Add sysfs implementation

kernel/src/fs/sysfs/mod.rs

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MPL-2.0
+
+mod fs;
+mod inode;
+#[cfg(ktest)]
+mod test;
+
+use alloc::sync::Arc;
+
+use spin::Once;
+
+pub use self::{fs::SysFs, inode::SysFsInode};
+
+static SYSFS_SINGLETON: Once<Arc<SysFs>> = Once::new();
+
+/// Returns a reference to the global SysFs instance. Panics if not initialized.
+pub fn singleton() -> &'static Arc<SysFs> {
+    SYSFS_SINGLETON.get().expect("SysFs not initialized")
+}
+
+/// Initializes the SysFs singleton.
+/// Ensures that the singleton is created by calling it.
+/// Should be called during kernel filesystem initialization, *after* systree::init().
+pub fn init() {
+    // Ensure systree is initialized first. This should be handled by the kernel's init order.
+    SYSFS_SINGLETON.call_once(|| SysFs::new());
+}