ub.c

Linux块设备驱动源码

	bcb->Lun = (cmd->lun != NULL) ? cmd->lun->num : 0;
	bcb->Length = cmd->cdb_len;

	/* copy the command payload */
	memcpy(bcb->CDB, cmd->cdb, UB_MAX_CDB_SIZE);

	UB_INIT_COMPLETION(sc->work_done);

	sc->last_pipe = sc->send_bulk_pipe;
	usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->send_bulk_pipe,
	    bcb, US_BULK_CB_WRAP_LEN, ub_urb_complete, sc);

	/* Fill what we shouldn't be filling, because usb-storage did so. */
	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) {
		/* XXX Clear stalls */
		ub_complete(&sc->work_done);
		return rc;
	}

	sc->work_timer.expires = jiffies + UB_URB_TIMEOUT;
	add_timer(&sc->work_timer);

	cmd->state = UB_CMDST_CMD;
	ub_cmdtr_state(sc, cmd);
	return 0;
}

/*
 * Timeout handler.
 */
static void ub_urb_timeout(unsigned long arg)
{
	struct ub_dev *sc = (struct ub_dev *) arg;
	unsigned long flags;

	spin_lock_irqsave(&sc->lock, flags);
	usb_unlink_urb(&sc->work_urb);
	spin_unlock_irqrestore(&sc->lock, flags);
}

/*
 * Completion routine for the work URB.
 *
 * This can be called directly from usb_submit_urb (while we have
 * the sc->lock taken) and from an interrupt (while we do NOT have
 * the sc->lock taken). Therefore, bounce this off to a tasklet.
 */
static void ub_urb_complete(struct urb *urb, struct pt_regs *pt)
{
	struct ub_dev *sc = urb->context;

	ub_complete(&sc->work_done);
	tasklet_schedule(&sc->tasklet);
}

static void ub_scsi_action(unsigned long _dev)
{
	struct ub_dev *sc = (struct ub_dev *) _dev;
	unsigned long flags;

	spin_lock_irqsave(&sc->lock, flags);
	del_timer(&sc->work_timer);
	ub_scsi_dispatch(sc);
	spin_unlock_irqrestore(&sc->lock, flags);
}

static void ub_scsi_dispatch(struct ub_dev *sc)
{
	struct ub_scsi_cmd *cmd;
	int rc;

	while ((cmd = ub_cmdq_peek(sc)) != NULL) {
		if (cmd->state == UB_CMDST_DONE) {
			ub_cmdq_pop(sc);
			(*cmd->done)(sc, cmd);
		} else if (cmd->state == UB_CMDST_INIT) {
			ub_cmdtr_new(sc, cmd);
			if ((rc = ub_scsi_cmd_start(sc, cmd)) == 0)
				break;
			cmd->error = rc;
			cmd->state = UB_CMDST_DONE;
			ub_cmdtr_state(sc, cmd);
		} else {
			if (!ub_is_completed(&sc->work_done))
				break;
			ub_scsi_urb_compl(sc, cmd);
		}
	}
}

static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	struct urb *urb = &sc->work_urb;
	struct bulk_cs_wrap *bcs;
	int rc;

	if (atomic_read(&sc->poison)) {
		/* A little too simplistic, I feel... */
		goto Bad_End;
	}

	if (cmd->state == UB_CMDST_CLEAR) {
		if (urb->status == -EPIPE) {
			/*
			 * STALL while clearning STALL.
			 * The control pipe clears itself - nothing to do.
			 * XXX Might try to reset the device here and retry.
			 */
			printk(KERN_NOTICE "%s: stall on control pipe\n",
			    sc->name);
			goto Bad_End;
		}

		/*
		 * We ignore the result for the halt clear.
		 */

		/* reset the endpoint toggle */
		usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
			usb_pipeout(sc->last_pipe), 0);

		ub_state_sense(sc, cmd);

	} else if (cmd->state == UB_CMDST_CLR2STS) {
		if (urb->status == -EPIPE) {
			/*
			 * STALL while clearning STALL.
			 * The control pipe clears itself - nothing to do.
			 * XXX Might try to reset the device here and retry.
			 */
			printk(KERN_NOTICE "%s: stall on control pipe\n",
			    sc->name);
			goto Bad_End;
		}

		/*
		 * We ignore the result for the halt clear.
		 */

		/* reset the endpoint toggle */
		usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
			usb_pipeout(sc->last_pipe), 0);

		ub_state_stat(sc, cmd);

