Re: USB serial linux kernel module

[Frank Pagliughi <fpagliughi at mindspring dot com>]

Andrew Lunn wrote:
> Hi Frank
>
> I worked on the Linux kernel module for the USB serial interface.
>
> Attached is a patch that allows it to compile with 2.6.26-rc9.  The
> patch also handles the device when it is in ACM mode. I found that
> Linux attaches a device to the ACM interface which just has an
> interrupt endpoint. This device is useless. By adding a probe function
> i can detect this interface and tell the usb-serial layer to ignore
> it.
>
> Please could you test this patch and let me know if it works for
> you. If so, i will commit it.
>
>      Thanks
>         Andrew
>   
Andrew,

This should patch your version of the ecos_usbserial.c Linux driver. It 
brings in endpoint check functions for older versions of the kernel. I 
tried this on Fedora 6 (older) and Fedora 8 (newer) and it worked on both.


Thanks for the help with this. I'm relieved to have a single version 
that works with both Windows and Linux hosts. I would have never thought 
of doing it this way.

Frank
--- andrews_ecos_usbserial.c	2008-08-09 09:26:54.000000000 -0400
+++ ecos_usbserial.c	2008-08-09 09:39:28.000000000 -0400
@@ -58,6 +58,18 @@
 
 static int debug;
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19) 
+static inline int usb_endpoint_xfer_bulk(
+			const struct usb_endpoint_descriptor *endpoint) {
+	return (endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+				USB_ENDPOINT_XFER_BULK;
+}
+
+static inline int usb_endpoint_dir_in(const struct usb_endpoint_descriptor *epd) {
+	return (epd->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN;
+}
+#endif
+
 /* Our probe function will detect if the interface has sufficient bulk
  * in and out endpoints to be useful. The ACM interface only has an
  * interrupt endpoint, so we don't want a serial device bound to it.
@@ -77,20 +89,21 @@
         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                 endpoint = &iface_desc->endpoint[i].desc;
                 
-                if (usb_endpoint_is_bulk_in(endpoint)) {
-                        /* we found a bulk in endpoint */
-                        dbg("found bulk in on endpoint %d", i);
+                if (usb_endpoint_xfer_bulk(endpoint)) {
+					if (usb_endpoint_dir_in(endpoint)) {
+						/* we found a bulk in endpoint */
+						dbg("found bulk in on endpoint %d", i);
                         ++num_bulk_in;
-                }
-                
-                if (usb_endpoint_is_bulk_out(endpoint)) {
-                        /* we found a bulk out endpoint */
+					}
+					else {
+						/* we found a bulk out endpoint */
                         dbg("found bulk out on endpoint %d", i);
                         ++num_bulk_out;
-                }
+					}
+				}
         }
         
-        if (!num_bulk_out || !num_bulk_out) {
+        if (!num_bulk_in || !num_bulk_out) {
                 info("Ignoring interface, insufficient endpoints");
                 return -ENODEV;
         }