NFC: pn533: Add support for ACS ACR122U reader
authorWaldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Wed, 3 Apr 2013 06:02:13 +0000 (08:02 +0200)
committerSamuel Ortiz <sameo@linux.intel.com>
Thu, 11 Apr 2013 14:29:07 +0000 (16:29 +0200)
commit53cf48399ad3b08c9115b4fce73dee0b6e726c91
tree69048951e15fc273952de4c019f0f26c8a799bf8
parent58520373d8aff974f4b3f1bd9eb84c1ff3d6bd8b
NFC: pn533: Add support for ACS ACR122U reader

ACS ACR122U is an USB NFC reader, PC/SC and CCID compilant, based
on NXP PN532 chip.

Internally, it's build of MCU, PN532 and an antenna. MCU makes the
device CCID and PC/SC compilant and provide USB connection.

In this achitecture, a host cannot talk directly to PN532 and must
rely on MCU. Luckily, MCU exposes pseud-APDU through PC/SC Escape
mechanism which let the host to transmit standard PN532 commands
directly to PN532 chip with some limitations.

The frame roughly looks like:

    CCID header    |          APDU header           |    PN532 header
(pc_to_rdr_escape) |  (pseudo apdu Direct Tramsmit) | (len, TFI, cmd, params)

Accordign to limitations, ACR122U does't provide any mechanism to
abort last issued command.

Signed-off-by: Waldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
drivers/nfc/pn533.c