drm: panfrost: add optional bus_clock

Allwinner H6 has an ARM Mali-T720 MP2 which required a bus_clock.

Add an optional bus_clock at the init of the panfrost driver.
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190521161102.29620-2-peron.clem@gmail.com

drivers/gpu/drm/panfrost/panfrost_device.c

@@ -55,11 +55,33 @@ static int panfrost_clk_init(struct panfrost_device *pfdev)
 	if (err)
 		return err;
 
+	pfdev->bus_clock = devm_clk_get_optional(pfdev->dev, "bus");
+	if (IS_ERR(pfdev->bus_clock)) {
+		dev_err(pfdev->dev, "get bus_clock failed %ld\n",
+			PTR_ERR(pfdev->bus_clock));
+		return PTR_ERR(pfdev->bus_clock);
+	}
+
+	if (pfdev->bus_clock) {
+		rate = clk_get_rate(pfdev->bus_clock);
+		dev_info(pfdev->dev, "bus_clock rate = %lu\n", rate);
+
+		err = clk_prepare_enable(pfdev->bus_clock);
+		if (err)
+			goto disable_clock;
+	}
+
 	return 0;
+
+disable_clock:
+	clk_disable_unprepare(pfdev->clock);
+
+	return err;
 }
 
 static void panfrost_clk_fini(struct panfrost_device *pfdev)
 {
+	clk_disable_unprepare(pfdev->bus_clock);
 	clk_disable_unprepare(pfdev->clock);
 }
 

drivers/gpu/drm/panfrost/panfrost_device.h

@@ -66,6 +66,7 @@ struct panfrost_device {
 
 	void __iomem *iomem;
 	struct clk *clock;
+	struct clk *bus_clock;
 	struct regulator *regulator;
 	struct reset_control *rstc;