[PATCH v1 4/8] drm/stm: ltdc: implement bus clock

[Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>]

From: Yannick Fertre <yannick.fertre@foss.st.com>

The latest hardware version of the LTDC presents the addition of a bus
clock, which contains the global configuration registers and the interrupt
register.

Signed-off-by: Yannick Fertre <yannick.fertre@foss.st.com>
---
 drivers/gpu/drm/stm/ltdc.c | 8 ++++++++
 drivers/gpu/drm/stm/ltdc.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 5576fdae4962..67064f47a4cb 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1896,6 +1896,8 @@ void ltdc_suspend(struct drm_device *ddev)
 
 	DRM_DEBUG_DRIVER("\n");
 	clk_disable_unprepare(ldev->pixel_clk);
+	if (ldev->bus_clk)
+		clk_disable_unprepare(ldev->bus_clk);
 }
 
 int ltdc_resume(struct drm_device *ddev)
@@ -1910,6 +1912,12 @@ int ltdc_resume(struct drm_device *ddev)
 		DRM_ERROR("failed to enable pixel clock (%d)\n", ret);
 		return ret;
 	}
+	if (ldev->bus_clk) {
+		if (clk_prepare_enable(ldev->bus_clk)) {
+			DRM_ERROR("Unable to prepare bus clock\n");
+			return -ENODEV;
+		}
+	}
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
index 9d488043ffdb..155d8e4a7c6b 100644
--- a/drivers/gpu/drm/stm/ltdc.h
+++ b/drivers/gpu/drm/stm/ltdc.h
@@ -44,6 +44,7 @@ struct ltdc_device {
 	void __iomem *regs;
 	struct regmap *regmap;
 	struct clk *pixel_clk;	/* lcd pixel clock */
+	struct clk *bus_clk;	/* bus clock */
 	struct mutex err_lock;	/* protecting error_status */
 	struct ltdc_caps caps;
 	u32 irq_status;
-- 
2.25.1