diff options
author | Mark A. Greer <mgreer@animalcreek.com> | 2014-09-24 03:38:11 +0400 |
---|---|---|
committer | Samuel Ortiz <sameo@linux.intel.com> | 2014-11-28 14:39:33 +0300 |
commit | a80509c76bf2b10dae76f3caea343ac4b85c72b4 (patch) | |
tree | 924f14ca602ddecd0bb5b81e7201628882b07375 /include/net | |
parent | c12715ab3f0122971f75731b9c2f5b35836165cb (diff) | |
download | linux-a80509c76bf2b10dae76f3caea343ac4b85c72b4.tar.xz |
NFC: digital: Add NFC-DEP Initiator-side NACK Support
When an NFC-DEP Initiator receives a frame with
an incorrect CRC or with a parity error, and the
frame is at least 4 bytes long, its supposed to
send a NACK to the Target. The Initiator can
send up to 'N(retry,nack)' consecutive NACKs
where 2 <= 'N(retry,nack)' <= 5. When the limit
is exceeded, a PROTOCOL EXCEPTION is raised.
Any other type of transmission error is to be
ignored and the Initiator should continue
waiting for a new frame. This is described
in section 14.12.5.4 of the NFC Digital Protocol
Spec.
The digital layer's NFC-DEP code doesn't implement
any of this so add it. This support diverges from
the spec in two significant ways:
a) NACKs will be sent for ANY error reported by the
driver except a timeout. This is done because
there is currently no way for the digital layer
to distinguish a CRC or parity error from any
other type of error reported by the driver.
b) All other errors will cause a PROTOCOL EXCEPTION
even frames with CRC errors that are less than 4
bytes.
The value chosen for 'N(retry,nack)' is 2.
Targets do not send NACK PDUs.
Reviewed-by: Thierry Escande <thierry.escande@linux.intel.com>
Tested-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'include/net')
-rw-r--r-- | include/net/nfc/digital.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/nfc/digital.h b/include/net/nfc/digital.h index 2fdff00e06cd..2fd498cdb818 100644 --- a/include/net/nfc/digital.h +++ b/include/net/nfc/digital.h @@ -233,6 +233,8 @@ struct nfc_digital_dev { struct sk_buff *chaining_skb; struct digital_data_exch *data_exch; + int nack_count; + u16 target_fsc; int (*skb_check_crc)(struct sk_buff *skb); |