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/*
* 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>
#include <linux/module.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;
}
EXPORT_SYMBOL(fbmon_valid_timings);
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