media: i2c: ds90ub953: Support non-sync mode

Add support for FPD-Link non-sync mode with external clock. The only
thing that needs to be added is the calculation for the clkout.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/i2c/ds90ub953.c

@@ -145,6 +145,7 @@ struct ub953_data {
 
 	struct i2c_client	*client;
 	struct regmap		*regmap;
+	struct clk		*clkin;
 
 	u32			num_data_lanes;
 	bool			non_continous_clk;
@@ -844,15 +845,21 @@ static int ub953_i2c_master_init(struct ub953_data *priv)
 
 static u64 ub953_get_fc_rate(struct ub953_data *priv)
 {
-	if (priv->mode != UB953_MODE_SYNC) {
-		/* Not supported */
-		return 0;
-	}
-
+	switch (priv->mode) {
+	case UB953_MODE_SYNC:
 		if (priv->hw_data->is_ub971)
 			return priv->plat_data->bc_rate * 160ull;
 		else
 			return priv->plat_data->bc_rate / 2 * 160ull;
+
+	case UB953_MODE_NONSYNC_EXT:
+		/* CLKIN_DIV = 1 always */
+		return clk_get_rate(priv->clkin) * 80ull;
+
+	default:
+		/* Not supported */
+		return 0;
+	}
 }
 
 static unsigned long ub953_calc_clkout_ub953(struct ub953_data *priv,
@@ -1195,9 +1202,15 @@ static int ub953_hw_init(struct ub953_data *priv)
 	dev_dbg(dev, "mode from %s: %#x\n", mode_override ? "reg" : "strap",
 		priv->mode);
 
-	if (priv->mode != UB953_MODE_SYNC)
+	if (priv->mode != UB953_MODE_SYNC &&
+	    priv->mode != UB953_MODE_NONSYNC_EXT)
 		return dev_err_probe(dev, -ENODEV,
-				     "Only synchronous mode supported\n");
+				     "Unsupported mode selected: %u\n",
+				     priv->mode);
+
+	if (priv->mode == UB953_MODE_NONSYNC_EXT && !priv->clkin)
+		return dev_err_probe(dev, -EINVAL,
+				     "clkin required for non-sync ext mode\n");
 
 	ret = ub953_read(priv, UB953_REG_REV_MASK_ID, &v);
 	if (ret)
@@ -1314,6 +1327,13 @@ static int ub953_probe(struct i2c_client *client)
 		goto err_mutex_destroy;
 	}
 
+	priv->clkin = devm_clk_get_optional(dev, "clkin");
+	if (IS_ERR(priv->clkin)) {
+		ret = PTR_ERR(priv->clkin);
+		dev_err_probe(dev, ret, "failed to parse 'clkin'\n");
+		goto err_mutex_destroy;
+	}
+
 	ret = ub953_parse_dt(priv);
 	if (ret)
 		goto err_mutex_destroy;