media: i2c: imx219: Support four-lane operation

The imx219 camera is capable of either two-lane or four-lane
operation.  When operating in four-lane, both the pixel rate and
link frequency change. Regardless of the mode, however, both
frequencies remain fixed.

Helper functions are needed to read and set pixel and link frequencies
which also reduces the number of fixed registers in the table of modes.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Author: aford173

drivers/media/i2c/imx219.c

@@ -42,10 +42,16 @@
 /* External clock frequency is 24.0M */
 #define IMX219_XCLK_FREQ		24000000
 
-/* Pixel rate is fixed at 182.4M for all the modes */
+/* Pixel rate is fixed for all the modes */
 #define IMX219_PIXEL_RATE		182400000
+#define IMX219_PIXEL_RATE_4LANE		280800000
 
 #define IMX219_DEFAULT_LINK_FREQ	456000000
+#define IMX219_DEFAULT_LINK_FREQ_4LANE	363000000
+
+#define IMX219_REG_CSI_LANE_MODE	0x0114
+#define IMX219_CSI_2_LANE_MODE		0x01
+#define IMX219_CSI_4_LANE_MODE		0x03
 
 /* V_TIMING internal */
 #define IMX219_REG_VTS			0x0160
@@ -299,6 +305,10 @@ static const s64 imx219_link_freq_menu[] = {
 	IMX219_DEFAULT_LINK_FREQ,
 };
 
+static const s64 imx219_link_freq_4lane_menu[] = {
+	IMX219_DEFAULT_LINK_FREQ_4LANE,
+};
+
 static const char * const imx219_test_pattern_menu[] = {
 	"Disabled",
 	"Color Bars",
@@ -474,6 +484,9 @@ struct imx219 {
 
 	/* Streaming on/off */
 	bool streaming;
+
+	/* Two or Four lanes */
+	u8 lanes;
 };
 
 static inline struct imx219 *to_imx219(struct v4l2_subdev *_sd)
@@ -936,6 +949,13 @@ static int imx219_get_selection(struct v4l2_subdev *sd,
 	return -EINVAL;
 }
 
+static int imx219_configure_lanes(struct imx219 *imx219)
+{
+	return imx219_write_reg(imx219, IMX219_REG_CSI_LANE_MODE,
+				IMX219_REG_VALUE_08BIT, (imx219->lanes == 2) ?
+				IMX219_CSI_2_LANE_MODE : IMX219_CSI_4_LANE_MODE);
+};
+
 static int imx219_start_streaming(struct imx219 *imx219)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(&imx219->sd);
@@ -953,6 +973,13 @@ static int imx219_start_streaming(struct imx219 *imx219)
 		goto err_rpm_put;
 	}
 
+	/* Configure two or four Lane mode */
+	ret = imx219_configure_lanes(imx219);
+	if (ret) {
+		dev_err(&client->dev, "%s failed to configure lanes\n", __func__);
+		goto err_rpm_put;
+	}
+
 	/* Apply default values of current mode */
 	reg_list = &imx219->mode->reg_list;
 	ret = imx219_write_regs(imx219, reg_list->regs, reg_list->num_of_regs);
@@ -1184,6 +1211,11 @@ static const struct v4l2_subdev_internal_ops imx219_internal_ops = {
 	.open = imx219_open,
 };
 
+static unsigned long imx219_get_pixel_rate(struct imx219 *imx219)
+{
+	return (imx219->lanes == 2) ? IMX219_PIXEL_RATE : IMX219_PIXEL_RATE_4LANE;
+}
+
 /* Initialize control handlers */
 static int imx219_init_controls(struct imx219 *imx219)
 {
@@ -1205,15 +1237,16 @@ static int imx219_init_controls(struct imx219 *imx219)
 	/* By default, PIXEL_RATE is read only */
 	imx219->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &imx219_ctrl_ops,
 					       V4L2_CID_PIXEL_RATE,
-					       IMX219_PIXEL_RATE,
-					       IMX219_PIXEL_RATE, 1,
-					       IMX219_PIXEL_RATE);
+					       imx219_get_pixel_rate(imx219),
+					       imx219_get_pixel_rate(imx219), 1,
+					       imx219_get_pixel_rate(imx219));
 
 	imx219->link_freq =
 		v4l2_ctrl_new_int_menu(ctrl_hdlr, &imx219_ctrl_ops,
 				       V4L2_CID_LINK_FREQ,
 				       ARRAY_SIZE(imx219_link_freq_menu) - 1, 0,
-				       imx219_link_freq_menu);
+				       (imx219->lanes == 2) ? imx219_link_freq_menu :
+				       imx219_link_freq_4lane_menu);
 	if (imx219->link_freq)
 		imx219->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
 
@@ -1308,7 +1341,7 @@ static void imx219_free_controls(struct imx219 *imx219)
 	mutex_destroy(&imx219->mutex);
 }
 
-static int imx219_check_hwcfg(struct device *dev)
+static int imx219_check_hwcfg(struct device *dev, struct imx219 *imx219)
 {
 	struct fwnode_handle *endpoint;
 	struct v4l2_fwnode_endpoint ep_cfg = {
@@ -1328,10 +1361,12 @@ static int imx219_check_hwcfg(struct device *dev)
 	}
 
 	/* Check the number of MIPI CSI2 data lanes */
-	if (ep_cfg.bus.mipi_csi2.num_data_lanes != 2) {
-		dev_err(dev, "only 2 data lanes are currently supported\n");
+	if (ep_cfg.bus.mipi_csi2.num_data_lanes != 2 &&
+	    ep_cfg.bus.mipi_csi2.num_data_lanes != 4) {
+		dev_err(dev, "only 2 or 4 data lanes are currently supported\n");
 		goto error_out;
 	}
+	imx219->lanes = ep_cfg.bus.mipi_csi2.num_data_lanes;
 
 	/* Check the link frequency set in device tree */
 	if (!ep_cfg.nr_of_link_frequencies) {
@@ -1340,7 +1375,8 @@ static int imx219_check_hwcfg(struct device *dev)
 	}
 
 	if (ep_cfg.nr_of_link_frequencies != 1 ||
-	    ep_cfg.link_frequencies[0] != IMX219_DEFAULT_LINK_FREQ) {
+	   (ep_cfg.link_frequencies[0] != ((imx219->lanes == 2) ?
+	    IMX219_DEFAULT_LINK_FREQ : IMX219_DEFAULT_LINK_FREQ_4LANE))) {
 		dev_err(dev, "Link frequency not supported: %lld\n",
 			ep_cfg.link_frequencies[0]);
 		goto error_out;
@@ -1368,7 +1404,7 @@ static int imx219_probe(struct i2c_client *client)
 	v4l2_i2c_subdev_init(&imx219->sd, client, &imx219_subdev_ops);
 
 	/* Check the hardware configuration in device tree */
-	if (imx219_check_hwcfg(dev))
+	if (imx219_check_hwcfg(dev, imx219))
 		return -EINVAL;
 
 	/* Get system clock (xclk) */