display_timing.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
 *
 * description of display timings
 */
 
#ifndef __LINUX_DISPLAY_TIMING_H
#define __LINUX_DISPLAY_TIMING_H
 
#include <linux/bitops.h>
#include <linux/types.h>
 
enum display_flags {
    DISPLAY_FLAGS_HSYNC_LOW     = BIT(0),
    DISPLAY_FLAGS_HSYNC_HIGH    = BIT(1),
    DISPLAY_FLAGS_VSYNC_LOW     = BIT(2),
    DISPLAY_FLAGS_VSYNC_HIGH    = BIT(3),
 
    /* data enable flag */
    DISPLAY_FLAGS_DE_LOW        = BIT(4),
    DISPLAY_FLAGS_DE_HIGH       = BIT(5),
    /* drive data on pos. edge */
    DISPLAY_FLAGS_PIXDATA_POSEDGE   = BIT(6),
    /* drive data on neg. edge */
    DISPLAY_FLAGS_PIXDATA_NEGEDGE   = BIT(7),
    DISPLAY_FLAGS_INTERLACED    = BIT(8),
    DISPLAY_FLAGS_DOUBLESCAN    = BIT(9),
    DISPLAY_FLAGS_DOUBLECLK     = BIT(10),
    /* drive sync on pos. edge */
    DISPLAY_FLAGS_SYNC_POSEDGE  = BIT(11),
    /* drive sync on neg. edge */
    DISPLAY_FLAGS_SYNC_NEGEDGE  = BIT(12),
};
 
/*
 * A single signal can be specified via a range of minimal and maximal values
 * with a typical value, that lies somewhere inbetween.
 */
struct timing_entry {
    u32 min;
    u32 typ;
    u32 max;
};
 
/*
 * Single "mode" entry. This describes one set of signal timings a display can
 * have in one setting. This struct can later be converted to struct videomode
 * (see include/video/videomode.h). As each timing_entry can be defined as a
 * range, one struct display_timing may become multiple struct videomodes.
 *
 * Example: hsync active high, vsync active low
 *
 *                  Active Video
 * Video  ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________
 *    |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..
 *    |      |   porch  |            |   porch   |
 *
 * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯
 *
 * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________
 */
struct display_timing {
    struct timing_entry pixelclock;
 
    struct timing_entry hactive;        /* hor. active video */
    struct timing_entry hfront_porch;   /* hor. front porch */
    struct timing_entry hback_porch;    /* hor. back porch */
    struct timing_entry hsync_len;      /* hor. sync len */
 
    struct timing_entry vactive;        /* ver. active video */
    struct timing_entry vfront_porch;   /* ver. front porch */
    struct timing_entry vback_porch;    /* ver. back porch */
    struct timing_entry vsync_len;      /* ver. sync len */
 
    enum display_flags flags;       /* display flags */
};
 
/*
 * This describes all timing settings a display provides.
 * The native_mode is the default setting for this display.
 * Drivers that can handle multiple videomodes should work with this struct and
 * convert each entry to the desired end result.
 */
struct display_timings {
    unsigned int num_timings;
    unsigned int native_mode;
 
    struct display_timing **timings;
};
 
/* get one entry from struct display_timings */
static inline struct display_timing *display_timings_get(const struct
                             display_timings *disp,
                             unsigned int index)
{
    if (disp->num_timings > index)
        return disp->timings[index];
    else
        return NULL;
}
 
void display_timings_release(struct display_timings *disp);
 
#endif