */
    status = usb_submit_urb (urb, GFP_ATOMIC);
    if (status)
        err ("can't resubmit intr, %s-%s/input0, status %d",
                mouse->usbdev->bus->bus_name,
                mouse->usbdev->devpath, status);
}

static int usb_mouse_open(struct input_dev *dev)
{
    struct usb_mouse *mouse = input_get_drvdata(dev);

    mouse->irq->dev = mouse->usbdev;
    if (usb_submit_urb(mouse->irq, GFP_KERNEL))
        return -EIO;

    return 0;
}

static void usb_mouse_close(struct input_dev *dev)
{
    struct usb_mouse *mouse = input_get_drvdata(dev);

    usb_kill_urb(mouse->irq);
}

static int usb_mouse_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
    /* 裝置描述 usb_device */
    /* 介面描述 usb_interface */
    struct usb_device *dev = interface_to_usbdev(intf); 

    /* 介面設定描述 */
    struct usb_host_interface *interface;

    /* 端點描述符 */
    struct usb_endpoint_descriptor *endpoint;

    struct usb_mouse *mouse;
    struct input_dev *input_dev;
    int pipe, maxp;
    int error = -ENOMEM;

    /* 獲取當前介面設定 */
    interface = intf->cur_altsetting;

　　   /* 根據HID規範，滑鼠只有一個端點（不包含0號控制端點）*/
    if (interface->desc.bNumEndpoints != 1)
        return -ENODEV;

    /* 獲取端點0描述符 */
    endpoint = &interface->endpoint[0].desc;

    /* 根據HID規範，滑鼠唯一的端點應為中斷端點 */
    if (!usb_endpoint_is_int_in(endpoint))
        return -ENODEV;

    /* 生成中斷管道 */
    pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);

    /* 返回該端點能夠傳輸的最大的包長度，滑鼠的返回的最大資料包為4個位元組。*/  
    maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));

    /* 建立input裝置 */
    mouse = kzalloc(sizeof(struct usb_mouse), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!mouse || !input_dev)
        goto fail1;

    /* 申請記憶體空間用於資料傳輸，data 為指向該空間的地址*/
    mouse->data = usb_buffer_alloc(dev, 8, GFP_ATOMIC, &mouse->data_dma);
    if (!mouse->data)
        goto fail1;

    /* 分配URB */
    mouse->irq = usb_alloc_urb(0, GFP_KERNEL);
    if (!mouse->irq)
        goto fail2;

    mouse->usbdev = dev;
    mouse->dev = input_dev;

    if (dev->manufacturer)
        strlcpy(mouse->name, dev->manufacturer, sizeof(mouse->name));

    if (dev->product) {
        if (dev->manufacturer)
            strlcat(mouse->name, " ", sizeof(mouse->name));
        strlcat(mouse->name, dev->product, sizeof(mouse->name));
    }

    if (!strlen(mouse->name))
        snprintf(mouse->name, sizeof(mouse->name),
             "USB HIDBP Mouse %04x:%04x",
             le16_to_cpu(dev->descriptor.idVendor),
             le16_to_cpu(dev->descriptor.idProduct));

    /* usb_make_path 用來獲取 USB 裝置在 Sysfs 中的路徑*/
    usb_make_path(dev, mouse->phys, sizeof(mouse->phys));

    strlcat(mouse->phys, "/input0", sizeof(mouse->phys));

    /* 字元裝置初始化 */
    input_dev->name = mouse->name;
    input_dev->phys = mouse->phys;
    usb_to_input_id(dev, &input_dev->id);
    input_dev->dev.parent = &intf->dev;

    input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
    input_dev->keybit[BIT_WORD(BTN_MOUSE)] = BIT_MASK(BTN_LEFT) |
        BIT_MASK(BTN_RIGHT) | BIT_MASK(BTN_MIDDLE);
    input_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);
    input_dev->keybit[BIT_WORD(BTN_MOUSE)] |= BIT_MASK(BTN_SIDE) |
        BIT_MASK(BTN_EXTRA);
    input_dev->relbit[0] |= BIT_MASK(REL_WHEEL);

    input_set_drvdata(input_dev, mouse);

    input_dev->open = usb_mouse_open;
    input_dev->close = usb_mouse_close;

