linux-kernel - [PATCH 1/3] drm/vc4: Turn the V3D clock on at runtime.

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Date:   Tue, 18 Apr 2017 12:11:55 -0700
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Eric Anholt <eric@...olt.net>
Subject: [PATCH 1/3] drm/vc4: Turn the V3D clock on at runtime.

For the Raspberry Pi's bindings, the power domain also implicitly
turns on the clock and deasserts reset, but for the new Cygnus port we
start representing the clock in the devicetree.

Signed-off-by: Eric Anholt <eric@...olt.net>
---
 .../devicetree/bindings/display/brcm,bcm-vc4.txt   |  3 ++
 drivers/gpu/drm/vc4/vc4_drv.h                      |  1 +
 drivers/gpu/drm/vc4/vc4_v3d.c                      | 33 ++++++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
index ca02d3e4db91..bc1756f4f791 100644
--- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
+++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
@@ -59,6 +59,9 @@ Required properties for V3D:
 - interrupts:	The interrupt number
 		  See bindings/interrupt-controller/brcm,bcm2835-armctrl-ic.txt
 
+Optional properties for V3D:
+- clocks:	The clock the unit runs on
+
 Required properties for DSI:
 - compatible:	Should be "brcm,bcm2835-dsi0" or "brcm,bcm2835-dsi1"
 - reg:		Physical base address and length of the DSI block's registers
diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 81d2bc08e766..08d5c2213c80 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -189,6 +189,7 @@ struct vc4_v3d {
 	struct vc4_dev *vc4;
 	struct platform_device *pdev;
 	void __iomem *regs;
+	struct clk *clk;
 };
 
 struct vc4_hvs {
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index 7cc346ad9b0b..2442622e6bff 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -16,6 +16,7 @@
  * this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "linux/clk.h"
 #include "linux/component.h"
 #include "linux/pm_runtime.h"
 #include "vc4_drv.h"
@@ -164,6 +165,9 @@ static int vc4_v3d_runtime_suspend(struct device *dev)
 
 	vc4_irq_uninstall(vc4->dev);
 
+	if (v3d->clk)
+		clk_disable_unprepare(v3d->clk);
+
 	return 0;
 }
 
@@ -172,6 +176,13 @@ static int vc4_v3d_runtime_resume(struct device *dev)
 	struct vc4_v3d *v3d = dev_get_drvdata(dev);
 	struct vc4_dev *vc4 = v3d->vc4;
 
+	if (v3d->clk) {
+		int ret = clk_prepare_enable(v3d->clk);
+
+		if (ret != 0)
+			return ret;
+	}
+
 	vc4_v3d_init_hw(vc4->dev);
 	vc4_irq_postinstall(vc4->dev);
 
@@ -202,12 +213,34 @@ static int vc4_v3d_bind(struct device *dev, struct device *master, void *data)
 	vc4->v3d = v3d;
 	v3d->vc4 = vc4;
 
+	v3d->clk = devm_clk_get(dev, "v3d_clk");
+	if (IS_ERR(v3d->clk)) {
+		int ret = PTR_ERR(v3d->clk);
+
+		if (ret == -ENODEV) {
+			/* bcm2835 didn't have a clock reference in the DT. */
+			ret = 0;
+			v3d->clk = NULL;
+		} else {
+			if (ret != -EPROBE_DEFER)
+				dev_err(dev, "Failed to get V3D clock: %d\n",
+					ret);
+			return ret;
+		}
+	}
+
 	if (V3D_READ(V3D_IDENT0) != V3D_EXPECTED_IDENT0) {
 		DRM_ERROR("V3D_IDENT0 read 0x%08x instead of 0x%08x\n",
 			  V3D_READ(V3D_IDENT0), V3D_EXPECTED_IDENT0);
 		return -EINVAL;
 	}
 
+	if (v3d->clk) {
+		ret = clk_prepare_enable(v3d->clk);
+		if (ret != 0)
+			return ret;
+	}
+
 	/* Reset the binner overflow address/size at setup, to be sure
 	 * we don't reuse an old one.
 	 */
-- 
2.11.0