	} else if (cmd->state == UB_CMDST_CLRRS) {
		if (urb->status == -EPIPE) {
			/*
			 * STALL while clearning STALL.
			 * The control pipe clears itself - nothing to do.
			 * XXX Might try to reset the device here and retry.
			 */
			printk(KERN_NOTICE "%s: stall on control pipe\n",
			    sc->name);
			goto Bad_End;
		}

		/*
		 * We ignore the result for the halt clear.
		 */

		/* reset the endpoint toggle */
		usb_settoggle(sc->dev, usb_pipeendpoint(sc->last_pipe),
			usb_pipeout(sc->last_pipe), 0);

		ub_state_stat_counted(sc, cmd);

	} else if (cmd->state == UB_CMDST_CMD) {
		if (urb->status == -EPIPE) {
			rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
			if (rc != 0) {
				printk(KERN_NOTICE "%s: "
				    "unable to submit clear (%d)\n",
				    sc->name, rc);
				/*
				 * This is typically ENOMEM or some other such shit.
				 * Retrying is pointless. Just do Bad End on it...
				 */
				goto Bad_End;
			}
			cmd->state = UB_CMDST_CLEAR;
			ub_cmdtr_state(sc, cmd);
			return;
		}
		if (urb->status != 0) {
			goto Bad_End;
		}
		if (urb->actual_length != US_BULK_CB_WRAP_LEN) {
			/* XXX Must do reset here to unconfuse the device */
			goto Bad_End;
		}

		if (cmd->dir == UB_DIR_NONE || cmd->nsg < 1) {
			ub_state_stat(sc, cmd);
			return;
		}

		// udelay(125);		// usb-storage has this
		ub_data_start(sc, cmd);

	} else if (cmd->state == UB_CMDST_DATA) {
		if (urb->status == -EPIPE) {
			rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
			if (rc != 0) {
				printk(KERN_NOTICE "%s: "
				    "unable to submit clear (%d)\n",
				    sc->name, rc);
				/*
				 * This is typically ENOMEM or some other such shit.
				 * Retrying is pointless. Just do Bad End on it...
				 */
				goto Bad_End;
			}
			cmd->state = UB_CMDST_CLR2STS;
			ub_cmdtr_state(sc, cmd);
			return;
		}
		if (urb->status == -EOVERFLOW) {
			/*
			 * A babble? Failure, but we must transfer CSW now.
			 * XXX This is going to end in perpetual babble. Reset.
			 */
			cmd->error = -EOVERFLOW;	/* A cheap trick... */
			ub_state_stat(sc, cmd);
			return;
		}
		if (urb->status != 0)
			goto Bad_End;

		cmd->act_len += urb->actual_length;
		ub_cmdtr_act_len(sc, cmd);

		if (++cmd->current_sg < cmd->nsg) {
			ub_data_start(sc, cmd);
			return;
		}
		ub_state_stat(sc, cmd);

	} else if (cmd->state == UB_CMDST_STAT) {
		if (urb->status == -EPIPE) {
			rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
			if (rc != 0) {
				printk(KERN_NOTICE "%s: "
				    "unable to submit clear (%d)\n",
				    sc->name, rc);
				/*
				 * This is typically ENOMEM or some other such shit.
				 * Retrying is pointless. Just do Bad End on it...
				 */
				goto Bad_End;
			}

			/*
			 * Having a stall when getting CSW is an error, so
			 * make sure uppper levels are not oblivious to it.
			 */
			cmd->error = -EIO;		/* A cheap trick... */

			cmd->state = UB_CMDST_CLRRS;
			ub_cmdtr_state(sc, cmd);
			return;
		}
		if (urb->status == -EOVERFLOW) {
			/*
			 * XXX We are screwed here. Retrying is pointless,
			 * because the pipelined data will not get in until
			 * we read with a big enough buffer. We must reset XXX.
			 */
			goto Bad_End;
		}
		if (urb->status != 0)
			goto Bad_End;

		if (urb->actual_length == 0) {
			ub_state_stat_counted(sc, cmd);
			return;
		}

		/*
		 * Check the returned Bulk protocol status.
		 * The status block has to be validated first.
		 */

		bcs = &sc->work_bcs;

		if (sc->signature == cpu_to_le32(0)) {
			/*
			 * This is the first reply, so do not perform the check.
			 * Instead, remember the signature the device uses
			 * for future checks. But do not allow a nul.
			 */
			sc->signature = bcs->Signature;
			if (sc->signature == cpu_to_le32(0)) {
				ub_state_stat_counted(sc, cmd);
				return;
			}
		} else {
			if (bcs->Signature != sc->signature) {
				ub_state_stat_counted(sc, cmd);
				return;
			}
		}

