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Diffstat (limited to 'Documentation/driver-api/usb/usb.rst')
| -rw-r--r-- | Documentation/driver-api/usb/usb.rst | 34 |
1 files changed, 22 insertions, 12 deletions
diff --git a/Documentation/driver-api/usb/usb.rst b/Documentation/driver-api/usb/usb.rst index dba0f876b36f..7f2f41e80c1c 100644 --- a/Documentation/driver-api/usb/usb.rst +++ b/Documentation/driver-api/usb/usb.rst @@ -13,7 +13,7 @@ structure, with the host as the root (the system's master), hubs as interior nodes, and peripherals as leaves (and slaves). Modern PCs support several such trees of USB devices, usually a few USB 3.0 (5 GBit/s) or USB 3.1 (10 GBit/s) and some legacy -USB 2.0 (480 MBit/s) busses just in case. +USB 2.0 (480 MBit/s) buses just in case. That master/slave asymmetry was designed-in for a number of reasons, one being ease of use. It is not physically possible to mistake upstream and @@ -42,7 +42,7 @@ two. One is intended for *general-purpose* drivers (exposed through driver frameworks), and the other is for drivers that are *part of the core*. Such core drivers include the *hub* driver (which manages trees of USB devices) and several different kinds of *host controller -drivers*, which control individual busses. +drivers*, which control individual buses. The device model seen by USB drivers is relatively complex. @@ -109,13 +109,19 @@ well as to make sure they aren't relying on some HCD-specific behavior. USB-Standard Types ================== -In ``<linux/usb/ch9.h>`` you will find the USB data types defined in -chapter 9 of the USB specification. These data types are used throughout +In ``include/uapi/linux/usb/ch9.h`` you will find the USB data types defined +in chapter 9 of the USB specification. These data types are used throughout USB, and in APIs including this host side API, gadget APIs, usb character -devices and debugfs interfaces. +devices and debugfs interfaces. That file is itself included by +``include/linux/usb/ch9.h``, which also contains declarations of a few +utility routines for manipulating these data types; the implementations +are in ``drivers/usb/common/common.c``. -.. kernel-doc:: include/linux/usb/ch9.h - :internal: +.. kernel-doc:: drivers/usb/common/common.c + :export: + +In addition, some functions useful for creating debugging output are +defined in ``drivers/usb/common/debug.c``. .. _usb_header: @@ -155,6 +161,7 @@ rely on 64bit DMA to eliminate another kind of bounce buffer. .. kernel-doc:: drivers/usb/core/urb.c :export: +.. c:namespace:: usb_core .. kernel-doc:: drivers/usb/core/message.c :export: @@ -414,6 +421,12 @@ USBDEVFS_CONNECTINFO know the devnum value already, it's the DDD value of the device file name. +USBDEVFS_GET_SPEED + Returns the speed of the device. The speed is returned as a + numerical value in accordance with enum usb_device_speed + + File modification time is not updated by this request. + USBDEVFS_GETDRIVER Returns the name of the kernel driver bound to a given interface (a string). Parameter is a pointer to this structure, which is @@ -690,9 +703,7 @@ The USB devices are now exported via debugfs: This file is handy for status viewing tools in user mode, which can scan the text format and ignore most of it. More detailed device status (including class and vendor status) is available from device-specific -files. For information about the current format of this file, see the -``Documentation/usb/proc_usb_info.txt`` file in your Linux kernel -sources. +files. For information about the current format of this file, see below. This file, in combination with the poll() system call, can also be used to detect when devices are added or removed:: @@ -767,8 +778,7 @@ Speed may be: ======= ====================================================== 1.5 Mbit/s for low speed USB 12 Mbit/s for full speed USB - 480 Mbit/s for high speed USB (added for USB 2.0); - also used for Wireless USB, which has no fixed speed + 480 Mbit/s for high speed USB (added for USB 2.0) 5000 Mbit/s for SuperSpeed USB (added for USB 3.0) ======= ====================================================== |