media: i2c: imx290: Add crop selection targets support

Implement read-only access to crop selection rectangles to expose the
analogue crop rectangle. The public (leaked) IMX290 documentation is not
very clear on how cropping is implemented and configured exactly, so
the margins may not be entirely accurate.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

drivers/media/i2c/imx290.c

@@ -105,6 +105,53 @@
 
 #define IMX290_VMAX_DEFAULT				1125
 
+
+/*
+ * The IMX290 pixel array is organized as follows:
+ *
+ *     +------------------------------------+
+ *     |           Optical Black            |     }  Vertical effective optical black (10)
+ * +---+------------------------------------+---+
+ * |   |                                    |   | }  Effective top margin (8)
+ * |   |   +----------------------------+   |   | \
+ * |   |   |                            |   |   |  |
+ * |   |   |                            |   |   |  |
+ * |   |   |                            |   |   |  |
+ * |   |   |    Recording Pixel Area    |   |   |  | Recommended height (1080)
+ * |   |   |                            |   |   |  |
+ * |   |   |                            |   |   |  |
+ * |   |   |                            |   |   |  |
+ * |   |   +----------------------------+   |   | /
+ * |   |                                    |   | }  Effective bottom margin (9)
+ * +---+------------------------------------+---+
+ *  <-> <-> <--------------------------> <-> <->
+ *                                            \----  Ignored right margin (4)
+ *                                        \--------  Effective right margin (9)
+ *                       \-------------------------  Recommended width (1920)
+ *       \-----------------------------------------  Effective left margin (8)
+ *   \---------------------------------------------  Ignored left margin (4)
+ *
+ * The optical black lines are output over CSI-2 with a separate data type.
+ *
+ * The pixel array is meant to have 1920x1080 usable pixels after image
+ * processing in an ISP. It has 8 (9) extra active pixels usable for color
+ * processing in the ISP on the top and left (bottom and right) sides of the
+ * image. In addition, 4 additional pixels are present on the left and right
+ * sides of the image, documented as "ignored area".
+ *
+ * As far as is understood, all pixels of the pixel array (ignored area, color
+ * processing margins and recording area) can be output by the sensor.
+ */
+
+#define IMX290_PIXEL_ARRAY_WIDTH			1945
+#define IMX290_PIXEL_ARRAY_HEIGHT			1097
+#define IMX920_PIXEL_ARRAY_MARGIN_LEFT			12
+#define IMX920_PIXEL_ARRAY_MARGIN_RIGHT			13
+#define IMX920_PIXEL_ARRAY_MARGIN_TOP			8
+#define IMX920_PIXEL_ARRAY_MARGIN_BOTTOM		9
+#define IMX290_PIXEL_ARRAY_RECORDING_WIDTH		1920
+#define IMX290_PIXEL_ARRAY_RECORDING_HEIGHT		1080
+
 static const char * const imx290_supply_name[] = {
 	"vdda",
 	"vddd",
@@ -667,6 +714,52 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
 	return 0;
 }
 
+static int imx290_get_selection(struct v4l2_subdev *sd,
+				struct v4l2_subdev_state *sd_state,
+				struct v4l2_subdev_selection *sel)
+{
+	struct imx290 *imx290 = to_imx290(sd);
+	struct v4l2_mbus_framefmt *format;
+
+	switch (sel->target) {
+	case V4L2_SEL_TGT_CROP: {
+		format = imx290_get_pad_format(imx290, sd_state, sel->which);
+
+		mutex_lock(&imx290->lock);
+
+		sel->r.top = IMX920_PIXEL_ARRAY_MARGIN_TOP
+			   + (IMX290_PIXEL_ARRAY_RECORDING_HEIGHT - format->height) / 2;
+		sel->r.left = IMX920_PIXEL_ARRAY_MARGIN_LEFT
+			    + (IMX290_PIXEL_ARRAY_RECORDING_WIDTH - format->width) / 2;
+		sel->r.width = format->width;
+		sel->r.height = format->height;
+
+		mutex_unlock(&imx290->lock);
+		return 0;
+	}
+
+	case V4L2_SEL_TGT_NATIVE_SIZE:
+	case V4L2_SEL_TGT_CROP_BOUNDS:
+		sel->r.top = 0;
+		sel->r.left = 0;
+		sel->r.width = IMX290_PIXEL_ARRAY_WIDTH;
+		sel->r.height = IMX290_PIXEL_ARRAY_HEIGHT;
+
+		return 0;
+
+	case V4L2_SEL_TGT_CROP_DEFAULT:
+		sel->r.top = IMX920_PIXEL_ARRAY_MARGIN_TOP;
+		sel->r.left = IMX920_PIXEL_ARRAY_MARGIN_LEFT;
+		sel->r.width = IMX290_PIXEL_ARRAY_RECORDING_WIDTH;
+		sel->r.height = IMX290_PIXEL_ARRAY_RECORDING_HEIGHT;
+
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
 static int imx290_entity_init_cfg(struct v4l2_subdev *subdev,
 				  struct v4l2_subdev_state *sd_state)
 {
@@ -883,6 +976,7 @@ static const struct v4l2_subdev_pad_ops imx290_pad_ops = {
 	.enum_frame_size = imx290_enum_frame_size,
 	.get_fmt = imx290_get_fmt,
 	.set_fmt = imx290_set_fmt,
+	.get_selection = imx290_get_selection,
 };
 
 static const struct v4l2_subdev_ops imx290_subdev_ops = {