diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/gadget.tmpl | 38 | ||||
| -rw-r--r-- | Documentation/usb/gadget_serial.txt | 35 | ||||
| -rw-r--r-- | Documentation/usb/persist.txt | 7 | ||||
| -rw-r--r-- | Documentation/usb/uhci.txt | 165 |
4 files changed, 69 insertions, 176 deletions
diff --git a/Documentation/DocBook/gadget.tmpl b/Documentation/DocBook/gadget.tmpl index 5a8ffa761e0..ea3bc9565e6 100644 --- a/Documentation/DocBook/gadget.tmpl +++ b/Documentation/DocBook/gadget.tmpl @@ -524,6 +524,44 @@ These utilities include endpoint autoconfiguration. <!-- !Edrivers/usb/gadget/epautoconf.c --> </sect1> +<sect1 id="composite"><title>Composite Device Framework</title> + +<para>The core API is sufficient for writing drivers for composite +USB devices (with more than one function in a given configuration), +and also multi-configuration devices (also more than one function, +but not necessarily sharing a given configuration). +There is however an optional framework which makes it easier to +reuse and combine functions. +</para> + +<para>Devices using this framework provide a <emphasis>struct +usb_composite_driver</emphasis>, which in turn provides one or +more <emphasis>struct usb_configuration</emphasis> instances. +Each such configuration includes at least one +<emphasis>struct usb_function</emphasis>, which packages a user +visible role such as "network link" or "mass storage device". +Management functions may also exist, such as "Device Firmware +Upgrade". +</para> + +!Iinclude/linux/usb/composite.h +!Edrivers/usb/gadget/composite.c + +</sect1> + +<sect1 id="functions"><title>Composite Device Functions</title> + +<para>At this writing, a few of the current gadget drivers have +been converted to this framework. +Near-term plans include converting all of them, except for "gadgetfs". +</para> + +!Edrivers/usb/gadget/f_acm.c +!Edrivers/usb/gadget/f_serial.c + +</sect1> + + </chapter> <chapter id="controllers"><title>Peripheral Controller Drivers</title> diff --git a/Documentation/usb/gadget_serial.txt b/Documentation/usb/gadget_serial.txt index 815f5c2301f..9b22bd14c34 100644 --- a/Documentation/usb/gadget_serial.txt +++ b/Documentation/usb/gadget_serial.txt @@ -1,6 +1,7 @@ Linux Gadget Serial Driver v2.0 11/20/2004 + (updated 8-May-2008 for v2.3) License and Disclaimer @@ -31,7 +32,7 @@ Prerequisites ------------- Versions of the gadget serial driver are available for the 2.4 Linux kernels, but this document assumes you are using -version 2.0 or later of the gadget serial driver in a 2.6 +version 2.3 or later of the gadget serial driver in a 2.6 Linux kernel. This document assumes that you are familiar with Linux and @@ -40,6 +41,12 @@ standard utilities, use minicom and HyperTerminal, and work with USB and serial devices. It also assumes you configure the Linux gadget and usb drivers as modules. +With version 2.3 of the driver, major and minor device nodes are +no longer statically defined. Your Linux based system should mount +sysfs in /sys, and use "mdev" (in Busybox) or "udev" to make the +/dev nodes matching the sysfs /sys/class/tty files. + + Overview -------- @@ -104,15 +111,8 @@ driver. All this are listed under "USB Gadget Support" when configuring the kernel. Then rebuild and install the kernel or modules. -The gadget serial driver uses major number 127, for now. So you -will need to create a device node for it, like this: - - mknod /dev/ttygserial c 127 0 - -You only need to do this once. - Then you must load the gadget serial driver. To load it as an -ACM device, do this: +ACM device (recommended for interoperability), do this: modprobe g_serial use_acm=1 @@ -125,6 +125,23 @@ controller driver. This must be done each time you reboot the gadget side Linux system. You can add this to the start up scripts, if desired. +Your system should use mdev (from busybox) or udev to make the +device nodes. After this gadget driver has been set up you should +then see a /dev/ttyGS0 node: + + # ls -l /dev/ttyGS0 | cat + crw-rw---- 1 root root 253, 0 May 8 14:10 /dev/ttyGS0 + # + +Note that the major number (253, above) is system-specific. If +you need to create /dev nodes by hand, the right numbers to use +will be in the /sys/class/tty/ttyGS0/dev file. + +When you link this gadget driver early, perhaps even statically, +you may want to set up an /etc/inittab entry to run "getty" on it. +The /dev/ttyGS0 line should