NFC: trf7970a: Handle extra byte in response to Type 5 RMB commands

The current versions of the trf7970a has an erratum where it returns
an extra byte in the response to 'Read Multiple Block' (RMB) commands.
This command is issued to Type 5 tags (i.e., ISO/IEC 15693 tags) by
the neard daemon.

To handle this, define a new Device Tree property,
't5t-rmb-extra-byte-quirk', which indicates that the associated
trf7970a device has this erratum.  The trf7970a device driver
will then ensure that the response length to RMB commands is
reduced by one byte (for devices with the erratum).

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
index 7c89ca290ced..32b35a07abe4 100644
--- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
+++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
@@ -18,6 +18,9 @@ Optional SoC Specific Properties:
   "IRQ Status Read" erratum.
 - en2-rf-quirk: Specify that the trf7970a being used has the "EN2 RF"
   erratum.
+- t5t-rmb-extra-byte-quirk: Specify that the trf7970a has the erratum
+  where an extra byte is returned by Read Multiple Block commands issued
+  to Type 5 tags.
 
 Example (for ARM-based BeagleBone with TRF7970A on SPI1):
 
@@ -39,6 +42,7 @@ Example (for ARM-based BeagleBone with TRF7970A on SPI1):
 		autosuspend-delay = <30000>;
 		irq-status-read-quirk;
 		en2-rf-quirk;
+		t5t-rmb-extra-byte-quirk;
 		status = "okay";
 	};
 };