Add GPIO class

This class is used for accessing a GPIO via the
/dev/gpiochipX interface.

It requests a GPIO line handle from the GPIO device to
do the actual operation on.

The GPIO number to use, for AST chips at least, is the
actual GPIO number, such as GPIOA0 = 0 and GPIOA7 = 7.

The class currently only supports writes.

Change-Id: I1c2ae38c23c5db502d5f14bcf9aa2e35094f1e9b
Signed-off-by: Matt Spinler <spinler@us.ibm.com>

1 files changed, 98 insertions, 0 deletions

diff --git a/gpio-util/gpio.cpp b/gpio-util/gpio.cpp
new file mode 100644
index 0000000..d5c2ce4
--- /dev/null
+++ b/gpio-util/gpio.cpp
@@ -0,0 +1,98 @@
+/**
+ * Copyright © 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <fcntl.h>
+#include <phosphor-logging/log.hpp>
+#include <sys/ioctl.h>
+#include "gpio.hpp"
+
+namespace phosphor
+{
+namespace gpio
+{
+
+using namespace phosphor::logging;
+
+void GPIO::set(Value value)
+{
+    assert(direction == Direction::output);
+
+    requestLine(value);
+
+    gpiohandle_data data{};
+    data.values[0] = static_cast<gpioValue_t>(value);
+
+    auto rc = ioctl(lineFD(), GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
+    if (rc == -1)
+    {
+        auto e = errno;
+        log<level::ERR>("Failed SET_LINE_VALUES ioctl",
+                        entry("ERRNO=%d", e));
+        throw std::runtime_error("Failed SET_LINE_VALUES ioctl");
+    }
+}
+
+
+void GPIO::requestLine(Value defaultValue)
+{
+    //Only need to do this once
+    if (lineFD)
+    {
+        return;
+    }
+
+    FileDescriptor fd{open(device.c_str(), 0)};
+    if (fd() == -1)
+    {
+        auto e = errno;
+        log<level::ERR>("Failed opening GPIO device",
+                        entry("DEVICE=%s", device),
+                        entry("ERRNO=%d", e));
+        throw std::runtime_error("Failed opening GPIO device");
+    }
+
+    //Make an ioctl call to request the GPIO line, which will
+    //return the descriptor to use to access it.
+    gpiohandle_request request{};
+    strncpy(request.consumer_label,
+            "phosphor-gpio-util",
+            sizeof(request.consumer_label));
+
+    request.flags = (direction == Direction::output) ?
+        GPIOHANDLE_REQUEST_OUTPUT : GPIOHANDLE_REQUEST_INPUT;
+
+    request.lineoffsets[0] = gpio;
+    request.lines = 1;
+
+    if (direction == Direction::output)
+    {
+        request.default_values[0] = static_cast<gpioValue_t>(defaultValue);
+    }
+
+    auto rc = ioctl(fd(), GPIO_GET_LINEHANDLE_IOCTL, &request);
+    if (rc == -1)
+    {
+        auto e = errno;
+        log<level::ERR>("Failed GET_LINEHANDLE ioctl",
+                        entry("GPIO=%d", gpio),
+                        entry("ERRNO=%d", e));
+        throw std::runtime_error("Failed GET_LINEHANDLE ioctl");
+    }
+
+    lineFD.set(request.fd);
+}
+
+}
+}