kernel: Add support for devfs

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

1 files changed, 190 insertions, 0 deletions

diff --git a/sys/fs/devfs.c b/sys/fs/devfs.c
new file mode 100644
index 0000000..c1eb761
--- /dev/null
+++ b/sys/fs/devfs.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * 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 Hyra 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.
+ */
+
+#include <sys/types.h>
+#include <sys/vnode.h>
+#include <sys/errno.h>
+#include <sys/mount.h>
+#include <sys/device.h>
+#include <fs/devfs.h>
+#include <vm/dynalloc.h>
+#include <string.h>
+
+struct devfs_node {
+    const char *name;
+    uint8_t is_block : 1;
+    mode_t mode;
+    devmajor_t major;
+    dev_t dev;
+    TAILQ_ENTRY(devfs_node) link;
+};
+
+static TAILQ_HEAD(, devfs_node) devlist;
+
+static inline int
+cdevsw_read(void *devsw, dev_t dev, struct sio_txn *sio)
+{
+    struct cdevsw *cdevsw = devsw;
+
+    return cdevsw->read(dev, sio, 0);
+}
+
+/*
+ * Get a devfs node by name.
+ *
+ * @name: Name to lookup.
+ */
+static struct devfs_node *
+devfs_get_node(const char *name)
+{
+    struct devfs_node *dnp;
+
+    TAILQ_FOREACH(dnp, &devlist, link) {
+        if (strcmp(dnp->name, name) == 0) {
+            return dnp;
+        }
+    }
+
+    return NULL;
+}
+
+static int
+devfs_lookup(struct vop_lookup_args *args)
+{
+    int vtype, error;
+    const char *name = args->name;
+    struct devfs_node *dnp;
+    struct vnode *vp;
+
+    if (*name == '/')
+        ++name;
+
+    /* Make sure it isn't a path */
+    for (const char *p = name; *p != '\0'; ++p) {
+        if (*p == '/') {
+            return -ENOENT;
+        }
+    }
+
+    if ((dnp = devfs_get_node(name)) == NULL)
+        return -ENOENT;
+
+    /* Now, create a vnode */
+    vtype = (dnp->is_block) ? VBLK : VCHR;
+    if ((error = vfs_alloc_vnode(&vp, vtype)) != 0)
+        return error;
+
+    vp->data = dnp;
+    vp->vops = &g_devfs_vops;
+    *args->vpp = vp;
+    return 0;
+}
+
+static int
+devfs_reclaim(struct vnode *vp)
+{
+    if (vp->data != NULL)
+        dynfree(vp->data);
+
+    vp->data = NULL;
+    return 0;
+}
+
+static int
+devfs_read(struct vnode *vp, struct sio_txn *sio)
+{
+    struct devfs_node *dnp;
+    void *devsw;
+
+    if ((dnp = vp->data) == NULL)
+        return -EIO;
+
+    devsw = dev_get(dnp->major, dnp->dev);
+
+    if (!dnp->is_block)
+        return cdevsw_read(devsw, dnp->dev, sio);
+
+    /* TODO: Block devices */
+    return -EIO;
+}
+
+static int
+devfs_init(struct fs_info *fip)
+{
+    struct vnode *vp;
+    struct mount *mp;
+    int error;
+
+    /* Create a new vnode for devfs */
+    if ((error = vfs_alloc_vnode(&vp, VDIR)) != 0)
+        return error;
+
+    vp->vops = &g_devfs_vops;
+    TAILQ_INIT(&devlist);
+    mp = vfs_alloc_mount(vp, fip);
+
+    vfs_name_mount(mp, "dev");
+    TAILQ_INSERT_TAIL(&g_mountlist, mp, mnt_list);
+    return 0;
+}
+
+/*
+ * Create an entry within devfs.
+ *
+ * @name: Device name.
+ * @major: Device major.
+ * @dev: Device minor.
+ * @mode: Permissions mask
+ */
+int
+devfs_create_entry(const char *name, devmajor_t major, dev_t dev, mode_t mode)
+{
+    struct devfs_node *dnp;
+
+    dnp = dynalloc(sizeof(*dnp));
+    if (dnp == NULL)
+        return -ENOMEM;
+
+    dnp->name = name;
+    dnp->major = major;
+    dnp->dev = dev;
+    dnp->mode = mode;
+    TAILQ_INSERT_TAIL(&devlist, dnp, link);
+    return 0;
+}
+
+const struct vops g_devfs_vops = {
+    .lookup = devfs_lookup,
+    .reclaim = devfs_reclaim,
+    .read = devfs_read
+};
+
+const struct vfsops g_devfs_vfsops = {
+    .init = devfs_init
+};