main.c

本源码是将述嵌入式LINUX驱动程序例程

      case SCULL_IOCRESET:
        scull_quantum = SCULL_QUANTUM;
        scull_qset = SCULL_QSET;
        break;
        
      case SCULL_IOCSQUANTUM: /* Set: arg points to the value */
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        ret = __get_user(scull_quantum, (int *)arg);
        break;

      case SCULL_IOCTQUANTUM: /* Tell: arg is the value */
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        scull_quantum = arg;
        break;

      case SCULL_IOCGQUANTUM: /* Get: arg is pointer to result */
        ret = __put_user(scull_quantum, (int *)arg);
        break;

      case SCULL_IOCQQUANTUM: /* Query: return it (it's positive) */
        return scull_quantum;

      case SCULL_IOCXQUANTUM: /* eXchange: use arg as pointer */
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        tmp = scull_quantum;
        ret = __get_user(scull_quantum, (int *)arg);
        if (ret == 0)
            ret = __put_user(tmp, (int *)arg);
        break;

      case SCULL_IOCHQUANTUM: /* sHift: like Tell + Query */
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        tmp = scull_quantum;
        scull_quantum = arg;
        return tmp;
        
      case SCULL_IOCSQSET:
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        ret = __get_user(scull_qset, (int *)arg);
        break;

      case SCULL_IOCTQSET:
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        scull_qset = arg;
        break;

      case SCULL_IOCGQSET:
        ret = __put_user(scull_qset, (int *)arg);
        break;

      case SCULL_IOCQQSET:
        return scull_qset;

      case SCULL_IOCXQSET:
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        tmp = scull_qset;
        ret = __get_user(scull_qset, (int *)arg);
        if (ret == 0)
            ret = put_user(tmp, (int *)arg);
        break;

      case SCULL_IOCHQSET:
        if (! capable (CAP_SYS_ADMIN))
            return -EPERM;
        tmp = scull_qset;
        scull_qset = arg;
        return tmp;

        /*
         * The following two change the buffer size for scullpipe.
         * The scullpipe device uses this same ioctl method, just to
         * write less code. Actually, it's the same driver, isn't it?
         */

      case SCULL_P_IOCTSIZE:
        scull_p_buffer = arg;
        break;

      case SCULL_P_IOCQSIZE:
        return scull_p_buffer;


      default:  /* redundant, as cmd was checked against MAXNR */
        return -ENOTTY;
    }
    return ret;

}

#else  /* LINUX_20 */

int scull_ioctl(struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg)
{

    int err = 0, tmp;
    
    /*
     * extract the type and number bitfields, and don't decode
     * wrong cmds: return ENOTTY before verify_area()
     */
    if (_IOC_TYPE(cmd) != SCULL_IOC_MAGIC) return -ENOTTY;
    if (_IOC_NR(cmd) > SCULL_IOC_MAXNR) return -ENOTTY;

    /*
     * the direction is a bitmask, and VERIFY_WRITE catches R/W
     * transfers. `Type' is user-oriented, while
     * verify_area is kernel-oriented, so the concept of "read" and
     * "write" is reversed
     */
    if (_IOC_DIR(cmd) & _IOC_READ)
        err = verify_area(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
    else if (_IOC_DIR(cmd) & _IOC_WRITE)
        err =  verify_area(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
    if (err) return err;

    switch(cmd) {

      case SCULL_IOCRESET:
        scull_quantum = SCULL_QUANTUM;
        scull_qset = SCULL_QSET;
        break;
        
      case SCULL_IOCSQUANTUM: /* Set: arg points to the value */
        scull_quantum = get_user((int *)arg);
        break;

      case SCULL_IOCTQUANTUM: /* Tell: arg is the value */
        scull_quantum = arg;
        break;

      case SCULL_IOCGQUANTUM: /* Get: arg is pointer to result */
        put_user(scull_quantum, (int *)arg);
        break;

      case SCULL_IOCQQUANTUM: /* Query: return it (it's positive) */
        return scull_quantum;

      case SCULL_IOCXQUANTUM: /* eXchange: use arg as pointer */
        tmp = scull_quantum;
        scull_quantum = get_user((int *)arg);
        put_user(tmp, (int *)arg);
        break;

      case SCULL_IOCHQUANTUM: /* sHift: like Tell + Query */
        tmp = scull_quantum;
        scull_quantum = arg;
        return tmp;
        
      case SCULL_IOCSQSET:
        scull_qset = get_user((int *)arg);
        break;

      case SCULL_IOCTQSET:
        scull_qset = arg;
        break;

      case SCULL_IOCGQSET:
        put_user(scull_qset, (int *)arg);
        break;

      case SCULL_IOCQQSET:
        return scull_qset;

      case SCULL_IOCXQSET:
        tmp = scull_qset;
        scull_qset = get_user((int *)arg);
        put_user(tmp, (int *)arg);
        break;

      case SCULL_IOCHQSET:
        tmp = scull_qset;
        scull_quantum = arg;
        return tmp;

        /*
         * The following two change the buffer size for scullpipe.
         * The scullpipe device uses this same ioctl method, just to
         * write less code. Actually, it's the same driver, isn't it?
         */

      case SCULL_P_IOCTSIZE:
        scull_p_buffer = arg;
        break;

      case SCULL_P_IOCQSIZE:
        return scull_p_buffer;


      default:  /* redundant, as cmd was checked against MAXNR */
        return -ENOTTY;
    }
    return 0;

