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ben-blinkenlights/ubb-vga/ubb-vga-old.c

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/*
* ubb-vga.c - Output video on UBB with more or less VGA timing
*
* Written 2011 by Werner Almesberger
* Copyright 2011 Werner Almesberger
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
/*
* WARNING: this program does very nasty things to the Ben and it doesn't
* like company. In particular, it resents:
*
* - the MMC driver - disable it with
* echo jz4740-mmc.0 >/sys/bus/platform/drivers/jz4740-mmc/unbind
* - the AT86RF230/1 kernel driver - use a kernel that doesn't have it
* - anything that accesses the screen - kill GUI, X server, etc.
* - the screen blanker - either disable it or make sure the screen stays
* dark, e.g., with
* echo 1 >/sys/devices/platform/jz4740-fb/graphics/fb0/blank
* - probably a fair number of other daemons and things as well - best to
* kill them all.
*/
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
static uint8_t thres = 63;
/* ----- I/O pin assignment ------------------------------------------------ */
#define DAT0 (1 << 10)
#define DAT1 (1 << 11)
#define DAT2 (1 << 12)
#define DAT3 (1 << 13)
#define CMD (1 << 8)
#define CLK (1 << 9)
#define R DAT3
#define G DAT0
#define B DAT1
#define HSYNC CMD
#define VSYNC CLK
/* ----- Ben hardware ------------------------------------------------------ */
#define TIMER 7
#define PAGE_SIZE 4096
#define SOC_BASE 0x10000000
static volatile uint32_t *icmr, *icmsr, *icmcr;
static uint32_t old_icmr;
static volatile uint32_t *clkgr;
static uint32_t old_clkgr;
static volatile uint32_t *pdpin, *pddats, *pddatc;
static volatile uint32_t *pddirs, *pddirc;
static volatile uint32_t *pdfuns, *pdfunc;
static volatile uint32_t *tssr, *tscr;
static volatile uint32_t *tesr, *tecr;
static volatile uint32_t *tcsr, *tdfr, *tcnt;
static void disable_interrupts(void)
{
/*
* @@@ Race condition alert ! If we get interrupted/preempted between
* reading ICMR and masking all interrupts, and the code that runs
* between these two operations changes ICMR, then we may set an
* incorrect mask when restoring interrupts, which may hang the system.
*/
old_icmr = *icmr;
*icmsr = 0xffffffff;
}
static void enable_interrupts(void)
{
*icmcr = ~old_icmr;
}
/*
* @@@ Disabling the LCD clock will hang operations that depend on the LCD
* subsystem to advance. This includes the screen saver.
*/
static void disable_lcd(void)
{
old_clkgr = *clkgr;
*clkgr = old_clkgr | 1 << 10;
}
static void enable_lcd(void)
{
*clkgr = old_clkgr;
}
static void get_timer(void)
{
*tscr = 1 << TIMER; /* enable clock */
*tcsr = 1; /* count at PCLK/1 */
*tdfr = 0xffff; /* count to 0xffff */
*tesr = 1 << TIMER;
}
static void release_timer(void)
{
*tecr = 1 << TIMER;
*tssr = 1 << TIMER;
}
static void *map(off_t addr, size_t size)
{
int fd;
void *mem;
fd = open("/dev/mem", O_RDWR | O_SYNC);
if (fd < 0) {
perror("/dev/mem");
exit(1);
}
mem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, addr);
if (mem == MAP_FAILED) {
perror("mmap");
exit(1);
}
return mem;
}
static void ben_setup(void)
{
volatile void *base;
base = map(SOC_BASE, PAGE_SIZE*3*16);
icmr = base+0x1004;
icmsr = base+0x1008;
icmcr = base+0x100c;
clkgr = base+0x20;
pdpin = base+0x10300;
pddats = base+0x10314;
pddatc = base+0x10318;
pdfuns = base+0x10344;
pdfunc = base+0x10348;
pddirs = base+0x10364;
pddirc = base+0x10368;
tssr = base+0x202c;
tscr = base+0x203c;
tesr = base+0x2014;
tecr = base+0x2018;
tcsr = base+0x204c+0x10*TIMER;
tdfr = base+0x2040+0x10*TIMER;
tcnt = base+0x2048+0x10*TIMER;
/*
* Ironically, switching the LCD clock on and off many times only
* increases the risk of a hang. Therefore, we leave stop it during
* all the measurements and only enable it again at the end.
