From 5c15e93fa87800b1f8fae7ef688a9d41221526f1 Mon Sep 17 00:00:00 2001
From: Nathan Lee <me@nwlee.tech>
Date: Fri, 19 Jun 2026 19:05:01 -0500
Subject: create dtb allocator

the parent commit (b106df2447d23d6b3fcffa7cc87edde218d054f3) discussed
the possibility of creating dtb device discovery. for that, we have
replaced wdt device discovery with dtb device discovery. in the future,
we will use the pci kernel module to use device discovery via a PCI
controller
---
 kernel/dtb.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 kernel/dtb.c

(limited to 'kernel/dtb.c')

diff --git a/kernel/dtb.c b/kernel/dtb.c
new file mode 100644
index 0000000..99b1679
--- /dev/null
+++ b/kernel/dtb.c
@@ -0,0 +1,86 @@
+
+#include <dtb.h>
+#include <bump.h>
+#include <common.h>
+
+struct dt_node *dt_parse(void *fdt) {
+    struct fdt_header *hdr = fdt;
+
+    if (hdr->magic != FDT_MAGIC) {
+        return NULL;
+    }
+
+    uint32_t *p = (uint32_t *)(fdt + be32_to_cpu(hdr->off_dt_struct));
+    char *strings = fdt + be32_to_cpu(hdr->off_dt_strings);
+
+    struct dt_node *root = NULL;
+    struct dt_node *stack[DTB_MAX_NODES];
+    int sp = 0;
+
+    while (1) {
+        uint32_t token = be32_to_cpu(*p++);
+        switch (token) {
+            case FDT_BEGIN_NODE: {
+                char *name = (char *)p;
+                p += (strlen(name) + 3) / 4;
+
+                struct dt_node *node = dt_node_alloc(name);
+                if (sp == 0) {
+                    root = node;
+                } else {
+                    node->next = stack[sp-1]->children;
+                    stack[sp-1]->children = node;
+                }
+                stack[sp++] = node;
+                break;
+            }
+            case FDT_PROP: {
+                uint32_t len = be32_to_cpu(*p++);
+                uint32_t nameoff = be32_to_cpu(*p++);
+                void *value = p;
+                p += (len + 3) / 4;
+
+                struct dt_prop *prop = dt_prop_alloc(strings + nameoff, value, len);
+                prop->next = stack[sp-1]->props;
+                stack[sp-1]->props = prop;
+                break;
+            }
+            case FDT_END_NODE: 
+                sp--;
+                break;
+            case FDT_END:
+                return root;
+        }
+    }
+}
+
+void *dt_get_prop(struct dt_node *node, char *name, size_t *len)  {
+    for (struct dt_prop *p = node->props; p; p = p->next) {
+        if (strcmp(p->name, name) == 0) {
+            if (len) *len = p->len;
+            return p->value;
+        }
+    }
+    return NULL;
+}
+
+struct dt_node *dt_node_alloc(char *name) {
+    struct dt_node *node = kemalloc(sizeof(struct dt_node));
+    node->name = name;
+    node->props = NULL;
+    node->children = NULL;
+    node->next = NULL;
+    return node;
+}
+
+struct dt_prop *dt_prop_alloc(char *name, void *value, size_t len) {
+    struct dt_prop *prop = kemalloc(sizeof(struct dt_prop));
+    prop->name = name;
+    prop->value = value;
+    prop->len = len;
+    prop->next = NULL;
+
+    return prop;
+}
+
+
-- 
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