| Message ID | 1308601481-15815-1-git-send-email-aloisio.almeida@openbossa.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, 20 Jun 2011 17:24:41 -0300 Aloisio Almeida Jr wrote: > Signed-off-by: Aloisio Almeida Jr <aloisio.almeida@openbossa.org> > Signed-off-by: Lauro Ramos Venancio <lauro.venancio@openbossa.org> > --- > Documentation/networking/nfc.txt | 128 ++++++++++++++++++++++++++++++++++++++ > 1 files changed, 128 insertions(+), 0 deletions(-) > create mode 100644 Documentation/networking/nfc.txt > > diff --git a/Documentation/networking/nfc.txt b/Documentation/networking/nfc.txt > new file mode 100644 > index 0000000..cb23b48 > --- /dev/null > +++ b/Documentation/networking/nfc.txt > @@ -0,0 +1,128 @@ > +Linux NFC subsystem > +=================== > + > +The Near Field Communication (NFC) subsystem is required to standardize the > +NFC device drivers development and to create an unified userspace interface. > + > +This document covers the architecture overview, the device driver interface > +description and the userspace interface description. > + > +Architecture overview > +--------------------- > + > +The NFC subsystem is responsible for: > + - NFC adapters management; > + - Polling for targets; > + - Low-level data exchange; > + > +The subsystem is divided in some parts. The 'core' is responsible for > +providing the device driver interface. On the other side, it is also > +responsible for providing an interface to control operations and low-level > +data exchange. > + > +The control operations are available to userspace via generic netlink. > + > +The low-level data exchange interface is provided by the new socket family > +PF_NFC. The NFC_SOCKPROTO_RAW performs raw communication with NFC targets. > + > + > + +--------------------------------------+ > + | USER SPACE | > + +--------------------------------------+ > + ^ ^ > + | low-level | control > + | data exchange | operations > + | | > + | v > + | +-----------+ > + | AF_NFC | netlink | > + | socket +-----------+ > + | raw ^ > + | | > + v v > + +---------+ +-----------+ > + | rawsock | <--------> | core | > + +---------+ +-----------+ > + ^ > + | > + v > + +-----------+ > + | driver | > + +-----------+ > + > +Device Driver Interface > +----------------------- > + > +When registering on the NFC subsystem, the device driver must inform the set must inform the core of the set > +of supported NFC protocols and the set of ops callbacks. The ops callbacks > +that must be implemented are the following: > + > +* start_poll - setup the device to poll for targets > +* stop_poll - stop on progress polling operation > +* activate_target - select and initialize one of the targets found > +* deactivate_target - deselect and deinitialize the selected target > +* data_exchange - send data and receive the response (transceive operation) > + > +Userspace interface > +-------------------- > + > +The userspace interface is divided in control operations and low-level data > +exchange operation. > + > +CONTROL OPERATIONS: > + > +Generic netlink was used to implement the interface to the control operations. is used > +The operations are composed by commands and events, all listed below: > + > +* NFC_CMD_GET_DEVICE - get an specific device info or dump the device list get specific device info or > +* NFC_CMD_START_POLL - setup a specific device to polling for targets > +* NFC_CMD_STOP_POLL - stop the polling operation in a specific device > +* NFC_CMD_GET_TARGET - dump the list of targets found by a specific device > + > +* NFC_EVENT_DEVICE_ADDED - reports a NFC device addition an NFC > +* NFC_EVENT_DEVICE_REMOVED - reports a NFC device removal an NFC > +* NFC_EVENT_TARGETS_FOUND - reports START_POLL results when 1 or more targets > +are found > + > +The user must call START_POLL to poll for NFC targets, passing the desired NFC > +protocols through NFC_ATTR_PROTOCOLS attribute. The device remains in polling > +state until it finds any target. However, the user can stop the polling > +operation by calling STOP_POLL command. In this case, it will be checked if > +the requester of STOP_POLL is the same of START_POLL. > + > +If the polling operation finds one or more targets, the event TARGETS_FOUND is > +sent (including the device id). The user must call GET_TARGET to get the list of > +all targets found by such device. Each reply message has target attributes with > +relevant information such as the supported NFC protocols. > + > +All polling operations requested through one netlink socket are stopped when > +it's closed. > + > +LOW-LEVEL DATA EXCHANGE: > + > +The userspace must use PF_NFC sockets to perform any data communication with > +targets. All NFC sockets use AF_NFC: > + > +struct sockaddr_nfc { > + sa_family_t sa_family; > + __u32 dev_idx; > + __u32 target_idx; > + __u32 nfc_protocol; > +}; > + > +To establish a connection with one target, the user must create a create an > +NFC_SOCKPROTO_RAW socket and call the 'connect' syscall with the sockaddr_nfc > +struct correctly filled. All information comes from NFC_EVENT_TARGETS_FOUND > +netlink event. As a target can support more than one NFC protocol, the user > +must inform which protocol it wants to use. > + > +Internally, 'connect' will result in a activate_target call to the driver. in an > +When the socket is closed, the target is deactivated. > + > +The