main.c

本源码是将述嵌入式LINUX驱动程序例程

    }
    if (count > quantum - q_pos)
        count = quantum - q_pos; /* write only up to the end of this quantum */
    if (copy_from_user (dptr->data[s_pos]+q_pos, buf, count)) {
        retval = -EFAULT;
        goto nomem;
    }
    *f_pos += count;
 
    /* update the size */
    if (dev->size < *f_pos)
        dev->size = *f_pos;
    up (&dev->sem);
    return count;

  nomem:
    up (&dev->sem);
    return retval;
}

/*
 * The ioctl() implementation
 */

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

    int err= 0, ret = 0, tmp;

    /* don't even decode wrong cmds: better returning  ENOTTY than EFAULT */
    if (_IOC_TYPE(cmd) != SCULLV_IOC_MAGIC) return -ENOTTY;
    if (_IOC_NR(cmd) > SCULLV_IOC_MAXNR) return -ENOTTY;

    /*
     * the type is a bitmask, and VERIFY_WRITE catches R/W
     * transfers. Note that the 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 = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
    else if (_IOC_DIR(cmd) & _IOC_WRITE)
        err =  !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
    if (err) return -EFAULT;

    switch(cmd) {

      case SCULLV_IOCRESET:
        scullv_qset = SCULLV_QSET;
        scullv_order = SCULLV_ORDER;
        break;
        
      case SCULLV_IOCSORDER: /* Set: arg points to the value */
        ret = __GET_USER(scullv_order, (int *) arg);
        break;

      case SCULLV_IOCTORDER: /* Tell: arg is the value */
        scullv_order = arg;
        break;

      case SCULLV_IOCGORDER: /* Get: arg is pointer to result */
        ret = __PUT_USER (scullv_order, (int *) arg);
        break;

      case SCULLV_IOCQORDER: /* Query: return it (it's positive) */
        return scullv_order;

      case SCULLV_IOCXORDER: /* eXchange: use arg as pointer */
        tmp = scullv_order;
        ret = __GET_USER(scullv_order, (int *) arg);
        if (ret == 0)
            ret = __PUT_USER(tmp, (int *) arg);
        break;

      case SCULLV_IOCHORDER: /* sHift: like Tell + Query */
        tmp = scullv_order;
        scullv_order = arg;
        return tmp;
        
      case SCULLV_IOCSQSET:
        ret = __GET_USER(scullv_qset, (int *) arg);
        break;

      case SCULLV_IOCTQSET:
        scullv_qset = arg;
        break;

      case SCULLV_IOCGQSET:
        ret = __PUT_USER(scullv_qset, (int *)arg);
        break;

      case SCULLV_IOCQQSET:
        return scullv_qset;

      case SCULLV_IOCXQSET:
        tmp = scullv_qset;
        ret = __GET_USER(scullv_qset, (int *) arg);
        if (ret == 0)
            ret = __PUT_USER(tmp, (int *)arg);
        break;

      case SCULLV_IOCHQSET:
        tmp = scullv_qset;
        scullv_qset = arg;
        return tmp;

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

    return ret;

}

/*
 * The "extended" operations
 */

loff_t scullv_llseek (struct file *filp, loff_t off, int whence)
{
    ScullV_Dev *dev = filp->private_data;
    long 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;
}
 
/*
 * Mmap *is* available, but confined in a different file
 */
#ifndef LINUX_20
extern int scullv_mmap(struct file *filp, struct vm_area_struct *vma);
#else
extern int scullv_mmap(struct inode *inode, struct file *filp,
		struct vm_area_struct *vma);
#endif

/*
 * The 2.0 wrappers
 */
#ifdef LINUX_20

int scullv_lseek_20 (struct inode *ino, struct file *f,
                off_t offset, int whence)
{
    return (int)scullv_llseek(f, offset, whence);
}

int scullv_read_20 (struct inode *ino, struct file *f, char *buf, int count)
{
    return (int)scullv_read(f, buf, count, &f->f_pos);
}

int scullv_write_20 (struct inode *ino, struct file *f, const char *b, int c)
{
    return (int)scullv_write(f, b, c, &f->f_pos);
}

void scullv_release_20 (struct inode *ino, struct file *f)
{
    scullv_release(ino, f);
}

#define scullv_llseek scullv_lseek_20
#define scullv_read scullv_read_20
#define scullv_write scullv_write_20
#define scullv_release scullv_release_20
#define llseek lseek

#endif /* LINUX_20 */

/*
 * The fops
 */

struct file_operations scullv_fops = {
    llseek: scullv_llseek,
    read: scullv_read,
    write: scullv_write,
    ioctl: scullv_ioctl,
    mmap: scullv_mmap,
    open: scullv_open,
    release: scullv_release,
};

int scullv_trim(ScullV_Dev *dev)
{
    ScullV_Dev *next, *dptr;
    int qset = dev->qset;   /* "dev" is not-null */
    int i;

    if (dev->vmas) /* don't trim: there are active mappings */
        return -EBUSY;

    for (dptr = dev; dptr; dptr = next) { /* all the list items */
        if (dptr->data) {
            /* Release the quantum-set */
            for (i = 0; i < qset; i++)
                if (dptr->data[i])
                    vfree(dptr->data[i]);

            kfree(dptr->data);
            dptr->data=NULL;
        }
        next=dptr->next;
        if (dptr != dev) kfree(dptr); /* all of them but the first */
    }
    dev->size = 0;
    dev->qset = scullv_qset;
    dev->order = scullv_order;
    dev->next = NULL;
    return 0;
}




/*
 * Finally, the module stuff
 */

int scullv_init(void)
{
    int result, i;

    SET_MODULE_OWNER(&scullv_fops);
    /*
     * Register your major, and accept a dynamic number
     */
    result = register_chrdev(scullv_major, "scullv", &scullv_fops);
    if (result < 0) return result;
    if (scullv_major == 0) scullv_major = result; /* dynamic */

    /* 
     * allocate the devices -- we can't have them static, as the number
     * can be specified at load time
     */
    scullv_devices = kmalloc(scullv_devs * sizeof (ScullV_Dev), GFP_KERNEL);
    if (!scullv_devices) {
        result = -ENOMEM;
        goto fail_malloc;
    }
    memset(scullv_devices, 0, scullv_devs * sizeof (ScullV_Dev));
    for (i=0; i < scullv_devs; i++) {
        scullv_devices[i].order = scullv_order;
        scullv_devices[i].qset = scullv_qset;
        sema_init (&scullv_devices[i].sem, 1);
    }


#ifdef SCULLV_USE_PROC /* only when available */
    create_proc_read_entry("scullvmem", 0, NULL, scullv_read_procmem, NULL);
#endif
    return 0; /* succeed */

  fail_malloc:
    unregister_chrdev(scullv_major, "scullv");
    return result;
}

void scullv_cleanup(void)
{
    int i;
    unregister_chrdev(scullv_major, "scullv");

#ifdef SCULLV_USE_PROC
    remove_proc_entry("scullvmem", 0);
#endif

    for (i=0; i<scullv_devs; i++)
        scullv_trim(scullv_devices+i);
    kfree(scullv_devices);
}


module_init(scullv_init);
module_exit(scullv_cleanup);