		if (bcs->Tag != cmd->tag) {
			/*
			 * This usually happens when we disagree with the
			 * device's microcode about something. For instance,
			 * a few of them throw this after timeouts. They buffer
			 * commands and reply at commands we timed out before.
			 * Without flushing these replies we loop forever.
			 */
			ub_state_stat_counted(sc, cmd);
			return;
		}

		rc = le32_to_cpu(bcs->Residue);
		if (rc != cmd->len - cmd->act_len) {
			/*
			 * It is all right to transfer less, the caller has
			 * to check. But it's not all right if the device
			 * counts disagree with our counts.
			 */
			/* P3 */ printk("%s: resid %d len %d act %d\n",
			    sc->name, rc, cmd->len, cmd->act_len);
			goto Bad_End;
		}

		switch (bcs->Status) {
		case US_BULK_STAT_OK:
			break;
		case US_BULK_STAT_FAIL:
			ub_state_sense(sc, cmd);
			return;
		case US_BULK_STAT_PHASE:
			/* XXX We must reset the transport here */
			/* P3 */ printk("%s: status PHASE\n", sc->name);
			goto Bad_End;
		default:
			printk(KERN_INFO "%s: unknown CSW status 0x%x\n",
			    sc->name, bcs->Status);
			goto Bad_End;
		}

		/* Not zeroing error to preserve a babble indicator */
		if (cmd->error != 0) {
			ub_state_sense(sc, cmd);
			return;
		}
		cmd->state = UB_CMDST_DONE;
		ub_cmdtr_state(sc, cmd);
		ub_cmdq_pop(sc);
		(*cmd->done)(sc, cmd);

	} else if (cmd->state == UB_CMDST_SENSE) {
		ub_state_done(sc, cmd, -EIO);

	} else {
		printk(KERN_WARNING "%s: "
		    "wrong command state %d\n",
		    sc->name, cmd->state);
		goto Bad_End;
	}
	return;

Bad_End: /* Little Excel is dead */
	ub_state_done(sc, cmd, -EIO);
}

/*
 * Factorization helper for the command state machine:
 * Initiate a data segment transfer.
 */
static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	struct scatterlist *sg = &cmd->sgv[cmd->current_sg];
	int pipe;
	int rc;

	UB_INIT_COMPLETION(sc->work_done);

	if (cmd->dir == UB_DIR_READ)
		pipe = sc->recv_bulk_pipe;
	else
		pipe = sc->send_bulk_pipe;
	sc->last_pipe = pipe;
	usb_fill_bulk_urb(&sc->work_urb, sc->dev, pipe,
	    page_address(sg->page) + sg->offset, sg->length,
	    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) {
		/* XXX Clear stalls */
		ub_complete(&sc->work_done);
		ub_state_done(sc, cmd, rc);
		return;
	}

	sc->work_timer.expires = jiffies + UB_DATA_TIMEOUT;
	add_timer(&sc->work_timer);

	cmd->state = UB_CMDST_DATA;
	ub_cmdtr_state(sc, cmd);
}

/*
 * Factorization helper for the command state machine:
 * Finish the command.
 */
static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc)
{

	cmd->error = rc;
	cmd->state = UB_CMDST_DONE;
	ub_cmdtr_state(sc, cmd);
	ub_cmdq_pop(sc);
	(*cmd->done)(sc, cmd);
}

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read.
 */
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	int rc;

	UB_INIT_COMPLETION(sc->work_done);

	sc->last_pipe = sc->recv_bulk_pipe;
	usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->recv_bulk_pipe,
	    &sc->work_bcs, US_BULK_CS_WRAP_LEN, 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) {
		/* XXX Clear stalls */
		ub_complete(&sc->work_done);
		ub_state_done(sc, cmd, rc);
		return -1;
	}

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

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read and go to STAT state.
 */
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

	if (__ub_state_stat(sc, cmd) != 0)
		return;

	cmd->stat_count = 0;
	cmd->state = UB_CMDST_STAT;
	ub_cmdtr_state(sc, cmd);
}

/*
 * Factorization helper for the command state machine:
 * Submit a CSW read and go to STAT state with counter (along [C] path).
 */
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{

	if (++cmd->stat_count >= 4) {
		ub_state_sense(sc, cmd);
		return;
	}

	if (__ub_state_stat(sc, cmd) != 0)
		return;

	cmd->state = UB_CMDST_STAT;
	ub_cmdtr_state(sc, cmd);
}

/*
 * Factorization helper for the command state machine:
 * Submit a REQUEST SENSE and go to SENSE state.
 */
static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	struct ub_scsi_cmd *scmd;
	struct scatterlist *sg;
	int rc;

	if (cmd->cdb[0] == REQUEST_SENSE) {
		rc = -EPIPE;
		goto error;
	}