data format exchanged through the sockets is NFC protocol dependent. For > +instance, when communicating with MIFARE tags, the data exchanged are MIFARE > +commands and their responses. > + > +The first received package is the response to the first sent package and so > +on. In order to allow valid "empty" responses, every data received has a NULL > +header of 1 byte. > -- --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Randy, Thanks for your comments, I'll apply all. Aloisio -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/networking/nfc.txt b/Documentation/networking/nfc.txt new file mode 100644 index 0000000..cb23b48 --- /dev/null +++ b/Documentation/networking/nfc.txt @@ -0,0 +1,128 @@ +Linux NFC subsystem +=================== + +The Near Field Communication (NFC) subsystem is required to standardize the +NFC device drivers development and to create an unified userspace interface. + +This document covers the architecture overview, the device driver interface +description and the userspace interface description. + +Architecture overview +--------------------- + +The NFC subsystem is responsible for: + - NFC adapters management; + - Polling for targets; + - Low-level data exchange; + +The subsystem is divided in some parts. The 'core' is responsible for +providing the device driver interface. On the other side, it is also +responsible for providing an interface to control operations and low-level +data exchange. + +The control operations are available to userspace via generic netlink. + +The low-level data exchange interface is provided by the new socket family +PF_NFC. The NFC_SOCKPROTO_RAW performs raw communication with NFC targets. + + + +--------------------------------------+ + | USER SPACE | + +--------------------------------------+ + ^ ^ + | low-level | control + | data exchange | operations + | | + | v + | +-----------+ + | AF_NFC | netlink | + | socket +-----------+ + | raw ^ + | | + v v + +---------+ +-----------+ + | rawsock | <--------> | core | + +---------+ +-----------+ + ^ + | + v + +-----------+ + | driver | + +-----------+ + +Device Driver Interface +----------------------- + +When registering on the NFC subsystem, the device driver must inform the set +of supported NFC protocols and the set of ops callbacks. The ops callbacks +that must be implemented are the following: + +* start_poll - setup the device to poll for targets +* stop_poll - stop on progress polling operation +* activate_target - select and initialize one of the targets found +* deactivate_target - deselect and deinitialize the selected target +* data_exchange - send data and receive the response (transceive operation) + +Userspace interface +-------------------- + +The userspace interface is divided in control operations and low-level data +exchange operation. + +CONTROL OPERATIONS: + +Generic netlink was used to implement the interface to the control operations. +The operations are composed by commands and events, all listed below: + +* NFC_CMD_GET_DEVICE - get an specific device info or dump the device list +* NFC_CMD_START_POLL - setup a specific device to polling for targets +* NFC_CMD_STOP_POLL - stop the polling operation in a specific device +* NFC_CMD_GET_TARGET - dump the list of targets found by a specific device + +* NFC_EVENT_DEVICE_ADDED - reports a NFC device addition +* NFC_EVENT_DEVICE_REMOVED - reports a NFC device removal +* NFC_EVENT_TARGETS_FOUND - reports START_POLL results when 1 or more targets +are found + +The user must call START_POLL to poll for NFC targets, passing the desired NFC +protocols through NFC_ATTR_PROTOCOLS attribute. The device remains in polling +state until it finds any target. However, the user can stop the polling +operation by calling STOP_POLL command. In this case, it will be checked if +the requester of STOP_POLL is the same of START_POLL. + +If the polling operation finds one or more targets, the event TARGETS_FOUND is +sent (including the device id). The user must call GET_TARGET to get the list of +all targets found by such device. Each reply message has target attributes with +relevant information such as the supported NFC protocols. + +All polling operations requested through one netlink socket are stopped when +it's closed. + +LOW-LEVEL DATA EXCHANGE: + +The userspace must use PF_NFC sockets to perform any data communication with +targets. All NFC sockets use AF_NFC: + +struct sockaddr_nfc { + sa_family_t sa_family; + __u32 dev_idx; + __u32 target_idx; + __u32 nfc_protocol; +}; + +To establish a connection with one target, the user must create a +NFC_SOCKPROTO_RAW socket and call the 'connect' syscall with the sockaddr_nfc +struct correctly filled. All information comes from NFC_EVENT_TARGETS_FOUND +netlink event. As a target can support more than one NFC protocol, the user +must inform which protocol it wants to use. + +Internally, 'connect' will result in a activate_target call to the driver. +When the socket is closed, the target is deactivated. + +The data format exchanged through the sockets is NFC protocol dependent. For +instance, when communicating with MIFARE tags, the data exchanged are MIFARE +commands and their responses. + +The first received package is the response to the first sent package and so +on. In order to allow valid "empty" responses, every data received has a NULL +header of 1 byte.