There's no usbfs anymore. The old features are now either
exported to /dev/bus/usb or via debugfs.
Update documentation accordingly, pointing to the new
places where the character devices and usb/devices are
now placed.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
---
Documentation/driver-api/usb/usb.rst | 180 ++++++++++++-----------------------
Documentation/usb/acm.txt | 2 +-
Documentation/usb/gadget_serial.txt | 4 +-
Documentation/usb/proc_usb_info.txt | 20 ++--
4 files changed, 73 insertions(+), 133 deletions(-)
diff --git a/Documentation/driver-api/usb/usb.rst b/Documentation/driver-api/usb/usb.rst
index 6824089ef4c8..a98f78c91ab6 100644
--- a/Documentation/driver-api/usb/usb.rst
+++ b/Documentation/driver-api/usb/usb.rst
@@ -111,7 +111,8 @@ 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
-USB, and in APIs including this host side API, gadget APIs, and usbfs.
+USB, and in APIs including this host side API, gadget APIs, usb character
+devices and debugfs interfaces.
.. kernel-doc:: include/linux/usb/ch9.h
:internal:
@@ -204,40 +205,32 @@ significantly reduce hcd-specific behaviors.
.. kernel-doc:: drivers/usb/core/buffer.c
:internal:
-The USB Filesystem (usbfs)
-==========================
+The USB character device nodes
+==============================
-This chapter presents the Linux *usbfs*. You may prefer to avoid writing
-new kernel code for your USB driver; that's the problem that usbfs set
-out to solve. User mode device drivers are usually packaged as
-applications or libraries, and may use usbfs through some programming
-library that wraps it. Such libraries include
+This chapter presents the Linux character device nodes. You may prefer
+to avoid writing new kernel code for your USB driver. User mode device
+drivers are usually packaged as applications or libraries, and may use
+character devices through some programming library that wraps it.
+Such libraries include
`libusb <http://libusb.sourceforge.net>`__ for C/C++, and
`jUSB <http://jUSB.sourceforge.net>`__ for Java.
.. note::
- This particular documentation is incomplete, especially with respect
- to the asynchronous mode. As of kernel 2.5.66 the code and this
- (new) documentation need to be cross-reviewed.
+ - They were used to be implemented via *usbfs*, but this is not part of
+ the sysfs debug interface.
-Configure usbfs into Linux kernels by enabling the *USB filesystem*
-option (CONFIG_USB_DEVICEFS), and you get basic support for user mode
-USB device drivers. Until relatively recently it was often (confusingly)
-called *usbdevfs* although it wasn't solving what *devfs* was. Every USB
-device will appear in usbfs, regardless of whether or not it has a
-kernel driver.
+ - This particular documentation is incomplete, especially with respect
+ to the asynchronous mode. As of kernel 2.5.66 the code and this
+ (new) documentation need to be cross-reviewed.
-What files are in "usbfs"?
---------------------------
+What files are in "devtmpfs"?
+-----------------------------
-Conventionally mounted at ``/proc/bus/usb``, usbfs features include:
+Conventionally mounted at ``/dev/bus/usb/``, usbfs features include:
-- ``/proc/bus/usb/devices`` ... a text file showing each of the USB
- devices on known to the kernel, and their configuration descriptors.
- You can also poll() this to learn about new devices.
-
-- ``/proc/bus/usb/BBB/DDD`` ... magic files exposing the each device's
+- ``/dev/bus/usb//BBB/DDD`` ... magic files exposing the each device's
configuration descriptors, and supporting a series of ioctls for
making device requests, including I/O to devices. (Purely for access
by programs.)
@@ -252,100 +245,7 @@ them. HID and networking devices expose these stable IDs, so that for
example you can be sure that you told the right UPS to power down its
second server. "usbfs" doesn't (yet) expose those IDs.
-Mounting and Access Control
----------------------------
-
-There are a number of mount options for usbfs, which will be of most
-interest to you if you need to override the default access control
-policy. That policy is that only root may read or write device files
-(``/proc/bus/BBB/DDD``) although anyone may read the ``devices`` or
-``drivers`` files. I/O requests to the device also need the
-CAP_SYS_RAWIO capability,
-
-The significance of that is that by default, all user mode device
-drivers need super-user privileges. You can change modes or ownership in
-a driver setup when the device hotplugs, or maye just start the driver
-right then, as a privileged server (or some activity within one). That's
-the most secure approach for multi-user systems, but for single user
-systems ("trusted" by that user) it's more convenient just to grant
-everyone all access (using the *devmode=0666* option) so the driver can
-start whenever it's needed.