    /* 初始化中斷URB */
    /* 思考實驗：將interval引數設定為1分鐘，觀察現象 */
    usb_fill_int_urb(mouse->irq, dev, pipe, mouse->data,
             (maxp > 8 ? 8 : maxp),
             usb_mouse_irq, mouse, endpoint->bInterval);
    mouse->irq->transfer_dma = mouse->data_dma;
    mouse->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

    error = input_register_device(mouse->dev);
    if (error)
        goto fail3;

    /*將mouse指標儲存到intf的dev成員中*/
    usb_set_intfdata(intf, mouse);
    return 0;

fail3:  
    usb_free_urb(mouse->irq);
fail2:  
    usb_buffer_free(dev, 8, mouse->data, mouse->data_dma);
fail1:  
    input_free_device(input_dev);
    kfree(mouse);
    return error;
}

static void usb_mouse_disconnect(struct usb_interface *intf)
{
    struct usb_mouse *mouse = usb_get_intfdata (intf);

    usb_set_intfdata(intf, NULL);
    if (mouse) {
        usb_kill_urb(mouse->irq);
        input_unregister_device(mouse->dev);
        usb_free_urb(mouse->irq);
        usb_buffer_free(interface_to_usbdev(intf), 8, mouse->data, mouse->data_dma);
        kfree(mouse);
    }
}

static struct usb_device_id usb_mouse_id_table [] = {
    { USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS_BOOT,
        USB_INTERFACE_PROTOCOL_MOUSE) },
    { } /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, usb_mouse_id_table);

static struct usb_driver usb_mouse_driver = {
    .name       = "usbmouse",   /* 驅動名 */
    .probe      = usb_mouse_probe, /* 捕獲函式 */
    .disconnect = usb_mouse_disconnect, /* 解除安裝函式 */
    .id_table   = usb_mouse_id_table, /* 裝置列表 */
};

static int __init usb_mouse_init(void)
{
    /* 註冊滑鼠驅動程式 */
    int retval = usb_register(&usb_mouse_driver);
    if (retval == 0)
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
                DRIVER_DESC "\n");
    return retval;
}

static void __exit usb_mouse_exit(void)
{
    usb_deregister(&usb_mouse_driver);
}

module_init(usb_mouse_init);
module_exit(usb_mouse_exit);

USB下載線驅動設計

核心驅動程式碼： 
dnw_usb.c:

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/usb.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/slab.h>

#define BULKOUT_BUFFER_SIZE 512
char *bulkout_buffer;
struct usb_device *udev;
__u8 bulk_out_endaddr;

static struct usb_device_id dnw_id_table [] = {
    { USB_DEVICE(0x5345, 0x1234) },//在啟動下載後，用lsusb命令在系統中檢視 
    { }     
};

static int dnw_open(struct inode* inode, struct file *file)
{
     bulkout_buffer = kmalloc(BULKOUT_BUFFER_SIZE,GFP_KERNEL);
     return 0;
}

static int dnw_release (struct inode* inode, struct file *file)
{
    kfree(bulkout_buffer);
    return 0;   
}

static ssize_t dnw_write(struct file *file, const char __user *buf, size_t len, loff_t *pos)
{
    size_t to_write;
    size_t total_write = 0;
    size_t act_len;

    while(len>0)    
    {
        to_write = min(len,(size_t)BULKOUT_BUFFER_SIZE);

    copy_from_user(bulkout_buffer,buf+total_write,to_write);

    usb_bulk_msg(udev,usb_sndbulkpipe(udev,bulk_out_endaddr),bulkout_buffer,to_write,&act_len,3*HZ);

    len -= to_write;
    total_write += to_write;
    }

    return total_write;
}

static struct file_operations dnw_ops =
{
    .owner =    THIS_MODULE,
    .write =    dnw_write,
    .open =     dnw_open,
    .release =  dnw_release,
};

static struct usb_class_driver dnw_class = {
    .name =     "secbulk%d",
    .fops =     &dnw_ops,
    .minor_base =   100,
};

static int dnw_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
    /* 介面設定描述 */
    struct usb_host_interface *interface;
    struct usb_endpoint_descriptor *endpoint;   
    int i;

    interface = intf->cur_altsetting;

    for(i=0;i<interface->desc.bNumEndpoints;i++)
    {
        endpoint = &interface->endpoint[i].desc;
        if(usb_endpoint_is_bulk_out(endpoint))
        {
            bulk_out_endaddr =  endpoint->bEndpointAddress;
            break;
        }

