1 /*
2  * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
3  *
4  * description of display timings
5  *
6  * This file is released under the GPLv2
7  */
8 
9 #ifndef __LINUX_DISPLAY_TIMING_H
10 #define __LINUX_DISPLAY_TIMING_H
11 
12 #include <linux/bitops.h>
13 #include <linux/types.h>
14 
15 enum display_flags {
16 	DISPLAY_FLAGS_HSYNC_LOW		= BIT(0),
17 	DISPLAY_FLAGS_HSYNC_HIGH	= BIT(1),
18 	DISPLAY_FLAGS_VSYNC_LOW		= BIT(2),
19 	DISPLAY_FLAGS_VSYNC_HIGH	= BIT(3),
20 
21 	/* data enable flag */
22 	DISPLAY_FLAGS_DE_LOW		= BIT(4),
23 	DISPLAY_FLAGS_DE_HIGH		= BIT(5),
24 	/* drive data on pos. edge */
25 	DISPLAY_FLAGS_PIXDATA_POSEDGE	= BIT(6),
26 	/* drive data on neg. edge */
27 	DISPLAY_FLAGS_PIXDATA_NEGEDGE	= BIT(7),
28 	DISPLAY_FLAGS_INTERLACED	= BIT(8),
29 	DISPLAY_FLAGS_DOUBLESCAN	= BIT(9),
30 };
31 
32 /*
33  * A single signal can be specified via a range of minimal and maximal values
34  * with a typical value, that lies somewhere inbetween.
35  */
36 struct timing_entry {
37 	u32 min;
38 	u32 typ;
39 	u32 max;
40 };
41 
42 /*
43  * Single "mode" entry. This describes one set of signal timings a display can
44  * have in one setting. This struct can later be converted to struct videomode
45  * (see include/video/videomode.h). As each timing_entry can be defined as a
46  * range, one struct display_timing may become multiple struct videomodes.
47  *
48  * Example: hsync active high, vsync active low
49  *
50  *				    Active Video
51  * Video  ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________
52  *	  |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..
53  *	  |	     |	 porch  |		     |	 porch	 |
54  *
55  * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯
56  *
57  * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________
58  */
59 struct display_timing {
60 	struct timing_entry pixelclock;
61 
62 	struct timing_entry hactive;		/* hor. active video */
63 	struct timing_entry hfront_porch;	/* hor. front porch */
64 	struct timing_entry hback_porch;	/* hor. back porch */
65 	struct timing_entry hsync_len;		/* hor. sync len */
66 
67 	struct timing_entry vactive;		/* ver. active video */
68 	struct timing_entry vfront_porch;	/* ver. front porch */
69 	struct timing_entry vback_porch;	/* ver. back porch */
70 	struct timing_entry vsync_len;		/* ver. sync len */
71 
72 	enum display_flags flags;		/* display flags */
73 };
74 
75 /*
76  * This describes all timing settings a display provides.
77  * The native_mode is the default setting for this display.
78  * Drivers that can handle multiple videomodes should work with this struct and
79  * convert each entry to the desired end result.
80  */
81 struct display_timings {
82 	unsigned int num_timings;
83 	unsigned int native_mode;
84 
85 	struct display_timing **timings;
86 };
87 
88 /* get one entry from struct display_timings */
89 static inline struct display_timing *display_timings_get(const struct
90 							 display_timings *disp,
91 							 unsigned int index)
92 {
93 	if (disp->num_timings > index)
94 		return disp->timings[index];
95 	else
96 		return NULL;
97 }
98 
99 void display_timings_release(struct display_timings *disp);
100 
101 #endif
102