USB: support for cdc-acm of single interface devices

This implement support in cdc-acm for acm devices another popular OS can handle

- adds support for autodetection of devices that use one interface
- autodetection of endpoints
- add a quirk for surpressing a setting that OS doesn't use
- autoassume that quirk for single interface devices

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 58 insertions, 12 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index ddeb69192537..778e023d1467 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -937,9 +937,9 @@ static int acm_probe(struct usb_interface *intf,
         int buflen = intf->altsetting->extralen;
         struct usb_interface *control_interface;
         struct usb_interface *data_interface;
-        struct usb_endpoint_descriptor *epctrl;
-        struct usb_endpoint_descriptor *epread;
-        struct usb_endpoint_descriptor *epwrite;
+        struct usb_endpoint_descriptor *epctrl = NULL;
+        struct usb_endpoint_descriptor *epread = NULL;
+        struct usb_endpoint_descriptor *epwrite = NULL;
         struct usb_device *usb_dev = interface_to_usbdev(intf);
         struct acm *acm;
         int minor;
@@ -952,6 +952,7 @@ static int acm_probe(struct usb_interface *intf,
         unsigned long quirks;
         int num_rx_buf;
         int i;
+        int combined_interfaces = 0;
 
         /* normal quirks */
         quirks = (unsigned long)id->driver_info;
@@ -1033,9 +1034,15 @@ next_desc:
                         data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num));
                         control_interface = intf;
                 } else {
-                        dev_dbg(&intf->dev,
-                                        "No union descriptor, giving up\n");
-                        return -ENODEV;
+                        if (intf->cur_altsetting->desc.bNumEndpoints != 3) {
+                                dev_dbg(&intf->dev,"No union descriptor, giving up\n");
+                                return -ENODEV;
+                        } else {
+                                dev_warn(&intf->dev,"No union descriptor, testing for castrated device\n");
+                                combined_interfaces = 1;
+                                control_interface = data_interface = intf;
+                                goto look_for_collapsed_interface;
+                        }
                 }
         } else {
                 control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
@@ -1049,6 +1056,36 @@ next_desc:
         if (data_interface_num != call_interface_num)
                 dev_dbg(&intf->dev, "Separate call control interface. That is not fully supported.\n");
 
+        if (control_interface == data_interface) {
+                /* some broken devices designed for windows work this way */
+                dev_warn(&intf->dev,"Control and data interfaces are not separated!\n");
+                combined_interfaces = 1;
+                /* a popular other OS doesn't use it */
+                quirks |= NO_CAP_LINE;
+                if (data_interface->cur_altsetting->desc.bNumEndpoints != 3) {
+                        dev_err(&intf->dev, "This needs exactly 3 endpoints\n");
+                        return -EINVAL;
+                }
+look_for_collapsed_interface:
+                for (i = 0; i < 3; i++) {
+                        struct usb_endpoint_descriptor *ep;
+                        ep = &data_interface->cur_altsetting->endpoint[i].desc;
+
+                        if (usb_endpoint_is_int_in(ep))
+                                epctrl = ep;
+                        else if (usb_endpoint_is_bulk_out(ep))
+                                epwrite = ep;
+                        else if (usb_endpoint_is_bulk_in(ep))
+                                epread = ep;
+                        else
+                                return -EINVAL;
+                }
+                if (!epctrl || !epread || !epwrite)
+                        return -ENODEV;
+                else
+                        goto made_compressed_probe;
+        }
+
 skip_normal_probe:
 
         /*workaround for switched interfaces */
@@ -1068,10 +1105,11 @@ skip_normal_probe:
         }
 
         /* Accept probe requests only for the control interface */
-        if (intf != control_interface)
+        if (!combined_interfaces && intf != control_interface)
                 return -ENODEV;
 
-        if (usb_interface_claimed(data_interface)) { /* valid in this context */
+        if (!combined_interfaces && usb_interface_claimed(data_interface)) {
+                /* valid in this context */
                 dev_dbg(&intf->dev, "The data interface isn't available\n");
                 return -EBUSY;
         }
@@ -1095,6 +1133,7 @@ skip_normal_probe:
                 epread = epwrite;
                 epwrite = t;
         }
+made_compressed_probe:
         dbg("interfaces are valid");
         for (minor = 0; minor < ACM_TTY_MINORS && acm_table[minor]; minor++);
 
@@ -1112,12 +1151,15 @@ skip_normal_probe:
         ctrlsize = le16_to_cpu(epctrl->wMaxPacketSize);
         readsize = le16_to_cpu(epread->wMaxPacketSize) *
                                 (quirks == SINGLE_RX_URB ? 1 : 2);
+        acm->combined_interfaces = combined_interfaces;
         acm->writesize = le16_to_cpu(epwrite->wMaxPacketSize) * 20;
         acm->control = control_interface;
         acm->data = data_interface;
         acm->minor = minor;
         acm->dev = usb_dev;
         acm->ctrl_caps = ac_management_function;
+        if (quirks & NO_CAP_LINE)
+                acm->ctrl_caps &= ~USB_CDC_CAP_LINE;
         acm->ctrlsize = ctrlsize;
         acm->readsize = readsize;
         acm->rx_buflimit = num_rx_buf;
@@ -1223,9 +1265,10 @@ skip_normal_probe:
 
 skip_countries:
         usb_fill_int_urb(acm->ctrlurb, usb_dev,
-                        usb_rcvintpipe(usb_dev, epctrl->bEndpointAddress),
-                        acm->ctrl_buffer, ctrlsize, acm_ctrl_irq, acm,
-                        epctrl->bInterval);
+                         usb_rcvintpipe(usb_dev, epctrl->bEndpointAddress),
+                         acm->ctrl_buffer, ctrlsize, acm_ctrl_irq, acm,
+                         /* works around buggy devices */
+                         epctrl->bInterval ? epctrl->bInterval : 0xff);
         acm->ctrlurb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
         acm->ctrlurb->transfer_dma = acm->ctrl_dma;
 
@@ -1312,7 +1355,8 @@ static void acm_disconnect(struct usb_interface *intf)
                                                                 acm->ctrl_dma);
         acm_read_buffers_free(acm);
 
-        usb_driver_release_interface(&acm_driver, intf == acm->control ?
+        if (!acm->combined_interfaces)
+                usb_driver_release_interface(&acm_driver, intf == acm->control ?
                                         acm->data : acm->control);
 
         if (acm->port.count == 0) {
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 4c3856420add..1602324808ba 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -125,6 +125,7 @@ struct acm {
         unsigned char clocal;                           /* termios CLOCAL */
         unsigned int ctrl_caps;                         /* control capabilities from the class specific header */
         unsigned int susp_count;                        /* number of suspended interfaces */
+        int combined_interfaces:1;                      /* control and data collapsed */
         struct acm_wb *delayed_wb;                      /* write queued for a device about to be woken */
 };
 
@@ -133,3 +134,4 @@ struct acm {
 /* constants describing various quirks and errors */
 #define NO_UNION_NORMAL                 1
 #define SINGLE_RX_URB                   2
+#define NO_CAP_LINE                     4