ub.c

Linux块设备驱动源码

	scmd = &sc->top_rqs_cmd;
	memset(scmd, 0, sizeof(struct ub_scsi_cmd));
	scmd->cdb[0] = REQUEST_SENSE;
	scmd->cdb[4] = UB_SENSE_SIZE;
	scmd->cdb_len = 6;
	scmd->dir = UB_DIR_READ;
	scmd->state = UB_CMDST_INIT;
	scmd->nsg = 1;
	sg = &scmd->sgv[0];
	sg->page = virt_to_page(sc->top_sense);
	sg->offset = (unsigned int)sc->top_sense & (PAGE_SIZE-1);
	sg->length = UB_SENSE_SIZE;
	scmd->len = UB_SENSE_SIZE;
	scmd->lun = cmd->lun;
	scmd->done = ub_top_sense_done;
	scmd->back = cmd;

	scmd->tag = sc->tagcnt++;

	cmd->state = UB_CMDST_SENSE;
	ub_cmdtr_state(sc, cmd);

	ub_cmdq_insert(sc, scmd);
	return;

error:
	ub_state_done(sc, cmd, rc);
}

/*
 * A helper for the command's state machine:
 * Submit a stall clear.
 */
static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
    int stalled_pipe)
{
	int endp;
	struct usb_ctrlrequest *cr;
	int rc;

	endp = usb_pipeendpoint(stalled_pipe);
	if (usb_pipein (stalled_pipe))
		endp |= USB_DIR_IN;

	cr = &sc->work_cr;
	cr->bRequestType = USB_RECIP_ENDPOINT;
	cr->bRequest = USB_REQ_CLEAR_FEATURE;
	cr->wValue = cpu_to_le16(USB_ENDPOINT_HALT);
	cr->wIndex = cpu_to_le16(endp);
	cr->wLength = cpu_to_le16(0);

	UB_INIT_COMPLETION(sc->work_done);

	usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
	    (unsigned char*) cr, NULL, 0, ub_urb_complete, sc);
	sc->work_urb.actual_length = 0;
	sc->work_urb.error_count = 0;
	sc->work_urb.status = 0;

	if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
		ub_complete(&sc->work_done);
		return rc;
	}

	sc->work_timer.expires = jiffies + UB_CTRL_TIMEOUT;
	add_timer(&sc->work_timer);
	return 0;
}

/*
 */
static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd)
{
	unsigned char *sense = sc->top_sense;
	struct ub_scsi_cmd *cmd;

	/*
	 * Ignoring scmd->act_len, because the buffer was pre-zeroed.
	 */
	ub_cmdtr_sense(sc, scmd, sense);

	/*
	 * Find the command which triggered the unit attention or a check,
	 * save the sense into it, and advance its state machine.
	 */
	if ((cmd = ub_cmdq_peek(sc)) == NULL) {
		printk(KERN_WARNING "%s: sense done while idle\n", sc->name);
		return;
	}
	if (cmd != scmd->back) {
		printk(KERN_WARNING "%s: "
		    "sense done for wrong command 0x%x\n",
		    sc->name, cmd->tag);
		return;
	}
	if (cmd->state != UB_CMDST_SENSE) {
		printk(KERN_WARNING "%s: "
		    "sense done with bad cmd state %d\n",
		    sc->name, cmd->state);
		return;
	}

	cmd->key = sense[2] & 0x0F;
	cmd->asc = sense[12];
	cmd->ascq = sense[13];

	ub_scsi_urb_compl(sc, cmd);
}

/*
 * This is called from a process context.
 */
static void ub_revalidate(struct ub_dev *sc, struct ub_lun *lun)
{

	lun->readonly = 0;	/* XXX Query this from the device */

	lun->capacity.nsec = 0;
	lun->capacity.bsize = 512;
	lun->capacity.bshift = 0;

	if (ub_sync_tur(sc, lun) != 0)
		return;			/* Not ready */
	lun->changed = 0;

	if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
		/*
		 * The retry here means something is wrong, either with the
		 * device, with the transport, or with our code.
		 * We keep this because sd.c has retries for capacity.
		 */
		if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
			lun->capacity.nsec = 0;
			lun->capacity.bsize = 512;
			lun->capacity.bshift = 0;
		}
	}
}

/*
 * The open funcion.
 * This is mostly needed to keep refcounting, but also to support
 * media checks on removable media drives.
 */
static int ub_bd_open(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ub_lun *lun;
	struct ub_dev *sc;
	unsigned long flags;
	int rc;

	if ((lun = disk->private_data) == NULL)
		return -ENXIO;
	sc = lun->udev;

	spin_lock_irqsave(&ub_lock, flags);
	if (atomic_read(&sc->poison)) {
		spin_unlock_irqrestore(&ub_lock, flags);
		return -ENXIO;
	}
	sc->openc++;
	spin_unlock_irqrestore(&ub_lock, flags);

