NFC: ST21NFCA: Add driver for STMicroelectronics ST21NFCA NFC Chip

Add driver for STMicroelectronics ST21NFCA NFC controller.
ST21NFCA is using HCI protocol, shdlc as LLC layer & I2C as
communication protocol.

Adding support for Reader/Writer mode with Tag type 1/2/3/4 A & B.
It is using proprietary gate 15 for ISO14443-3 such as type 1 &
type 2 tags. It is using proprietary gate 14 for type F tags.
ST21NFCA_DEVICE_MGNT_GATE gives access to proprietary CLF configuration.
Standard gate for ISO14443-4 A (13) & B (11) are also used.

ST21NFCA specific mecanism:

One particular point to notice for the data handling is that frame
does not contain any length value. Therefore the i2c part of this driver
is managing the reception with a read length sequence until the end of
frame (0x7e) is reached.

In order to avoid conflict between sof & eof a mecanism
called byte stuffing concist of an escape byte (0x7d) insertion before
special byte (0x7e, 0x7d). The special byte is then xored with 0x20.

In this driver, When data are available in the CLF, the interrupt
gpio is driven to active state and triggered an interrupt.
Once the i2c_master_recv start, the interrupt gpio is driven to idle
state until its complete. If the frame is incomplete or data are still
available, interrupts will be triggered again.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/nfc/st21nfca/Kconfig b/drivers/nfc/st21nfca/Kconfig
new file mode 100644
index 000000000000..ee459f066ade
--- /dev/null
+++ b/drivers/nfc/st21nfca/Kconfig
@@ -0,0 +1,23 @@
+config NFC_ST21NFCA
+	tristate "STMicroelectronics ST21NFCA NFC driver"
+	depends on NFC_HCI
+	select CRC_CCITT
+	default n
+	---help---
+	  STMicroelectronics ST21NFCA core driver. It implements the chipset
+	  HCI logic and hooks into the NFC kernel APIs. Physical layers will
+	  register against it.
+
+	  To compile this driver as a module, choose m here. The module will
+	  be called st21nfca.
+	  Say N if unsure.
+
+config NFC_ST21NFCA_I2C
+	tristate "NFC ST21NFCA i2c support"
+	depends on NFC_ST21NFCA && I2C && NFC_SHDLC
+	---help---
+	  This module adds support for the STMicroelectronics st21nfca i2c interface.
+	  Select this if your platform is using the i2c bus.
+
+	  If you choose to build a module, it'll be called st21nfca_i2c.
+	  Say N if unsure.