Implement storedevs, prepare to port littlefs

kernel/storedev/storedev.h

@@ -0,0 +1,44 @@
+#ifndef STOREDEV_STOREDEV_H_
+#define STOREDEV_STOREDEV_H_
+
+#include <stdint.h>
+#include <stddef.h>
+#include "spinlock/spinlock.h"
+#include "ramsd.h"
+
+enum {
+  STOREDEV_RAMSD,
+};
+
+static const char *storedev_strings[] = {
+  "RAMSD",
+};
+
+typedef struct StoreDev {
+  struct StoreDev *next;
+  int32_t sdtype;
+
+  int32_t (*init)(struct StoreDev *sd, void *extra);
+  int32_t (*read)(struct StoreDev *sd, uint8_t *const buffer, size_t n, size_t off);
+  int32_t (*write)(struct StoreDev *sd, const uint8_t *const buffer, size_t n, size_t off);
+  int32_t (*cleanup)(struct StoreDev *sd);
+
+  union {
+    RamSd ramsd;
+  } sd;
+  SpinLock spinlock;
+} StoreDev;
+
+typedef struct {
+  StoreDev *head;
+  SpinLock spinlock;
+} StoreDevList;
+
+extern StoreDevList STOREDEV_LIST;
+
+void storedev_init(void);
+
+StoreDev *storedev_create(int32_t sdtype, void *extra);
+int32_t storedev_delete(StoreDev *sd);
+
+#endif // STOREDEV_STOREDEV_H_