The NFC Forum NCI specification defines both a hardware and software
protocol when using a SPI physical transport to connect an NFC NCI
Chipset. The hardware requirement is that, after having raised the chip
select line, the SPI driver must wait for an INT line from the NFC
chipset to raise before it sends the data. The chip select must be
raised first though, because this is the signal that the NFC chipset
will detect to wake up and then raise its INT line. If the INT line
doesn't raise in a timely fashion, the SPI driver should abort
operation.
When data is transferred from Device host (DH) to NFC Controller (NFCC),
the signaling sequence is the following:
Data Transfer from DH to NFCC
• 1-Master asserts SPI_CSN
• 2-Slave asserts SPI_INT
• 3-Master sends NCI-over-SPI protocol header and payload data
• 4-Slave deasserts SPI_INT
• 5-Master deasserts SPI_CSN
When data must be transferred from NFCC to DH, things are a little bit
different.
Data Transfer from NFCC to DH
• 1-Slave asserts SPI_INT -> NFC chipset irq handler called -> process
reading from SPI
• 2-Master asserts SPI_CSN
• 3-Master send 2-octet NCI-over-SPI protocol header
• 4-Slave sends 2-octet NCI-over-SPI protocol payload length
• 5-Slave sends NCI-over-SPI protocol payload
• 6-Master deasserts SPI_CSN
In this case, SPI driver should function normally as it does today. Note
that the INT line can and will be lowered anytime between beginning of
step 3 and end of step 5. A low INT is therefore valid after chip select
has been raised.
This would be easily implemented in a single driver. Unfortunately, we
don't write the SPI driver and I had to imagine some workaround trick to
get the SPI and NFC drivers to work in a synchronized fashion. The trick
is the following:
- send an empty spi message: this will raise the chip select line, and
send nothing. We expect the /CS line will stay arisen because we asked
for it in the spi_transfer cs_change field
- wait for a completion, that will be completed by the NFC driver IRQ
handler when it knows we are in the process of sending data (NFC spec
says that we use SPI in a half duplex mode, so we are either sending or
receiving).
- when completed, proceed with the normal data send.
This has been tested and verified to work very consistently on a Nexus
10 (spi-s3c64xx driver). It may not work the same with other spi
drivers.
The previously defined nci_spi_ops{} whose intended purpose were to
address this problem are not used anymore and therefore totally removed.
The nci_spi_send() takes a new optional write_handshake_completion
completion pointer. If non NULL, the nci spi layer will run the above
trick when sending data to the NFC Chip. If NULL, the data is sent
normally all at once and it is then the NFC driver responsibility to
know what it's doing.
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Previously, nci_spi_recv_frame() would directly transmit incoming frames
to the NCI Core. However, it turns out that some NFC NCI Chips will add
additional proprietary headers that must be handled/removed before NCI
Core gets a chance to handle the frame. With this modification, the chip
phy or driver are now responsible to transmit incoming frames to NCI
Core after proper treatment, and NCI SPI becomes a driver helper instead
of sitting between the NFC driver and NCI Core.
As a general rule in NFC, *_recv_frame() APIs are used to deliver an
incoming frame to an upper layer. To better suit the actual purpose of
nci_spi_recv_frame(), and go along with its nci_spi_send()
counterpart, the function is renamed to nci_spi_read()
The skb is returned as the function result
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
NCI SPI layer should not manage the nci dev, this is the job of the nci
chipset driver. This layer should be limited to frame/deframe nci
packets, and optionnaly check integrity (crc) and manage the ack/nak
protocol.
The NCI SPI must not be mixed up with an NCI dev. spi_[dev|device] are
therefore renamed to a simple spi for more clarity.
The header and crc sizes are moved to nci.h so that drivers can use
them to reserve space in outgoing skbs.
nci_spi_send() is exported to be accessible by drivers.
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
An hci dev is an hdev. An nci dev is an ndev. Calling an nci spi dev an
ndev is misleading since it's not the same thing. The nci dev contained
in the nci spi dev is also named inconsistently.
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Supported secure elements are typically found during a discovery process
initiated when the NFC controller is up and running. For a given NFC
chipset there can be many configurations (embedded SE or not, with or
without a SIM card wired to the NFC controller SWP interface, etc...) and
thus driver code will never know before hand which SEs are available.
