diff options
| author | David Hendricks <dhendrix@chromium.org> | 2013-02-02 16:57:11 -0800 |
|---|---|---|
| committer | Ronald G. Minnich <rminnich@gmail.com> | 2013-02-04 05:38:32 +0100 |
| commit | d58ba2add4b0ae955126ca746db39aa9fa98fd9f (patch) | |
| tree | 1429381c06000cab6eb14038b2da530f06315f37 /src/include | |
| parent | 10883945dcb089d7c4908eacaab7cb8d955657a3 (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.h | 63 |
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 */ |