Update hwmon fan target sysfs entries

Override the default FanSpeed.Target set implementation so when a target
value is written to the FanSpeed interface it is also updated in the
related fan target sysfs file. This sets a particular fan to the given
target speed.

Resolves openbmc/openbmc#962
Resolves openbmc/phosphor-hwmon#1

Change-Id: I867811737269b3f42d2a0dc15b37782a74f147b8
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/fan_speed.cpp b/fan_speed.cpp
new file mode 100644
index 0000000..74bbea3
--- /dev/null
+++ b/fan_speed.cpp
@@ -0,0 +1,26 @@
+#include "fan_speed.hpp"
+#include "hwmon.hpp"
+#include "sysfs.hpp"
+
+namespace hwmon
+{
+
+uint64_t FanSpeed::target(uint64_t value)
+{
+    auto curValue = FanSpeedObject::target();
+
+    if (curValue != value)
+    {
+        //Write target out to sysfs
+        curValue = writeSysfsWithCallout(value,
+                                         sysfsRoot,
+                                         instance,
+                                         type,
+                                         id,
+                                         entry::target);
+    }
+
+    return FanSpeedObject::target(value);
+}
+
+} // namespace hwmon