pseq: Create PMBusDriverDevice class

Create the PMBusDriverDevice class in the phosphor-power-sequencer
application.

This class is used for power sequencer devices that are bound to a PMBus
device driver.  It obtains PMBus information from sysfs/hwmon files
created by the driver.

Tested:
* Performed all of the following tests on Rainier and Everest systems
* Correct sysfs/hwmon files and directories found
* GPIO values obtained successfully
* STATUS_WORD values obtained successfully
* STATUS_VOUT values obtained successfully
* READ_VOUT values obtained successfully
* VOUT_UV_FAULT_LIMIT values obtained successfully
* Mapping built from PMBus PAGE numbers to hwmon file numbers
* Verified error paths and exceptions thrown

Change-Id: I2efd3146fa08d3584857c94c2bbbf691b1e2ad7d
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
diff --git a/phosphor-power-sequencer/src/meson.build b/phosphor-power-sequencer/src/meson.build
index 2d14caf..ee6057e 100644
--- a/phosphor-power-sequencer/src/meson.build
+++ b/phosphor-power-sequencer/src/meson.build
@@ -6,6 +6,7 @@
 phosphor_power_sequencer_library = static_library(
     'phosphor-power-sequencer',
     'config_file_parser.cpp',
+    'pmbus_driver_device.cpp',
     'rail.cpp',
     'services.cpp',
     'standard_device.cpp',
diff --git a/phosphor-power-sequencer/src/pmbus_driver_device.cpp b/phosphor-power-sequencer/src/pmbus_driver_device.cpp
new file mode 100644
index 0000000..e8c0e04
--- /dev/null
+++ b/phosphor-power-sequencer/src/pmbus_driver_device.cpp
@@ -0,0 +1,253 @@
+/**
+ * Copyright © 2024 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 "pmbus_driver_device.hpp"
+
+#include <ctype.h> // for tolower()
+
+#include <algorithm>
+#include <exception>
+#include <filesystem>
+#include <format>
+#include <regex>
+#include <stdexcept>
+
+namespace phosphor::power::sequencer
+{
+
+using namespace pmbus;
+namespace fs = std::filesystem;
+
+std::vector<int> PMBusDriverDevice::getGPIOValues(Services& services)
+{
+    // Get lower case version of device name to use as chip label
+    std::string label{name};
+    std::transform(label.begin(), label.end(), label.begin(), ::tolower);
+
+    // Read the GPIO values by specifying the chip label
+    std::vector<int> values;
+    try
+    {
+        values = services.getGPIOValues(label);
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{std::format(
+            "Unable to read GPIO values from device {} using label {}: {}",
+            name, label, e.what())};
+    }
+    return values;
+}
+
+uint16_t PMBusDriverDevice::getStatusWord(uint8_t page)
+{
+    uint16_t value{0};
+    try
+    {
+        std::string fileName = std::format("status{:d}", page);
+        value = pmbusInterface->read(fileName, Type::Debug);
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{std::format(
+            "Unable to read STATUS_WORD for PAGE {:d} of device {}: {}", page,
+            name, e.what())};
+    }
+    return value;
+}
+
+uint8_t PMBusDriverDevice::getStatusVout(uint8_t page)
+{
+    uint8_t value{0};
+    try
+    {
+        std::string fileName = std::format("status{:d}_vout", page);
+        value = pmbusInterface->read(fileName, Type::Debug);
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{std::format(
+            "Unable to read STATUS_VOUT for PAGE {:d} of device {}: {}", page,
+            name, e.what())};
+    }
+    return value;
+}
+
+double PMBusDriverDevice::getReadVout(uint8_t page)
+{
+    double volts{0.0};
+    try
+    {
+        unsigned int fileNumber = getFileNumber(page);
+        std::string fileName = std::format("in{}_input", fileNumber);
+        std::string millivoltsStr = pmbusInterface->readString(fileName,
+                                                               Type::Hwmon);
+        unsigned long millivolts = std::stoul(millivoltsStr);
+        volts = millivolts / 1000.0;
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{std::format(
+            "Unable to read READ_VOUT for PAGE {:d} of device {}: {}", page,
+            name, e.what())};
+    }
+    return volts;
+}
+
+double PMBusDriverDevice::getVoutUVFaultLimit(uint8_t page)
+{
+    double volts{0.0};
+    try
+    {
+        unsigned int fileNumber = getFileNumber(page);
+        std::string fileName = std::format("in{}_lcrit", fileNumber);
