i have tried the driver now on a small application in which i print
what i receive from the gadget so
when the gadget sends "hello" for example, the application just prints
some noise characters.
i thinks that copy_to_user does not work right or its location should
be adjusted?
does copy_to_user arguments are: destination,source,count respectively ?
here is my code till now:
*********************************************************************************
static void skel_read_bulk_callback(struct urb *urb, struct pt_regs *regs)
{
struct usb_skel *dev;
struct my_data *mine = (struct my_data *)urb->context;
complete(&(mine->done));
dev = mine->dev;
up(&dev->limit_sem);
}
static ssize_t skel_read(struct file *file, char *user_buffer, size_t
count, loff_t *ppos)
{
// struct completion done;
// struct usb_skel *dev;
int retval = 0;
struct urb *urb = NULL;
char *buf = NULL;
size_t readsize = min(count, (size_t)MAX_TRANSFER);
mydata1.dev = (struct usb_skel *)file->private_data;
/* verify that we actually have some data to read */
if (count == 0)
goto exit;
/* limit the number of URBs in flight to stop a user from using up all
RAM */
if ( down_interruptible( & (mydata1.dev->limit_sem) ) )
{
retval = -ERESTARTSYS;
goto exit;
}
init_completion(& ( mydata1.done) );
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
retval = -ENOMEM;
goto error;
}
buf = usb_buffer_alloc(mydata1.dev->udev, readsize, GFP_KERNEL,
&urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, mydata1.dev->udev,
usb_rcvbulkpipe(mydata1.dev->udev,
mydata1.dev->bulk_in_endpointAddr),
buf, readsize, skel_read_bulk_callback, &mydata1);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
if (retval) {
err("%s - failed submitting read urb, error %d", __FUNCTION__,
retval);
goto error;
}
wait_for_completion( &(mydata1.done) );
if ( copy_to_user( mydata1.dev->bulk_in_buffer,
user_buffer,urb->actual_length) )
retval = -EFAULT;
else
retval = urb->actual_length;
/* free up our allocated buffer */
usb_buffer_free(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
/* release our reference to this urb, the USB core will eventually
free it entirely */
usb_free_urb(urb);
return retval;
exit:
return retval;
error:
usb_buffer_free(mydata1.dev->udev, readsize, buf, urb->transfer_dma);
usb_free_urb(urb);
up( &(mydata1.dev->limit_sem) );
return retval;
}
****************************************************************************************
so when the gadget sends "hello", i tried to print what the host
receives and the size of data it receives , it prints the size correct
as 5 for "hello" but when i print what it receives i got some noise
characters.so what is still wrong i dont know?
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