[PATCH v3 02/11] media: qcom: camss: Introduce SOF sequence tracking

[bryan.odonoghue@linaro.org]

From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>

In order to communicate to user-space CSI2 SOF events we will need to hook
into and control v4l2_ctrl_subdev_subscribe_event. In-line with other
implementations of FRAME_SYNC have CSI decoders which support the event
always generate it in our case if and only if an atomic user count
indicates it should be so.

A flag in the CSID descriptor indicates if frame_sync_en is supported so
for each SoC that supports it this flag should be true. Since bool is false
by default no negative enumeration of existing or in-flight CSID is
required.

Subsequent patches will enable on a per-CSID basis.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
---
 drivers/media/platform/qcom/camss/camss-csid.c | 54 +++++++++++++++++++++++++-
 drivers/media/platform/qcom/camss/camss-csid.h | 12 ++++++
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/camss/camss-csid.c b/drivers/media/platform/qcom/camss/camss-csid.c
index a00791b00feb7..7f33fb81ca8cc 100644
--- a/drivers/media/platform/qcom/camss/camss-csid.c
+++ b/drivers/media/platform/qcom/camss/camss-csid.c
@@ -760,6 +760,7 @@ static int csid_set_power(struct v4l2_subdev *sd, int on)
 static int csid_set_stream(struct v4l2_subdev *sd, int enable)
 {
 	struct csid_device *csid = v4l2_get_subdevdata(sd);
+	unsigned int i;
 	int ret;
 
 	if (enable) {
@@ -778,6 +779,10 @@ static int csid_set_stream(struct v4l2_subdev *sd, int enable)
 	}
 
 	if (csid->phy.need_vc_update) {
+		/* Set to -1 as we want to do atomic_inc_return to read */
+		for (i = 0; i < MSM_CSID_MAX_SRC_STREAMS; i++)
+			atomic_set(&csid->sof_seq[i], -1);
+
 		csid->res->hw_ops->configure_stream(csid, enable);
 		csid->phy.need_vc_update = false;
 	}
@@ -1316,9 +1321,56 @@ static int csid_link_setup(struct media_entity *entity,
 	return 0;
 }
 
+static int csid_frame_sync_add(struct v4l2_subscribed_event *sev, unsigned int elems)
+{
+	struct csid_device *csid = v4l2_get_subdevdata(vdev_to_v4l2_subdev(sev->fh->vdev));
+
+	atomic_inc(&csid->frame_sync_users);
+
+	return 0;
+}
+
+static void csid_frame_sync_del(struct v4l2_subscribed_event *sev)
+{
+	struct csid_device *csid = v4l2_get_subdevdata(vdev_to_v4l2_subdev(sev->fh->vdev));
+
+	atomic_dec(&csid->frame_sync_users);
+}
+
+static const struct v4l2_subscribed_event_ops csid_frame_sync_ops = {
+	.add = csid_frame_sync_add,
+	.del = csid_frame_sync_del,
+};
+
+static int csid_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
+				struct v4l2_event_subscription *sub)
+{
+	struct csid_device *csid = v4l2_get_subdevdata(sd);
+
+	if (sub->type != V4L2_EVENT_FRAME_SYNC)
+		return v4l2_ctrl_subdev_subscribe_event(sd, fh, sub);
+
+	if (!csid->res->frame_sync_en)
+		return -EINVAL;
+
+	return v4l2_event_subscribe(fh, sub, 0, &csid_frame_sync_ops);
+}
+
+void csid_sof_event(struct csid_device *csid, unsigned int id)
+{
+	struct v4l2_event event = {
+		.type = V4L2_EVENT_FRAME_SYNC,
+		.u.frame_sync.frame_sequence =
+			atomic_inc_return(&csid->sof_seq[id]),
+	};
+
+	if (atomic_read(&csid->frame_sync_users))
+		v4l2_event_queue(csid->subdev.devnode, &event);
+}
+
 static const struct v4l2_subdev_core_ops csid_core_ops = {
 	.s_power = csid_set_power,
-	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
+	.subscribe_event = csid_subscribe_event,
 	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
 };
 
diff --git a/drivers/media/platform/qcom/camss/camss-csid.h b/drivers/media/platform/qcom/camss/camss-csid.h
index 5296b10f6bac8..a9d88909d37fc 100644
--- a/drivers/media/platform/qcom/camss/camss-csid.h
+++ b/drivers/media/platform/qcom/camss/camss-csid.h
@@ -141,6 +141,7 @@ struct csid_hw_ops {
 
 struct csid_subdev_resources {
 	bool is_lite;
+	bool frame_sync_en;
 	const struct csid_hw_ops *hw_ops;
 	const struct parent_dev_ops *parent_dev_ops;
 	const struct csid_formats *formats;
@@ -167,6 +168,8 @@ struct csid_device {
 	struct v4l2_ctrl_handler ctrls;
 	struct v4l2_ctrl *testgen_mode;
 	const struct csid_subdev_resources *res;
+	atomic_t frame_sync_users;
+	atomic_t sof_seq[MSM_CSID_MAX_SRC_STREAMS];
 };
 
 struct camss_subdev_resources;
@@ -248,4 +251,13 @@ u32 csid_hw_version(struct csid_device *csid);
 u32 csid_src_pad_code(struct csid_device *csid, u32 sink_code,
 		      unsigned int match_format_idx, u32 match_code);
 
+/*
+ * csid_sof_event - Track SOF generate V4L2_EVENT_FRAME_SYNC
+ * @csid: CSID device
+ * @id: CSID src-stream ID
+ *
+ *  Called from the CSID interrupt handler on SOF of the path driving the event.
+ */
+void csid_sof_event(struct csid_device *csid, unsigned int id);
+
 #endif /* QC_MSM_CAMSS_CSID_H */

-- 
2.56.0