work like most any other serial port. + + If gadget serial is loaded as an ACM device you will want to use either the Windows or Linux ACM driver on the host side. If gadget serial is loaded as a bulk in/out device, you will want to use the diff --git a/Documentation/usb/persist.txt b/Documentation/usb/persist.txt index d56cb1a1155..074b159b77c 100644 --- a/Documentation/usb/persist.txt +++ b/Documentation/usb/persist.txt @@ -81,8 +81,11 @@ re-enumeration shows that the device now attached to that port has the same descriptors as before, including the Vendor and Product IDs, then the kernel continues to use the same device structure. In effect, the kernel treats the device as though it had merely been reset instead of -unplugged. The same thing happens if the host controller is in the -expected state but a USB device was unplugged and then replugged. +unplugged. + +The same thing happens if the host controller is in the expected state +but a USB device was unplugged and then replugged, or if a USB device +fails to carry out a normal resume. If no device is now attached to the port, or if the descriptors are different from what the kernel remembers, then the treatment is what diff --git a/Documentation/usb/uhci.txt b/Documentation/usb/uhci.txt deleted file mode 100644 index 2f25952c86c..00000000000 --- a/Documentation/usb/uhci.txt +++ /dev/null @@ -1,165 +0,0 @@ -Specification and Internals for the New UHCI Driver (Whitepaper...) - - brought to you by - - Georg Acher, acher@in.tum.de (executive slave) (base guitar) - Deti Fliegl, deti@fliegl.de (executive slave) (lead voice) - Thomas Sailer, sailer@ife.ee.ethz.ch (chief consultant) (cheer leader) - - $Id: README.uhci,v 1.1 1999/12/14 14:03:02 fliegl Exp $ - -This document and the new uhci sources can be found on - http://hotswap.in.tum.de/usb - -1. General issues - -1.1 Why a new UHCI driver, we already have one?!? - -Correct, but its internal structure got more and more mixed up by the (still -ongoing) efforts to get isochronous transfers (ISO) to work. -Since there is an increasing need for reliable ISO-transfers (especially -for USB-audio needed by TS and for a DAB-USB-Receiver build by GA and DF), -this state was a bit unsatisfying in our opinion, so we've decided (based -on knowledge and experiences with the old UHCI driver) to start -from scratch with a new approach, much simpler but at the same time more -powerful. -It is inspired by the way Win98/Win2000 handles USB requests via URBs, -but it's definitely 100% free of MS-code and doesn't crash while -unplugging an used ISO-device like Win98 ;-) -Some code for HW setup and root hub management was taken from the -original UHCI driver, but heavily modified to fit into the new code. -The invention of the basic concept, and major coding were completed in two -days (and nights) on the 16th and 17th of October 1999, now known as the -great USB-October-Revolution started by GA, DF, and TS ;-) - -Since the concept is in no way UHCI dependent, we hope that it will also be -transferred to the OHCI-driver, so both drivers share a common API. - -1.2. Advantages and disadvantages - -+ All USB transfer types work now! -+ Asynchronous operation -+ Simple, but powerful interface (only two calls for start and cancel) -+ Easy migration to the new API, simplified by a compatibility API -+ Simple usage of ISO transfers -+ Automatic linking of requests -+ ISO transfers allow variable length for each frame and striping -+ No CPU dependent and non-portable atomic memory access, no asm()-inlines -+ Tested on x86 and Alpha - -- Rewriting for ISO transfers needed - -1.3. Is there some compatibility to the old API? - -Yes, but only for control, bulk and interrupt transfers. We've implemented -some wrapper calls for these transfer types. The usbcore works fine with -these wrappers. For ISO there's no compatibility, because the old ISO-API -and its semantics were unnecessary complicated in our opinion. - -1.4. What's really working? - -As said above, CTRL and BULK already work fine even with the wrappers, -so legacy code wouldn't notice the change. -Regarding to Thomas, ISO transfers now run stable with USB audio. -INT transfers (e.g. mouse driver) work fine, too. - -1.5. Are there any bugs? - -No ;-) -Hm... -Well, of course this implementation needs extensive testing on all available -hardware, but we believe that any fixes shouldn't harm