CDC: common parser for extra headers

CDC drivers all implement their own parser for the extra headers.
This patch fixes the code duplication introducing a single common
parser in usbnet.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index b4cf107..060918f 100644 (file)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -42,6 +42,7 @@
 #include <linux/mii.h>
 #include <linux/usb.h>
 #include <linux/usb/usbnet.h>
+#include <linux/usb/cdc.h>
 #include <linux/slab.h>
 #include <linux/kernel.h>
 #include <linux/pm_runtime.h>
@@ -1962,6 +1963,143 @@ out:
        return err;
 }
 
+int cdc_parse_cdc_header(struct usb_cdc_parsed_header *hdr,
+                               struct usb_interface *intf,
+                               u8 *buffer,
+                               int buflen)
+{
+       /* duplicates are ignored */
+       struct usb_cdc_union_desc *union_header = NULL;
+
+       /* duplicates are not tolerated */
+       struct usb_cdc_header_desc *header = NULL;
+       struct usb_cdc_ether_desc *ether = NULL;
+       struct usb_cdc_mdlm_detail_desc *detail = NULL;
+       struct usb_cdc_mdlm_desc *desc = NULL;
+
+       unsigned int elength;
+       int cnt = 0;
+
+       memset(hdr, 0x00, sizeof(struct usb_cdc_parsed_header));
+       hdr->phonet_magic_present = false;
+       while (buflen > 0) {
+               elength = buffer[0];
+               if (!elength) {
+                       dev_err(&intf->dev, "skipping garbage byte\n");
+                       elength = 1;
+                       goto next_desc;
+               }
+               if (buffer[1] != USB_DT_CS_INTERFACE) {
+                       dev_err(&intf->dev, "skipping garbage\n");
+                       goto next_desc;
+               }
+
+               switch (buffer[2]) {
+               case USB_CDC_UNION_TYPE: /* we've found it */
+                       if (elength < sizeof(struct usb_cdc_union_desc))
+                               goto next_desc;
+                       if (union_header) {
+                               dev_err(&intf->dev, "More than one union descriptor, skipping ...\n");
+                               goto next_desc;
+                       }
+                       union_header = (struct usb_cdc_union_desc *)buffer;
+                       break;
+               case USB_CDC_COUNTRY_TYPE:
+                       if (elength < sizeof(struct usb_cdc_country_functional_desc))
+                               goto next_desc;
+                       hdr->usb_cdc_country_functional_desc =
+                               (struct usb_cdc_country_functional_desc *)buffer;
+                       break;
+               case USB_CDC_HEADER_TYPE:
+                       if (elength != sizeof(struct usb_cdc_header_desc))
+                               goto next_desc;
+                       if (header)
+                               return -EINVAL;
+                       header = (struct usb_cdc_header_desc *)buffer;
+                       break;
+               case USB_CDC_ACM_TYPE:
+                       if (elength < sizeof(struct usb_cdc_acm_descriptor))
+                               goto next_desc;
+                       hdr->usb_cdc_acm_descriptor =
+                               (struct usb_cdc_acm_descriptor *)buffer;
+                       break;
+               case USB_CDC_ETHERNET_TYPE:
+                       if (elength != sizeof(struct usb_cdc_ether_desc))
+                               goto next_desc;
+                       if (ether)
+                               return -EINVAL;
+                       ether = (struct usb_cdc_ether_desc *)buffer;
+                       break;
+               case USB_CDC_CALL_MANAGEMENT_TYPE:
+                       if (elength < sizeof(struct usb_cdc_call_mgmt_descriptor))
+                               goto next_desc;
+                       hdr->usb_cdc_call_mgmt_descriptor =
+                               (struct usb_cdc_call_mgmt_descriptor *)buffer;
+                       break;
+               case USB_CDC_DMM_TYPE:
+                       if (elength < sizeof(struct usb_cdc_dmm_desc))
+                               goto next_desc;
+                       hdr->usb_cdc_dmm_desc =
+                               (struct usb_cdc_dmm_desc *)buffer;
+                       break;
+               case USB_CDC_MDLM_TYPE:
+                       if (elength < sizeof(struct usb_cdc_mdlm_desc *))
+                               goto next_desc;
+                       if (desc)
+                               return -EINVAL;
+                       desc = (struct usb_cdc_mdlm_desc *)buffer;
+                       break;
+               case USB_CDC_MDLM_DETAIL_TYPE:
+                       if (elength < sizeof(struct usb_cdc_mdlm_detail_desc *))
+                               goto next_desc;
+                       if (detail)
+                               return -EINVAL;
+                       detail = (struct usb_cdc_mdlm_detail_desc *)buffer;
+                       break;
+               case USB_CDC_NCM_TYPE:
+                       if (elength < sizeof(struct usb_cdc_ncm_desc))
+                               goto next_desc;
+                       hdr->usb_cdc_ncm_desc = (struct usb_cdc_ncm_desc *)buffer;
+                       break;
+               case USB_CDC_MBIM_TYPE:
+                       if (elength < sizeof(struct usb_cdc_mbim_desc))
+                               goto next_desc;
+
+                       hdr->usb_cdc_mbim_desc = (struct usb_cdc_mbim_desc *)buffer;
+                       break;
+               case USB_CDC_MBIM_EXTENDED_TYPE:
+                       if (elength < sizeof(struct usb_cdc_mbim_extended_desc))
+                               break;
+                       hdr->usb_cdc_mbim_extended_desc =
+                               (struct usb_cdc_mbim_extended_desc *)buffer;
+                       break;
+               case CDC_PHONET_MAGIC_NUMBER:
+                       hdr->phonet_magic_present = true;
+                       break;
+               default:
+                       /*
+                        * there are LOTS more CDC descriptors that
+                        * could legitimately be found here.
+                        */
+                       dev_dbg(&intf->dev, "Ignoring descriptor: type %02x, length %ud\n",
+                                       buffer[2], elength);
+                       goto next_desc;
+               }
+               cnt++;
+next_desc:
+               buflen -= elength;
+               buffer += elength;
+       }
+       hdr->usb_cdc_union_desc = union_header;
+       hdr->usb_cdc_header_desc = header;
+       hdr->usb_cdc_mdlm_detail_desc = detail;
+       hdr->usb_cdc_mdlm_desc = desc;
+       hdr->usb_cdc_ether_desc = ether;
+       return cnt;
+}
+
+EXPORT_SYMBOL(cdc_parse_cdc_header);
+
 /*
  * The function can't be called inside suspend/resume callback,
  * otherwise deadlock will be caused.

