Changes between Version 12 and Version 13 of linux/OTG

Timestamp:

06/13/2025 07:21:12 PM (4 days ago)

Author:

Tim Harvey

Comment:

updated g_multi

linux/OTG

@@ -101 +101 @@
 The Serial Gadget supports CDC-ACM and CDC-OBEX which can inter-operate with the MS-Windows hosts or with Linux hosts using the 'cdc-acm' driver to create a 'USB-to-Serial' connection.
 
-On the target a serial device will be created as {{{/dev/ttyGS0}}} (or the next avaialble ttyGS device).
+On the target a serial device will be created as {{{/dev/ttyGS0}}} (or the next available ttyGS device).
 
 On a host device (ie PC) a USB CDC ACM device (VID:PID 0525:a4a7 by default) will appear and behave as a serial device. Module parameters can specify the VID, PID, device version, manufacturer string, product string, serialnumber and whether or not to use CDC ACM, CDC OBEX, and the number of ports to create.
@@ -158 +158 @@
 
 [=#g_multi]
-=== g_multi - Composite Ethernet + Serial + Mass Storage Gadget ===
+=== g_multi - Composite Ethernet + Serial + Mass Storage Gadget
 The g_multi gadget supports multiple functions in one configuration:
  * a CDC Ethernet (ECM) link
@@ -164 +164 @@
  * a USB Mass Storage device
 
-Example:
- * on target device (Gateworks board with OTG controller):
-{{{#!bash
-modprobe g_cdc
-}}}
- * on host device (ie PC) a USB CDC ACM device (VID:PID 1d6b:0104 by default) will appear
- * module parameters can specify the VID, PID, device version, manufacturer string, product string, serialnumber
- * module parameters can specify the ethernet device and host address and queue length multiplier at high speed
-
-Linux USB Host notes:
- * the cdc_acm driver will enumerate this device as '/dev/ttyACM<n>'
- * the cdc_ether driver will enumerate this device as a 'usb<n>' network device
- * the usb-storage driver will provide the USB Mass Storage feature
-
-Windows USB Host notes:
- * A Multifunction Composite Gadget device will appear in Device Manager
- * see [https://www.kernel.org/doc/Documentation/usb/gadget_multi.txt ​here] for details on Windows configuration
+On the target the following devices will be created:
+ * serial device {{{/dev/ttyGS0}}} (or the next available ttyGS device)
+ * usb network device {{{/sys/class/net/usb0}}} (or the next available usb network device) 
+
+Module parameters can specify the VID, PID, device version, manufacturer string, product string, serialnumber and a range of other options (use '{{{modinfo g_multi}}}' to examine).
+
+On a host device (ie PC) a USB Composite Gadget device will enumerate.
+
+A Linux USB Host supports this with:
+ * the {{{cdc_ether}}} driver which will create a {{{/sys/class/net/usb0}}} device (or the next available usb netdev)
+ * the {{{usb_storage}}} driver which will create a {{{/dev/sdc}}} device (or the next available sd device letter)
+ * the {{{cdc_acm}}} driver which will create a {{{/dev/ttyACM0}}} device (or the next available ttyACM).
+
+
+For a Windows host a Multifunction Composite Gadget device will appear in Device Manager. See [https://www.kernel.org/doc/Documentation/usb/gadget_multi.txt ​here] for details on Windows configuration
+
+
+Example:
+ * on target device (Gateworks board with OTG controller):
+{{{#!bash
+# create a backing store file (or use a physical blkdev)
+dd bs=1M count=64 if=/dev/zero of=/backing_file
+# load the module
+modprobe g_multi file=/backing_file
+}}}
+
 
 References: