[PATCH] fbdev: Add generic ddc read functionality
Dennis Munsie [Tue, 3 Oct 2006 08:14:42 +0000 (01:14 -0700)]
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

Signed-off-by: Dennis Munsie <dmunsie@cecropia.com>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/Kconfig
drivers/video/Makefile
drivers/video/fb_ddc.c [new file with mode: 0644]
include/linux/fb.h

index 652d202..d498e90 100644 (file)
@@ -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 (file)
@@ -18,6 +18,7 @@ obj-$(CONFIG_FB_CFB_FILLRECT)  += cfbfillrect.o
 obj-$(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
diff --git a/drivers/video/fb_ddc.c b/drivers/video/fb_ddc.c
new file mode 100644 (file)
index 0000000..3aa6ebf
--- /dev/null
@@ -0,0 +1,116 @@
+/*
+ * driver/vide/fb_ddc.c - DDC/EDID read support.
+ *
+ *  Copyright (C) 2006 Dennis Munsie <dmunsie@cecropia.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/fb.h>
+#include <linux/i2c-algo-bit.h>
+
+#include "edid.h"
+
+#define DDC_ADDR       0x50
+
+static unsigned char *fb_do_probe_ddc_edid(struct i2c_adapter *adapter)
+{
+       unsigned char start = 0x0;
+       struct i2c_msg msgs[] = {
+               {
+                       .addr   = DDC_ADDR,
+                       .len    = 1,
+                       .buf    = &start,
+               }, {
+                       .addr   = DDC_ADDR,
+                       .flags  = I2C_M_RD,
+                       .len    = EDID_LENGTH,
+               }
+       };
+       unsigned char *buf;
+
+       buf = kmalloc(EDID_LENGTH, GFP_KERNEL);
+       if (!buf) {
+               dev_warn(&adapter->dev, "unable to allocate memory for EDID "
+                        "block.\n");
+               return NULL;
+       }
+       msgs[1].buf = buf;
+
+       if (i2c_transfer(adapter, msgs, 2) == 2)
+               return buf;
+
+       dev_warn(&adapter->dev, "unable to read EDID block.\n");
+       kfree(buf);
+       return NULL;
+}
+
+unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
+{
+       struct i2c_algo_bit_data *algo_data = adapter->algo_data;
+       unsigned char *edid = NULL;
+       int i, j;
+
+       algo_data->setscl(algo_data->data, 1);
+       algo_data->setscl(algo_data->data, 0);
+
+       for (i = 0; i < 3; i++) {
+               /* For some old monitors we need the
+                * following process to initialize/stop DDC
+                */
+               algo_data->setsda(algo_data->data, 0);
+               msleep(13);
+
+               algo_data->setscl(algo_data->data, 1);
+               for (j = 0; j < 5; j++) {
+                       msleep(10);
+                       if (algo_data->getscl(algo_data->data))
+                               break;
+               }
+               if (j == 5)
+                       continue;
+
+               algo_data->setsda(algo_data->data, 0);
+               msleep(15);
+               algo_data->setscl(algo_data->data, 0);
+               msleep(15);
+               algo_data->setsda(algo_data->data, 1);
+               msleep(15);
+
+               /* Do the real work */
+               edid = fb_do_probe_ddc_edid(adapter);
+               algo_data->setsda(algo_data->data, 0);
+               algo_data->setscl(algo_data->data, 0);
+               msleep(15);
+
+               algo_data->setscl(algo_data->data, 1);
+               for (j = 0; j < 10; j++) {
+                       msleep(10);
+                       if (algo_data->getscl(algo_data->data))
+                               break;
+               }
+
+               algo_data->setsda(algo_data->data, 1);
+               msleep(15);
+               algo_data->setscl(algo_data->data, 0);
+               if (edid)
+                       break;
+       }
+       /* Release the DDC lines when done or the Apple Cinema HD display
+        * will switch off
+        */
+       algo_data->setsda(algo_data->data, 0);
+       algo_data->setscl(algo_data->data, 0);
+
+       return edid;
+}
+
+EXPORT_SYMBOL_GPL(fb_ddc_read);
+
+MODULE_AUTHOR("Dennis Munsie <dmunsie@cecropia.com>");
+MODULE_DESCRIPTION("DDC/EDID reading support");
+MODULE_LICENSE("GPL");
index 2f335e9..37aab31 100644 (file)
@@ -2,6 +2,7 @@
 #define _LINUX_FB_H
 
 #include <asm/types.h>
+#include <linux/i2c.h>
 
 /* Definitions of frame buffers                                                */
 
@@ -940,6 +941,7 @@ extern void fb_edid_to_monspecs(unsigned char *edid,
                                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