thunderbolt: Add support for frame mode

When high-speed DMA paths are used to transfer arbitrary data over a
Thunderbolt link, DMA rings should be in frame mode instead of raw mode.
The latter is used by the control channel (ring 0). In frame mode each
data frame can hold up to 4kB payload.

This patch modifies the DMA ring code to allow configuring a ring to be
in frame mode by passing a new flag (RING_FLAG_FRAME) to the ring when
it is allocated. In addition there might be need to enable end-to-end
(E2E) workaround for the ring to prevent losing Rx frames in certain
situations. We add another flag (RING_FLAG_E2E) that can be used for
this purpose.

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, 9 insertions, 1 deletions

diff --git a/drivers/thunderbolt/nhi.h b/drivers/thunderbolt/nhi.h
index 0e05828983db..4503ddbeccb3 100644
--- a/drivers/thunderbolt/nhi.h
+++ b/drivers/thunderbolt/nhi.h
@@ -56,6 +56,8 @@ struct tb_nhi {
  * @irq: MSI-X irq number if the ring uses MSI-X. %0 otherwise.
  * @vector: MSI-X vector number the ring uses (only set if @irq is > 0)
  * @flags: Ring specific flags
+ * @sof_mask: Bit mask used to detect start of frame PDF
+ * @eof_mask: Bit mask used to detect end of frame PDF
  */
 struct tb_ring {
 	struct mutex lock;
@@ -74,10 +76,16 @@ struct tb_ring {
 	int irq;
 	u8 vector;
 	unsigned int flags;
+	u16 sof_mask;
+	u16 eof_mask;
 };
 
 /* Leave ring interrupt enabled on suspend */
 #define RING_FLAG_NO_SUSPEND	BIT(0)
+/* Configure the ring to be in frame mode */
+#define RING_FLAG_FRAME		BIT(1)
+/* Enable end-to-end flow control */
+#define RING_FLAG_E2E		BIT(2)
 
 struct ring_frame;
 typedef void (*ring_cb)(struct tb_ring*, struct ring_frame*, bool canceled);
@@ -100,7 +108,7 @@ struct ring_frame {
 struct tb_ring *ring_alloc_tx(struct tb_nhi *nhi, int hop, int size,
 			      unsigned int flags);
 struct tb_ring *ring_alloc_rx(struct tb_nhi *nhi, int hop, int size,
-			      unsigned int flags);
+			      unsigned int flags, u16 sof_mask, u16 eof_mask);
 void ring_start(struct tb_ring *ring);
 void ring_stop(struct tb_ring *ring);
 void ring_free(struct tb_ring *ring);