coreboot-kgpe-d16/src/lib/tristate_gpios.c
Daisuke Nojiri 573e21132f fix how to interpret board id read from gpios
nyan blaze fails to boot because tristates of the board id are interpreted in
the reverse order. this change fixes it.

BUG=none
TEST=Booted Blaze to Linux. Built firmware for Storm.
Branch=none
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Change-Id: I4ff8a15cf62869cea22931b5255c3a408a778ed2
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 3f59b13d615a8985edf2029d89af05e95aefad33
Original-Change-Id: I6d81092becb60d12e1cd2a92fc2c261da42c60f5
Original-Reviewed-on: https://chromium-review.googlesource.com/211700
Original-Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: http://review.coreboot.org/8980
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-03-26 00:26:50 +01:00

79 lines
2.1 KiB
C

/*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <delay.h>
#include <gpiolib.h>
int gpio_get_in_tristate_values(gpio_t gpio[], int num_gpio, int tertiary)
{
/*
* 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.
*/
int temp;
int index;
int id = 0;
char value[num_gpio];
/* 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_in_value(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
*/
for (index = num_gpio - 1; index >= 0; --index) {
if (tertiary)
id *= 3;
else
id <<= 2;
temp = gpio_get_in_value(gpio[index]);
id += ((value[index] ^ temp) << 1) | temp;
}
/* Disable pull up / pull down to conserve power */
for (index = 0; index < num_gpio; ++index)
gpio_input(gpio[index]);
return id;
}