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authorDavid Hendricks <dhendrix@chromium.org>2013-02-02 16:57:11 -0800
committerRonald G. Minnich <rminnich@gmail.com>2013-02-04 05:38:32 +0100
commitd58ba2add4b0ae955126ca746db39aa9fa98fd9f (patch)
tree1429381c06000cab6eb14038b2da530f06315f37 /src/include
parent10883945dcb089d7c4908eacaab7cb8d955657a3 (diff)
add gpio.h for generic GPIO-related definitions
This adds /src/include/gpio.h which currently contains generic GPIO enums for type (in/out/alt) and 3-state logic. The header was originally written for another FOSS project (code.google.com/p/mosys) and thus the BSD license. Change-Id: Id1dff69169e8b1ec372107737d356b0fa0d80498 Signed-off-by: David Hendricks <dhendrix@chromium.org> Reviewed-on: http://review.coreboot.org/2265 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Diffstat (limited to 'src/include')
-rw-r--r--src/include/gpio.h63
1 files changed, 63 insertions, 0 deletions
diff --git a/src/include/gpio.h b/src/include/gpio.h
new file mode 100644
index 0000000000..f602b1ed6e
--- /dev/null
+++ b/src/include/gpio.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2012, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ * * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef GPIO_H
+#define GPIO_H
+
+enum gpio_types {
+ GPIO_IN,
+ GPIO_OUT,
+ GPIO_ALT, /* catch-all for alternate functions */
+};
+
+/*
+ * Many-value logic (3 states). This can be used for inputs whereby presence
+ * of external pull-up or pull-down resistors can be added to overcome internal
+ * pull-ups/pull-downs and force a single value.
+ *
+ * Thus, external pull resistors can force a 0 or 1 and if the value changes
+ * along with internal pull-up/down enable then the input is floating.
+ *
+ * Vpd | Vpu | MVL
+ * -----------------
+ * 0 | 0 | 0
+ * -----------------
+ * 0 | 1 | Z <-- floating input will follow internal pull up/down
+ * -----------------
+ * 1 | 1 | 1
+ */
+enum mvl3 {
+ LOGIC_0,
+ LOGIC_1,
+ LOGIC_Z, /* high impedence / tri-stated / floating */
+};
+
+#endif /* GPIO_H */