-
-The mount options for usbfs, usable in /etc/fstab or in command line
-invocations of *mount*, are:
-
-*busgid*\ =NNNNN
- Controls the GID used for the /proc/bus/usb/BBB directories.
- (Default: 0)
-
-*busmode*\ =MMM
- Controls the file mode used for the /proc/bus/usb/BBB directories.
- (Default: 0555)
-
-*busuid*\ =NNNNN
- Controls the UID used for the /proc/bus/usb/BBB directories.
- (Default: 0)
-
-*devgid*\ =NNNNN
- Controls the GID used for the /proc/bus/usb/BBB/DDD files. (Default:
- 0)
-
-*devmode*\ =MMM
- Controls the file mode used for the /proc/bus/usb/BBB/DDD files.
- (Default: 0644)
-
-*devuid*\ =NNNNN
- Controls the UID used for the /proc/bus/usb/BBB/DDD files. (Default:
- 0)
-
-*listgid*\ =NNNNN
- Controls the GID used for the /proc/bus/usb/devices and drivers
- files. (Default: 0)
-
-*listmode*\ =MMM
- Controls the file mode used for the /proc/bus/usb/devices and
- drivers files. (Default: 0444)
-
-*listuid*\ =NNNNN
- Controls the UID used for the /proc/bus/usb/devices and drivers
- files. (Default: 0)
-
-Note that many Linux distributions hard-wire the mount options for usbfs
-in their init scripts, such as ``/etc/rc.d/rc.sysinit``, rather than
-making it easy to set this per-system policy in ``/etc/fstab``.
-
-/proc/bus/usb/devices
----------------------
-
-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.
-
-This file, in combination with the poll() system call, can also be used
-to detect when devices are added or removed::
-
- int fd;
- struct pollfd pfd;
-
- fd = open("/proc/bus/usb/devices", O_RDONLY);
- pfd = { fd, POLLIN, 0 };
- for (;;) {
- /* The first time through, this call will return immediately. */
- poll(&pfd, 1, -1);
-
- /* To see what's changed, compare the file's previous and current
- contents or scan the filesystem. (Scanning is more precise.) */
- }
-
-Note that this behavior is intended to be used for informational and
-debug purposes. It would be more appropriate to use programs such as
-udev or HAL to initialize a device or start a user-mode helper program,
-for instance.
-
-/proc/bus/usb/BBB/DDD
+/dev/bus/usb//BBB/DDD
---------------------
Use these files in one of these basic ways:
@@ -376,7 +276,7 @@ Life Cycle of User Mode Drivers
Such a driver first needs to find a device file for a device it knows
how to handle. Maybe it was told about it because a ``/sbin/hotplug``
event handling agent chose that driver to handle the new device. Or
-maybe it's an application that scans all the /proc/bus/usb device files,
+maybe it's an application that scans all the /dev/bus/usb/ device files,
and ignores most devices. In either case, it should :c:func:`read()`
all the descriptors from the device file, and check them against what it
knows how to handle. It might just reject everything except a particular
@@ -734,3 +634,43 @@ USBDEVFS_REAPURBNDELAY
USBDEVFS_SUBMITURB
*TBS*
+
+The USB devices
+===============
+
+The USB devices are now exported via debugfs:
+
+- ``/sys/kernel/debug/usb/devices`` ... a text file showing each of the USB
+ devices on known to the kernel, and their configuration descriptors.
+ You can also poll() this to learn about new devices.
+
+/sys/kernel/debug/usb/devices
+-----------------------------
+
+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.
+
+This file, in combination with the poll() system call, can also be used
+to detect when devices are added or removed::
+
+ int fd;
+ struct pollfd pfd;
+
+ fd = open("/sys/kernel/debug/usb/devices", O_RDONLY);
+ pfd = { fd, POLLIN, 0 };
+ for (;;) {
+ /* The first time through, this call will return immediately. */
+ poll(&pfd, 1, -1);
+
+ /* To see what's changed, compare the file's previous and current
+ contents or scan the filesystem. (Scanning is more precise.) */
+ }
+
+Note that this behavior is intended to be used for informational and
+debug purposes. It would be more appropriate to use programs such as
+udev or HAL to initialize a device or start a user-mode helper program,
+for instance.
diff --git a/Documentation/usb/acm.txt b/Documentation/usb/acm.txt
index 17f5c2e1a570..903abca10517 100644
--- a/Documentation/usb/acm.txt
+++ b/Documentation/usb/acm.txt
@@ -64,7 +64,7 @@ minicom, ppp and mgetty with them.
