V4L/DVB (13908): cx18: Add initial working VIDIOC_G_ENC_INDEX ioctl() support

VIDIOC_G_ENC_INDEX support see the light of day.
Some notes:
1. With default capture parameters, the CX23418 seems to transfer 192 index
entries (4.5 kB worth) at 10 second intervals.

2. Index streams don't seem to be supported for MPEG 2 TS streams

3. The index entries seem to claim every frame is a B-Frame.  Possible
firmware bug.

4. The cx18 driver does not try to capture an index stream when inserting
sliced VBI into the MPEg stream as the offsets would need fixup.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-driver.h

@@ -288,6 +288,18 @@ struct cx18_options {
 #define CX18_SLICED_TYPE_WSS_625        (5)
 #define CX18_SLICED_TYPE_VPS            (7)
 
+/**
+ * list_entry_is_past_end - check if a previous loop cursor is off list end
+ * @pos:	the type * previously used as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Check if the entry's list_head is the head of the list, thus it's not a
+ * real entry but was the loop cursor that walked past the end
+ */
+#define list_entry_is_past_end(pos, head, member) \
+	(&pos->member == (head))
+
 struct cx18_buffer {
 	struct list_head list;
 	dma_addr_t dma_handle;

drivers/media/video/cx18/cx18-fileops.c

@@ -392,18 +392,6 @@ static size_t cx18_copy_buf_to_user(struct cx18_stream *s,
 	return len;
 }
 
-/**
- * list_entry_is_past_end - check if a previous loop cursor is off list end
- * @pos:	the type * previously used as a loop cursor.
- * @head:	the head for your list.
- * @member:	the name of the list_struct within the struct.
- *
- * Check if the entry's list_head is the head of the list, thus it's not a
- * real entry but was the loop cursor that walked past the end
- */
-#define list_entry_is_past_end(pos, head, member) \
-	(&pos->member == (head))
-
 static size_t cx18_copy_mdl_to_user(struct cx18_stream *s,
 		struct cx18_mdl *mdl, char __user *ubuf, size_t ucount)
 {

drivers/media/video/cx18/cx18-ioctl.c

@@ -775,10 +775,143 @@ static int cx18_g_sliced_vbi_cap(struct file *file, void *fh,
 	return 0;
 }
 
