transport.c

底层驱动开发

	}

	/* If not UFI, we interpret the data as a result code 
	 * The first byte should always be a 0x0.
	 *
	 * Some bogus devices don't follow that rule.  They stuff the ASC
	 * into the first byte -- so if it's non-zero, call it a failure.
	 */
	if (us->iobuf[0]) {
		US_DEBUGP("CBI IRQ data showed reserved bType 0x%x\n",
				us->iobuf[0]);
		goto Failed;

	}

	/* The second byte & 0x0F should be 0x0 for good, otherwise error */
	switch (us->iobuf[1] & 0x0F) {
		case 0x00: 
			return USB_STOR_TRANSPORT_GOOD;
		case 0x01: 
			goto Failed;
	}
	return USB_STOR_TRANSPORT_ERROR;

	/* the CBI spec requires that the bulk pipe must be cleared
	 * following any data-in/out command failure (section 2.4.3.1.3)
	 */
  Failed:
	if (pipe)
		usb_stor_clear_halt(us, pipe);
	return USB_STOR_TRANSPORT_FAILED;
}

/*
 * Control/Bulk transport
 */
int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	unsigned int transfer_length = srb->request_bufflen;
	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) {
		unsigned int 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("CB 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 */
	/* NOTE: CB does not have a status stage.  Silly, I know.  So
	 * we have to catch this at a higher level.
	 */
	return USB_STOR_TRANSPORT_GOOD;
}

/*
 * Bulk only transport
 */

/* Determine what the maximum LUN supported is */
int usb_stor_Bulk_max_lun(struct us_data *us)
{
	int result;

	/* issue the command */
	result = usb_stor_control_msg(us, us->recv_ctrl_pipe,
				 US_BULK_GET_MAX_LUN, 
				 USB_DIR_IN | USB_TYPE_CLASS | 
				 USB_RECIP_INTERFACE,
				 0, us->ifnum, us->iobuf, 1, HZ);

	US_DEBUGP("GetMaxLUN command result is %d, data is %d\n", 
		  result, us->iobuf[0]);

	/* if we have a successful request, return the result */
	if (result > 0)
		return us->iobuf[0];

	/* 
	 * Some devices (i.e. Iomega Zip100) need this -- apparently
	 * the bulk pipes get STALLed when the GetMaxLUN request is
	 * processed.   This is, in theory, harmless to all other devices
	 * (regardless of if they stall or not).
	 */
	if (result == -EPIPE) {
		usb_stor_clear_halt(us, us->recv_bulk_pipe);
		usb_stor_clear_halt(us, us->send_bulk_pipe);
	}

	/*
	 * Some devices don't like GetMaxLUN.  They may STALL the control
	 * pipe, they may return a zero-length result, they may do nothing at
	 * all and timeout, or they may fail in even more bizarrely creative
	 * ways.  In these cases the best approach is to use the default
	 * value: only one LUN.
	 */
	return 0;
}

int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *) us->iobuf;
	struct bulk_cs_wrap *bcs = (struct bulk_cs_wrap *) us->iobuf;
	unsigned int transfer_length = srb->request_bufflen;
	unsigned int residue;
	int result;
	int fake_sense = 0;
	unsigned int cswlen;
	unsigned int cbwlen = US_BULK_CB_WRAP_LEN;

	/* Take care of BULK32 devices; set extra byte to 0 */
	if ( unlikely(us->flags & US_FL_BULK32)) {
		cbwlen = 32;
		us->iobuf[31] = 0;
	}

	/* set up the command wrapper */
	bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
	bcb->DataTransferLength = cpu_to_le32(transfer_length);
	bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ? 1 << 7 : 0;
	bcb->Tag = ++us->tag;
	bcb->Lun = srb->device->lun;
	if (us->flags & US_FL_SCM_MULT_TARG)
		bcb->Lun |= srb->device->id << 4;
	bcb->Length = srb->cmd_len;

	/* copy the command payload */
	memset(bcb->CDB, 0, sizeof(bcb->CDB));
	memcpy(bcb->CDB, srb->cmnd, bcb->Length);

