drivers/usb/storage/transport.c

Source file repositories/reference/linux-study-clean/drivers/usb/storage/transport.c

File Facts

System
Linux kernel
Corpus path
drivers/usb/storage/transport.c
Extension
.c
Size
45105 bytes
Lines
1463
Domain
Driver Families
Bucket
drivers/usb
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
			usb_stor_dbg(us, "-- cancelling URB\n");
			usb_unlink_urb(us->current_urb);
		}
	}
 
	/* wait for the completion of the URB */
	timeleft = wait_for_completion_interruptible_timeout(
			&urb_done, timeout ? : MAX_SCHEDULE_TIMEOUT);
 
	clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags);

	if (timeleft <= 0) {
		usb_stor_dbg(us, "%s -- cancelling URB\n",
			     timeleft == 0 ? "Timeout" : "Signal");
		usb_kill_urb(us->current_urb);
	}

	/* return the URB status */
	return us->current_urb->status;
}

/*
 * Transfer one control message, with timeouts, and allowing early
 * termination.  Return codes are usual -Exxx, *not* USB_STOR_XFER_xxx.
 */
int usb_stor_control_msg(struct us_data *us, unsigned int pipe,
		 u8 request, u8 requesttype, u16 value, u16 index, 
		 void *data, u16 size, int timeout)
{
	int status;

	usb_stor_dbg(us, "rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
		     request, requesttype, value, index, size);

	/* fill in the devrequest structure */
	us->cr->bRequestType = requesttype;
	us->cr->bRequest = request;
	us->cr->wValue = cpu_to_le16(value);
	us->cr->wIndex = cpu_to_le16(index);
	us->cr->wLength = cpu_to_le16(size);

	/* fill and submit the URB */
	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe, 
			 (unsigned char*) us->cr, data, size, 
			 usb_stor_blocking_completion, NULL);
	status = usb_stor_msg_common(us, timeout);

	/* return the actual length of the data transferred if no error */
	if (status == 0)
		status = us->current_urb->actual_length;
	return status;
}
EXPORT_SYMBOL_GPL(usb_stor_control_msg);

/*
 * This is a version of usb_clear_halt() that allows early termination and
 * doesn't read the status from the device -- this is because some devices
 * crash their internal firmware when the status is requested after a halt.
 *
 * A definitive list of these 'bad' devices is too difficult to maintain or
 * make complete enough to be useful.  This problem was first observed on the
 * Hagiwara FlashGate DUAL unit.  However, bus traces reveal that neither
 * MacOS nor Windows checks the status after clearing a halt.
 *
 * Since many vendors in this space limit their testing to interoperability
 * with these two OSes, specification violations like this one are common.
 */
int usb_stor_clear_halt(struct us_data *us, unsigned int pipe)
{
	int result;
	int endp = usb_pipeendpoint(pipe);

	if (usb_pipein (pipe))
		endp |= USB_DIR_IN;

	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
		USB_ENDPOINT_HALT, endp,
		NULL, 0, 3*HZ);

	if (result >= 0)
		usb_reset_endpoint(us->pusb_dev, endp);

	usb_stor_dbg(us, "result = %d\n", result);
	return result;
}
EXPORT_SYMBOL_GPL(usb_stor_clear_halt);

Annotation

Implementation Notes