    }

    usb_register_dev(intf,&dnw_class);//建立USB型字元裝置 

    udev = usb_get_dev(interface_to_usbdev(intf));  
}

static void dnw_disconnect(struct usb_interface *intf)
{
    usb_deregister_dev(intf,&dnw_class);
}

struct usb_driver dnw_driver = {
    .name       = "dnw",   /* 驅動名 */
    .probe      = dnw_probe, /* 捕獲函式 */
    .disconnect = dnw_disconnect, /* 解除安裝函式 */
    .id_table   = dnw_id_table, /* 裝置列表 */
};

int dnw_init() //初始化入口函式 
{
    usb_register(&dnw_driver);//註冊匯流排裝置 
    return 0;   
}

void dnw_exit() //退出函式 
{
    usb_deregister(&dnw_driver);    
}

module_init(dnw_init);
module_exit(dnw_exit);
MODULE_LICENSE("GPL");

應用程式程式碼： 
dnw.c

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

const char* dev = "/dev/dnw0";


int main(int argc, char* argv[])
{
    unsigned char* file_buffer = NULL;

    long int addr  =  0;

    if( 3 != argc ) {
        printf("Usage: dwn <filename> address\n");
        return 1;
    }


    int fd = open(argv[1], O_RDONLY);
    if(-1 == fd) {
        printf("Can not open file - %s\n", argv[1]);
        return 1;
    }
    addr = strtol((char *) argv[2] ,NULL, 16);

    printf("addr = %x \n", addr);


    // get file size 
    struct stat file_stat;
    if( -1 == fstat(fd, &file_stat) ) {
        printf("Get file size filed!\n");
        return 1;
    }   

    file_buffer = (unsigned char*)malloc(file_stat.st_size+10);
    if(NULL == file_buffer) {
        printf("malloc failed!\n");
        goto error;
    }
    //memset(file_buffer, '\0', sizeof(file_buffer)); // bad code ! corrected by Qulory
    memset(file_buffer, '\0', sizeof(char)*(file_stat.st_size+10));

    // the first 8 bytes in the file_buffer is reserved, the last 2 bytes also;
    if( file_stat.st_size !=  read(fd, file_buffer+8, file_stat.st_size))   {
        printf("Read file failed!\n");
        goto error;
    }

    printf("File name : %s\n", argv[1]);
    printf("File size : %ld bytes\n", file_stat.st_size);// off_t is long int 

    int fd_dev = open(dev, O_WRONLY);
    if( -1 == fd_dev)   {
        printf("Can not open %s\n", dev);
        goto error;
    }

    /*
     * Note: the first 4 bytes store the dest addr ;
     * the following 4 bytes store the file size ;
     * and the last 2 bytes store the sum of each bytes of the file ;
     */
    *((unsigned long*)file_buffer) = addr;  //load address
    *((unsigned long*)file_buffer+1) = file_stat.st_size+10;    //file size
    unsigned short sum = 0;
    int i;
    for(i=8; i<file_stat.st_size+8; i++)    {
        sum += file_buffer[i];
    }

    *((unsigned short*)(file_buffer+8+file_stat.st_size)) = sum;

    printf("Start Sending data...\n");
    size_t remain_size = file_stat.st_size+10;
    size_t block_size = 512;
    size_t written = 0;
    while(remain_size > 0)  {
        size_t to_write = remain_size > block_size ? block_size:remain_size;
        size_t real_write = write(fd_dev, file_buffer+written, to_write);
        if( to_write != real_write) {
            printf(" write  /dev/secbulk0 failed!  to_write = %u real_write = %u \n" , to_write ,real_write );
            return 1;
        }
        remain_size -= to_write;
        written += to_write;
        printf("\rSent %lu%% \t %u bytes !", written*100/(file_stat.st_size+10),  written);
        fflush(stdout);

    }   

    printf("OK\n");
    return 0;

error:
    if(-1 != fd_dev) {
        close(fd_dev);
    }
    if(fd != -1)  {
        close(fd);
    }
    if( NULL != file_buffer ) {
        free(file_buffer);
    }
    return -1;
}