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/*
* 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.
*/
#include <assert.h>
#include <base3.h>
#include <compiler.h>
#include <console/console.h>
#include <delay.h>
#include <gpio.h>
static int _gpio_base2_value(const gpio_t gpio[], int num_gpio)
{
int i, result = 0;
/* Wait until signals become stable */
udelay(10);
for (i = 0; i < num_gpio; i++)
result |= gpio_get(gpio[i]) << i;
return result;
}
int gpio_base2_value(const gpio_t gpio[], int num_gpio)
{
int i;
for (i = 0; i < num_gpio; i++)
gpio_input(gpio[i]);
return _gpio_base2_value(gpio, num_gpio);
}
int gpio_pulldown_base2_value(const gpio_t gpio[], int num_gpio)
{
int i;
for (i = 0; i < num_gpio; i++)
gpio_input_pulldown(gpio[i]);
return _gpio_base2_value(gpio, num_gpio);
}
int gpio_pullup_base2_value(const gpio_t gpio[], int num_gpio)
{
int i;
for (i = 0; i < num_gpio; i++)
gpio_input_pullup(gpio[i]);
return _gpio_base2_value(gpio, num_gpio);
}
int _gpio_base3_value(const gpio_t gpio[], int num_gpio, int binary_first)
{
/*
* 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;
int has_z = 0;
int binary_below = 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;
/*
* For binary_first we keep track of the normal ternary result
* and whether we found any pin that was a Z. We also determine
* the amount of numbers that can be represented with only
* binary digits (no Z) whose value in the normal ternary system
* is lower than the one we are parsing. Counting from the left,
* we add 2^i for any '1' digit to account for the binary
* numbers whose values would be below it if all following
* digits we parsed would be '0'. As soon as we find a '2' digit
* we can total the remaining binary numbers below as 2^(i+1)
* because we know that all binary representations counting only
* this and following digits must have values below our number
* (since 1xxx is always smaller than 2xxx).
*
* Example: 1 0 2 1 (counting from the left / most significant)
* '1' at 3^3: Add 2^3 = 8 to account for binaries 0000-0111
* '0' at 3^2: Ignore (not all binaries 1000-1100 are below us)
* '2' at 3^1: Add 2^(1+1) = 4 to account for binaries 1000-1011
* Stop adding for lower digits (3^0), all already accounted
* now. We know that there can be no binary numbers 1020-102X.
*/
if (binary_first && !has_z) {
switch (temp) {
case 0: /* Ignore '0' digits. */
break;
case 1: /* Account for binaries 0 to 2^index - 1. */
binary_below += 1 << index;
break;
case 2: /* Account for binaries 0 to 2^(index+1) - 1. */
binary_below += 1 << (index + 1);
has_z = 1;
}
}
}
if (binary_first) {
if (has_z)
result = result + (1 << num_gpio) - binary_below;
else /* binary_below is normal binary system value if !has_z. */
result = binary_below;
}
printk(BIOS_DEBUG, "= %d (%s base3 number system)\n", result,
binary_first ? "binary_first" : "standard");
/* Disable pull up / pull down to conserve power */
for (index = 0; index < num_gpio; ++index)
gpio_input(gpio[index]);
return result;
}
/* Default handler for ACPI path is to return NULL */
__weak const char *gpio_acpi_path(gpio_t gpio)
{
return NULL;
}
/* Default handler returns 0 because type of gpio_t is unknown */
__weak uint16_t gpio_acpi_pin(gpio_t gpio)
{
return 0;
}
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