2. Verifying that it works
~~~~~~~~~~~~~~~~~~~~~~~~~~
- The first step would be to check /proc/bus/usb/devices, it should look
+ The first step would be to check /sys/kernel/debug/usb/devices, it should look
like this:
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
diff --git a/Documentation/usb/gadget_serial.txt b/Documentation/usb/gadget_serial.txt
index 6b4a88a8c8e3..d1def3186782 100644
--- a/Documentation/usb/gadget_serial.txt
+++ b/Documentation/usb/gadget_serial.txt
@@ -189,7 +189,7 @@ Once the gadget serial driver is loaded and the USB device connected
to the Linux host with a USB cable, the host system should recognize
the gadget serial device. For example, the command
- cat /proc/bus/usb/devices
+ cat /sys/kernel/debug/usb/devices
should show something like this:
@@ -221,7 +221,7 @@ Once the gadget serial driver is loaded and the USB device connected
to the Linux host with a USB cable, the host system should recognize
the gadget serial device. For example, the command
- cat /proc/bus/usb/devices
+ cat /sys/kernel/debug/usb/devices
should show something like this:
diff --git a/Documentation/usb/proc_usb_info.txt b/Documentation/usb/proc_usb_info.txt
index 98be91982677..06d7960e9ae6 100644
--- a/Documentation/usb/proc_usb_info.txt
+++ b/Documentation/usb/proc_usb_info.txt
@@ -4,7 +4,7 @@
The usbfs filesystem for USB devices is traditionally mounted at
-/proc/bus/usb. It provides the /proc/bus/usb/devices file, as well as
+/proc/bus/usb. It provides the /sys/kernel/debug/usb/devices file, as well as
the /proc/bus/usb/BBB/DDD files.
In many modern systems the usbfs filesystem isn't used at all. Instead
@@ -24,7 +24,7 @@ USB device nodes are created under /dev/usb/ or someplace similar. The
none /proc/bus/usb usbfs defaults 0 0
to /etc/fstab. This will mount usbfs at each reboot.
- You can then issue `cat /proc/bus/usb/devices` to extract
+ You can then issue `cat /sys/kernel/debug/usb/devices` to extract
USB device information, and user mode drivers can use usbfs
to interact with USB devices.
@@ -60,7 +60,7 @@ descriptors are in bus endian format! The configuration descriptor
are wTotalLength bytes apart. If a device returns less configuration
descriptor data than indicated by wTotalLength there will be a hole in
the file for the missing bytes. This information is also shown
-in text form by the /proc/bus/usb/devices file, described later.
+in text form by the /sys/kernel/debug/usb/devices file, described later.
These files may also be used to write user-level drivers for the USB
devices. You would open the /proc/bus/usb/BBB/DDD file read/write,
@@ -79,9 +79,9 @@ usbfs mount options such as "devmode=0666" may be helpful.
-THE /proc/bus/usb/devices FILE:
+THE /sys/kernel/debug/usb/devices FILE:
-------------------------------
-In /proc/bus/usb/devices, each device's output has multiple
+In /sys/kernel/debug/usb/devices, each device's output has multiple
lines of ASCII output.
I made it ASCII instead of binary on purpose, so that someone
can obtain some useful data from it without the use of an
@@ -104,7 +104,7 @@ E = Endpoint descriptor info.
=======================================================================
-/proc/bus/usb/devices output format:
+/sys/kernel/debug/usb/devices output format:
Legend:
d = decimal number (may have leading spaces or 0's)
@@ -277,16 +277,16 @@ E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=dddss
If a user or script is interested only in Topology info, for
-example, use something like "grep ^T: /proc/bus/usb/devices"
+example, use something like "grep ^T: /sys/kernel/debug/usb/devices"
for only the Topology lines. A command like
-"grep -i ^[tdp]: /proc/bus/usb/devices" can be used to list
+"grep -i ^[tdp]: /sys/kernel/debug/usb/devices" can be used to list
only the lines that begin with the characters in square brackets,
where the valid characters are TDPCIE. With a slightly more able
script, it can display any selected lines (for example, only T, D,
and P lines) and change their output format. (The "procusb"
Perl script is the beginning of this idea. It will list only
selected lines [selected from TBDPSCIE] or "All" lines from
-/proc/bus/usb/devices.)
+/sys/kernel/debug/usb/devices.)
The Topology lines can be used to generate a graphic/pictorial
of the USB devices on a system's root hub. (See more below
@@ -297,7 +297,7 @@ being used for each device, and which altsetting it activated.
The Configuration lines could be used to list maximum power
(in milliamps) that a system's USB devices are using.
-For example, "grep ^C: /proc/bus/usb/devices".
+For example, "grep ^C: /sys/kernel/debug/usb/devices".
Here's an example, from a system which has a UHCI root hub,
--
2.9.3
--
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