disp: msm: dp: Add support for USB3 GDSC vote from displayport driver

On kailua onwards USB3 DP SSPHY power is control using GDSC.
This change adds support to vote for GDSC when displayport
driver is active.

Change-Id: I2e741f2091018f5dae9a1e7e886179bc6b982d40
Signed-off-by: Vara Reddy <quic_varar@quicinc.com>

msm/dp/dp_power.c

@@ -81,6 +81,23 @@ static void dp_power_regulator_deinit(struct dp_power_private *power)
 	}
 }
 
+static void dp_power_phy_gdsc(struct dp_power *dp_power, bool on)
+{
+	int rc = 0;
+
+	if (IS_ERR_OR_NULL(dp_power->dp_phy_gdsc))
+		return;
+
+	if (on)
+		rc = regulator_enable(dp_power->dp_phy_gdsc);
+	else
+		rc = regulator_disable(dp_power->dp_phy_gdsc);
+
+	if (rc)
+		DP_ERR("Fail to %s dp_phy_gdsc regulator ret =%d\n",
+				on ? "enable" : "disable", rc);
+}
+
 static int dp_power_regulator_ctrl(struct dp_power_private *power, bool enable)
 {
 	int rc = 0, i = 0, j = 0;
@@ -94,6 +111,8 @@ static int dp_power_regulator_ctrl(struct dp_power_private *power, bool enable)
 		 * on the link configuration.
 		 */
 		if (i == DP_PLL_PM) {
+			/* DP GDSC vote is needed for new chipsets, define gdsc phandle if needed */
+			dp_power_phy_gdsc(&power->dp_power, enable);
 			DP_DEBUG("skipping: '%s' vregs for %s\n",
 					enable ? "enable" : "disable",
 					dp_parser_pm_name(i));
@@ -822,6 +841,7 @@ struct dp_power *dp_power_get(struct dp_parser *parser, struct dp_pll *pll)
 	int rc = 0;
 	struct dp_power_private *power;
 	struct dp_power *dp_power;
+	struct device *dev;
 
 	if (!parser || !pll) {
 		DP_ERR("invalid input\n");
@@ -840,6 +860,7 @@ struct dp_power *dp_power_get(struct dp_parser *parser, struct dp_pll *pll)
 	power->pdev = parser->pdev;
 
 	dp_power = &power->dp_power;
+	dev = &power->pdev->dev;
 
 	dp_power->init = dp_power_init;
 	dp_power->deinit = dp_power_deinit;
@@ -852,6 +873,12 @@ struct dp_power *dp_power_get(struct dp_parser *parser, struct dp_pll *pll)
 	dp_power->power_client_deinit = dp_power_client_deinit;
 	dp_power->power_mmrm_init = dp_power_mmrm_init;
 
+	dp_power->dp_phy_gdsc = devm_regulator_get(dev, "dp_phy_gdsc");
+	if (IS_ERR(dp_power->dp_phy_gdsc)) {
+		dp_power->dp_phy_gdsc = NULL;
+		DP_DEBUG("Optional GDSC regulator is missing\n");
+	}
+
 	return dp_power;
 error:
 	return ERR_PTR(rc);