the overall concept. - -1.6. What should be done next? - -A large part of the request handling seems to be identical for UHCI and -OHCI, so it would be a good idea to extract the common parts and have only -the HW specific stuff in uhci.c. Furthermore, all other USB device drivers -should need URBification, if they use isochronous or interrupt transfers. -One thing missing in the current implementation (and the old UHCI driver) -is fair queueing for BULK transfers. Since this would need (in principle) -the alteration of already constructed TD chains (to switch from depth to -breadth execution), another way has to be found. Maybe some simple -heuristics work with the same effect. - ---------------------------------------------------------------------------- - -2. Internal structure and mechanisms - -To get quickly familiar with the internal structures, here's a short -description how the new UHCI driver works. However, the ultimate source of -truth is only uhci.c! - -2.1. Descriptor structure (QHs and TDs) - -During initialization, the following skeleton is allocated in init_skel: - - framespecific | common chain - -framelist[] -[ 0 ]-----> TD --> TD -------\ -[ 1 ]-----> TD --> TD --------> TD ----> QH -------> QH -------> QH ---> NULL - ... TD --> TD -------/ -[1023]-----> TD --> TD ------/ - - ^^ ^^ ^^ ^^ ^^ ^^ - 1024 TDs for 7 TDs for 1 TD for Start of Start of End Chain - ISO INT (2-128ms) 1ms-INT CTRL Chain BULK Chain - -For each CTRL or BULK transfer a new QH is allocated and the containing data -transfers are appended as (vertical) TDs. After building the whole QH with its -dangling TDs, the QH is inserted before the BULK Chain QH (for CTRL) or -before the End Chain QH (for BULK). Since only the QH->next pointers are -affected, no atomic memory operation is required. The three QHs in the -common chain are never equipped with TDs! - -For ISO or INT, the TD for each frame is simply inserted into the appropriate -ISO/INT-TD-chain for the desired frame. The 7 skeleton INT-TDs are scattered -among the 1024 frames similar to the old UHCI driver. - -For CTRL/BULK/ISO, the last TD in the transfer has the IOC-bit set. For INT, -every TD (there is only one...) has the IOC-bit set. - -Besides the data for the UHCI controller (2 or 4 32bit words), the descriptors -are double-linked through the .vertical and .horizontal elements in the -SW data of the descriptor (using the double-linked list structures and -operations), but SW-linking occurs only in closed domains, i.e. for each of -the 1024 ISO-chains and the 8 INT-chains there is a closed cycle. This -simplifies all insertions and unlinking operations and avoids costly -bus_to_virt()-calls. - -2.2. URB structure and linking to QH/TDs - -During assembly of the QH and TDs of the requested action, these descriptors -are stored in urb->urb_list, so the allocated QH/TD descriptors are bound to -this URB. -If the assembly was successful and the descriptors were added to the HW chain, -the corresponding URB is inserted into a global URB list for this controller. -This list stores all pending URBs. - -2.3. Interrupt processing - -Since UHCI provides no means to directly detect completed transactions, the -following is done in each UHCI interrupt (uhci_interrupt()): - -For each URB in the pending queue (process_urb()), the ACTIVE-flag of the -associated TDs are processed (depending on the transfer type -process_{transfer|interrupt|iso}()). If the TDs are not active anymore, -they indicate the completion of the transaction and the status is calculated. -Inactive QH/TDs are removed from the HW chain (since the host controller -already removed the TDs from the QH, no atomic access is needed) and -eventually the URB is marked as completed (OK or errors) and removed from the -pending queue. Then the next linked URB is submitted. After (or immediately -before) that, the completion handler is called. - -2.4. Unlinking URBs - -First, all QH/TDs stored in the URB are unlinked from the HW chain. -To ensure that the host controller really left a vertical TD chain, we -wait for one frame. After that, the TDs are physically destroyed. - -2.5. URB linking and the consequences - -Since URBs can be linked and the corresponding submit_urb is called in -the UHCI-interrupt, all work associated with URB/QH/TD assembly has to be -interrupt save. This forces kmalloc to use GFP_ATOMIC in the interrupt. |