annotate py/touch/touch.c @ 196:e27075b1e088

Make sure we close descriptor before rename
author Matt Johnston <matt@ucc.asn.au>
date Wed, 12 Feb 2014 20:57:30 +0800
parents bed65c321b46
children
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1 //
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2 // How to access GPIO registers from C-code on the Raspberry-Pi
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3 // Example program
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4 // 15-January-2012
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5 // Dom and Gert
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6 //
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7
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8
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9 // Access from ARM Running Linux
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10
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11 #define BCM2708_PERI_BASE 0x20000000
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12 #define GPIO_BASE (BCM2708_PERI_BASE + 0x200000) /* GPIO controller */
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13
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14
156
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15 // for usleep
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16 #define _BSD_SOURCE
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17
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18 // clock_gettime
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19 #define _POSIX_C_SOURCE 199309L
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20
155
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21 #include <stdio.h>
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22 #include <string.h>
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23 #include <stdlib.h>
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24 #include <stdint.h>
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25 #include <dirent.h>
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26 #include <fcntl.h>
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27 #include <assert.h>
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28 #include <sys/mman.h>
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29 #include <sys/types.h>
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30 #include <sys/stat.h>
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31 #include <time.h>
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32 #include <sched.h>
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33
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34 #include <unistd.h>
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35
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36 #define PAGE_SIZE (4*1024)
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37 #define BLOCK_SIZE (4*1024)
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38
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39 int mem_fd;
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40 char *gpio_mem, *gpio_map;
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41 char *spi0_mem, *spi0_map;
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42
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43
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44 // I/O access
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45 volatile unsigned *gpio;
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46
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47
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48 // GPIO setup macros. Always use INP_GPIO(x) before using OUT_GPIO(x) or SET_GPIO_ALT(x,y)
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49 #define INP_GPIO(g) *(gpio+((g)/10)) &= ~(7<<(((g)%10)*3))
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50 #define OUT_GPIO(g) *(gpio+((g)/10)) |= (1<<(((g)%10)*3))
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51 #define SET_GPIO_ALT(g,a) *(gpio+(((g)/10))) |= (((a)<=3?(a)+4:(a)==4?3:2)<<(((g)%10)*3))
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52
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53 #define FSEL_OFFSET 0 // 0x0000
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54 #define SET_OFFSET 7 // 0x001c / 4
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55 #define CLR_OFFSET 10 // 0x0028 / 4
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56 #define PINLEVEL_OFFSET 13 // 0x0034 / 4
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57 #define EVENT_DETECT_OFFSET 16 // 0x0040 / 4
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58 #define RISING_ED_OFFSET 19 // 0x004c / 4
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59 #define FALLING_ED_OFFSET 22 // 0x0058 / 4
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60 #define HIGH_DETECT_OFFSET 25 // 0x0064 / 4
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61 #define LOW_DETECT_OFFSET 28 // 0x0070 / 4
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62 #define PULLUPDN_OFFSET 37 // 0x0094 / 4
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63 #define PULLUPDNCLK_OFFSET 38 // 0x0098 / 4
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64
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65
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66 #define GPIO_GET(g) ((*(gpio+PINLEVEL_OFFSET) & (1<<(g))) >> (g))
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67 #define GPIO_SET(g) (*(gpio+SET_OFFSET) = 1<<(g)) // sets bits which are 1 ignores bits which are 0
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68 #define GPIO_CLR(g) (*(gpio+CLR_OFFSET) = 1<<(g))// clears bits which are 1 ignores bits which are 0
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69
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70 #define TOUCH_IN 24
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71 #define TOUCH_OUT 25
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72
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73 void setup_io();
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74
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75 static int cmp_int(const void *a, const void *b)
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76 {
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77 const int *ia = a;
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78 const int *ib = b;
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79 return (*ia - *ib);
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80 }
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81
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82 static int clock_diff(struct timespec *t1, struct timespec *t2)
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83 {
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84 uint64_t v1 = t1->tv_sec * 1000000000 + t1->tv_nsec;
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85 uint64_t v2 = t2->tv_sec * 1000000000 + t2->tv_nsec;
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86 return v2-v1;
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87 }
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88
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89 int main(int argc, char **argv)
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90 {
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91 // Set up gpi pointer for direct register access
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92 setup_io();
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93
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94 INP_GPIO(TOUCH_IN);
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95 INP_GPIO(TOUCH_OUT);
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96 OUT_GPIO(TOUCH_OUT);
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97
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98 const int num = 200;
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99 const int margin = 30;
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100 int print = 0;
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101 if (argc > 1)
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102 {
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103 print = 1;
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104 }
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105
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106 while (1)
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107 {
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108 int vals[num];
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109 int nsecs[num];
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110 for (int n = 0; n < num; n++)
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111 {
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112 GPIO_CLR(TOUCH_OUT);
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113 struct timespec t = {.tv_nsec=20};
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114 nanosleep(&t, NULL);
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115 //sched_yield();
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116 //usleep(1);
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117 if (GPIO_GET(TOUCH_IN))
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118 {
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119 printf("short ");
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120 }
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121 GPIO_SET(TOUCH_OUT);
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122 int val = 0;
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123 while (GPIO_GET(TOUCH_IN) == 0)
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124 {
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125 val++;
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126 }
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127
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128 vals[n] = val;
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129 }
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130 qsort(vals, num, sizeof(*vals), cmp_int);
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131 int sum = 0, count = 0;
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132 for (int n = 0; n < num; n++)
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133 {
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134 if (print)
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135 {
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136 printf("%3d ", vals[n]);
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137 if (n == num-1 || n % 10 == 9)
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138 {
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139 printf("\n");
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140 }
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141 if (n == margin || n == num-margin)
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142 {
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143 printf("#");
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144 }
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145 }
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146 if (n >= margin && n < (num-margin))
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147 {
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148 sum += vals[n];
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149 count ++;
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150 }
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151 }
156
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152 printf("total %f from %d\n", (float)sum / count, count);
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153 usleep(500000);
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154 }
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155 return 0;
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156
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157 } // main
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158
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159
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160 //
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161 // Set up a memory regions to access GPIO
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162 //
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163 void setup_io()
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164 {
156
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165 /* open /dev/mem */
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166 if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
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167 printf("can't open /dev/mem \n");
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168 exit (-1);
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169 }
155
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170
156
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171 /* mmap GPIO */
155
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172
156
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173 // Allocate MAP block
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174 if ((gpio_mem = malloc(BLOCK_SIZE + (PAGE_SIZE-1))) == NULL) {
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175 printf("allocation error \n");
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176 exit (-1);
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177 }
155
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178
156
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179 // Make sure pointer is on 4K boundary
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180 if ((unsigned long)gpio_mem % PAGE_SIZE)
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181 gpio_mem += PAGE_SIZE - ((unsigned long)gpio_mem % PAGE_SIZE);
155
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182
156
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183 // Now map it
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184 gpio_map = mmap(
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185 (caddr_t)gpio_mem,
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186 BLOCK_SIZE,
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187 PROT_READ|PROT_WRITE,
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188 MAP_SHARED|MAP_FIXED,
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189 mem_fd,
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190 GPIO_BASE
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191 );
155
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192
156
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193 if ((long)gpio_map < 0) {
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194 printf("mmap error %d\n", (int)gpio_map);
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195 exit (-1);
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196 }
155
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197
156
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198 // Always use volatile pointer!
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199 gpio = (volatile unsigned *)gpio_map;
155
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200
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201
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202 } // setup_io