*/
disable_lcd();
get_timer();
}
static void cleanup(void)
{
release_timer();
enable_lcd();
}
/* ----- Prefetch and delay logic ------------------------------------------ */
#define BURST 32 /* bytes */
static inline void prefetch(const uint8_t *prefetch, int words)
{
volatile const uint8_t *p = prefetch;
while (p != prefetch+words) {
(void) *p;
p += BURST;
}
}
#define US(us) ((uint16_t) ((us)*112))
static void until(uint16_t cycles)
{
while ((*tcnt & 0xffff) < cycles);
}
/* ----- Frame buffer output ----------------------------------------------- */
static int line_pairs = 160; /* set/clear pairs */
static int line_cycles = US(36); /* nominally 31.77 us, but we're too slow */
void setup(void)
{
mlockall(MCL_CURRENT | MCL_FUTURE);
ben_setup();
*pdfunc = R | G | B | HSYNC | VSYNC;
*pddirs = R | G | B | HSYNC | VSYNC;
}
static void line(const uint8_t *line, const uint8_t *fetch)
{
const uint8_t *p = line;
/* HSYNC */
*tcnt = 0;
*pddatc = HSYNC;
prefetch(fetch, line_pairs);
until(US(3.77));
*pddats = HSYNC;
/* Front porch */
until(US(3.77+1.79));
while (p != line+2*line_pairs) {
*pddats = *p++ << 8;
*pddatc = *p++ << 8;
}
/* Back porch */
until(line_cycles);
}
static void hdelay(int cycles)
{
while (cycles--) {
*tcnt = 0;
*pddatc = HSYNC;
until(US(3.77));
*pddats = HSYNC;
until(line_cycles);
}
}
static void frame(const uint8_t *f)
{
const uint8_t *p;
/* VSYNC */
*pddatc = VSYNC;
hdelay(2);
*pddats = VSYNC;
/* Front porch */
*tcnt = 0;
*pddatc = HSYNC;
until(US(3.77));
*pddats = HSYNC;
prefetch(f, line_pairs);
until(line_cycles);
hdelay(31);
for (p = f; p != f+240*2*line_pairs; p += 2*line_pairs) {
line(p, p+line_pairs);
line(p, p+2*line_pairs);
}
/* Back porch */
hdelay(14);
}
/* ----- Frame buffer image generation ------------------------------------- */
static uint32_t pick(int set, int bit, uint32_t val)
{
return set == bit ? val >> 8 : 0;
}
static uint32_t pattern(int set, int r, int g, int b)
{
return pick(set, r, R) | pick(set, g, G) | pick(set, b, B);
}
static void tricolor(uint32_t *f)
{
int pairs = 2*line_pairs*240;
int i;
for (i = 0; i != pairs/3; i++) {
f[i & ~1] = R;
f[i | 1] = G | B;
}
for (; i != pairs*2/3; i++) {
f[i & ~1] = G;
f[i | 1] = R | B;
}
for (; i != pairs; i++) {
f[i & ~1] = B;
f[i | 1] = R | G;
}
}
static void grid(uint8_t *f)
{
static uint32_t col[8] = {
R | G | B,
R,
R | G,
G,
G | B,
B,
R | B,
R | G | B,
};
int i, x, y;
for (i = 0; i != 8; i++) {
x = i*line_pairs/4+line_pairs/8;
for (y = 0; y != 240; y++) {
uint8_t *p = f+y*2*line_pairs+x;
p[0] = p[1] = col[i] >> 8;
}
}
}
static void grab(uint8_t *f, int single)
{
uint32_t *fb = map(0x01d00000, 4*320*240);
int x, y;
uint32_t pix;
uint8_t r, g, b;
for (y = 0; y != 240; y++)
for (x = 0; x != 320; x++) {
pix = *fb++;
r = pix >> 16;
g = pix >> 8;
b = pix;
if (single)
*f++ = pattern(!(x & 1),
r >= thres, g >= thres, b >= thres);
else {
*f++ = pattern(1,
r >= thres, g >= thres, b >= thres);
*f++ = pattern(0,
r >= thres, g >= thres, b >= thres);
}
}
}
/* ----- Command-line parsing and main loop -------------------------------- */
static void session(int frames, int single)
{
uint8_t f[2*line_pairs*(240+1)];
int i;
memset(f, 0, sizeof(f));
grab(f, single);
// grid(f);
disable_interrupts();
for (i = 0; i != frames; i++)
frame(f);
enable_interrupts();
}
static void usage(const char *name)
{
fprintf(stderr,
"usage: %s frames -d [threshold]\n\n"
" frames number of frames to display\n"
" threshold channel on/off threshold\n\n"
" -d double the number of set/clear pairs\n"
, name);
exit(1);
}
int main(int argc, char *const *argv)
{
int frames;
int single = 1;
int c;
while ((c = getopt(argc, argv, "d")) != EOF)
switch (c) {
case 'd':
single = 0;
line_pairs = 320;
line_cycles = US(36+26);
break;
default:
usage(*argv);
}
switch (argc-optind) {
case 2:
thres = atoi(argv[optind+1]);
/* fall through */
case 1:
frames = atoi(argv[optind]);
break;
default:
usage(*argv);
}
setup();
session(frames, single);
cleanup();
return 0;
}
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