drm/stm: dsi: add regulator support

Add support of regulator for the phy part of the DSI
controller.
Signed-off-by: Yannick Fertré <yannick.fertre@st.com>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1557826556-10079-3-git-send-email-yannick.fertre@st.com

drivers/gpu/drm/stm/dw_mipi_dsi-stm.c

@@ -9,6 +9,7 @@
 #include <linux/clk.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
+#include <linux/regulator/consumer.h>
 #include <drm/drmP.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/bridge/dw_mipi_dsi.h>
@@ -76,6 +77,7 @@ struct dw_mipi_dsi_stm {
 	u32 hw_version;
 	int lane_min_kbps;
 	int lane_max_kbps;
+	struct regulator *vdd_supply;
 };
 
 static inline void dsi_write(struct dw_mipi_dsi_stm *dsi, u32 reg, u32 val)
@@ -314,21 +316,36 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	dsi->base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(dsi->base)) {
-		DRM_ERROR("Unable to get dsi registers\n");
-		return PTR_ERR(dsi->base);
+		ret = PTR_ERR(dsi->base);
+		DRM_ERROR("Unable to get dsi registers %d\n", ret);
+		return ret;
+	}
+
+	dsi->vdd_supply = devm_regulator_get(dev, "phy-dsi");
+	if (IS_ERR(dsi->vdd_supply)) {
+		ret = PTR_ERR(dsi->vdd_supply);
+		if (ret != -EPROBE_DEFER)
+			DRM_ERROR("Failed to request regulator: %d\n", ret);
+		return ret;
+	}
+
+	ret = regulator_enable(dsi->vdd_supply);
+	if (ret) {
+		DRM_ERROR("Failed to enable regulator: %d\n", ret);
+		return ret;
 	}
 
 	dsi->pllref_clk = devm_clk_get(dev, "ref");
 	if (IS_ERR(dsi->pllref_clk)) {
 		ret = PTR_ERR(dsi->pllref_clk);
-		dev_err(dev, "Unable to get pll reference clock: %d\n", ret);
-		return ret;
+		DRM_ERROR("Unable to get pll reference clock: %d\n", ret);
+		goto err_clk_get;
 	}
 
 	ret = clk_prepare_enable(dsi->pllref_clk);
 	if (ret) {
-		dev_err(dev, "%s: Failed to enable pllref_clk\n", __func__);
-		return ret;
+		DRM_ERROR("Failed to enable pllref_clk: %d\n", ret);
+		goto err_clk_get;
 	}
 
 	dw_mipi_dsi_stm_plat_data.base = dsi->base;
@@ -338,20 +355,28 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
 
 	dsi->dsi = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data);
 	if (IS_ERR(dsi->dsi)) {
-		DRM_ERROR("Failed to initialize mipi dsi host\n");
-		clk_disable_unprepare(dsi->pllref_clk);
-		return PTR_ERR(dsi->dsi);
+		ret = PTR_ERR(dsi->dsi);
+		DRM_ERROR("Failed to initialize mipi dsi host: %d\n", ret);
+		goto err_dsi_probe;
 	}
 
 	return 0;
+
+err_dsi_probe:
+	clk_disable_unprepare(dsi->pllref_clk);
+err_clk_get:
+	regulator_disable(dsi->vdd_supply);
+
+	return ret;
 }
 
 static int dw_mipi_dsi_stm_remove(struct platform_device *pdev)
 {
 	struct dw_mipi_dsi_stm *dsi = platform_get_drvdata(pdev);
 
-	clk_disable_unprepare(dsi->pllref_clk);
 	dw_mipi_dsi_remove(dsi->dsi);
+	clk_disable_unprepare(dsi->pllref_clk);
+	regulator_disable(dsi->vdd_supply);
 
 	return 0;
 }
@@ -363,6 +388,7 @@ static int __maybe_unused dw_mipi_dsi_stm_suspend(struct device *dev)
 	DRM_DEBUG_DRIVER("\n");
 
 	clk_disable_unprepare(dsi->pllref_clk);
+	regulator_disable(dsi->vdd_supply);
 
 	return 0;
 }
@@ -370,10 +396,22 @@ static int __maybe_unused dw_mipi_dsi_stm_suspend(struct device *dev)
 static int __maybe_unused dw_mipi_dsi_stm_resume(struct device *dev)
 {
 	struct dw_mipi_dsi_stm *dsi = dw_mipi_dsi_stm_plat_data.priv_data;
+	int ret;
 
 	DRM_DEBUG_DRIVER("\n");
 
-	clk_prepare_enable(dsi->pllref_clk);
+	ret = regulator_enable(dsi->vdd_supply);
+	if (ret) {
+		DRM_ERROR("Failed to enable regulator: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(dsi->pllref_clk);
+	if (ret) {
+		regulator_disable(dsi->vdd_supply);
+		DRM_ERROR("Failed to enable pllref_clk: %d\n", ret);
+		return ret;
+	}
 
 	return 0;
 }