	/*
	 * This is a workaround for a specific problem in our block layer.
	 * In 2.6.9, register_disk duplicates the code from rescan_partitions.
	 * However, if we do add_disk with a device which persistently reports
	 * a changed media, add_disk calls register_disk, which does do_open,
	 * which will call rescan_paritions for changed media. After that,
	 * register_disk attempts to do it all again and causes double kobject
	 * registration and a eventually an oops on module removal.
	 *
	 * The bottom line is, Al Viro says that we should not allow
	 * bdev->bd_invalidated to be set when doing add_disk no matter what.
	 */
	if (lun->first_open) {
		lun->first_open = 0;
		if (lun->changed) {
			rc = -ENOMEDIUM;
			goto err_open;
		}
	}

	if (lun->removable || lun->readonly)
		check_disk_change(inode->i_bdev);

	/*
	 * The sd.c considers ->media_present and ->changed not equivalent,
	 * under some pretty murky conditions (a failure of READ CAPACITY).
	 * We may need it one day.
	 */
	if (lun->removable && lun->changed && !(filp->f_flags & O_NDELAY)) {
		rc = -ENOMEDIUM;
		goto err_open;
	}

	if (lun->readonly && (filp->f_mode & FMODE_WRITE)) {
		rc = -EROFS;
		goto err_open;
	}

	return 0;

err_open:
	ub_put(sc);
	return rc;
}

/*
 */
static int ub_bd_release(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ub_lun *lun = disk->private_data;
	struct ub_dev *sc = lun->udev;

	ub_put(sc);
	return 0;
}

/*
 * The ioctl interface.
 */
static int ub_bd_ioctl(struct inode *inode, struct file *filp,
    unsigned int cmd, unsigned long arg)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	void __user *usermem = (void __user *) arg;

	return scsi_cmd_ioctl(filp, disk, cmd, usermem);
}

/*
 * This is called once a new disk was seen by the block layer or by ub_probe().
 * The main onjective here is to discover the features of the media such as
 * the capacity, read-only status, etc. USB storage generally does not
 * need to be spun up, but if we needed it, this would be the place.
 *
 * This call can sleep.
 *
 * The return code is not used.
 */
static int ub_bd_revalidate(struct gendisk *disk)
{
	struct ub_lun *lun = disk->private_data;

	ub_revalidate(lun->udev, lun);

	/* XXX Support sector size switching like in sr.c */
	blk_queue_hardsect_size(disk->queue, lun->capacity.bsize);
	set_capacity(disk, lun->capacity.nsec);
	// set_disk_ro(sdkp->disk, lun->readonly);

	return 0;
}

/*
 * The check is called by the block layer to verify if the media
 * is still available. It is supposed to be harmless, lightweight and
 * non-intrusive in case the media was not changed.
 *
 * This call can sleep.
 *
 * The return code is bool!
 */
static int ub_bd_media_changed(struct gendisk *disk)
{
	struct ub_lun *lun = disk->private_data;

	if (!lun->removable)
		return 0;

	/*
	 * We clean checks always after every command, so this is not
	 * as dangerous as it looks. If the TEST_UNIT_READY fails here,
	 * the device is actually not ready with operator or software
	 * intervention required. One dangerous item might be a drive which
	 * spins itself down, and come the time to write dirty pages, this
	 * will fail, then block layer discards the data. Since we never
	 * spin drives up, such devices simply cannot be used with ub anyway.
	 */
	if (ub_sync_tur(lun->udev, lun) != 0) {
		lun->changed = 1;
		return 1;
	}

	return lun->changed;
}

static struct block_device_operations ub_bd_fops = {
	.owner		= THIS_MODULE,
	.open		= ub_bd_open,
	.release	= ub_bd_release,
	.ioctl		= ub_bd_ioctl,
	.media_changed	= ub_bd_media_changed,
	.revalidate_disk = ub_bd_revalidate,
};

/*
 * Common ->done routine for commands executed synchronously.
 */
static void ub_probe_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	struct completion *cop = cmd->back;
	complete(cop);
}

/*
 * Test if the device has a check condition on it, synchronously.
 */
static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun)
{
	struct ub_scsi_cmd *cmd;
	enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) };
	unsigned long flags;
	struct completion compl;
	int rc;

	init_completion(&compl);

	rc = -ENOMEM;
	if ((cmd = kmalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
		goto err_alloc;
	memset(cmd, 0, ALLOC_SIZE);

	cmd->cdb[0] = TEST_UNIT_READY;
	cmd->cdb_len = 6;
	cmd->dir = UB_DIR_NONE;
	cmd->state = UB_CMDST_INIT;
	cmd->lun = lun;			/* This may be NULL, but that's ok */
	cmd->done = ub_probe_done;
	cmd->back = &compl;

	spin_lock_irqsave(&sc->lock, flags);
	cmd->tag = sc->tagcnt++;

