Add hwmon model option

On NVME devices a file is available to differentiate them by model.

My thinkpad has one internal NVME slot, but I also use external USB-C
and Thunderbolt NVME enclosures.

The internal slot shows up as hwmon3:
`/sys/class/hwmon/hwmon3/device/model`

Which contains:
`WD_BLACK SN770 1TB`
and some trailing white-space characters.

This change adds an option to allow you to specify the model with or
without the hwmon-name.

I have tested both configurations successfully:

```
  - hwmon: /sys/class/hwmon
    name: nvme
    model: WD_BLACK SN770 1TB
    indices: [1]
```
and
```
  - hwmon: /sys/class/hwmon
    model: WD_BLACK SN770 1TB
    indices: [1]
```

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>

src/fans.cpp

@@ -201,7 +201,7 @@ string TpFanDriver::type_name() const
 
 HwmonFanDriver::HwmonFanDriver(const string &path)
 : HwmonFanDriver(
-	std::make_shared<HwmonInterface<FanDriver>>(path, nullopt, nullopt),
+	std::make_shared<HwmonInterface<FanDriver>>(path, nullopt, nullopt, nullopt),
 	false,
 	0
 )

src/hwmon.cpp

@@ -65,7 +65,6 @@ vector<string> HwmonInterface<HwmonT>::find_files(const string &path, const vect
 	return rv;
 }
 
-
 template<>
 string HwmonInterface<SensorDriver>::filename(int index)
 { return "temp" + std::to_string(index) + "_input"; }
@@ -81,13 +80,13 @@ HwmonInterface<HwmonT>::HwmonInterface()
 {}
 
 template<class HwmonT>
-HwmonInterface<HwmonT>::HwmonInterface(const string &base_path, opt<const string> name, opt<vector<unsigned int>> indices)
+HwmonInterface<HwmonT>::HwmonInterface(const string &base_path, opt<const string> name, opt<const string> model, opt<vector<unsigned int>> indices)
 : base_path_(base_path)
 , name_(name)
+, model_(model)
 , indices_(indices)
 {}
 
-
 template<class HwmonT>
 vector<string> HwmonInterface<HwmonT>::find_hwmons_by_name(
 	const string &path,
@@ -131,6 +130,51 @@ vector<string> HwmonInterface<HwmonT>::find_hwmons_by_name(
 	return result;
 }
 
+template<class HwmonT>
+vector<string> HwmonInterface<HwmonT>::find_hwmons_by_model(
+	const string &path,
+	const string &model,
+	unsigned char depth
+) {
+	const unsigned char max_depth = 5;
+	vector<string> result;
+
+	ifstream f(path + "/model");
+	if (f.is_open() && f.good()) {
+		string tmp;
+		if (getline(f, tmp)) {
+			tmp = tmp.erase(tmp.find_last_not_of(" \t\n\r\f\v") + 1);
+			if (tmp == model) {
+				result.push_back(path);
+				return result;
+			}
+		}
+	}
+	if (depth >= max_depth) {
+		return result; // don't recurse to subdirs
+	}
+
+	struct dirent **entries;
+	int nentries = ::scandir(path.c_str(), &entries, filter_subdirs, nullptr);
+	if (nentries == -1) {
+		return result;
+	}
+	for (int i = 0; i < nentries; i++) {
+		auto subdir = path + "/" + entries[i]->d_name;
+		free(entries[i]);
+
+		struct stat statbuf;
+		int err = stat(path.c_str(), &statbuf);
+		if (err || (statbuf.st_mode & S_IFMT) != S_IFDIR)
+			continue;
+
+		auto found = find_hwmons_by_model(subdir, model, depth + 1);
+		result.insert(result.end(), found.begin(), found.end());
+	}
+	free(entries);
+
+	return result;
+}
 
 template<class HwmonT>
 vector<string> HwmonInterface<HwmonT>::find_hwmons_by_indices(
@@ -197,7 +241,21 @@ string HwmonInterface<HwmonT>::lookup()
 			}
 			path = paths[0];
 		}
-
+		if (model_) {
+			vector<string> paths = find_hwmons_by_model(path, model_.value(), 1);
+			if (paths.size() != 1) {
+				string msg(path + ": ");
+				if (paths.size() == 0) {
+					msg += "Could not find a hwmon with this model: " + model_.value();
+				} else {
+					msg += MSG_MULTIPLE_HWMONS_FOUND;
+					for (string hwmon_path : paths)
+						msg += " " + hwmon_path;
+				}
+				throw DriverInitError(msg);
+			}
+			path = paths[0];
+		}
 		if (indices_) {
 			found_paths_ = find_hwmons_by_indices(path, indices_.value(), 0);
 			if (found_paths_.size() == 0)

src/hwmon.h

@@ -36,7 +36,7 @@ template<class HwmonT>
 class HwmonInterface {
 public:
 	HwmonInterface();
-	HwmonInterface(const string &base_path, opt<const string> name, opt<vector<unsigned int>> indices);
+	HwmonInterface(const string &base_path, opt<const string> name, opt<const string> model,  opt<vector<unsigned int>> indices);
 
 	string lookup();
 
