drm/rockchip: add ability to handle external dphys in mipi-dsi

While the common case is that the dsi controller uses an internal dphy,
accessed through the phy registers inside the dsi controller, there is
also the possibility to use a separate dphy from a different vendor.

One such case is the Rockchip px30 that uses a Innosilicon Mipi dphy,
so add the support for handling such a constellation, including the pll
also getting generated inside that external phy.

changes in v5:
- rebased on top of 5.5-rc1
- merged with dsi timing change to prevent ordering conflicts
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191209143130.4553-5-heiko@sntech.de

drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c

@@ -12,6 +12,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/phy/phy.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 
@@ -223,6 +224,10 @@ struct dw_mipi_dsi_rockchip {
 	bool is_slave;
 	struct dw_mipi_dsi_rockchip *slave;
 
+	/* optional external dphy */
+	struct phy *phy;
+	union phy_configure_opts phy_opts;
+
 	unsigned int lane_mbps; /* per lane */
 	u16 input_div;
 	u16 feedback_div;
@@ -359,6 +364,9 @@ static int dw_mipi_dsi_phy_init(void *priv_data)
 	struct dw_mipi_dsi_rockchip *dsi = priv_data;
 	int ret, i, vco;
 
+	if (dsi->phy)
+		return 0;
+
 	/*
 	 * Get vco from frequency(lane_mbps)
 	 * vco	frequency table
@@ -467,6 +475,28 @@ static int dw_mipi_dsi_phy_init(void *priv_data)
 	return ret;
 }
 
+static void dw_mipi_dsi_phy_power_on(void *priv_data)
+{
+	struct dw_mipi_dsi_rockchip *dsi = priv_data;
+	int ret;
+
+	ret = phy_set_mode(dsi->phy, PHY_MODE_MIPI_DPHY);
+	if (ret) {
+		DRM_DEV_ERROR(dsi->dev, "failed to set phy mode: %d\n", ret);
+		return;
+	}
+
+	phy_configure(dsi->phy, &dsi->phy_opts);
+	phy_power_on(dsi->phy);
+}
+
+static void dw_mipi_dsi_phy_power_off(void *priv_data)
+{
+	struct dw_mipi_dsi_rockchip *dsi = priv_data;
+
+	phy_power_off(dsi->phy);
+}
+
 static int
 dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 			  unsigned long mode_flags, u32 lanes, u32 format,
@@ -504,6 +534,17 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 				      "DPHY clock frequency is out of range\n");
 	}
 
+	/* for external phy only a the mipi_dphy_config is necessary */
+	if (dsi->phy) {
+		phy_mipi_dphy_get_default_config(mode->clock * 1000 * 10 / 8,
+						 bpp, lanes,
+						 &dsi->phy_opts.mipi_dphy);
+		dsi->lane_mbps = target_mbps;
+		*lane_mbps = dsi->lane_mbps;
+
+		return 0;
+	}
+
 	fin = clk_get_rate(dsi->pllref_clk);
 	fout = target_mbps * USEC_PER_SEC;
 
@@ -638,6 +679,8 @@ dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
 
 static const struct dw_mipi_dsi_phy_ops dw_mipi_dsi_rockchip_phy_ops = {
 	.init = dw_mipi_dsi_phy_init,
+	.power_on = dw_mipi_dsi_phy_power_on,
+	.power_off = dw_mipi_dsi_phy_power_off,
 	.get_lane_mbps = dw_mipi_dsi_get_lane_mbps,
 	.get_timing = dw_mipi_dsi_phy_get_timing,
 };
@@ -998,13 +1041,30 @@ static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	/* try to get a possible external dphy */
+	dsi->phy = devm_phy_optional_get(dev, "dphy");
+	if (IS_ERR(dsi->phy)) {
+		ret = PTR_ERR(dsi->phy);
+		DRM_DEV_ERROR(dev, "failed to get mipi dphy: %d\n", ret);
+		return ret;
+	}
+
 	dsi->pllref_clk = devm_clk_get(dev, "ref");
 	if (IS_ERR(dsi->pllref_clk)) {
+		if (dsi->phy) {
+			/*
+			 * if external phy is present, pll will be
+			 * generated there.
+			 */
+			dsi->pllref_clk = NULL;
+		} else {
 			ret = PTR_ERR(dsi->pllref_clk);
 			DRM_DEV_ERROR(dev,
-			      "Unable to get pll reference clock: %d\n", ret);
+				      "Unable to get pll reference clock: %d\n",
+				      ret);
 			return ret;
 		}
+	}
 
 	if (dsi->cdata->flags & DW_MIPI_NEEDS_PHY_CFG_CLK) {
 		dsi->phy_cfg_clk = devm_clk_get(dev, "phy_cfg");