diff options
Diffstat (limited to 'src/lib')
| -rw-r--r-- | src/lib/Makefile.inc | 1 | ||||
| -rw-r--r-- | src/lib/tristate_gpios.c | 79 |
2 files changed, 80 insertions, 0 deletions
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc index d1e3a92b21..1e70e2e01a 100644 --- a/src/lib/Makefile.inc +++ b/src/lib/Makefile.inc @@ -57,6 +57,7 @@ ifeq ($(CONFIG_COMPILER_GCC),y) romstage-$(CONFIG_ARCH_ROMSTAGE_X86_32) += gcc.c ramstage-$(CONFIG_ARCH_RAMSTAGE_X86_32) += gcc.c endif +romstage-$(CONFIG_TERTIARY_BOARD_ID) += tristate_gpios.c ramstage-y += hardwaremain.c ramstage-y += selfboot.c diff --git a/src/lib/tristate_gpios.c b/src/lib/tristate_gpios.c new file mode 100644 index 0000000000..b1ebbc0f71 --- /dev/null +++ b/src/lib/tristate_gpios.c @@ -0,0 +1,79 @@ +/* + * 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_board_id(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 = 0; index < num_gpio; ++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; +} |