uvesafb: the driver core

From: Michal Januszewski <[email protected]>

uvesafb is an enhanced version of vesafb. It uses a userspace helper (v86d) to execute calls to the x86 Video BIOS functions. The driver is not limited to any specific arch and whether it works on a given arch or not depends on that arch being supported by the userspace daemon. It has been tested on x86_32 and x86_64.

A single BIOS call is represented by an instance of the uvesafb_ktask structure. This structure contains a buffer, a completion struct and a uvesafb_task substructure, containing the values of the x86 registers, a flags field and a field indicating the length of the buffer. Whenever a BIOS call is made in the driver, uvesafb_exec() builds a message using the uvesafb_task substructure and the contents of the buffer. This message is then assigned a random ack number and sent to the userspace daemon using the connector interface.

The message's sequence number is used as an index for the uvfb_tasks array, which provides a mapping from the messages coming from userspace to the in-kernel uvesafb_ktask structs.

The userspace daemon performs the requested operation and sends a reply in the form of a uvesafb_task struct and, optionally, a buffer. The seq and ack numbers in the reply should be exactly the same as those in the request.

Each message from userspace is processed by uvesafb_cn_callback() and after passing a few sanity checks leads to the completion of a BIOS call request.

---

 drivers/video/Kconfig   |   18 
 drivers/video/Makefile  |    1 
 drivers/video/uvesafb.c | 2032 +++++++++++++++++++++++++++++++++++++++++++++++
 include/video/Kbuild    |    2 
 include/video/uvesafb.h |  193 ++++
 5 files changed, 2245 insertions(+), 1 deletions(-)

index 7e26d62..85f68cc 100644
@@ -591,6 +591,24 @@ config FB_TGA
 
 	  Say Y if you have one of those.
 
+config FB_UVESA
+	tristate "Userspace VESA VGA graphics support"
+	depends on FB && CONNECTOR
+	select FB_CFB_FILLRECT
+	select FB_CFB_COPYAREA
+	select FB_CFB_IMAGEBLIT
+	select FB_MODE_HELPERS
+	help
+	  This is the frame buffer driver for generic VBE 2.0 compliant
+	  graphic cards. It can also take advantage of VBE 3.0 features,
+	  such as refresh rate adjustment.
+
+	  This driver generally provides more features than vesafb but
+	  requires a userspace helper application called 'v86d'. See
+	  <file:Documentation/fb/uvesafb.txt> for more information.
+
+	  If unsure, say N.
+
 config FB_VESA
 	bool "VESA VGA graphics support"
 	depends on (FB = y) && X86

index 06eec7b..67dc278 100644
@@ -115,6 +115,7 @@ obj-$(CONFIG_FB_XILINX)           += xil
 obj-$(CONFIG_FB_OMAP)             += omap/
 
 # Platform or fallback drivers go here
+obj-$(CONFIG_FB_UVESA)            += uvesafb.o
 obj-$(CONFIG_FB_VESA)             += vesafb.o
 obj-$(CONFIG_FB_IMAC)             += imacfb.o
 obj-$(CONFIG_FB_VGA16)            += vga16fb.o

index a14f9c0..53a6c73 100644
@@ -1 +1 @@
-unifdef-y += sisfb.h
+unifdef-y += sisfb.h uvesafb.h

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