transport.c

底层驱动开发

	void *buf, unsigned int length, unsigned int *act_len)
{
	int result;

	US_DEBUGP("%s: xfer %u bytes\n", __FUNCTION__, length);

	/* fill and submit the URB */
	usb_fill_bulk_urb(us->current_urb, us->pusb_dev, pipe, buf, length,
		      usb_stor_blocking_completion, NULL);
	result = usb_stor_msg_common(us, 0);

	/* store the actual length of the data transferred */
	if (act_len)
		*act_len = us->current_urb->actual_length;
	return interpret_urb_result(us, pipe, length, result, 
			us->current_urb->actual_length);
}

/*
 * Transfer a scatter-gather list via bulk transfer
 *
 * This function does basically the same thing as usb_stor_bulk_transfer_buf()
 * above, but it uses the usbcore scatter-gather library.
 */
static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
		struct scatterlist *sg, int num_sg, unsigned int length,
		unsigned int *act_len)
{
	int result;

	/* don't submit s-g requests during abort/disconnect processing */
	if (us->flags & ABORTING_OR_DISCONNECTING)
		return USB_STOR_XFER_ERROR;

	/* initialize the scatter-gather request block */
	US_DEBUGP("%s: xfer %u bytes, %d entries\n", __FUNCTION__,
			length, num_sg);
	result = usb_sg_init(&us->current_sg, us->pusb_dev, pipe, 0,
			sg, num_sg, length, SLAB_NOIO);
	if (result) {
		US_DEBUGP("usb_sg_init returned %d\n", result);
		return USB_STOR_XFER_ERROR;
	}

	/* since the block has been initialized successfully, it's now
	 * okay to cancel it */
	set_bit(US_FLIDX_SG_ACTIVE, &us->flags);

	/* did an abort/disconnect occur during the submission? */
	if (us->flags & ABORTING_OR_DISCONNECTING) {

		/* cancel the request, if it hasn't been cancelled already */
		if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->flags)) {
			US_DEBUGP("-- cancelling sg request\n");
			usb_sg_cancel(&us->current_sg);
		}
	}

	/* wait for the completion of the transfer */
	usb_sg_wait(&us->current_sg);
	clear_bit(US_FLIDX_SG_ACTIVE, &us->flags);

	result = us->current_sg.status;
	if (act_len)
		*act_len = us->current_sg.bytes;
	return interpret_urb_result(us, pipe, length, result,
			us->current_sg.bytes);
}

/*
 * Transfer an entire SCSI command's worth of data payload over the bulk
 * pipe.
 *
 * Note that this uses usb_stor_bulk_transfer_buf() and
 * usb_stor_bulk_transfer_sglist() to achieve its goals --
 * this function simply determines whether we're going to use
 * scatter-gather or not, and acts appropriately.
 */
int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
		void *buf, unsigned int length_left, int use_sg, int *residual)
{
	int result;
	unsigned int partial;

	/* are we scatter-gathering? */
	if (use_sg) {
		/* use the usb core scatter-gather primitives */
		result = usb_stor_bulk_transfer_sglist(us, pipe,
				(struct scatterlist *) buf, use_sg,
				length_left, &partial);
		length_left -= partial;
	} else {
		/* no scatter-gather, just make the request */
		result = usb_stor_bulk_transfer_buf(us, pipe, buf, 
				length_left, &partial);
		length_left -= partial;
	}

	/* store the residual and return the error code */
	if (residual)
		*residual = length_left;
	return result;
}

/***********************************************************************
 * Transport routines
 ***********************************************************************/

/* Invoke the transport and basic error-handling/recovery methods
 *
 * This is used by the protocol layers to actually send the message to
 * the device and receive the response.
 */
void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	int need_auto_sense;
	int result;

	/* send the command to the transport layer */
	srb->resid = 0;
	result = us->transport(srb, us);

	/* if the command gets aborted by the higher layers, we need to
	 * short-circuit all other processing
	 */
	if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
		US_DEBUGP("-- command was aborted\n");
		srb->result = DID_ABORT << 16;
		goto Handle_Errors;
	}

	/* if there is a transport error, reset and don't auto-sense */
	if (result == USB_STOR_TRANSPORT_ERROR) {
		US_DEBUGP("-- transport indicates error, resetting\n");
		srb->result = DID_ERROR << 16;
		goto Handle_Errors;
	}

	/* if the transport provided its own sense data, don't auto-sense */
	if (result == USB_STOR_TRANSPORT_NO_SENSE) {
		srb->result = SAM_STAT_CHECK_CONDITION;
		return;
	}

	srb->result = SAM_STAT_GOOD;

	/* Determine if we need to auto-sense
	 *
	 * I normally don't use a flag like this, but it's almost impossible
	 * to understand what's going on here if I don't.
	 */
	need_auto_sense = 0;

