thunderbolt: Add support for DMA configuration based mailbox

The DMA (NHI) port of a switch provides access to the NVM of the host
controller (and devices starting from Intel Alpine Ridge). The NVM
contains also more complete DROM for the root switch including vendor
and device identification strings.

This will look for the DMA port capability for each switch and if found
populates sw->dma_port. We then teach tb_drom_read() to read the DROM
information from NVM if available for the root switch.

The DMA port capability also supports upgrading the NVM for both host
controller and devices which will be added in subsequent patches.

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: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 6384061100b0..4b47e0999cda 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -377,6 +377,8 @@ static void tb_switch_release(struct device *dev)
 {
 	struct tb_switch *sw = tb_to_switch(dev);
 
+	dma_port_free(sw->dma_port);
+
 	kfree(sw->uuid);
 	kfree(sw->device_name);
 	kfree(sw->vendor_name);
@@ -570,6 +572,25 @@ static void tb_switch_set_uuid(struct tb_switch *sw)
 	sw->uuid = kmemdup(uuid, sizeof(uuid), GFP_KERNEL);
 }
 
+static void tb_switch_add_dma_port(struct tb_switch *sw)
+{
+	switch (sw->generation) {
+	case 3:
+		break;
+
+	case 2:
+		/* Only root switch can be upgraded */
+		if (tb_route(sw))
+			return;
+		break;
+
+	default:
+		return;
+	}
+
+	sw->dma_port = dma_port_alloc(sw);
+}
+
 /**
  * tb_switch_add() - Add a switch to the domain
  * @sw: Switch to add
@@ -586,6 +607,15 @@ int tb_switch_add(struct tb_switch *sw)
 {
 	int i, ret;
 
+	/*
+	 * Initialize DMA control port now before we read DROM. Recent
+	 * host controllers have more complete DROM on NVM that includes
+	 * vendor and model identification strings which we then expose
+	 * to the userspace. NVM can be accessed through DMA
+	 * configuration based mailbox.
+	 */
+	tb_switch_add_dma_port(sw);
+
 	/* read drom */
 	ret = tb_drom_read(sw);
 	if (ret) {