feat: vmm_vmap/ioremap/iounmap to make MMIO more flexible and easy

[lunaix-os.git] / lunaix-os / kernel / mm / vmap.c

diff --git a/lunaix-os/kernel/mm/vmap.c b/lunaix-os/kernel/mm/vmap.c
new file mode 100644 (file)
index 0000000..0c10610
--- /dev/null
+++ b/lunaix-os/kernel/mm/vmap.c
@@ -0,0 +1,64 @@
+#include <lunaix/mm/pmm.h>
+#include <lunaix/mm/vmm.h>
+#include <lunaix/spike.h>
+
+#define VMAP_START PG_MOUNT_BASE + MEM_4MB
+#define VMAP_END PD_REFERENCED
+
+static uintptr_t start = VMAP_START;
+
+void*
+vmm_vmap(uintptr_t paddr, size_t size, pt_attr attr, pp_attr_t pattr)
+{
+    // next fit
+    assert_msg((paddr & 0xfff) == 0, "vmap: bad alignment");
+    size = ROUNDUP(size, PG_SIZE);
+
+    uintptr_t current_addr = start;
+    size_t examed_size = 0, wrapped = 0;
+    x86_page_table* pd = (x86_page_table*)L1_BASE_VADDR;
+
+    while (!wrapped || current_addr >= start) {
+        size_t l1inx = L1_INDEX(current_addr);
+        if (!(pd->entry[l1inx])) {
+            // empty 4mb region
+            examed_size += MEM_4MB;
+            current_addr = (current_addr & 0xffc00000) + MEM_4MB;
+        } else {
+            x86_page_table* ptd = (x86_page_table*)(L2_VADDR(l1inx));
+            size_t i = L2_INDEX(current_addr);
+            for (; i < 1024 && examed_size < size; i++) {
+                if (!ptd->entry[i]) {
+                    examed_size += PG_SIZE;
+                } else if (examed_size) {
+                    // found a discontinuity, start from beginning
+                    examed_size = 0;
+                    i++;
+                    break;
+                }
+            }
+            current_addr += i << 12;
+        }
+
+        if (examed_size >= size) {
+            goto done;
+        }
+
+        if (current_addr >= VMAP_END) {
+            wrapped = 1;
+            current_addr = VMAP_START;
+        }
+    }
+    panick("vmm: out of memory");
+
+done:
+    uintptr_t alloc_begin = current_addr - examed_size;
+    for (size_t i = 0; i < size; i += PG_SIZE) {
+        vmm_set_mapping(
+          PD_REFERENCED, alloc_begin + i, paddr + i, PG_PREM_RW, 0);
+        pmm_ref_page(KERNEL_PID, paddr + i);
+    }
+    start = alloc_begin + size;
+
+    return (void*)alloc_begin;
+}
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