kern: fs: Add initial devfs implementation

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 166 insertions, 0 deletions

diff --git a/src/sys/fs/devfs.c b/src/sys/fs/devfs.c
new file mode 100644
index 0000000..7553003
--- /dev/null
+++ b/src/sys/fs/devfs.c
@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Description: Device filesystem
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/errno.h>
+#include <sys/mount.h>
+#include <sys/syslog.h>
+#include <os/vnode.h>
+#include <os/kalloc.h>
+#include <fs/devfs.h>
+#include <string.h>
+
+static struct vop devfs_vops;
+static TAILQ_HEAD(, devfs_node) nodelist;
+
+/*
+ * Find a node within the device filesystem
+ */
+static int
+devfs_lookup(struct vop_lookup_args *args)
+{
+    int error;
+    struct devfs_node *dnp = NULL;
+    struct vnode *vp;
+
+    if (args == NULL) {
+        return -EINVAL;
+    }
+
+    /* Need a pointer to write the result */
+    if (args->vpp == NULL) {
+        return -EINVAL;
+    }
+
+    TAILQ_FOREACH(dnp, &nodelist, link) {
+        if (dnp == NULL) {
+            continue;
+        }
+
+        if (strcmp(dnp->name, args->name) != 0) {
+            continue;
+        }
+
+        /* Found it! Create a vnode */
+        error = vfs_valloc(&vp, VTYPE_FILE, 0);
+        if (error < 0) {
+            return error;
+        }
+
+        vp->data = dnp;
+        *args->vpp = vp;
+        return 0;
+    }
+
+    return -ENOENT;
+}
+
+/*
+ * Register a new device to devfs
+ */
+int
+devfs_register(const char *name, dev_type_t type, void *devsw, int flags)
+{
+    struct devfs_node *dnp;
+    size_t devname_len;
+    struct vop_lookup_args args;
+    struct vnode *vp;
+
+    if (name == NULL || devsw == NULL) {
+        return -EINVAL;
+    }
+
+    if (type >= __DEVFS_NTYPE) {
+        return -EINVAL;
+    }
+
+    dnp = kalloc(sizeof(*dnp));
+    if (dnp == NULL) {
+        return -ENOMEM;
+    }
+
+    switch (type) {
+    case DEVFS_NONE:
+    case DEVFS_CDEV:
+        dnp->type = type;
+        break;
+    }
+
+    devname_len = strlen(name);
+    memcpy(dnp->name, name, devname_len);
+    TAILQ_INSERT_TAIL(&nodelist, dnp, link);
+    return 0;
+}
+
+/*
+ * Initialize the device filesystem
+ */
+static int
+devfs_init(struct fs_info *fip)
+{
+    (void)fip;
+    TAILQ_INIT(&nodelist);
+    return 0;
+}
+
+/*
+ * Mount the device filesystem
+ */
+static int
+devfs_mount(struct fs_info *fip, struct mount_args *margs)
+{
+    int error;
+    struct vnode *vp;
+
+    if (fip == NULL || margs == NULL) {
+        return -1;
+    }
+
+    error = vfs_valloc(&margs->vp_res, VTYPE_DIR, 0);
+    if (error < 0) {
+        return error;
+    }
+
+    vp = margs->vp_res;
+    vp->vops = &devfs_vops;
+    return 0;
+}
+
+static struct vop devfs_vops = {
+    .lookup = devfs_lookup
+};
+
+struct vfsops g_devfs_vfops = {
+    .init = devfs_init,
+    .mount = devfs_mount
+};