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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 09:10:03 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 09:10:03 -0700 |
commit | ee9ec4f82049c678373a611ce20ac67fe9ad836e (patch) | |
tree | e5ec44a30720f1db1cd4a803b3711a2293322dc5 /Documentation/hid/hidraw.txt | |
parent | e0c6b8a17fb3d4a740386b380ea72aa8388fbf2f (diff) | |
parent | 366a2382c68d01638350efcf23d46a47d661c595 (diff) | |
download | blackbird-op-linux-ee9ec4f82049c678373a611ce20ac67fe9ad836e.tar.gz blackbird-op-linux-ee9ec4f82049c678373a611ce20ac67fe9ad836e.zip |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid: (36 commits)
HID: hid-multitouch: cosmetic changes, sort classes and devices
HID: hid-multitouch: class MT_CLS_STANTUM is redundant with MT_CLS_CONFIDENCE
HID: hid-multitouch: add support for Unitec panels
HID: hid-multitouch: add support for Touch International panels
HID: hid-multitouch: add support for GoodTouch panels
HID: hid-multitouch: add support for CVTouch panels
HID: hid-multitouch: add support for ActionStar panels
HID: hiddev: fix race between hiddev_disconnect and hiddev_release
HID: magicmouse: ignore 'ivalid report id' while switching modes
HID: fix a crash in hid_report_raw_event() function.
HID: hid-multitouch: add support for Elo TouchSystems 2515 IntelliTouch Plus
HID: assorted usage updates from hut 1.12
HID: roccat: fix actual/startup profile sysfs attribute in koneplus
HID: hid-multitouch: Add support for Lumio panels
HID: 'name' and 'phys' in 'struct hid_device' can never be NULL
HID: hid-multitouch: add support for Ilitek dual-touch panel
HID: picolcd: Avoid compile warning/error triggered by copy_from_user()
HID: add support for Logitech G27 wheel
HID: hiddev: fix error path in hiddev_read when interrupted
HID: add support for Sony Navigation Controller
...
Diffstat (limited to 'Documentation/hid/hidraw.txt')
-rw-r--r-- | Documentation/hid/hidraw.txt | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/Documentation/hid/hidraw.txt b/Documentation/hid/hidraw.txt new file mode 100644 index 000000000000..029e6cb9a7e8 --- /dev/null +++ b/Documentation/hid/hidraw.txt @@ -0,0 +1,119 @@ + HIDRAW - Raw Access to USB and Bluetooth Human Interface Devices + ================================================================== + +The hidraw driver provides a raw interface to USB and Bluetooth Human +Interface Devices (HIDs). It differs from hiddev in that reports sent and +received are not parsed by the HID parser, but are sent to and received from +the device unmodified. + +Hidraw should be used if the userspace application knows exactly how to +communicate with the hardware device, and is able to construct the HID +reports manually. This is often the case when making userspace drivers for +custom HID devices. + +Hidraw is also useful for communicating with non-conformant HID devices +which send and receive data in a way that is inconsistent with their report +descriptors. Because hiddev parses reports which are sent and received +through it, checking them against the device's report descriptor, such +communication with these non-conformant devices is impossible using hiddev. +Hidraw is the only alternative, short of writing a custom kernel driver, for +these non-conformant devices. + +A benefit of hidraw is that its use by userspace applications is independent +of the underlying hardware type. Currently, Hidraw is implemented for USB +and Bluetooth. In the future, as new hardware bus types are developed which +use the HID specification, hidraw will be expanded to add support for these +new bus types. + +Hidraw uses a dynamic major number, meaning that udev should be relied on to +create hidraw device nodes. Udev will typically create the device nodes +directly under /dev (eg: /dev/hidraw0). As this location is distribution- +and udev rule-dependent, applications should use libudev to locate hidraw +devices attached to the system. There is a tutorial on libudev with a +working example at: + http://www.signal11.us/oss/udev/ + +The HIDRAW API +--------------- + +read() +------- +read() will read a queued report received from the HID device. On USB +devices, the reports read using read() are the reports sent from the device +on the INTERRUPT IN endpoint. By default, read() will block until there is +a report available to be read. read() can be made non-blocking, by passing +the O_NONBLOCK flag to open(), or by setting the O_NONBLOCK flag using +fcntl(). + +On a device which uses numbered reports, the first byte of the returned data +will be the report number; the report data follows, beginning in the second +byte. For devices which do not use numbered reports, the report data +will begin at the first byte. + +write() +-------- +The write() function will write a report to the device. For USB devices, if +the device has an INTERRUPT OUT endpoint, the report will be sent on that +endpoint. If it does not, the report will be sent over the control endpoint, +using a SET_REPORT transfer. + +The first byte of the buffer passed to write() should be set to the report +number. If the device does not use numbered reports, the first byte should +be set to 0. The report data itself should begin at the second byte. + +ioctl() +-------- +Hidraw supports the following ioctls: + +HIDIOCGRDESCSIZE: Get Report Descriptor Size +This ioctl will get the size of the device's report descriptor. + +HIDIOCGRDESC: Get Report Descriptor +This ioctl returns the device's report descriptor using a +hidraw_report_descriptor struct. Make sure to set the size field of the +hidraw_report_descriptor struct to the size returned from HIDIOCGRDESCSIZE. + +HIDIOCGRAWINFO: Get Raw Info +This ioctl will return a hidraw_devinfo struct containing the bus type, the +vendor ID (VID), and product ID (PID) of the device. The bus type can be one +of: + BUS_USB + BUS_HIL + BUS_BLUETOOTH + BUS_VIRTUAL +which are defined in linux/input.h. + +HIDIOCGRAWNAME(len): Get Raw Name +This ioctl returns a string containing the vendor and product strings of +the device. The returned string is Unicode, UTF-8 encoded. + +HIDIOCGRAWPHYS(len): Get Physical Address +This ioctl returns a string representing the physical address of the device. +For USB devices, the string contains the physical path to the device (the +USB controller, hubs, ports, etc). For Bluetooth devices, the string +contains the hardware (MAC) address of the device. + +HIDIOCSFEATURE(len): Send a Feature Report +This ioctl will send a feature report to the device. Per the HID +specification, feature reports are always sent using the control endpoint. +Set the first byte of the supplied buffer to the report number. For devices +which do not use numbered reports, set the first byte to 0. The report data +begins in the second byte. Make sure to set len accordingly, to one more +than the length of the report (to account for the report number). + +HIDIOCGFEATURE(len): Get a Feature Report +This ioctl will request a feature report from the device using the control +endpoint. The first byte of the supplied buffer should be set to the report +number of the requested report. For devices which do not use numbered +reports, set the first byte to 0. The report will be returned starting at +the first byte of the buffer (ie: the report number is not returned). + +Example +--------- +In samples/, find hid-example.c, which shows examples of read(), write(), +and all the ioctls for hidraw. The code may be used by anyone for any +purpose, and can serve as a starting point for developing applications using +hidraw. + +Document by: + Alan Ott <alan@signal11.us>, Signal 11 Software |