+        std::string millivoltsStr = pmbusInterface->readString(fileName,
+                                                               Type::Hwmon);
+        unsigned long millivolts = std::stoul(millivoltsStr);
+        volts = millivolts / 1000.0;
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{std::format(
+            "Unable to read VOUT_UV_FAULT_LIMIT for PAGE {:d} of device {}: {}",
+            page, name, e.what())};
+    }
+    return volts;
+}
+
+unsigned int PMBusDriverDevice::getFileNumber(uint8_t page)
+{
+    if (pageToFileNumber.empty())
+    {
+        buildPageToFileNumberMap();
+    }
+
+    auto it = pageToFileNumber.find(page);
+    if (it == pageToFileNumber.end())
+    {
+        throw std::runtime_error{std::format(
+            "Unable to find hwmon file number for PAGE {:d} of device {}", page,
+            name)};
+    }
+
+    return it->second;
+}
+
+void PMBusDriverDevice::buildPageToFileNumberMap()
+{
+    // Clear any existing mappings
+    pageToFileNumber.clear();
+
+    // Build mappings using voltage label files in hwmon directory
+    try
+    {
+        fs::path hwmonDir = pmbusInterface->getPath(Type::Hwmon);
+        if (fs::is_directory(hwmonDir))
+        {
+            // Loop through all files in hwmon directory
+            std::string fileName;
+            unsigned int fileNumber;
+            std::optional<uint8_t> page;
+            for (const auto& f : fs::directory_iterator{hwmonDir})
+            {
+                // If this is a voltage label file
+                fileName = f.path().filename().string();
+                if (isLabelFile(fileName, fileNumber))
+                {
+                    // Read PMBus PAGE number from label file contents
+                    page = readPageFromLabelFile(fileName);
+                    if (page)
+                    {
+                        // Add mapping from PAGE number to file number
+                        pageToFileNumber.emplace(*page, fileNumber);
+                    }
+                }
+            }
+        }
+    }
+    catch (const std::exception& e)
+    {
+        throw std::runtime_error{
+            std::format("Unable to map PMBus PAGE numbers to hwmon file "
+                        "numbers for device {}: {}",
+                        name, e.what())};
+    }
+}
+
+bool PMBusDriverDevice::isLabelFile(const std::string& fileName,
+                                    unsigned int& fileNumber)
+{
+    bool isLabel{false};
+    try
+    {
+        // Check if file name has expected pattern for voltage label file
+        std::regex regex{"in(\\d+)_label"};
+        std::smatch results;
+        if (std::regex_match(fileName, results, regex))
+        {
+            // Verify 2 match results: entire match and one sub-match
+            if (results.size() == 2)
+            {
+                // Get sub-match that contains the file number
+                std::string fileNumberStr = results.str(1);
+                fileNumber = std::stoul(fileNumberStr);
+                isLabel = true;
+            }
+        }
+    }
+    catch (...)
+    {
+        // Ignore error.  If this file is needed for pgood fault detection, an
+        // error will occur later when the necessary mapping is missing.  Avoid
+        // logging unnecessary errors for files that may not be required.
+    }
+    return isLabel;
+}
+
+std::optional<uint8_t>
+    PMBusDriverDevice::readPageFromLabelFile(const std::string& fileName)
+{
+    std::optional<uint8_t> page;
+    try
+    {
+        // Read voltage label file contents
+        std::string contents = pmbusInterface->readString(fileName,
+                                                          Type::Hwmon);
+
+        // Check if file contents match the expected pattern
+        std::regex regex{"vout(\\d+)"};
+        std::smatch results;
+        if (std::regex_match(contents, results, regex))
+        {
+            // Verify 2 match results: entire match and one sub-match
+            if (results.size() == 2)
+            {
+                // Get sub-match that contains the page number + 1
+                std::string pageStr = results.str(1);
+                page = std::stoul(pageStr) - 1;
+            }
+        }
+    }
+    catch (...)
