imp: can properly find available and reserved memory in dtb

src/kernel/hal/mod.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <dtb>
 #include <io>
 
 void hal_setup(void);
@@ -8,3 +9,5 @@ void hal_putc(int ch);
 Writer hal_writer(void);
 
 void hal_brkpoint(void);
+
+DTBNode* hal_dtb_root(void);

src/kernel/hal/rv32/boot.c

@@ -6,29 +6,24 @@
 #include <string.h>
 
 #include "exception.h"
+#include "mem.h"
 
 extern char __bss[], __bss_end[];
 extern void kmain(void);
 
 static uint8_t early_heap[kib$(20)];
+static DTBNode* dtb_root = NULL;
 
 void rv32_start(__attribute__((unused)) size_t hartid, uintptr_t dtb) {
     write_csr$(stvec, (uint32_t)interrupt_kernel);
 
     BumpAllocator alloc = bump_allocator_create((void*)early_heap, sizeof(early_heap));
-    DTBNode* root       = dtb_init(dtb, &alloc.base);
-    DTBNode* mem        = dtb_lookup(root, "reserved-memory");
-
-    if (mem == NULL) {
-        error$("Failed to find reserved-memory node in device tree");
-        __asm__ volatile("ebreak");
-    }
-
-    DTBProp* prop = mem->props;
-    while (prop != NULL) {
-        debug$("prop: %s", prop->name);
-        prop = prop->next;
-    }
+    dtb_root            = dtb_init(dtb, &alloc.base);
 
+    mem_init();
     kmain();
 }
+
+DTBNode* hal_dtb_root(void) {
+    return dtb_root;
+}

src/kernel/hal/rv32/mem.c

@@ -0,0 +1,42 @@
+#include <hal>
+#include <helpers/mem.h>
+#include <logger>
+
+#include "mem.h"
+
+void mem_init(void) {
+    DTBNode* root = hal_dtb_root();
+    if (root == NULL) {
+        error$("No DTB found");
+        hal_brkpoint();
+    }
+
+    DTBNode* mem = dtb_lookup(root, "memory");
+    if (mem == NULL) {
+        error$("No memory node found in DTB");
+        hal_brkpoint();
+    }
+
+    RegValue reg_val = dtb_lookup_reg(mem);
+    if (reg_val.len == 0) {
+        warn$("Memory node size is larger than 4GB. Defaulting to 4GB");
+        reg_val.len = align_down$(gib$(4) - 1, 4096);
+    }
+
+    debug$("Memory node found at %x with size %x", reg_val.addr, reg_val.len);
+
+    DTBNode* reserved = dtb_lookup(root, "reserved-memory");
+    if (reserved == NULL) {
+        error$("No reserved memory node found in DTB");
+        hal_brkpoint();
+    }
+
+    DTBNode* child = reserved->children;
+
+    while (child != NULL) {
+        RegValue reg = dtb_lookup_reg(child);
+        debug$("Reserved memory node with name %s found at %x with size %x", child->name, reg.addr, reg.len);
+
+        child = child->next;
+    }
+}

src/kernel/hal/rv32/mem.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void mem_init(void);

src/libs/dtb/mod.c

@@ -1,7 +1,6 @@
 #include <helpers/endian.h>
 #include <helpers/mem.h>
 #include <logger>
-#include <stdlib.h>
 #include <string.h>
 
 #include "mod.h"
@@ -15,7 +14,7 @@ static uint32_t read_offset(uint8_t** offset) {
 static DTBNode* dtb_parse(FDTHeader* dtb_header, Allocator* alloc) {
     if (dtb_header == NULL) {
         error$("Device tree blob not initialized");
-        abort();
+        return NULL;
     }
 
