fbdev: Add generic ddc read functionality

From: Dennis Munsie <[email protected]>

Adds functionality to read the EDID information over the DDC bus in a generic way. This code is based on the DDC implementation in the radeon driver.

[adaplas]
- separate from fbmon.c and place in new file fb_ddc.c
- remove dependency to CONFIG_I2C and CONFIG_I2C_ALGOBIT, otherwise, feature will not compile if i2c support is compiled as a module
- feature is selectable only by drivers needing it. It must have a 'select FB_DDC if xxx' in Kconfig
- change printk's to dev_*, the i2c people prefers it

---

 drivers/video/Kconfig  |    5 ++
 drivers/video/Makefile |    1 
 drivers/video/fb_ddc.c |  116 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fb.h     |    2 +
 4 files changed, 124 insertions(+), 0 deletions(-)

index 4dc10b7..3bacde1 100644
@@ -53,6 +53,11 @@ config FB
 	  (e.g. an accelerated X server) and that are not frame buffer
 	  device-aware may cause unexpected results. If unsure, say N.
 
+config FB_DDC
+       tristate
+       depends on FB && I2C && I2C_ALGOBIT
+       default n
+
 config FB_CFB_FILLRECT
 	tristate
 	depends on FB

index 481c6c9..a6980e9 100644
@@ -18,6 +18,7 @@ obj-$(CONFIG_FB_CFB_FILLRECT)  += cfbfil
 obj-$(CONFIG_FB_CFB_COPYAREA)  += cfbcopyarea.o
 obj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimgblt.o
 obj-$(CONFIG_FB_MACMODES)      += macmodes.o
+obj-$(CONFIG_FB_DDC)           += fb_ddc.o
 
 # Hardware specific drivers go first
 obj-$(CONFIG_FB_RETINAZ3)         += retz3fb.o

index 4ad0673..a49ba06 100644
@@ -3,6 +3,7 @@ #define _LINUX_FB_H
 
 #include <linux/backlight.h>
 #include <asm/types.h>
+#include <linux/i2c.h>
 
 /* Definitions of frame buffers						*/
 

@@ -940,6 +941,7 @@ extern void fb_edid_to_monspecs(unsigned
 				struct fb_monspecs *specs);
 extern void fb_destroy_modedb(struct fb_videomode *modedb);
 extern int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb);
+extern unsigned char *fb_ddc_read(struct i2c_adapter *adapter);
 
 /* drivers/video/modedb.c */
 #define VESA_MODEDB_SIZE 34

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