Add hwmon io wrapper class
Add a convenience class for doing hwmon attribute sysfs
IO.
A convenience class is warranted given some necessary
workarounds for some GCC io exception bugs, and more importantly
to remove the burden of the rest of the application
checking for ENOENT in the case of a driver unbind event.
Change-Id: I73d5a9aaaac1d5546109ae18854fe5db0b5acb26
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/sysfs.hpp b/sysfs.hpp
index f0e92db..a526198 100644
--- a/sysfs.hpp
+++ b/sysfs.hpp
@@ -116,6 +116,81 @@
const std::string& id,
const std::string& sensor);
+namespace hwmonio
+{
+
+/** @class HwmonIO
+ * @brief Convenience wrappers for HWMON sysfs attribute IO.
+ *
+ * Unburden the rest of the application from having to check
+ * ENOENT after every hwmon attribute io operation. Hwmon
+ * device drivers can be unbound at any time; the program
+ * cannot always be terminated externally before we try to
+ * do an io.
+ */
+class HwmonIO
+{
+ public:
+ HwmonIO() = delete;
+ HwmonIO(const HwmonIO&) = default;
+ HwmonIO(HwmonIO&&) = default;
+ HwmonIO& operator=(const HwmonIO&) = default;
+ HwmonIO& operator=(HwmonIO&&) = default;
+ ~HwmonIO() = default;
+
+ /** @brief Constructor
+ *
+ * @param[in] path - hwmon instance root - eg:
+ * /sys/class/hwmon/hwmon<N>
+ */
+ explicit HwmonIO(const std::string& path);
+
+ /** @brief Perform formatted hwmon sysfs read.
+ *
+ * Propogates any exceptions other than ENOENT.
+ * ENOENT will result in a call to exit(0) in case
+ * the underlying hwmon driver is unbound and
+ * the program is inadvertently left running.
+ *
+ * @param[in] type - The hwmon type (ex. temp).
+ * @param[in] id - The hwmon id (ex. 1).
+ * @param[in] sensor - The hwmon sensor (ex. input).
+ *
+ * @return val - The read value.
+ */
+ uint32_t read(
+ const std::string& type,
+ const std::string& id,
+ const std::string& sensor) const;
+
+ /** @brief Perform formatted hwmon sysfs write.
+ *
+ * Propogates any exceptions other than ENOENT.
+ * ENOENT will result in a call to exit(0) in case
+ * the underlying hwmon driver is unbound and
+ * the program is inadvertently left running.
+ *
+ * @param[in] val - The value to be written.
+ * @param[in] type - The hwmon type (ex. fan).
+ * @param[in] id - The hwmon id (ex. 1).
+ * @param[in] sensor - The hwmon sensor (ex. target).
+ */
+ void write(
+ uint32_t val,
+ const std::string& type,
+ const std::string& id,
+ const std::string& sensor) const;
+
+ /** @brief Hwmon instance path access.
+ *
+ * @return path - The hwmon instance path.
+ */
+ std::string path() const;
+
+ private:
+ std::string p;
+};
+} // namespace hwmonio
}
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