1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/video/fbmon.c b/drivers/video/fbmon.c
new file mode 100644
index 000000000..38fb6adc9
--- /dev/null
+++ b/drivers/video/fbmon.c
@@ -0,0 +1,74 @@
+/*
+ *   linux/drivers/video/fbmon.c
+ *
+ *  Copyright (C) 1999 James Simmons
+ *
+ * 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.
+ *
+ * Notes:
+ *      This code handles the different types of monitors that are out their. 
+ *   Most video cards for example can support a mode like 800x600 but fix
+ *   frequency monitors can't. So the code here checks if the monitor can
+ *   support the mode as well as the card can. Fbmonospecs takes on 
+ *   different meaning with different types of monitors. For multifrequency 
+ *   monitors fbmonospecs represents the range of frequencies the monitor 
+ *   can support. Only one fbmonospec needs to be allocated. The fbmonospecs 
+ *   pointer in fb_info points to this one. If you specific a mode that has 
+ *   timing greater than the allowed range then setting the video mode will 
+ *   fail. With multifrequency monitors you can set any mode you like as long
+ *   as you have a programmable clock on the video card. 
+ *       With fixed frequency monitors you have only a SET of very narrow 
+ *   allowed frequency ranges. So for a fixed fequency monitor you have a 
+ *   array of fbmonospecs. The fbmonospecs in fb_info represents the 
+ *   monitor frequency for the CURRENT mode. If you change the mode and ask
+ *   for fbmonospecs you will NOT get the same values as before. Note this
+ *   is not true for multifrequency monitors where you do get the same 
+ *   fbmonospecs each time. Also the values in each fbmonospecs represent the 
+ *   very narrow frequency band for range. Well you can't have exactly the 
+ *   same frequencies from fixed monitor. So some tolerance is excepted.
+ *       By DEFAULT all monitors are assumed fixed frequency since they are so
+ *   easy to fry or screw up a mode with. Just try setting a 800x600 mode on
+ *   one. After you boot you can run a simple program the tells what kind of 
+ *   monitor you have. If you have a multifrequency monitor then you can set 
+ *   any mode size you like as long as your video card has a programmable clock.
+ *   By default also besides assuming you have a fixed frequency monitor it 
+ *   assumes the monitor only supports lower modes. This way for example you
+ *   can't set a 1280x1024 mode on a fixed frequency monitor that can only 
+ *   support up to 1024x768.
+ *
+ */
+#include <linux/tty.h>
+#include <linux/fb.h>
+
+int fbmon_valid_timings(u_int pixclock, u_int htotal, u_int vtotal,
+                        const struct fb_info *fb_info)
+{
+#if 0
+  /*
+   * long long divisions .... $#%%#$
+   */
+    unsigned long long hpicos, vpicos;
+    const unsigned long long _1e12 = 1000000000000ULL;
+    const struct fb_monspecs *monspecs = &fb_info->monspecs;
+
+    hpicos = (unsigned long long)htotal*(unsigned long long)pixclock;
+    vpicos = (unsigned long long)vtotal*(unsigned long long)hpicos;
+    if (!vpicos)
+      return 0;
+    
+    if (monspecs->hfmin == 0)
+      return 1;
+    
+    if (hpicos*monspecs->hfmin > _1e12 || hpicos*monspecs->hfmax < _1e12 ||
+        vpicos*monspecs->vfmin > _1e12 || vpicos*monspecs->vfmax < _1e12)
+      return 0;
+#endif
+    return 1;
+}
+
+int fbmon_dpms(const struct fb_info *fb_info)
+{
+  return fb_info->monspecs.dpms;
+}