gpio: Extend common GPIO header, simplify function names

We've had gpiolib.h which defines a few common GPIO access functions for
a while, but it wasn't really complete. This patch adds the missing
gpio_output() function, and also renames the unwieldy
gpio_get_in_value() and gpio_set_out_value() to the much easier to
handle gpio_get() and gpio_set(). The header is renamed to the simpler
gpio.h while we're at it (there was never really anything "lib" about
it, and it was presumably just chosen due to the IPQ806x include/
conflict problem that is now resolved).

It also moves the definition of gpio_t into SoC-specific code, so that
different implementations are free to encode their platform-specific
GPIO parameters in those 4 bytes in the most convenient way (such as the
rk3288 with a bitfield struct). Every SoC intending to use this common
API should supply a <soc/gpio.h> that typedefs gpio_t to a type at most
4 bytes in length. Files accessing the API only need to include <gpio.h>
which may pull in additional things (like a gpio_t creation macro) from
<soc/gpio.h> on its own.

For now the API is still only used on non-x86 SoCs. Whether it makes
sense to expand it to x86 as well should be separately evaluated at a
later point (by someone who understands those systems better). Also,
Exynos retains its old, incompatible GPIO API even though it would be a
prime candidate, because it's currently just not worth the effort.

BUG=None
TEST=Compiled on Daisy, Peach_Pit, Nyan_Blaze, Rush_Ryu, Storm and
Veyron_Pinky.

Change-Id: Ieee77373c2bd13d07ece26fa7f8b08be324842fe
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 9e04902ada56b929e3829f2c3b4aeb618682096e
Original-Change-Id: I6c1e7d1e154d9b02288aabedb397e21e1aadfa15
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/220975
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9400
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/include/gpio.h b/src/include/gpio.h
new file mode 100644
index 000000000000..af066970500e
--- /dev/null
+++ b/src/include/gpio.h
@@ -0,0 +1,52 @@
+/*
+ * 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
+ */
+
+#ifndef __SRC_INCLUDE_GPIO_H__
+#define __SRC_INCLUDE_GPIO_H__
+
+#include <soc/gpio.h>
+#include <types.h>
+
+/* <soc/gpio.h> must typedef a gpio_t that fits in 32 bits. */
+_Static_assert(sizeof(gpio_t) <= sizeof(u32), "gpio_t doesn't fit in lb_gpio");
+
+/* The following functions must be implemented by SoC/board code. */
+int gpio_get(gpio_t gpio);
+void gpio_set(gpio_t gpio, int value);
+void gpio_input_pulldown(gpio_t gpio);
+void gpio_input_pullup(gpio_t gpio);
+void gpio_input(gpio_t gpio);
+void gpio_output(gpio_t gpio, int value);
+
+/*
+ * Read the value presented by the set of GPIOs, when each pin is interpreted
+ * as a number in 0..2 range depending on the external pullup situation.
+ *
+ * Depending on the third parameter, the return value is either a set of two
+ * bit fields, each representing one GPIO value, or a number where each GPIO is
+ * included multiplied by 3^gpio_num, resulting in a true tertiary value.
+ *
+ * gpio[]: pin positions to read. little-endian (less significant value first).
+ * num_gpio: number of pins to read.
+ * tertiary: 1: pins are interpreted as a quad coded tertiary.
+ *           0: pins are interpreted as a set of two bit fields.
+ */
+int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary);
+
+#endif /* __SRC_INCLUDE_GPIO_H__ */