Integrate 5.x SMC API changes, add 4.x specific setup, implement target firmware selection

exosphere/src/exocfg.c

@@ -0,0 +1,37 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "utils.h"
+#include "exocfg.h"
+#include "mmu.h"
+#include "memory_map.h"
+
+#define MAILBOX_BASE  (MMIO_GET_DEVICE_ADDRESS(MMIO_DEVID_NXBOOTLOADER_MAILBOX))
+
+/* TODO: Should this be at a non-static location? */
+#define MAILBOX_EXOSPHERE_CONFIG (*((volatile exosphere_config_t *)(MAILBOX_BASE + 0xE40ULL)))
+
+static exosphere_config_t g_exosphere_cfg = {MAGIC_ATMOSPHERE, EXOSPHERE_TARGET_FIRMWARE_DEFAULT_FOR_DEBUG};
+static bool g_has_loaded_config = false;
+
+/* Read config out of IRAM, return target firmware version. */
+unsigned int exosphere_load_config(void) {
+    if (g_has_loaded_config) {
+        generic_panic();
+    }
+    g_has_loaded_config = true;
+    
+    if (MAILBOX_EXOSPHERE_CONFIG.magic == MAGIC_ATMOSPHERE) {
+        g_exosphere_cfg = MAILBOX_EXOSPHERE_CONFIG;
+    }
+    
+    return g_exosphere_cfg.target_firmware;
+}
+
+unsigned int exosphere_get_target_firmware(void) {
+    if (!g_has_loaded_config) {
+        generic_panic();
+    }
+    
+    return g_exosphere_cfg.target_firmware;
+}