}


#endif /* LINUX_20 */


/*
 * The "extended" operations -- only seek
 */

loff_t scull_llseek(struct file *filp, loff_t off, int whence)
{
    Scull_Dev *dev = filp->private_data;
    loff_t newpos;

    switch(whence) {
      case 0: /* SEEK_SET */
        newpos = off;
        break;

      case 1: /* SEEK_CUR */
        newpos = filp->f_pos + off;
        break;

      case 2: /* SEEK_END */
        newpos = dev->size + off;
        break;

      default: /* can't happen */
        return -EINVAL;
    }
    if (newpos<0) return -EINVAL;
    filp->f_pos = newpos;
    return newpos;
}


/*
 * The following wrappers are meant to make things work with 2.0 kernels
 */
#ifdef LINUX_20
int scull_lseek_20(struct inode *ino, struct file *f,
                off_t offset, int whence)
{
    return (int)scull_llseek(f, offset, whence);
}

int scull_read_20(struct inode *ino, struct file *f, char *buf, int count)
{
    return (int)scull_read(f, buf, count, &f->f_pos);
}

int scull_write_20(struct inode *ino, struct file *f, const char *b, int c)
{
    return (int)scull_write(f, b, c, &f->f_pos);
}

void scull_release_20(struct inode *ino, struct file *f)
{
    scull_release(ino, f);
}

/* Redefine "real" names to the 2.0 ones */
#define scull_llseek scull_lseek_20
#define scull_read scull_read_20
#define scull_write scull_write_20
#define scull_release scull_release_20
#define llseek lseek
#endif  /* LINUX_20 */

struct file_operations scull_fops = {
    llseek:     scull_llseek,
    read:       scull_read,
    write:      scull_write,
    ioctl:      scull_ioctl,
    open:       scull_open,
    release:    scull_release,
};

/*
 * Finally, the module stuff
 */

#ifdef CONFIG_DEVFS_FS
devfs_handle_t scull_devfs_dir;
static char devname[4];
#endif

/*
 * The cleanup function is used to handle initialization failures as well.
 * Thefore, it must be careful to work correctly even if some of the items
 * have not been initialized
 */
void scull_cleanup_module(void)
{
    int i;

#ifndef CONFIG_DEVFS_FS
    /* cleanup_module is never called if registering failed */
    unregister_chrdev(scull_major, "scull");
#endif

#ifdef SCULL_DEBUG /* use proc only if debugging */
    scull_remove_proc();
#endif
    if (scull_devices) {
        for (i=0; i<scull_nr_devs; i++) {
            scull_trim(scull_devices+i);
            /* the following line is only used for devfs */
            devfs_unregister(scull_devices[i].handle);
        }
        kfree(scull_devices);
    }

    /* and call the cleanup functions for friend devices */
    scull_p_cleanup();
    scull_access_cleanup();

    /* once again, only for devfs */
    devfs_unregister(scull_devfs_dir);

}


int scull_init_module(void)
{
    int result, i;

    SET_MODULE_OWNER(&scull_fops);
#ifdef CONFIG_DEVFS_FS
    /* If we have devfs, create /dev/scull to put files in there */
    scull_devfs_dir = devfs_mk_dir(NULL, "scull", NULL);
    if (!scull_devfs_dir) return -EBUSY; /* problem */

#else /* no devfs, do it the "classic" way  */    

    /*
     * Register your major, and accept a dynamic number. This is the
     * first thing to do, in order to avoid releasing other module's
     * fops in scull_cleanup_module()
     */
    result = register_chrdev(scull_major, "scull", &scull_fops);
    if (result < 0) {
        printk(KERN_WARNING "scull: can't get major %d\n",scull_major);
        return result;
    }
    if (scull_major == 0) scull_major = result; /* dynamic */

#endif /* CONFIG_DEVFS_FS */
    /* 
     * allocate the devices -- we can't have them static, as the number
     * can be specified at load time
     */
    scull_devices = kmalloc(scull_nr_devs * sizeof(Scull_Dev), GFP_KERNEL);
    if (!scull_devices) {
        result = -ENOMEM;
        goto fail;
    }
    memset(scull_devices, 0, scull_nr_devs * sizeof(Scull_Dev));
    for (i=0; i < scull_nr_devs; i++) {
        scull_devices[i].quantum = scull_quantum;
        scull_devices[i].qset = scull_qset;
        sema_init(&scull_devices[i].sem, 1);
#ifdef CONFIG_DEVFS_FS
        sprintf(devname, "%i", i);
        devfs_register(scull_devfs_dir, devname,
                       DEVFS_FL_AUTO_DEVNUM,
                       0, 0, S_IFCHR | S_IRUGO | S_IWUGO,
                       &scull_fops,
                       scull_devices+i);
#endif  
    }

    /* At this point call the init function for any friend device */
    if ( (result = scull_p_init()) )
        goto fail;
    if ( (result = scull_access_init()) )
        goto fail;
    /* ... */

#ifndef SCULL_DEBUG
    EXPORT_NO_SYMBOLS; /* otherwise, leave global symbols visible */
#endif

#ifdef SCULL_DEBUG /* only when debugging */
    scull_create_proc();
#endif

    return 0; /* succeed */

  fail:
    scull_cleanup_module();
    return result;
}



module_init(scull_init_module);
module_exit(scull_cleanup_module);