sysfs: add sysfs_bin_read()

	return 0;

}

/*

 * Read method for bin files.  As reading a bin file can have side-effects,

 * the exact offset and bytes specified in read(2) call should be passed to

 * the read callback making it difficult to use seq_file.  Implement

 * simplistic custom buffering for bin files.

 */

static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,

			      size_t bytes, loff_t *off)

{

	struct sysfs_open_file *of = sysfs_of(file);

	struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr;

	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;

	int size = file_inode(file)->i_size;

	int count = min_t(size_t, bytes, PAGE_SIZE);

	loff_t offs = *off;

	char *buf;

	if (!bytes)

		return 0;

	if (size) {

		if (offs > size)

			return 0;

		if (offs + count > size)

			count = size - offs;

	}

	buf = kmalloc(count, GFP_KERNEL);

	if (!buf)

		return -ENOMEM;

	/* need of->sd for battr, its parent for kobj */

	mutex_lock(&of->mutex);

	if (!sysfs_get_active(of->sd)) {

		count = -ENODEV;

		mutex_unlock(&of->mutex);

		goto out_free;

	}

	if (battr->read)

		count = battr->read(file, kobj, battr, buf, offs, count);

	else

		count = -EIO;

	sysfs_put_active(of->sd);

	mutex_unlock(&of->mutex);

	if (count < 0)

		goto out_free;

	if (copy_to_user(userbuf, buf, count)) {

		count = -EFAULT;

		goto out_free;

	}

	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);

	*off = offs + count;

 out_free:

	kfree(buf);

	return count;

}

/**

 * flush_write_buffer - push buffer to kobject

 * @of: open file

};

const struct file_operations sysfs_bin_operations = {

	.read		= sysfs_bin_read,

	.write		= sysfs_write_file,

	.llseek		= generic_file_llseek,

};