+static int _cx18_process_idx_data(struct cx18_buffer *buf,
+				  struct v4l2_enc_idx *idx)
+{
+	int consumed, remaining;
+	struct v4l2_enc_idx_entry *e_idx;
+	struct cx18_enc_idx_entry *e_buf;
+
+	/* Frame type lookup: 1=I, 2=P, 4=B */
+	const int mapping[8] = {
+		-1, V4L2_ENC_IDX_FRAME_I, V4L2_ENC_IDX_FRAME_P,
+		-1, V4L2_ENC_IDX_FRAME_B, -1, -1, -1
+	};
+
+	/*
+	 * Assumption here is that a buf holds an integral number of
+	 * struct cx18_enc_idx_entry objects and is properly aligned.
+	 * This is enforced by the module options on IDX buffer sizes.
+	 */
+	remaining = buf->bytesused - buf->readpos;
+	consumed = 0;
+	e_idx = &idx->entry[idx->entries];
+	e_buf = (struct cx18_enc_idx_entry *) &buf->buf[buf->readpos];
+
+	while (remaining >= sizeof(struct cx18_enc_idx_entry) &&
+	       idx->entries < V4L2_ENC_IDX_ENTRIES) {
+
+		e_idx->offset = (((u64) le32_to_cpu(e_buf->offset_high)) << 32)
+				| le32_to_cpu(e_buf->offset_low);
+
+		e_idx->pts = (((u64) (le32_to_cpu(e_buf->pts_high) & 1)) << 32)
+			     | le32_to_cpu(e_buf->pts_low);
+
+		e_idx->length = le32_to_cpu(e_buf->length);
+
+		e_idx->flags = mapping[le32_to_cpu(e_buf->flags) & 0x7];
+
+		e_idx->reserved[0] = 0;
+		e_idx->reserved[1] = 0;
+
+		idx->entries++;
+		e_idx = &idx->entry[idx->entries];
+		e_buf++;
+
+		remaining -= sizeof(struct cx18_enc_idx_entry);
+		consumed += sizeof(struct cx18_enc_idx_entry);
+	}
+
+	/* Swallow any partial entries at the end, if there are any */
+	if (remaining > 0 && remaining < sizeof(struct cx18_enc_idx_entry))
+		consumed += remaining;
+
+	buf->readpos += consumed;
+	return consumed;
+}
+
+static int cx18_process_idx_data(struct cx18_stream *s, struct cx18_mdl *mdl,
+				 struct v4l2_enc_idx *idx)
+{
+	if (s->type != CX18_ENC_STREAM_TYPE_IDX)
+		return -EINVAL;
+
+	if (mdl->curr_buf == NULL)
+		mdl->curr_buf = list_first_entry(&mdl->buf_list,
+						 struct cx18_buffer, list);
+
+	if (list_entry_is_past_end(mdl->curr_buf, &mdl->buf_list, list)) {
+		/*
+		 * For some reason we've exhausted the buffers, but the MDL
+		 * object still said some data was unread.
+		 * Fix that and bail out.
+		 */
+		mdl->readpos = mdl->bytesused;
+		return 0;
+	}
+
+	list_for_each_entry_from(mdl->curr_buf, &mdl->buf_list, list) {
+
+		/* Skip any empty buffers in the MDL */
+		if (mdl->curr_buf->readpos >= mdl->curr_buf->bytesused)
+			continue;
+
+		mdl->readpos += _cx18_process_idx_data(mdl->curr_buf, idx);
+
+		/* exit when MDL drained or request satisfied */
+		if (idx->entries >= V4L2_ENC_IDX_ENTRIES ||
+		    mdl->curr_buf->readpos < mdl->curr_buf->bytesused ||
+		    mdl->readpos >= mdl->bytesused)
+			break;
+	}
+	return 0;
+}
+
 static int cx18_g_enc_index(struct file *file, void *fh,
 				struct v4l2_enc_idx *idx)
 {
-	return -EINVAL;
+	struct cx18 *cx = ((struct cx18_open_id *)fh)->cx;
+	struct cx18_stream *s = &cx->streams[CX18_ENC_STREAM_TYPE_IDX];
+	s32 tmp;
+	struct cx18_mdl *mdl;
+
+	if (!cx18_stream_enabled(s)) /* Module options inhibited IDX stream */
+		return -EINVAL;
+
+	/* Compute the best case number of entries we can buffer */
+	tmp = s->buffers -
+			  s->bufs_per_mdl * CX18_ENC_STREAM_TYPE_IDX_FW_MDL_MIN;
+	if (tmp <= 0)
+		tmp = 1;
+	tmp = tmp * s->buf_size / sizeof(struct cx18_enc_idx_entry);
+
+	/* Fill out the header of the return structure */
+	idx->entries = 0;
+	idx->entries_cap = tmp;
+	memset(idx->reserved, 0, sizeof(idx->reserved));
+
+	/* Pull IDX MDLs and buffers from q_full and populate the entries */
+	do {
+		mdl = cx18_dequeue(s, &s->q_full);
+		if (mdl == NULL) /* No more IDX data right now */
+			break;
+
+		/* Extract the Index entry data from the MDL and buffers */
+		cx18_process_idx_data(s, mdl, idx);
+		if (mdl->readpos < mdl->bytesused) {
+			/* We finished with data remaining, push the MDL back */
+			cx18_push(s, mdl, &s->q_full);
+			break;
+		}
+
+		/* We drained this MDL, schedule it to go to the firmware */
+		cx18_enqueue(s, mdl, &s->q_free);
+
+	} while (idx->entries < V4L2_ENC_IDX_ENTRIES);
+
+	/* Tell the work handler to send free IDX MDLs to the firmware */
+	cx18_stream_load_fw_queue(s);
+	return 0;
 }
 
 static int cx18_encoder_cmd(struct file *file, void *fh,