1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
/*
* This file is part of the coreboot project.
*
* Copyright 2014 Google Inc.
*
* 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; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc.
*/
#include <assert.h>
#include <base3.h>
#include <console/console.h>
#include <delay.h>
#include <gpio.h>
int gpio_base2_value(gpio_t gpio[], int num_gpio)
{
int i, result = 0;
for (i = 0; i < num_gpio; i++)
gpio_input(gpio[i]);
/* Wait until signals become stable */
udelay(10);
for (i = 0; i < num_gpio; i++)
result |= gpio_get(gpio[i]) << i;
return result;
}
int gpio_base3_value(gpio_t gpio[], int num_gpio)
{
/*
* GPIOs which are tied to stronger external pull up or pull down
* will stay there regardless of the internal pull up or pull
* down setting.
*
* GPIOs which are floating will go to whatever level they're
* internally pulled to.
*/
static const char tristate_char[] = {[0] = '0', [1] = '1', [Z] = 'Z'};
int temp;
int index;
int result = 0;
char value[32];
assert(num_gpio <= 32);
/* Enable internal pull up */
for (index = 0; index < num_gpio; ++index)
gpio_input_pullup(gpio[index]);
/* Wait until signals become stable */
udelay(10);
/* Get gpio values at internal pull up */
for (index = 0; index < num_gpio; ++index)
value[index] = gpio_get(gpio[index]);
/* Enable internal pull down */
for (index = 0; index < num_gpio; ++index)
gpio_input_pulldown(gpio[index]);
/* Wait until signals become stable */
udelay(10);
/*
* Get gpio values at internal pull down.
* Compare with gpio pull up value and then
* determine a gpio final value/state:
* 0: pull down
* 1: pull up
* 2: floating
*/
printk(BIOS_DEBUG, "Reading tristate GPIOs: ");
for (index = num_gpio - 1; index >= 0; --index) {
temp = gpio_get(gpio[index]);
temp |= ((value[index] ^ temp) << 1);
printk(BIOS_DEBUG, "%c ", tristate_char[temp]);
result = (result * 3) + temp;
}
printk(BIOS_DEBUG, "= %d\n", result);
/* Disable pull up / pull down to conserve power */
for (index = 0; index < num_gpio; ++index)
gpio_input(gpio[index]);
return result;
}
|