	/* send it to out endpoint */
	US_DEBUGP("Bulk Command S 0x%x T 0x%x L %d F %d Trg %d LUN %d CL %d\n",
			le32_to_cpu(bcb->Signature), bcb->Tag,
			le32_to_cpu(bcb->DataTransferLength), bcb->Flags,
			(bcb->Lun >> 4), (bcb->Lun & 0x0F), 
			bcb->Length);
	result = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
				bcb, cbwlen, NULL);
	US_DEBUGP("Bulk command transfer result=%d\n", result);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* DATA STAGE */
	/* send/receive data payload, if there is any */

	/* Some USB-IDE converter chips need a 100us delay between the
	 * command phase and the data phase.  Some devices need a little
	 * more than that, probably because of clock rate inaccuracies. */
	if (unlikely(us->flags & US_FL_GO_SLOW))
		udelay(125);

	if (transfer_length) {
		unsigned int 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("Bulk data transfer result 0x%x\n", result);
		if (result == USB_STOR_XFER_ERROR)
			return USB_STOR_TRANSPORT_ERROR;

		/* If the device tried to send back more data than the
		 * amount requested, the spec requires us to transfer
		 * the CSW anyway.  Since there's no point retrying the
		 * the command, we'll return fake sense data indicating
		 * Illegal Request, Invalid Field in CDB.
		 */
		if (result == USB_STOR_XFER_LONG)
			fake_sense = 1;
	}

	/* See flow chart on pg 15 of the Bulk Only Transport spec for
	 * an explanation of how this code works.
	 */

	/* get CSW for device status */
	US_DEBUGP("Attempting to get CSW...\n");
	result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, &cswlen);

	/* Some broken devices add unnecessary zero-length packets to the
	 * end of their data transfers.  Such packets show up as 0-length
	 * CSWs.  If we encounter such a thing, try to read the CSW again.
	 */
	if (result == USB_STOR_XFER_SHORT && cswlen == 0) {
		US_DEBUGP("Received 0-length CSW; retrying...\n");
		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
	}

	/* did the attempt to read the CSW fail? */
	if (result == USB_STOR_XFER_STALLED) {

		/* get the status again */
		US_DEBUGP("Attempting to get CSW (2nd try)...\n");
		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, NULL);
	}

	/* if we still have a failure at this point, we're in trouble */
	US_DEBUGP("Bulk status result = %d\n", result);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* check bulk status */
	residue = le32_to_cpu(bcs->Residue);
	US_DEBUGP("Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
			le32_to_cpu(bcs->Signature), bcs->Tag, 
			residue, bcs->Status);
	if (bcs->Tag != us->tag || bcs->Status > US_BULK_STAT_PHASE) {
		US_DEBUGP("Bulk logical error\n");
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* Some broken devices report odd signatures, so we do not check them
	 * for validity against the spec. We store the first one we see,
	 * and check subsequent transfers for validity against this signature.
	 */
	if (!us->bcs_signature) {
		us->bcs_signature = bcs->Signature;
		if (us->bcs_signature != cpu_to_le32(US_BULK_CS_SIGN))
			US_DEBUGP("Learnt BCS signature 0x%08X\n",
					le32_to_cpu(us->bcs_signature));
	} else if (bcs->Signature != us->bcs_signature) {
		US_DEBUGP("Signature mismatch: got %08X, expecting %08X\n",
			  le32_to_cpu(bcs->Signature),
			  le32_to_cpu(us->bcs_signature));
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* try to compute the actual residue, based on how much data
	 * was really transferred and what the device tells us */
	if (residue) {
		if (!(us->flags & US_FL_IGNORE_RESIDUE)) {
			residue = min(residue, transfer_length);
			srb->resid = max(srb->resid, (int) residue);
		}
	}

	/* based on the status code, we report good or bad */
	switch (bcs->Status) {
		case US_BULK_STAT_OK:
			/* device babbled -- return fake sense data */
			if (fake_sense) {
				memcpy(srb->sense_buffer, 
				       usb_stor_sense_invalidCDB, 
				       sizeof(usb_stor_sense_invalidCDB));
				return USB_STOR_TRANSPORT_NO_SENSE;
			}

