[PATCH v1 15/30] drm/tegra: hdmi: Support OPP and SoC core voltage scaling

[Dmitry Osipenko]

Add OPP and SoC core voltage scaling support to the HDMI driver.
This is required for enabling system-wide DVFS on older Tegra SoCs.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
 drivers/gpu/drm/tegra/hdmi.c | 63 +++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/hdmi.c b/drivers/gpu/drm/tegra/hdmi.c
index d09a24931c87..92e96990854b 100644
--- a/drivers/gpu/drm/tegra/hdmi.c
+++ b/drivers/gpu/drm/tegra/hdmi.c
@@ -11,6 +11,7 @@
 #include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
@@ -1195,7 +1196,7 @@ static void tegra_hdmi_encoder_enable(struct drm_encoder *encoder)
 	h_back_porch = mode->htotal - mode->hsync_end;
 	h_front_porch = mode->hsync_start - mode->hdisplay;
 
-	err = clk_set_rate(hdmi->clk, hdmi->pixel_clock);
+	err = dev_pm_opp_set_rate(hdmi->dev, hdmi->pixel_clock);
 	if (err < 0) {
 		dev_err(hdmi->dev, "failed to set HDMI clock frequency: %d\n",
 			err);
@@ -1499,6 +1500,7 @@ static int tegra_hdmi_runtime_suspend(struct host1x_client *client)
 	usleep_range(1000, 2000);
 
 	clk_disable_unprepare(hdmi->clk);
+	dev_pm_opp_set_rate(hdmi->dev, 0);
 	pm_runtime_put_sync(dev);
 
 	return 0;
@@ -1633,6 +1635,60 @@ static irqreturn_t tegra_hdmi_irq(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static void tegra_hdmi_deinit_opp_table(void *data)
+{
+	struct device *dev = data;
+	struct opp_table *opp_table;
+
+	opp_table = dev_pm_opp_get_opp_table(dev);
+	dev_pm_opp_of_remove_table(dev);
+	dev_pm_opp_put_regulators(opp_table);
+	dev_pm_opp_put_opp_table(opp_table);
+}
+
+static int devm_tegra_hdmi_init_opp_table(struct device *dev)
+{
+	struct opp_table *opp_table;
+	const char *rname = "core";
+	int err;
+
+	/* voltage scaling is optional */
+	if (device_property_present(dev, "core-supply"))
+		opp_table = dev_pm_opp_set_regulators(dev, &rname, 1);
+	else
+		opp_table = dev_pm_opp_get_opp_table(dev);
+
+	if (IS_ERR(opp_table))
+		return dev_err_probe(dev, PTR_ERR(opp_table),
+				    "failed to prepare OPP table\n");
+
+	/*
+	 * OPP table presence is optional and we want the set_rate() of OPP
+	 * API to work similarly to clk_set_rate() if table is missing in a
+	 * device-tree.  The add_table() errors out if OPP is missing in DT.
+	 */
+	if (device_property_present(dev, "operating-points-v2")) {
+		err = dev_pm_opp_of_add_table(dev);
+		if (err) {
+			dev_err(dev, "failed to add OPP table: %d\n", err);
+			goto put_table;
+		}
+	}
+
+	err = devm_add_action(dev, tegra_hdmi_deinit_opp_table, dev);
+	if (err)
+		goto remove_table;
+
+	return 0;
+
+remove_table:
+	dev_pm_opp_of_remove_table(dev);
+put_table:
+	dev_pm_opp_put_regulators(opp_table);
+
+	return err;
+}
+
 static int tegra_hdmi_probe(struct platform_device *pdev)
 {
 	const char *level = KERN_ERR;
@@ -1667,6 +1723,11 @@ static int tegra_hdmi_probe(struct platform_device *pdev)
 	if (IS_ERR(hdmi->clk_parent))
 		return PTR_ERR(hdmi->clk_parent);
 
+	err = devm_tegra_hdmi_init_opp_table(&pdev->dev);
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to initialize OPP\n");
+
 	err = clk_set_parent(hdmi->clk, hdmi->clk_parent);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to setup clocks: %d\n", err);
-- 
2.27.0