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

[Raphael Gallais-Pou]

From: Yannick Fertre <yannick.fer...@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.fer...@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