	rc = ub_submit_scsi(sc, cmd);
	spin_unlock_irqrestore(&sc->lock, flags);

	if (rc != 0) {
		printk("ub: testing ready: submit error (%d)\n", rc); /* P3 */
		goto err_submit;
	}

	wait_for_completion(&compl);

	rc = cmd->error;

	if (rc == -EIO && cmd->key != 0)	/* Retries for benh's key */
		rc = cmd->key;

err_submit:
	kfree(cmd);
err_alloc:
	return rc;
}

/*
 * Read the SCSI capacity synchronously (for probing).
 */
static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_capacity *ret)
{
	struct ub_scsi_cmd *cmd;
	struct scatterlist *sg;
	char *p;
	enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) + 8 };
	unsigned long flags;
	unsigned int bsize, shift;
	unsigned long nsec;
	struct completion compl;
	int rc;

	init_completion(&compl);

	rc = -ENOMEM;
	if ((cmd = kmalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
		goto err_alloc;
	memset(cmd, 0, ALLOC_SIZE);
	p = (char *)cmd + sizeof(struct ub_scsi_cmd);

	cmd->cdb[0] = 0x25;
	cmd->cdb_len = 10;
	cmd->dir = UB_DIR_READ;
	cmd->state = UB_CMDST_INIT;
	cmd->nsg = 1;
	sg = &cmd->sgv[0];
	sg->page = virt_to_page(p);
	sg->offset = (unsigned int)p & (PAGE_SIZE-1);
	sg->length = 8;
	cmd->len = 8;
	cmd->lun = lun;
	cmd->done = ub_probe_done;
	cmd->back = &compl;

	spin_lock_irqsave(&sc->lock, flags);
	cmd->tag = sc->tagcnt++;

	rc = ub_submit_scsi(sc, cmd);
	spin_unlock_irqrestore(&sc->lock, flags);

	if (rc != 0) {
		printk("ub: reading capacity: submit error (%d)\n", rc); /* P3 */
		goto err_submit;
	}

	wait_for_completion(&compl);

	if (cmd->error != 0) {
		printk("ub: reading capacity: error %d\n", cmd->error); /* P3 */
		rc = -EIO;
		goto err_read;
	}
	if (cmd->act_len != 8) {
		printk("ub: reading capacity: size %d\n", cmd->act_len); /* P3 */
		rc = -EIO;
		goto err_read;
	}

	/* sd.c special-cases sector size of 0 to mean 512. Needed? Safe? */
	nsec = be32_to_cpu(*(__be32 *)p) + 1;
	bsize = be32_to_cpu(*(__be32 *)(p + 4));
	switch (bsize) {
	case 512:	shift = 0;	break;
	case 1024:	shift = 1;	break;
	case 2048:	shift = 2;	break;
	case 4096:	shift = 3;	break;
	default:
		printk("ub: Bad sector size %u\n", bsize); /* P3 */
		rc = -EDOM;
		goto err_inv_bsize;
	}

	ret->bsize = bsize;
	ret->bshift = shift;
	ret->nsec = nsec << shift;
	rc = 0;

err_inv_bsize:
err_read:
err_submit:
	kfree(cmd);
err_alloc:
	return rc;
}

/*
 */
static void ub_probe_urb_complete(struct urb *urb, struct pt_regs *pt)
{
	struct completion *cop = urb->context;
	complete(cop);
}

static void ub_probe_timeout(unsigned long arg)
{
	struct completion *cop = (struct completion *) arg;
	complete(cop);
}

/*
 * Get number of LUNs by the way of Bulk GetMaxLUN command.
 */
static int ub_sync_getmaxlun(struct ub_dev *sc)
{
	int ifnum = sc->intf->cur_altsetting->desc.bInterfaceNumber;
	unsigned char *p;
	enum { ALLOC_SIZE = 1 };
	struct usb_ctrlrequest *cr;
	struct completion compl;
	struct timer_list timer;
	int nluns;
	int rc;

	init_completion(&compl);

	rc = -ENOMEM;
	if ((p = kmalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
		goto err_alloc;
	*p = 55;

	cr = &sc->work_cr;
	cr->bRequestType = USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE;
	cr->bRequest = US_BULK_GET_MAX_LUN;
	cr->wValue = cpu_to_le16(0);
	cr->wIndex = cpu_to_le16(ifnum);
	cr->wLength = cpu_to_le16(1);

	usb_fill_control_urb(&sc->work_urb, sc->dev, sc->recv_ctrl_pipe,
	    (unsigned char*) cr, p, 1, ub_probe_urb_complete, &compl);
	sc->work_urb.actual_length = 0;
	sc->work_urb.error_count = 0;
	sc->work_urb.status = 0;

	if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0) {
		if (rc == -EPIPE) {
			printk("%s: Stall submitting GetMaxLUN, using 1 LUN\n",
			     sc->name); /* P3 */
		} else {