	/*
	 * If we're running the CB transport, which is incapable
	 * of determining status on its own, we will auto-sense
	 * unless the operation involved a data-in transfer.  Devices
	 * can signal most data-in errors by stalling the bulk-in pipe.
	 */
	if ((us->protocol == US_PR_CB || us->protocol == US_PR_DPCM_USB) &&
			srb->sc_data_direction != DMA_FROM_DEVICE) {
		US_DEBUGP("-- CB transport device requiring auto-sense\n");
		need_auto_sense = 1;
	}

	/*
	 * If we have a failure, we're going to do a REQUEST_SENSE 
	 * automatically.  Note that we differentiate between a command
	 * "failure" and an "error" in the transport mechanism.
	 */
	if (result == USB_STOR_TRANSPORT_FAILED) {
		US_DEBUGP("-- transport indicates command failure\n");
		need_auto_sense = 1;
	}

	/*
	 * A short transfer on a command where we don't expect it
	 * is unusual, but it doesn't mean we need to auto-sense.
	 */
	if ((srb->resid > 0) &&
	    !((srb->cmnd[0] == REQUEST_SENSE) ||
	      (srb->cmnd[0] == INQUIRY) ||
	      (srb->cmnd[0] == MODE_SENSE) ||
	      (srb->cmnd[0] == LOG_SENSE) ||
	      (srb->cmnd[0] == MODE_SENSE_10))) {
		US_DEBUGP("-- unexpectedly short transfer\n");
	}

	/* Now, if we need to do the auto-sense, let's do it */
	if (need_auto_sense) {
		int temp_result;
		void* old_request_buffer;
		unsigned short old_sg;
		unsigned old_request_bufflen;
		unsigned char old_sc_data_direction;
		unsigned char old_cmd_len;
		unsigned char old_cmnd[MAX_COMMAND_SIZE];
		int old_resid;

		US_DEBUGP("Issuing auto-REQUEST_SENSE\n");

		/* save the old command */
		memcpy(old_cmnd, srb->cmnd, MAX_COMMAND_SIZE);
		old_cmd_len = srb->cmd_len;

		/* set the command and the LUN */
		memset(srb->cmnd, 0, MAX_COMMAND_SIZE);
		srb->cmnd[0] = REQUEST_SENSE;
		srb->cmnd[1] = old_cmnd[1] & 0xE0;
		srb->cmnd[4] = 18;

		/* FIXME: we must do the protocol translation here */
		if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI)
			srb->cmd_len = 6;
		else
			srb->cmd_len = 12;

		/* set the transfer direction */
		old_sc_data_direction = srb->sc_data_direction;
		srb->sc_data_direction = DMA_FROM_DEVICE;

		/* use the new buffer we have */
		old_request_buffer = srb->request_buffer;
		srb->request_buffer = srb->sense_buffer;

		/* set the buffer length for transfer */
		old_request_bufflen = srb->request_bufflen;
		srb->request_bufflen = 18;

		/* set up for no scatter-gather use */
		old_sg = srb->use_sg;
		srb->use_sg = 0;

		/* issue the auto-sense command */
		old_resid = srb->resid;
		srb->resid = 0;
		temp_result = us->transport(us->srb, us);

		/* let's clean up right away */
		srb->resid = old_resid;
		srb->request_buffer = old_request_buffer;
		srb->request_bufflen = old_request_bufflen;
		srb->use_sg = old_sg;
		srb->sc_data_direction = old_sc_data_direction;
		srb->cmd_len = old_cmd_len;
		memcpy(srb->cmnd, old_cmnd, MAX_COMMAND_SIZE);

		if (test_bit(US_FLIDX_TIMED_OUT, &us->flags)) {
			US_DEBUGP("-- auto-sense aborted\n");
			srb->result = DID_ABORT << 16;
			goto Handle_Errors;
		}
		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
			US_DEBUGP("-- auto-sense failure\n");

			/* we skip the reset if this happens to be a
			 * multi-target device, since failure of an
			 * auto-sense is perfectly valid
			 */
			srb->result = DID_ERROR << 16;
			if (!(us->flags & US_FL_SCM_MULT_TARG))
				goto Handle_Errors;
			return;
		}

		US_DEBUGP("-- Result from auto-sense is %d\n", temp_result);
		US_DEBUGP("-- code: 0x%x, key: 0x%x, ASC: 0x%x, ASCQ: 0x%x\n",
			  srb->sense_buffer[0],
			  srb->sense_buffer[2] & 0xf,
			  srb->sense_buffer[12], 
			  srb->sense_buffer[13]);
#ifdef CONFIG_USB_STORAGE_DEBUG
		usb_stor_show_sense(
			  srb->sense_buffer[2] & 0xf,
			  srb->sense_buffer[12], 
			  srb->sense_buffer[13]);
#endif

		/* set the result so the higher layers expect this data */
		srb->result = SAM_STAT_CHECK_CONDITION;