@@ -44,12 +44,14 @@ private:
 	static vector<string> find_files(const string &path, const vector<unsigned int> &indices);
 	static string filename(int index);
 
+	static vector<string> find_hwmons_by_model(const string &path, const string &model, unsigned char depth);
 	static vector<string> find_hwmons_by_name(const string &path, const string &name, unsigned char depth);
 	static vector<string> find_hwmons_by_indices(const string &path, const vector<unsigned int> &indices, unsigned char depth);
 
 protected:
 	opt<const string> base_path_;
 	opt<const string> name_;
+	opt<const string> model_;
 	opt<vector<unsigned int>> indices_;
 	vector<string> found_paths_;
 	opt<vector<string>::const_iterator> paths_it_;

src/sensors.cpp

@@ -135,7 +135,7 @@ void SensorDriver::skip_io_error(const ExpectedError &e)
 
 HwmonSensorDriver::HwmonSensorDriver(const string &path, bool optional)
 : HwmonSensorDriver(
-	std::make_shared<HwmonInterface<SensorDriver>>(path, nullopt, nullopt),
+	std::make_shared<HwmonInterface<SensorDriver>>(path, nullopt, nullopt, nullopt),
 	optional,
 	nullopt,
 	0

src/thinkfan.conf.5.cmake

@@ -92,6 +92,7 @@ The syntax for identifying each type of sensors looks as follows:
 \f[CB]sensors:
 \f[CB]  \- hwmon: \f[CI]hwmon-path\f[CR]          # A path to a sysfs/hwmon sensor
 \f[CB]    name: \f[CI]hwmon-name\f[CR]           # Optional entry
+\f[CB]    model: \f[CI]hwmon-model\f[CR]         # Optional entry for nvme
 \f[CB]    indices: \f[CI]index-list\f[CR]        # Optional entry
 
 \f[CB]  \- chip: \f[CI]chip-name\f[CR]            # An lm_sensors/libsensors chip...
@@ -225,6 +226,14 @@ This method of specifying sensors is particularly useful if the full path to a
 particular hwmon keeps changing between bootups, e.g. due to changing load order
 of the driver modules.
 
+.TP
+.I hwmon-model
+The model of a device in a hwmon interface usually found for NVME devices in a 
+file under \*(lqdevice\*(rq called \*(lqmodel\*(rq.
+For example, you might have an NVME \*(lq/sys/class/hwmon/hwmon3/device/model\*(rq
+and you might have an external NVME over USB or Thunderbolt that you don't want
+to monitor or you might have two NVME's.
+
 .TP
 .I index-list
 A YAML list

src/yamlconfig.cpp

@@ -102,11 +102,12 @@ bool convert_driver<vector<wtf_ptr<HwmonSensorDriver>>>(
 
 	opt<vector<int>> correction = decode_opt<vector<int>>(node[kw_correction]);
 	opt<const string> name = decode_opt<string>(node[kw_name]);
+	opt<const string> model = decode_opt<string>(node[kw_model]);
 	bool optional = node[kw_optional] ? node[kw_optional].as<bool>() : false;
 	opt<unsigned int> max_errors = decode_opt<unsigned int>(node[kw_max_errors]);
 	opt<vector<unsigned int>> indices = decode_opt<vector<unsigned int>>(node[kw_indices]);
 
-	auto hwmon_iface = std::make_shared<HwmonInterface<SensorDriver>>(path, name, indices);
+	auto hwmon_iface = std::make_shared<HwmonInterface<SensorDriver>>(path, name, model, indices);
 
 	if (indices) {
 		if (correction && correction->size() != indices->size())
@@ -285,12 +286,13 @@ bool convert_driver<vector<wtf_ptr<HwmonFanDriver>>>(const Node &node, vector<wt
 
 	string path = node[kw_hwmon].as<string>();
 	opt<string> name = decode_opt<string>(node[kw_name]);
+	opt<string> model = decode_opt<string>(node[kw_model]);
 	bool optional = node[kw_optional] ? node[kw_optional].as<bool>() : false;
 	opt<vector<unsigned int>> indices = decode_opt<vector<unsigned int>>(node[kw_indices]);
 	opt<unsigned int> max_errors = decode_opt<unsigned int>(node[kw_max_errors]);
 
 	shared_ptr<HwmonInterface<FanDriver>> hwmon_iface = std::make_shared<HwmonInterface<FanDriver>>(
-		path, name, indices
+		path, name, model, indices
 	);
 
 	if (!indices && optional)

src/yamlconfig.h

@@ -32,6 +32,7 @@ const string kw_speed("speed");
 const string kw_upper("upper_limit");
 const string kw_lower("lower_limit");
 const string kw_name("name");
+const string kw_model("model");
 const string kw_indices("indices");
 const string kw_correction("correction");
 const string kw_optional("optional");