So we remove this field, it will be replaced by a real SE discovery
mechanism.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Before any operation, driver interruption is de-asserted to prevent
race condition between TX and RX.
Transaction starts by emitting "Direct read" and acknowledged mode
bytes. Then packet length is read allowing to allocate correct NCI
socket buffer. After that payload is retrieved.
A delay after the transaction can be added.
This delay is determined by the driver during nci_spi_allocate_device()
call and can be 0.
If acknowledged mode is set:
- CRC of header and payload is checked
- if frame reception fails (CRC error): NACK is sent
- if received frame has ACK or NACK flag: unblock nci_spi_send()
Payload is passed to NCI module.
At the end, driver interruption is re asserted.
Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Before any operation, driver interruption is de-asserted to prevent
race condition between TX and RX.
The NCI over SPI header is added in front of NCI packet.
If acknowledged mode is set, CRC-16-CCITT is added to the packet.
Then the packet is forwarded to SPI module to be sent.
A delay after the transaction is added.
This delay is determined by the driver during nci_spi_allocate_device()
call and can be 0.
After data has been sent, driver interruption is re-asserted.
If acknowledged mode is set, nci_spi_send will block until
acknowledgment is received.
Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
The NFC Forum defines a transport interface based on
Serial Peripheral Interface (SPI) for the NFC Controller
Interface (NCI).
This module implements the SPI transport of NCI, calling SPI module
directly to read/write data to NFC controller (NFCC).
NFCC driver should provide functions performing device open and close.
It should also provide functions asserting/de-asserting interruption
to prevent TX/RX race conditions.
NFCC driver can also fix a delay between transactions if needed by
the hardware.
Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
skb->dev is used for carrying a net_device pointer and not
an nci_dev pointer.
Remove usage of skb-dev to carry nci_dev and replace it by parameter
in nci_recv_frame(), nci_send_frame() and driver send() functions.
NfcWilink driver is also updated to use those functions.
Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Each NFC adapter can have several links to different secure elements and
that property needs to be exported by the drivers.
A secure element link can be enabled and disabled, and card emulation will
be handled by the currently active one. Otherwise card emulation will be
host implemented.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
During NFC-DEP target activation, store the remote
general bytes to be used later in dep_link_up.
When dep_link_up is called, activate the NFC-DEP target,
and forward the remote general bytes.
When dep_link_down is called, deactivate the target.
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
If initiator protocol is NFC-DEP, set the local general bytes
in nci_start_poll.
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Add the ability to select between multiple targets in NCI.
If only one target is found, it will be auto-activated.
If more than one target is found, then DISCOVER_NTF will be
generated for each target, and the host should select one by
calling DISCOVER_SELECT_CMD. Then, the target will be activated.
If the activation fails, GENERIC_ERROR_NTF is generated.
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Make a clear separation between NCI states and flags.
This is required in order to support more NCI states (e.g.
for multiple targets support).
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Add NCI data exchange timer to catch timeouts,
and call the data exchange callback with an error.
Signed-off-by: Ilan Elias <ilane@ti.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Increase NCI deactivate timeout from 5 sec to 30 sec.
NCI deactivate procedure might take a long time,
depending on the local and remote parameters.
Signed-off-by: Ilan Elias <ilane@ti.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Addition, deletion, and modification of NCI constants.
Changes in NCI commands, responses, and notifications structures.
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Remove unused NCI operations, e.g. create static rf connection.
Signed-off-by: Ilan Elias <ilane@ti.com>
Acked-by: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Addition, deletion and modification of NCI constants.
Changes in NCI commands, responses and notifications structures.
Signed-off-by: Ilan Elias <ilane@ti.com>
Acked-by: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Protect 'cb' and 'cb_context' arguments in nci_data_exchange.
In fact, this implements a queue with max length of 1 data
exchange transactions in parallel.
Signed-off-by: Ilan Elias <ilane@ti.com>
Acked-by: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The NFC Controller Interface (NCI) is a standard
communication protocol between an NFC Controller (NFCC)
and a Device Host (DH), defined by the NFC Forum.
Signed-off-by: Ilan Elias <ilane@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
