diff --git a/phosphor-power-sequencer/src/power_sequencer_device.hpp b/phosphor-power-sequencer/src/power_sequencer_device.hpp
new file mode 100644
index 0000000..e7ec274
--- /dev/null
+++ b/phosphor-power-sequencer/src/power_sequencer_device.hpp
@@ -0,0 +1,161 @@
+/**
+ * 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 "services.hpp"
+
+#include <cstdint>
+#include <map>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+namespace phosphor::power::sequencer
+{
+
+/**
+ * @class PowerSequencerDevice
+ *
+ * Abstract base class for a hardware device that performs the following tasks:
+ * - Enables (turns on) the voltage rails in the proper sequence
+ * - Checks the pgood (power good) status of each voltage rail
+ */
+class PowerSequencerDevice
+{
+  public:
+    // Specify which compiler-generated methods we want
+    PowerSequencerDevice() = default;
+    PowerSequencerDevice(const PowerSequencerDevice&) = delete;
+    PowerSequencerDevice(PowerSequencerDevice&&) = delete;
+    PowerSequencerDevice& operator=(const PowerSequencerDevice&) = delete;
+    PowerSequencerDevice& operator=(PowerSequencerDevice&&) = delete;
+    virtual ~PowerSequencerDevice() = default;
+
+    /**
+     * Returns the device name.
+     *
+     * @return device name
+     */
+    virtual const std::string& getName() const = 0;
+
+    /**
+     * Returns the GPIO values that can be read from the device.
+     *
+     * The vector indices correspond to the libgpiod line offsets.  For example,
+     * the element at vector index 0 is the GPIO value at libgpiod line offset
+     * 0.  These offsets may correspond to logical pin IDs, but they are usually
+     * different from the physical pin numbers on the device.  Consult the
+     * device documentation for more information.
+     *
+     * Throws an exception if the values could not be read or the device does
+     * not support GPIO values.
+     *
+     * @return GPIO values
+     */
+    virtual std::vector<int> getGPIOValues() = 0;
+
+    /**
+     * Returns the value of the PMBus STATUS_WORD command for the specified
+     * PMBus page.
+     *
+     * The returned value is in host-endian order.
+     *
+     * Throws an exception if the value could not be obtained or the device does
+     * not support the STATUS_WORD command.
+     *
+     * @param page PMBus page
+     * @return STATUS_WORD value
+     */
+    virtual uint16_t getStatusWord(uint8_t page) = 0;
+
+    /**
+     * Returns the value of the PMBus STATUS_VOUT command for the specified
+     * PMBus page.
+     *
+     * Throws an exception if the value could not be obtained or the device does
+     * not support the STATUS_VOUT command.
+     *
+     * @param page PMBus page
+     * @return STATUS_VOUT value
+     */
+    virtual uint8_t getStatusVout(uint8_t page) = 0;
+
+    /**
+     * Returns the value of the PMBus READ_VOUT command for the specified
+     * PMBus page.
+     *
+     * The returned value is in Volts.
+     *
+     * Throws an exception if the value could not be obtained or the device does
+     * not support the READ_VOUT command.
+     *
+     * @param page PMBus page
+     * @return READ_VOUT value in volts
+     */
+    virtual double getReadVout(uint8_t page) = 0;
+
+    /**
+     * Returns the value of the PMBus VOUT_UV_FAULT_LIMIT command for the
+     * specified PMBus page.
+     *
+     * The returned value is in Volts.
+     *
+     * Throws an exception if the value could not be obtained or the device does
+     * not support the VOUT_UV_FAULT_LIMIT command.
+     *
+     * @param page PMBus page
+     * @return VOUT_UV_FAULT_LIMIT value in volts
+     */
+    virtual double getVoutUVFaultLimit(uint8_t page) = 0;
+
+    /**
+     * Returns the value of the PMBus VOUT_OV_FAULT_LIMIT command for the
+     * specified PMBus page.
+     *
+     * The returned value is in Volts.
+     *
+     * Throws an exception if the value could not be obtained or the device does
+     * not support the VOUT_OV_FAULT_LIMIT command.
+     *
+     * @param page PMBus page
+     * @return VOUT_OV_FAULT_LIMIT value in volts
+     */
+    virtual double getVoutOVFaultLimit(uint8_t page) = 0;
+
+    /**
+     * Returns whether a pgood fault has occurred on one of the rails being
+     * monitored by this device.
+     *
+     * Throws an exception if an error occurs while trying to obtain the status
+     * of the rails.
+     *
+     * @param powerSupplyError Power supply error that occurred before the pgood
+     *                         fault.  Set to the empty string if no power
+     *                         supply error occurred.  This error may be the
+     *                         root cause if a pgood fault occurred on a power
+     *                         supply rail monitored by this device.
+     * @param error Error that should be logged if this method returns true.
+     * @param additionalData Additional data to include in the error log if
+     *                       this method returns true.
+     * @return true if a pgood fault was found on a rail monitored by this
+     *         device, false otherwise
+     */
+    virtual bool
+        hasPgoodFault(const std::string& powerSupplyError, std::string& error,
+                      std::map<std::string, std::string>& additionalData) = 0;
+};
+
+} // namespace phosphor::power::sequencer
diff --git a/phosphor-power-sequencer/test/mock_device.hpp b/phosphor-power-sequencer/test/mock_device.hpp
new file mode 100644
index 0000000..2d2e0ca
--- /dev/null
+++ b/phosphor-power-sequencer/test/mock_device.hpp
@@ -0,0 +1,54 @@
+/**
+ * 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 "power_sequencer_device.hpp"
+
+#include <gmock/gmock.h>
+
+namespace phosphor::power::sequencer
+{
+
+/**
+ * @class MockDevice
+ *
+ * Mock implementation of the PowerSequencerDevice interface.
+ */
+class MockDevice : public PowerSequencerDevice
+{
+  public:
+    // Specify which compiler-generated methods we want
+    MockDevice() = default;
+    MockDevice(const MockDevice&) = delete;
+    MockDevice(MockDevice&&) = delete;
+    MockDevice& operator=(const MockDevice&) = delete;
+    MockDevice& operator=(MockDevice&&) = delete;
+    virtual ~MockDevice() = default;
+
+    MOCK_METHOD(const std::string&, getName, (), (const, override));
+    MOCK_METHOD(std::vector<int>, getGPIOValues, (), (override));
+    MOCK_METHOD(uint16_t, getStatusWord, (uint8_t page), (override));
+    MOCK_METHOD(uint8_t, getStatusVout, (uint8_t page), (override));
+    MOCK_METHOD(double, getReadVout, (uint8_t page), (override));
+    MOCK_METHOD(double, getVoutUVFaultLimit, (uint8_t page), (override));
+    MOCK_METHOD(double, getVoutOVFaultLimit, (uint8_t page), (override));
+    MOCK_METHOD(bool, hasPgoodFault,
+                (const std::string& powerSupplyError, std::string& error,
+                 std::map<std::string, std::string>& additionalData),
+                (override));
+};
+
+} // namespace phosphor::power::sequencer