			/* command good -- note that data could be short */
			return USB_STOR_TRANSPORT_GOOD;

		case US_BULK_STAT_FAIL:
			/* command failed */
			return USB_STOR_TRANSPORT_FAILED;

		case US_BULK_STAT_PHASE:
			/* phase error -- note that a transport reset will be
			 * invoked by the invoke_transport() function
			 */
			return USB_STOR_TRANSPORT_ERROR;
	}

	/* we should never get here, but if we do, we're in trouble */
	return USB_STOR_TRANSPORT_ERROR;
}

/***********************************************************************
 * Reset routines
 ***********************************************************************/

/* This is the common part of the device reset code.
 *
 * It's handy that every transport mechanism uses the control endpoint for
 * resets.
 *
 * Basically, we send a reset with a 5-second timeout, so we don't get
 * jammed attempting to do the reset.
 */
static int usb_stor_reset_common(struct us_data *us,
		u8 request, u8 requesttype,
		u16 value, u16 index, void *data, u16 size)
{
	int result;
	int result2;

	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
		US_DEBUGP("No reset during disconnect\n");
		return -EIO;
	}

	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
			request, requesttype, value, index, data, size,
			5*HZ);
	if (result < 0) {
		US_DEBUGP("Soft reset failed: %d\n", result);
		return result;
	}

 	/* Give the device some time to recover from the reset,
 	 * but don't delay disconnect processing. */
 	wait_event_interruptible_timeout(us->delay_wait,
 			test_bit(US_FLIDX_DISCONNECTING, &us->flags),
 			HZ*6);
	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
		US_DEBUGP("Reset interrupted by disconnect\n");
		return -EIO;
	}

	US_DEBUGP("Soft reset: clearing bulk-in endpoint halt\n");
	result = usb_stor_clear_halt(us, us->recv_bulk_pipe);

	US_DEBUGP("Soft reset: clearing bulk-out endpoint halt\n");
	result2 = usb_stor_clear_halt(us, us->send_bulk_pipe);

	/* return a result code based on the result of the clear-halts */
	if (result >= 0)
		result = result2;
	if (result < 0)
		US_DEBUGP("Soft reset failed\n");
	else
		US_DEBUGP("Soft reset done\n");
	return result;
}

/* This issues a CB[I] Reset to the device in question
 */
#define CB_RESET_CMD_SIZE	12

int usb_stor_CB_reset(struct us_data *us)
{
	US_DEBUGP("%s called\n", __FUNCTION__);

	memset(us->iobuf, 0xFF, CB_RESET_CMD_SIZE);
	us->iobuf[0] = SEND_DIAGNOSTIC;
	us->iobuf[1] = 4;
	return usb_stor_reset_common(us, US_CBI_ADSC, 
				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
				 0, us->ifnum, us->iobuf, CB_RESET_CMD_SIZE);
}

/* This issues a Bulk-only Reset to the device in question, including
 * clearing the subsequent endpoint halts that may occur.
 */
int usb_stor_Bulk_reset(struct us_data *us)
{
	US_DEBUGP("%s called\n", __FUNCTION__);

	return usb_stor_reset_common(us, US_BULK_RESET_REQUEST, 
				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
				 0, us->ifnum, NULL, 0);
}

/* Issue a USB port reset to the device.  But don't do anything if
 * there's more than one interface in the device, so that other users
 * are not affected. */
int usb_stor_port_reset(struct us_data *us)
{
	int result, rc;

	if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
		result = -EIO;
		US_DEBUGP("No reset during disconnect\n");
	} else if (us->pusb_dev->actconfig->desc.bNumInterfaces != 1) {
		result = -EBUSY;
		US_DEBUGP("Refusing to reset a multi-interface device\n");
	} else {
		result = rc =
			usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
		if (result < 0) {
			US_DEBUGP("unable to lock device for reset: %d\n",
					result);
		} else {
			result = usb_reset_device(us->pusb_dev);
			if (rc)
				usb_unlock_device(us->pusb_dev);
			US_DEBUGP("usb_reset_device returns %d\n", result);
		}
	}
	return result;
}