     DTBNode* current_node = NULL;
@@ -36,13 +35,13 @@ static DTBNode* dtb_parse(FDTHeader* dtb_header, Allocator* alloc) {
             if (!root) {
                 if (*node_name) {
                     error$("Invalid device tree blob. Expected root node to be empty");
-                    abort();
+                    return NULL;
                 }
 
                 root = alloc->alloc(alloc, sizeof(DTBNode));
                 if (root == NULL) {
                     error$("Failed to allocate memory for device tree node");
-                    abort();
+                    return NULL;
                 }
 
                 memset(current_node, 0, sizeof(DTBNode));
@@ -55,7 +54,7 @@ static DTBNode* dtb_parse(FDTHeader* dtb_header, Allocator* alloc) {
             DTBNode* new_node = alloc->alloc(alloc, sizeof(DTBNode));
             if (new_node == NULL) {
                 error$("Failed to allocate memory for device tree node");
-                abort();
+                return NULL;
             }
 
             memset(new_node, 0, sizeof(DTBNode));
@@ -94,7 +93,7 @@ static DTBNode* dtb_parse(FDTHeader* dtb_header, Allocator* alloc) {
             DTBProp* prop = alloc->alloc(alloc, sizeof(DTBProp));
             if (prop == NULL) {
                 error$("Failed to allocate memory for device tree property");
-                abort();
+                return NULL;
             }
 
             char const* prop_name = strtab + nameoff;
@@ -128,7 +127,7 @@ static DTBNode* dtb_parse(FDTHeader* dtb_header, Allocator* alloc) {
 
         default: {
             error$("Unknown token %x", token);
-            abort();
+            return NULL;
         }
         }
     }
@@ -141,7 +140,7 @@ DTBNode* dtb_init(uintptr_t dtb, Allocator* alloc) {
 
     if (from_be32(dtb_header->magic) != DTB_MAGIC) {
         error$("Invalid device tree blob magic number. Excecting %x, got %x", DTB_MAGIC, from_be32(dtb_header->magic));
-        abort();
+        return NULL;
     }
 
     return dtb_parse(dtb_header, alloc);
@@ -174,3 +173,46 @@ DTBProp* dtb_lookup_prop(DTBNode* node, char const* name) {
 
     return NULL;
 }
+
+RegValue dtb_lookup_reg(DTBNode* node) {
+    RegValue reg = {0};
+
+    DTBProp* prop = dtb_lookup_prop(node, "reg");
+    if (prop == NULL) {
+        error$("Failed to find reg property in device tree node %s", node->name);
+        return reg;
+    }
+
+    uint8_t* offset = (uint8_t*)prop->value;
+
+    DTBProp* address_cells_prop = dtb_lookup_prop(node->parent, "#address-cells");
+    if (address_cells_prop == NULL) {
+        error$("Failed to find #address-cells property in device tree node %s", node->parent->name);
+        return reg;
+    }
+
+    DTBProp* size_cells_prop = dtb_lookup_prop(node->parent, "#size-cells");
+    if (size_cells_prop == NULL) {
+        error$("Failed to find #size-cells property in device tree node %s", node->parent->name);
+        return reg;
+    }
+
+    size_t address_cells = from_be32(*(uint32_t*)address_cells_prop->value);
+    size_t size_cells    = from_be32(*(uint32_t*)size_cells_prop->value);
+
+    uint64_t tmp_addr = 0;
+    uint64_t tmp_len  = 0;
+
+    for (size_t i = 0; i < address_cells; i++) {
+        tmp_addr = (tmp_addr << 32) | read_offset(&offset);
+    }
+
+    for (size_t i = 0; i < size_cells; i++) {
+        tmp_len = (tmp_len << 32) | read_offset(&offset);
+    }
+
+    reg.addr = tmp_addr;
+    reg.len  = tmp_len;
+
+    return reg;
+}

src/libs/dtb/mod.h

@@ -40,8 +40,15 @@ typedef struct _DTBNode {
     struct _DTBNode* parent;
 } DTBNode;
 
+typedef struct {
+    uintptr_t addr;
+    size_t len;
+} RegValue;
+
 DTBNode* dtb_init(uintptr_t dtb, Allocator* alloc);
 
 DTBNode* dtb_lookup(DTBNode* root, char const* name);
 
 DTBProp* dtb_lookup_prop(DTBNode* node, char const* name);
+
+RegValue dtb_lookup_reg(DTBNode* node);