+    {
+        // Ignore error.  If this file is needed for pgood fault detection, an
+        // error will occur later when the necessary mapping is missing.  Avoid
+        // logging unnecessary errors for files that may not be required.
+    }
+    return page;
+}
+
+} // namespace phosphor::power::sequencer
diff --git a/phosphor-power-sequencer/src/pmbus_driver_device.hpp b/phosphor-power-sequencer/src/pmbus_driver_device.hpp
new file mode 100644
index 0000000..e7e85ac
--- /dev/null
+++ b/phosphor-power-sequencer/src/pmbus_driver_device.hpp
@@ -0,0 +1,258 @@
+/**
+ * Copyright © 2024 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.
+ */
+#pragma once
+
+#include "pmbus.hpp"
+#include "rail.hpp"
+#include "services.hpp"
+#include "standard_device.hpp"
+
+#include <stddef.h> // for size_t
+
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <optional>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace phosphor::power::sequencer
+{
+
+/**
+ * @class PMBusDriverDevice
+ *
+ * StandardDevice sub-class for power sequencer devices that are bound to a
+ * PMBus device driver.
+ */
+class PMBusDriverDevice : public StandardDevice
+{
+  public:
+    // Specify which compiler-generated methods we want
+    PMBusDriverDevice() = delete;
+    PMBusDriverDevice(const PMBusDriverDevice&) = delete;
+    PMBusDriverDevice(PMBusDriverDevice&&) = delete;
+    PMBusDriverDevice& operator=(const PMBusDriverDevice&) = delete;
+    PMBusDriverDevice& operator=(PMBusDriverDevice&&) = delete;
+    virtual ~PMBusDriverDevice() = default;
+
+    /**
+     * Constructor.
+     *
+     * @param name Device name
+     * @param rails Voltage rails that are enabled and monitored by this device
+     * @param services System services like hardware presence and the journal
+     * @param bus I2C bus for the device
+     * @param address I2C address for the device
+     * @param driverName Device driver name
+     * @param instance Chip instance number
+     */
+    explicit PMBusDriverDevice(const std::string& name,
+                               std::vector<std::unique_ptr<Rail>> rails,
+                               Services& services, uint8_t bus,
+                               uint16_t address,
+                               const std::string& driverName = "",
+                               size_t instance = 0) :
+        StandardDevice(name, std::move(rails)),
+        bus{bus}, address{address}, driverName{driverName}, instance{instance}
+    {
+        pmbusInterface = services.createPMBus(bus, address, driverName,
+                                              instance);
+    }
+
+    /**
+     * Returns the I2C bus for the device.
+     *
+     * @return I2C bus
+     */
+    uint8_t getBus() const
+    {
+        return bus;
+    }
+
+    /**
+     * Returns the I2C address for the device.
+     *
+     * @return I2C address
+     */
+    uint16_t getAddress() const
+    {
+        return address;
+    }
+
+    /**
+     * Returns the device driver name.
+     *
+     * @return driver name
+     */
+    const std::string& getDriverName() const
+    {
+        return driverName;
+    }
+
+    /**
+     * Returns the chip instance number.
+     *
+     * @return chip instance
+     */
+    size_t getInstance() const
+    {
+        return instance;
+    }
+
+    /**
+     * Returns interface to the PMBus information that is provided by the device
+     * driver in sysfs.
