Add sensor value mutability interface

This adds and documents the new sensor value mutability interface. IPMI
will check the mutability interface before overriding a sensor value.

Signed-off-by: Josh Lehan <krellan@google.com>
Change-Id: I4e90800a79469a87ef63f7395dbfc402976c73aa
Signed-off-by: Jie Yang <jjy@google.com>
diff --git a/gen/xyz/openbmc_project/Sensor/ValueMutability/meson.build b/gen/xyz/openbmc_project/Sensor/ValueMutability/meson.build
new file mode 100644
index 0000000..88c4d98
--- /dev/null
+++ b/gen/xyz/openbmc_project/Sensor/ValueMutability/meson.build
@@ -0,0 +1,14 @@
+# Generated file; do not modify.
+generated_sources += custom_target(
+    'xyz/openbmc_project/Sensor/ValueMutability__cpp'.underscorify(),
+    input: [ '../../../../../yaml/xyz/openbmc_project/Sensor/ValueMutability.interface.yaml',  ],
+    output: [ 'server.cpp', 'server.hpp', 'client.hpp',  ],
+    command: [
+        sdbuspp_gen_meson_prog, '--command', 'cpp',
+        '--output', meson.current_build_dir(),
+        '--tool', sdbusplusplus_prog,
+        '--directory', meson.current_source_dir() / '../../../../../yaml',
+        'xyz/openbmc_project/Sensor/ValueMutability',
+    ],
+)
+
diff --git a/gen/xyz/openbmc_project/Sensor/meson.build b/gen/xyz/openbmc_project/Sensor/meson.build
index 4e899bd..9e018b3 100644
--- a/gen/xyz/openbmc_project/Sensor/meson.build
+++ b/gen/xyz/openbmc_project/Sensor/meson.build
@@ -41,3 +41,17 @@
     ],
 )
 
+subdir('ValueMutability')
+generated_others += custom_target(
+    'xyz/openbmc_project/Sensor/ValueMutability__markdown'.underscorify(),
+    input: [ '../../../../yaml/xyz/openbmc_project/Sensor/ValueMutability.interface.yaml',  ],
+    output: [ 'ValueMutability.md' ],
+    command: [
+        sdbuspp_gen_meson_prog, '--command', 'markdown',
+        '--output', meson.current_build_dir(),
+        '--tool', sdbusplusplus_prog,
+        '--directory', meson.current_source_dir() / '../../../../yaml',
+        'xyz/openbmc_project/Sensor/ValueMutability',
+    ],
+)
+
diff --git a/yaml/xyz/openbmc_project/Sensor/ValueMutability.interface.yaml b/yaml/xyz/openbmc_project/Sensor/ValueMutability.interface.yaml
new file mode 100644
index 0000000..0ed8fe0
--- /dev/null
+++ b/yaml/xyz/openbmc_project/Sensor/ValueMutability.interface.yaml
@@ -0,0 +1,14 @@
+description: >
+    Implement to provide sensor value mutability.
+properties:
+    - name: Mutable
+      type: boolean
+      default: false
+      description: >
+          A hint to a server that provides sensor access
+          to external users, such as an IPMI server,
+          as to whether or not to allow external users
+          to modify the value, via "set sensor value"
+          commands or similar. True to allow
+          modification (read-write). False to disallow
+          modification (read-only).