Add I2C OCC support for P8 systems

P8 system uses I2C OCC and it uses different driver for occ-hwmon.
Add `--enable-i2c-occ` configure option to enable the support.

It searches i2c device names in sysfs to get all occ-hwmon devices and
use the i2c device name to bind/unbind the driver.

The occ control object path for I2C OCC hwmon becomes something like
/org/open_power/control/3_0050, where 3_0050 is the i2c address.

Change-Id: I8b9d8d4429c563528dc88fb2679b265c53d7a2d5
Signed-off-by: Lei YU <mine260309@gmail.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/i2c_occ.cpp b/i2c_occ.cpp
new file mode 100644
index 0000000..ffbb844
--- /dev/null
+++ b/i2c_occ.cpp
@@ -0,0 +1,73 @@
+#include <algorithm>
+#include <fstream>
+
+#include "config.h"
+#include "i2c_occ.hpp"
+
+#ifdef I2C_OCC
+
+namespace i2c_occ
+{
+
+namespace fs = std::experimental::filesystem;
+
+// The device name's length, e.g. "p8-occ-hwmon"
+constexpr auto DEVICE_NAME_LENGTH = 12;
+
+// static assert to make sure the i2c occ device name is expected
+static_assert(sizeof(I2C_OCC_DEVICE_NAME) -1 == DEVICE_NAME_LENGTH);
+
+std::string getFileContent(const fs::path& f)
+{
+    std::string ret(DEVICE_NAME_LENGTH, 0);
+    std::ifstream ifs(f.c_str(), std::ios::binary);
+    if (ifs.is_open())
+    {
+        ifs.read(&ret[0], DEVICE_NAME_LENGTH);
+        ret.resize(ifs.gcount());
+    }
+    return ret;
+}
+
+std::vector<std::string> getOccHwmonDevices(const char* path)
+{
+    std::vector<std::string> result{};
+
+    if (fs::is_directory(path))
+    {
+        for (auto & p : fs::directory_iterator(path))
+        {
+            // Check if a device's name is "p8-occ-hwmon"
+            auto f = p / "name";
+            auto str = getFileContent(f);
+            if (str == I2C_OCC_DEVICE_NAME)
+            {
+                result.emplace_back(p.path().filename());
+            }
+        }
+        std::sort(result.begin(), result.end());
+    }
+    return result;
+}
+
+void i2cToDbus(std::string& path)
+{
+    std::replace(path.begin(), path.end(), '-', '_');
+}
+
+void dbusToI2c(std::string& path)
+{
+    std::replace(path.begin(), path.end(), '_', '-');
+}
+
+std::string getI2cDeviceName(const std::string& dbusPath)
+{
+    auto name = fs::path(dbusPath).filename().string();
+    dbusToI2c(name);
+    return name;
+}
+
+} // namespace i2c_occ
+
+#endif
+