kernel: fs: Add devfs

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

1 files changed, 208 insertions, 0 deletions

diff --git a/sys/fs/devfs.c b/sys/fs/devfs.c
new file mode 100644
index 0000000..0438b14
--- /dev/null
+++ b/sys/fs/devfs.c
@@ -0,0 +1,208 @@
+/*
+ * 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 <fs/devfs.h>
+#include <sys/vfs.h>
+#include <sys/mount.h>
+#include <sys/spinlock.h>
+#include <sys/queue.h>
+#include <sys/vnode.h>
+#include <sys/errno.h>
+#include <sys/cdefs.h>
+#include <vm/dynalloc.h>
+#include <string.h>
+
+struct device_node {
+    struct spinlock lock;
+    char *name;
+    uint8_t is_block : 1;
+    dev_t major, minor;
+    TAILQ_ENTRY(device_node) link;
+};
+
+static TAILQ_HEAD(, device_node) nodes;
+static bool nodelist_init = false;
+
+static struct device_node *
+node_from_name(const char *name)
+{
+    struct device_node *n;
+
+    TAILQ_FOREACH(n, &nodes, link) {
+        if (strcmp(n->name, name) == 0) {
+            return n;
+        }
+    }
+
+    return NULL;
+}
+
+static int
+blkdev_read(struct device *dev, struct device_node *node, struct sio_txn *sio)
+{
+    char *buf;
+    struct sio_txn dev_txn = {0};
+    size_t buf_size = dev->blocksize * sio->len;
+
+    if (dev->blocksize == 0 || sio->len == 0) {
+        /* Sizes can't be zero! */
+        return -EIO;
+    }
+
+    spinlock_acquire(&node->lock);
+    buf = dynalloc_memalign(buf_size, 0x1000);
+    if (buf == NULL) {
+        spinlock_release(&node->lock);
+        return -ENOMEM;
+    }
+
+    dev_txn.len = __DIV_ROUNDUP(sio->len, 512);
+    dev_txn.buf = buf;
+    dev_txn.offset = sio->offset;
+    dev->read(dev, &dev_txn);
+    spinlock_release(&node->lock);
+
+    for (size_t i = 0; i < sio->len; ++i) {
+        ((uint8_t *)sio->buf)[i] = buf[i];
+    }
+
+    dynfree(buf);
+    return sio->len;
+}
+
+
+static int
+vop_vget(struct vnode *parent, const char *name, struct vnode **vp)
+{
+    struct device_node *dev;
+    struct vnode *vnode;
+    int status, vtype;
+
+    if (!nodelist_init) {
+        return -EIO;
+    }
+
+    if ((dev = node_from_name(name)) == NULL) {
+        return -ENOENT;
+    }
+
+    vtype = dev->is_block ? VBLK : VCHR;
+    if ((status = vfs_alloc_vnode(&vnode, NULL, vtype)) != 0) {
+        return status;
+    }
+
+    vnode->parent = parent;
+    vnode->data = dev;
+    vnode->vops = &g_devfs_vops;
+    *vp = vnode;
+    return 0;
+}
+
+static int
+vop_read(struct vnode *vp, struct sio_txn *sio)
+{
+    struct device_node *node;
+    struct device *dev;
+
+    if (vp == NULL) {
+        return -EIO;
+    }
+
+    node = vp->data;
+    dev = device_fetch(node->major, node->minor);
+    return blkdev_read(dev, node, sio);
+}
+
+static int
+devfs_init(struct fs_info *info)
+{
+    TAILQ_INIT(&nodes);
+    nodelist_init = true;
+    return 0;
+}
+
+static int
+devfs_make_devicenode(const char *name, struct device_node **node_out)
+{
+    size_t name_len = 0;
+    const char *p = name;
+    struct device_node *node;
+
+    /*
+     * Only one filename, no paths.
+     *
+     * TODO: Do something better here... */
+    for (; *p; ++p, ++name_len) {
+        if (*p == '/')
+            return -EINVAL;
+    }
+
+    /* Ensure this filename has valid chars */
+    if (!vfs_is_valid_path(name)) {
+        return -EINVAL;
+    }
+
+    node = dynalloc(sizeof(struct device_node));
+    if (node == NULL)
+        return -ENOMEM;
+
+    node->name = dynalloc(sizeof(char) * name_len);
+    if (node->name == NULL)
+        return -ENOMEM;
+
+    memcpy(node->name, name, name_len + 1);
+    *node_out = node;
+    return 0;
+}
+
+int
+devfs_add_blkdev(const char *name, const struct device *blkdev)
+{
+    struct device_node *node;
+    int status;
+
+    if ((status = devfs_make_devicenode(name, &node)) != 0) {
+        return status;
+    }
+
+    node->major = blkdev->major;
+    node->minor = blkdev->minor;
+    node->is_block = 1;
+    TAILQ_INSERT_HEAD(&nodes, node, link);
+    return 0;
+}
+
+struct vfsops g_devfs_ops = {
+    .init = devfs_init
+};
+
+struct vops g_devfs_vops = {
+    .vget = vop_vget,
+    .read = vop_read
+};