The MIPI DSI ip found in the RZ/G3E SoC select the video input clock
based on the DU instance actually connected using the GPO0R register.

Add this feature to the driver using `RZ_MIPI_DSI_FEATURE_GPO0R`, update
the code accordingly to manage the vclk selection with the introduction
of `rzg2l_mipi_dsi_get_input_port()`.

Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
---
 .../gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c    | 67 +++++++++++++++++--
 .../drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h   |  3 +
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
index ccc2758bafb0..59125460cf57 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -37,7 +37,9 @@ MODULE_IMPORT_NS("RZV2H_CPG");
 
 #define RZG2L_DCS_BUF_SIZE	128 /* Maximum DCS buffer size in external memory. */
 
+#define RZ_MIPI_DSI_MAX_INPUT	2
 #define RZ_MIPI_DSI_FEATURE_16BPP	BIT(0)
+#define RZ_MIPI_DSI_FEATURE_GPO0R	BIT(1)
 
 struct rzg2l_mipi_dsi;
 
@@ -81,13 +83,14 @@ struct rzg2l_mipi_dsi {
 	struct drm_bridge bridge;
 	struct drm_bridge *next_bridge;
 
-	struct clk *vclk;
+	struct clk *vclk[RZ_MIPI_DSI_MAX_INPUT];
 	struct clk *lpclk;
 
 	enum mipi_dsi_pixel_format format;
 	unsigned int num_data_lanes;
 	unsigned int lanes;
 	unsigned long mode_flags;
+	u8 vclk_idx;
 
 	struct rzv2h_dsi_mode_calc mode_calc;
 
@@ -552,8 +555,8 @@ static int rzg2l_dphy_conf_clks(struct rzg2l_mipi_dsi *dsi, unsigned long mode_f
 	unsigned long vclk_rate;
 	unsigned int bpp;
 
-	clk_set_rate(dsi->vclk, mode_freq * KILO);
-	vclk_rate = clk_get_rate(dsi->vclk);
+	clk_set_rate(dsi->vclk[dsi->vclk_idx], mode_freq * KILO);
+	vclk_rate = clk_get_rate(dsi->vclk[dsi->vclk_idx]);
 	if (vclk_rate != mode_freq * KILO)
 		dev_dbg(dsi->dev, "Requested vclk rate %lu, actual %lu mismatch\n",
 			mode_freq * KILO, vclk_rate);
@@ -764,6 +767,11 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
 	if (ret < 0)
 		goto err_phy;
 
+	if (dsi->info->features & RZ_MIPI_DSI_FEATURE_GPO0R)
+		rzg2l_mipi_dsi_link_write(dsi, GPO0R, dsi->vclk_idx);
+
+	dev_dbg(dsi->dev, "selected du%d input channel\n", dsi->vclk_idx);
+
 	/* Enable Data lanes and Clock lanes */
 	txsetr = TXSETR_DLEN | TXSETR_NUMLANEUSE(dsi->lanes - 1) | TXSETR_CLEN;
 	rzg2l_mipi_dsi_link_write(dsi, TXSETR, txsetr);
@@ -1006,6 +1014,37 @@ static int rzg2l_mipi_dsi_stop_video(struct rzg2l_mipi_dsi *dsi)
 	return ret;
 }
 
+static int rzg2l_mipi_dsi_get_input_port(struct rzg2l_mipi_dsi *dsi)
+{
+	struct device_node *np = dsi->dev->of_node;
+	struct device_node *remote_ep, *ep_node;
+	struct of_endpoint ep;
+	bool ep_enabled;
+	int in_port;
+
+	/* DSI can have only one port enabled */
+	for_each_endpoint_of_node(np, ep_node) {
+		of_graph_parse_endpoint(ep_node, &ep);
+		if (ep.port >= RZ_MIPI_DSI_MAX_INPUT)
+			break;
+
+		remote_ep = of_graph_get_remote_endpoint(ep_node);
+		ep_enabled = of_device_is_available(remote_ep);
+		of_node_put(remote_ep);
+
+		if (ep_enabled) {
+			in_port = ep.port;
+			break;
+		}
+	}
+
+	if (!ep_enabled)
+		return -EINVAL;
+
+	dev_dbg(dsi->dev, "input port@%d\n", in_port);
+	return in_port;
+}
+
 /* -----------------------------------------------------------------------------
  * Bridge
  */
@@ -1400,9 +1439,25 @@ static int rzg2l_mipi_dsi_probe(struct platform_device *pdev)
 	if (IS_ERR(dsi->mmio))
 		return PTR_ERR(dsi->mmio);
 
-	dsi->vclk = devm_clk_get(dsi->dev, "vclk");
-	if (IS_ERR(dsi->vclk))
-		return PTR_ERR(dsi->vclk);
+	if (dsi->info->features & RZ_MIPI_DSI_FEATURE_GPO0R) {
+		dsi->vclk[0] = devm_clk_get(dsi->dev, "vclk1");
+		if (IS_ERR(dsi->vclk[0]))
+			return PTR_ERR(dsi->vclk[0]);
+
+		dsi->vclk[1] = devm_clk_get(dsi->dev, "vclk2");
+		if (IS_ERR(dsi->vclk[1]))
+			return PTR_ERR(dsi->vclk[1]);
+
+		ret = rzg2l_mipi_dsi_get_input_port(dsi);
+		if (ret < 0)
+			return dev_err_probe(dsi->dev, -EINVAL,
+					     "No available input port\n");
+		dsi->vclk_idx = ret;
+	} else {
+		dsi->vclk[0] = devm_clk_get(dsi->dev, "vclk");
+		if (IS_ERR(dsi->vclk[0]))
+			return PTR_ERR(dsi->vclk[0]);
+	}
 
 	dsi->lpclk = devm_clk_get(dsi->dev, "lpclk");
 	if (IS_ERR(dsi->lpclk))
diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h
index 2bef20566648..cee2e0bc5dc5 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h
@@ -83,6 +83,9 @@
 #define LINKSR_SQCHRUN1			BIT(4)
 #define LINKSR_SQCHRUN0			BIT(0)
 
+/* RZ/G3E General Purpose Output 0 Register */
+#define GPO0R				0xc0
+
 /* Tx Set Register */
 #define TXSETR				0x100
 #define TXSETR_NUMLANECAP		(0x3 << 16)
-- 
2.43.0