[PATCH v2 12/17] drm/display/dp_mst: Add helpers to query payload allocation properties

[Imre Deak <imre.deak@intel.com>]

Add helper functions to query the virtual channel and time slots for a
payload and the current payload count and total allocated time slots in
an MST topology. These are needed by a follow-up i915 patch verifying
the SW vs. HW state of the MST topology.

Cc: Lyude Paul <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 36 +++++++++++++++++++
 include/drm/display/drm_dp_mst_helper.h       | 21 +++++++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index f2081f3fad0da..47605f67578ad 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3448,6 +3448,42 @@ bool drm_dp_mst_has_payload_alloc_errors(const struct drm_dp_mst_topology_state
 }
 EXPORT_SYMBOL(drm_dp_mst_has_payload_alloc_errors);
 
+/**
+ * drm_dp_mst_payload_vchannel - Return the DP virtual channel for a payload
+ * @mst_state: The MST atomic state containing @payload
+ * @payload: The payload to get the virtual channel for
+ *
+ * Return the DP virtual channel for @payload. The virtual channel is a
+ * contiguous range of MST Transmission Units on the DP main lanes between
+ * the source DPTX and the first downstream MST hub DPRX. Accordingly the
+ * channel is determined by the payload's position on the payload list
+ * ordered by VC start slot.
+ *
+ * Returns the 0-based virtual channel of @payload if it's in @mst_state with
+ * its time slots being allocated, or -1 otherwise.
+ */
+int drm_dp_mst_payload_vchannel(const struct drm_dp_mst_topology_state *mst_state,
+				const struct drm_dp_mst_atomic_payload *payload)
+{
+	struct drm_dp_mst_atomic_payload *pos;
+	int vc = 0;
+	bool found = false;
+
+	list_for_each_entry(pos, &mst_state->payloads, next) {
+		if (pos->vc_start_slot == -1)
+			continue;
+
+		if (pos == payload)
+			found = true;
+
+		if (pos->vc_start_slot < payload->vc_start_slot)
+			vc++;
+	}
+
+	return found ? vc : -1;
+}
+EXPORT_SYMBOL(drm_dp_mst_payload_vchannel);
+
 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_port *port,
 				 int offset, int size, u8 *bytes)
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 53b251b264e89..bb7c595096fed 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -846,6 +846,27 @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
 			   const struct drm_dp_mst_atomic_payload *old_payload,
 			   struct drm_dp_mst_atomic_payload *new_payload);
 bool drm_dp_mst_has_payload_alloc_errors(const struct drm_dp_mst_topology_state *mst_state);
+int drm_dp_mst_payload_vchannel(const struct drm_dp_mst_topology_state *mst_state,
+				const struct drm_dp_mst_atomic_payload *payload);
+
+static inline int
+drm_dp_mst_payload_count(const struct drm_dp_mst_topology_state *mst_state)
+{
+	return mst_state->mgr->payload_count;
+}
+
+static inline int
+drm_dp_mst_allocated_time_slots(const struct drm_dp_mst_topology_state *mst_state)
+{
+	return drm_dp_mst_payload_count(mst_state) ?
+		mst_state->mgr->next_start_slot - mst_state->start_slot : 0;
+}
+
+static inline int
+drm_dp_mst_payload_time_slots(const struct drm_dp_mst_atomic_payload *payload)
+{
+	return payload->time_slots;
+}
 
 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
 
-- 
2.37.1