		/* If things are really okay, then let's show that.  Zero
		 * out the sense buffer so the higher layers won't realize
		 * we did an unsolicited auto-sense. */
		if (result == USB_STOR_TRANSPORT_GOOD &&
			/* Filemark 0, ignore EOM, ILI 0, no sense */
				(srb->sense_buffer[2] & 0xaf) == 0 &&
			/* No ASC or ASCQ */
				srb->sense_buffer[12] == 0 &&
				srb->sense_buffer[13] == 0) {
			srb->result = SAM_STAT_GOOD;
			srb->sense_buffer[0] = 0x0;
		}
	}

	/* Did we transfer less than the minimum amount required? */
	if (srb->result == SAM_STAT_GOOD &&
			srb->request_bufflen - srb->resid < srb->underflow)
		srb->result = (DID_ERROR << 16) | (SUGGEST_RETRY << 24);

	return;

	/* Error and abort processing: try to resynchronize with the device
	 * by issuing a port reset.  If that fails, try a class-specific
	 * device reset. */
  Handle_Errors:

	/* Let the SCSI layer know we are doing a reset, set the
	 * RESETTING bit, and clear the ABORTING bit so that the reset
	 * may proceed. */
	scsi_lock(us_to_host(us));
	usb_stor_report_bus_reset(us);
	set_bit(US_FLIDX_RESETTING, &us->flags);
	clear_bit(US_FLIDX_ABORTING, &us->flags);
	scsi_unlock(us_to_host(us));

	result = usb_stor_port_reset(us);
	if (result < 0) {
		scsi_lock(us_to_host(us));
		usb_stor_report_device_reset(us);
		scsi_unlock(us_to_host(us));
		us->transport_reset(us);
	}
	clear_bit(US_FLIDX_RESETTING, &us->flags);
}

/* Stop the current URB transfer */
void usb_stor_stop_transport(struct us_data *us)
{
	US_DEBUGP("%s called\n", __FUNCTION__);

	/* If the state machine is blocked waiting for an URB,
	 * let's wake it up.  The test_and_clear_bit() call
	 * guarantees that if a URB has just been submitted,
	 * it won't be cancelled more than once. */
	if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->flags)) {
		US_DEBUGP("-- cancelling URB\n");
		usb_unlink_urb(us->current_urb);
	}

	/* If we are waiting for a scatter-gather operation, cancel it. */
	if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->flags)) {
		US_DEBUGP("-- cancelling sg request\n");
		usb_sg_cancel(&us->current_sg);
	}
}

/*
 * Control/Bulk/Interrupt transport
 */

int usb_stor_CBI_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	unsigned int transfer_length = srb->request_bufflen;
	unsigned int pipe = 0;
	int result;

	/* COMMAND STAGE */
	/* let's send the command via the control pipe */
	result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
				      US_CBI_ADSC, 
				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
				      us->ifnum, srb->cmnd, srb->cmd_len);

	/* check the return code for the command */
	US_DEBUGP("Call to usb_stor_ctrl_transfer() returned %d\n", result);

	/* if we stalled the command, it means command failed */
	if (result == USB_STOR_XFER_STALLED) {
		return USB_STOR_TRANSPORT_FAILED;
	}

	/* Uh oh... serious problem here */
	if (result != USB_STOR_XFER_GOOD) {
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* DATA STAGE */
	/* transfer the data payload for this command, if one exists*/
	if (transfer_length) {
		pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
				us->recv_bulk_pipe : us->send_bulk_pipe;
		result = usb_stor_bulk_transfer_sg(us, pipe,
					srb->request_buffer, transfer_length,
					srb->use_sg, &srb->resid);
		US_DEBUGP("CBI data stage result is 0x%x\n", result);

		/* if we stalled the data transfer it means command failed */
		if (result == USB_STOR_XFER_STALLED)
			return USB_STOR_TRANSPORT_FAILED;
		if (result > USB_STOR_XFER_STALLED)
			return USB_STOR_TRANSPORT_ERROR;
	}

	/* STATUS STAGE */
	result = usb_stor_intr_transfer(us, us->iobuf, 2);
	US_DEBUGP("Got interrupt data (0x%x, 0x%x)\n", 
			us->iobuf[0], us->iobuf[1]);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* UFI gives us ASC and ASCQ, like a request sense
	 *
	 * REQUEST_SENSE and INQUIRY don't affect the sense data on UFI
	 * devices, so we ignore the information for those commands.  Note
	 * that this means we could be ignoring a real error on these
	 * commands, but that can't be helped.
	 */
	if (us->subclass == US_SC_UFI) {
		if (srb->cmnd[0] == REQUEST_SENSE ||
		    srb->cmnd[0] == INQUIRY)
			return USB_STOR_TRANSPORT_GOOD;
		if (us->iobuf[0])
			goto Failed;
		return USB_STOR_TRANSPORT_GOOD;