thunderbolt: Add support for XDomain discovery protocol

When two hosts are connected over a Thunderbolt cable, there is a
protocol they can use to communicate capabilities supported by the host.
The discovery protocol uses automatically configured control channel
(ring 0) and is build on top of request/response transactions using
special XDomain primitives provided by the Thunderbolt base protocol.

The capabilities consists of a root directory block of basic properties
used for identification of the host, and then there can be zero or more
directories each describing a Thunderbolt service and its capabilities.

Once both sides have discovered what is supported the two hosts can
setup high-speed DMA paths and transfer data to the other side using
whatever protocol was agreed based on the properties. The software
protocol used to communicate which DMA paths to enable is service
specific.

This patch adds support for the XDomain discovery protocol to the
Thunderbolt bus. We model each remote host connection as a Linux XDomain
device. For each Thunderbolt service found supported on the XDomain
device, we create Linux Thunderbolt service device which Thunderbolt
service drivers can then bind to based on the protocol identification
information retrieved from the property directory describing the
service.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/thunderbolt/ctl.c b/drivers/thunderbolt/ctl.c
index e6a4c9458c76..46e393c5fd1d 100644
--- a/drivers/thunderbolt/ctl.c
+++ b/drivers/thunderbolt/ctl.c
@@ -368,10 +368,10 @@ static int tb_ctl_tx(struct tb_ctl *ctl, const void *data, size_t len,
 /**
  * tb_ctl_handle_event() - acknowledge a plug event, invoke ctl->callback
  */
-static void tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,
+static bool tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,
 				struct ctl_pkg *pkg, size_t size)
 {
-	ctl->callback(ctl->callback_data, type, pkg->buffer, size);
+	return ctl->callback(ctl->callback_data, type, pkg->buffer, size);
 }
 
 static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
@@ -444,6 +444,8 @@ static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
 		break;
 
 	case TB_CFG_PKG_EVENT:
+	case TB_CFG_PKG_XDOMAIN_RESP:
+	case TB_CFG_PKG_XDOMAIN_REQ:
 		if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
 			tb_ctl_err(pkg->ctl,
 				   "RX: checksum mismatch, dropping packet\n");
@@ -451,8 +453,9 @@ static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
 		}
 		/* Fall through */
 	case TB_CFG_PKG_ICM_EVENT:
-		tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size);
-		goto rx;
+		if (tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size))
+			goto rx;
+		break;
 
 	default:
 		break;