[PATCH v2] video: Add copy_fb_to_hw op

[Anatolij Gustschin]

From: Frederik Aalund <fpa at sbtinstruments.com>

Some devices have their own framebuffer memory that is not
shared directly with the CPU. For said devices, we need to
copy U-boot's framebuffer (priv->fb) to the device's own
framebuffer memory. E.g., via SPI.

To support these devices, I've added the copy_fb_to_hw op.
It's optional, so existing drivers do not need to define this
op.

I've used this new op to add support for the SSD2119 display
panel driver over 4-wire SPI. I'll add this video driver in
a subsequent patch.

Signed-off-by: Frederik Aalund <fpa at sbtinstruments.com>
[agust: add Kconfig option]
Signed-off-by: Anatolij Gustschin <agust at denx.de>
---
Changes in v2:
 - make this copy op optional and add Kconfig entry
 - check 'ops' pointer before dereferencing

 drivers/video/Kconfig        | 10 ++++++++++
 drivers/video/video-uclass.c | 18 ++++++++++++++++++
 include/video.h              |  8 +++++++-
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index e2e1f9c476..bb8c033d3d 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -53,6 +53,16 @@ config VIDEO_COPY
 	  To use this, your video driver must set @copy_base in
 	  struct video_uc_platdata.
 
+config VIDEO_COPY_TO_HW
+	bool "Enable copying the frame buffer to external display hardware"
+	depends on DM_VIDEO
+	help
+	  Some devices have their own framebuffer memory that is not
+	  shared directly with the CPU. For such devices, the framebuffer
+	  must be copied to the device's own framebuffer memory, e.g. via SPI.
+	  Enable this option and implement video_ops copy_fb_to_hw() to
+	  support this feature.
+
 config BACKLIGHT_PWM
 	bool "Generic PWM based Backlight Driver"
 	depends on BACKLIGHT && DM_PWM
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 650891e49d..00e861bd55 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -196,6 +196,24 @@ void video_sync(struct udevice *vid, bool force)
 		last_sync = get_timer(0);
 	}
 #endif
+	/*
+	 * Some devices have their own framebuffer memory that is not
+	 * shared directly with the CPU. For said devices, we need to
+	 * copy U-Boot's framebuffer (priv->fb) to the device's own
+	 * framebuffer memory. E.g., via SPI.
+	 */
+	if (IS_ENABLED(CONFIG_VIDEO_COPY_TO_HW)) {
+		struct video_ops *ops = video_get_ops(vid);
+		int ret;
+
+		if (ops && ops->copy_fb_to_hw) {
+			ret = ops->copy_fb_to_hw(vid);
+			if (ret) {
+				dev_err(vid, "Could not copy frame buffer to hardware: %d\n",
+					ret);
+			}
+		}
+	}
 }
 
 void video_sync_all(void)
diff --git a/include/video.h b/include/video.h
index 9d09d2409a..91ade65a73 100644
--- a/include/video.h
+++ b/include/video.h
@@ -114,8 +114,14 @@ struct video_priv {
 	u8 bg_col_idx;
 };
 
-/* Placeholder - there are no video operations at present */
 struct video_ops {
+	/**
+	 * copy_fb_to_hw() - Copy the current frame buffer to the hardware
+	 *
+	 * @dev:	Video device
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*copy_fb_to_hw)(struct udevice *dev);
 };
 
 #define video_get_ops(dev)        ((struct video_ops *)(dev)->driver->ops)
-- 
2.17.1