dt: add /model and /compatible to sysfs

kernel/lib/device-tree/src/util.rs

@@ -1,10 +1,11 @@
 //! Utility functions for device tree handling
+use alloc::string::String;
 use fdt_rs::index::iters::DevTreeIndexNodeSiblingIter;
 use libk::{
     error::Error,
     fs::sysfs::{
         self,
-        attribute::{BytesAttribute, BytesAttributeOps},
+        attribute::{BytesAttribute, BytesAttributeOps, StringAttribute, StringAttributeOps},
         object::KObject,
     },
 };
@@ -56,6 +57,13 @@ impl Iterator for DeviceTreeMemoryRegionIter<'_> {
 /// Registers sysfs objects related to the device tree
 pub fn create_sysfs_nodes(dt: &'static DeviceTree) {
     struct Raw;
+    struct Compatible;
+    struct Model;
+
+    struct MachineNodeInfo {
+        compatible: Option<&'static str>,
+        model: Option<&'static str>,
+    }
 
     impl BytesAttributeOps for Raw {
         type Data = &'static DeviceTree<'static>;
@@ -76,11 +84,41 @@ pub fn create_sysfs_nodes(dt: &'static DeviceTree) {
         }
     }
 
+    impl StringAttributeOps for Compatible {
+        type Data = MachineNodeInfo;
+        const NAME: &'static str = "compatible";
+
+        fn read(state: &Self::Data) -> Result<String, Error> {
+            Ok(state.compatible.unwrap_or("").into())
+        }
+    }
+
+    impl StringAttributeOps for Model {
+        type Data = MachineNodeInfo;
+        const NAME: &'static str = "model";
+
+        fn read(state: &Self::Data) -> Result<String, Error> {
+            Ok(state.model.unwrap_or("").into())
+        }
+    }
+
     if let Some(device) = sysfs::device() {
         let object = KObject::new(dt);
 
         object.add_attribute(BytesAttribute::from(Raw)).ok();
 
+        let compatible = dt.root().prop_string("compatible");
+        let model = dt.root().prop_string("model");
+
+        let machine = KObject::new(MachineNodeInfo { compatible, model });
+
+        machine
+            .add_attribute(StringAttribute::from(Compatible))
+            .ok();
+        machine.add_attribute(StringAttribute::from(Model)).ok();
+
+        object.add_object("machine", machine).ok();
+
         device.add_object("device-tree", object).ok();
     }
 }