kern: Add initial DMS framework

DMS stands for Disk Management and Supervision, drivers can register
themselves to DMS so that they can be looked up and operated on.

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

1 files changed, 138 insertions, 0 deletions

diff --git a/src/sys/dms/dms_subr.c b/src/sys/dms/dms_subr.c
new file mode 100644
index 0000000..240449a
--- /dev/null
+++ b/src/sys/dms/dms_subr.c
@@ -0,0 +1,138 @@
+/*
+ * 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.
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/queue.h>
+#include <os/kalloc.h>
+#include <dms/dms.h>
+#include <string.h>
+#include <stdbool.h>
+
+static TAILQ_HEAD(, dms_disk) diskq;
+static bool diskq_is_init = false;
+static disk_id_t next_id = 0;
+
+int
+dms_register(const char *name, struct dms_ops *ops, struct dms_disk **res)
+{
+    struct dms_disk *dp;
+    size_t name_len;
+
+    if (name == NULL || ops == NULL) {
+        return -EINVAL;
+    }
+
+    if (!diskq_is_init) {
+        TAILQ_INIT(&diskq);
+        diskq_is_init = true;
+    }
+
+    dp = kalloc(sizeof(*dp));
+    if (dp == NULL) {
+        return -ENOMEM;
+    }
+
+    name_len = strlen(name);
+    if (name_len >= DISKNAME_MAX - 1) {
+        kfree(dp);
+        return -ENAMETOOLONG;
+    }
+
+    /* Copy the name and set the ID */
+    memcpy(dp->name, name, name_len + 1);
+    dp->id = next_id++;
+    dp->ops = ops;
+    TAILQ_INSERT_TAIL(&diskq, dp, link);
+
+    if (res != NULL) {
+        *res = dp;
+    }
+    return 0;
+}
+
+struct dms_disk *
+dms_get(disk_id_t disk_id)
+{
+    struct dms_disk *dp = NULL;
+    struct dms_disk *dp_cur;
+
+    TAILQ_FOREACH(dp_cur, &diskq, link) {
+        if (dp_cur == NULL) {
+            continue;
+        }
+
+        if (dp_cur->id == disk_id) {
+            dp = dp_cur;
+            break;
+        }
+    }
+
+    return dp_cur;
+}
+
+ssize_t
+dms_write(struct dms_disk *dp, void *p, off_t off, size_t len)
+{
+    struct dms_ops *ops;
+
+    if (dp == NULL || p == NULL) {
+        return -EINVAL;
+    }
+
+    if ((ops = dp->ops) == NULL) {
+        return -EIO;
+    }
+
+    if (ops->write == NULL) {
+        return -ENOTSUP;
+    }
+
+    return ops->write(dp, p, off, len);
+}
+
+ssize_t
+dms_read(struct dms_disk *dp, void *p, off_t off, size_t len)
+{
+    struct dms_ops *ops;
+
+    if (dp == NULL || p == NULL) {
+        return -EINVAL;
+    }
+
+    if ((ops = dp->ops) == NULL) {
+        return -EIO;
+    }
+
+    if (ops->read == NULL) {
+        return -ENOTSUP;
+    }
+
+    return ops->read(dp, p, off, len);
+}