diff --git a/include/linux/usb/cdc.h b/include/linux/usb/cdc.h
new file mode 100644 (file)
index 0000000..cd8f2e1
--- /dev/null
+++ b/include/linux/usb/cdc.h
@@ -0,0 +1,47 @@
+/*
+ * USB CDC common helpers
+ *
+ * Copyright (c) 2015 Oliver Neukum <oneukum@suse.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+#include <uapi/linux/usb/cdc.h>
+
+/*
+ * inofficial magic numbers
+ */
+
+#define CDC_PHONET_MAGIC_NUMBER                0xAB
+
+/*
+ * parsing CDC headers
+ */
+
+struct usb_cdc_parsed_header {
+       struct usb_cdc_union_desc *usb_cdc_union_desc;
+       struct usb_cdc_header_desc *usb_cdc_header_desc;
+
+       struct usb_cdc_call_mgmt_descriptor *usb_cdc_call_mgmt_descriptor;
+       struct usb_cdc_acm_descriptor *usb_cdc_acm_descriptor;
+       struct usb_cdc_country_functional_desc *usb_cdc_country_functional_desc;
+       struct usb_cdc_network_terminal_desc *usb_cdc_network_terminal_desc;
+       struct usb_cdc_ether_desc *usb_cdc_ether_desc;
+       struct usb_cdc_dmm_desc *usb_cdc_dmm_desc;
+       struct usb_cdc_mdlm_desc *usb_cdc_mdlm_desc;
+       struct usb_cdc_mdlm_detail_desc *usb_cdc_mdlm_detail_desc;
+       struct usb_cdc_obex_desc *usb_cdc_obex_desc;
+       struct usb_cdc_ncm_desc *usb_cdc_ncm_desc;
+       struct usb_cdc_mbim_desc *usb_cdc_mbim_desc;
+       struct usb_cdc_mbim_extended_desc *usb_cdc_mbim_extended_desc;
+
+       bool phonet_magic_present;
+};
+
+
+int cdc_parse_cdc_header(struct usb_cdc_parsed_header *hdr,
+                               struct usb_interface *intf,
+                               u8 *buffer,
+                               int buflen);