+     *
+     * @return PMBus interface object
+     */
+    pmbus::PMBusBase& getPMBusInterface()
+    {
+        return *pmbusInterface;
+    }
+
+    /** @copydoc PowerSequencerDevice::getGPIOValues() */
+    virtual std::vector<int> getGPIOValues(Services& services) override;
+
+    /** @copydoc PowerSequencerDevice::getStatusWord() */
+    virtual uint16_t getStatusWord(uint8_t page) override;
+
+    /** @copydoc PowerSequencerDevice::getStatusVout() */
+    virtual uint8_t getStatusVout(uint8_t page) override;
+
+    /** @copydoc PowerSequencerDevice::getReadVout() */
+    virtual double getReadVout(uint8_t page) override;
+
+    /** @copydoc PowerSequencerDevice::getVoutUVFaultLimit() */
+    virtual double getVoutUVFaultLimit(uint8_t page) override;
+
+    /**
+     * Returns map from PMBus PAGE numbers to sysfs hwmon file numbers.
+     *
+     * Throws an exception if an error occurs trying to build the map.
+     *
+     * @return page to file number map
+     */
+    const std::map<uint8_t, unsigned int>& getPageToFileNumberMap()
+    {
+        if (pageToFileNumber.empty())
+        {
+            buildPageToFileNumberMap();
+        }
+        return pageToFileNumber;
+    }
+
+    /**
+     * Returns the hwmon file number that corresponds to the specified PMBus
+     * PAGE number.
+     *
+     * Throws an exception if a file number was not found for the specified PAGE
+     * number.
+     *
+     * @param page PMBus PAGE number
+     * @return hwmon file number
+     */
+    unsigned int getFileNumber(uint8_t page);
+
+  protected:
+    /** @copydoc StandardDevice::prepareForPgoodFaultDetection() */
+    virtual void prepareForPgoodFaultDetection(Services& services) override
+    {
+        // Rebuild PMBus PAGE to hwmon file number map
+        buildPageToFileNumberMap();
+
+        // Call parent class method to do any actions defined there
+        StandardDevice::prepareForPgoodFaultDetection(services);
+    }
+
+    /**
+     * Build mapping from PMBus PAGE numbers to the hwmon file numbers in
+     * sysfs.
+     *
+     * hwmon file names have the format:
+     *   <type><number>_<item>
+     *
+     * The <number> is not the PMBus PAGE number.  The PMBus PAGE is determined
+     * by reading the contents of the <type><number>_label file.
+     *
+     * If the map is not empty, it is cleared and rebuilt.  This is necessary
+     * over time because power devices may have been added or removed.
+     *
+     * Throws an exception if an error occurs trying to build the map.
+     */
+    virtual void buildPageToFileNumberMap();
+
+    /**
+     * Returns whether the specified sysfs hwmon file is a voltage label file.
+     *
+     * If it is a label file, the hwmon file number is obtained from the file
+     * name and returned.
+     *
+     * @param fileName file within the sysfs hwmon directory
+     * @param fileNumber the hwmon file number is stored in this output
+     *                   parameter if this is a label file
+     * @return true if specified file is a voltage label file, false otherwise
+     */
+    virtual bool isLabelFile(const std::string& fileName,
+                             unsigned int& fileNumber);
+
+    /**
+     * Reads the specified voltage label file to obtain the associated PMBus
+     * PAGE number.
+     *
+     * The returned optional variable will have no value if the PMBus PAGE
+     * number could not be obtained due to an error.
+     *
+     * @param fileName voltage label file within the sysfs hwmon directory
+     * @return PMBus page number
+     */
+    virtual std::optional<uint8_t>
+        readPageFromLabelFile(const std::string& fileName);
+
+    /**
+     * I2C bus for the device.
+     */
+    uint8_t bus;
+
+    /**
+     * I2C address for the device.
+     */
+    uint16_t address;
+
+    /**
+     * Device driver name.
+     */
+    std::string driverName;
+
+    /**
+     * Chip instance number.
+     */
+    size_t instance;
+
+    /**
+     * Interface to the PMBus information that is provided by the device driver
+     * in sysfs.
+     */
+    std::unique_ptr<pmbus::PMBusBase> pmbusInterface;
+
+    /**
+     * Map from PMBus PAGE numbers to sysfs hwmon file numbers.
+     */
+    std::map<uint8_t, unsigned int> pageToFileNumber;
+};
+
+} // namespace phosphor::power::sequencer