git subrepo clone https://github.com/Atmosphere-NX/libstratosphere stratosphere/libstratosphere

subrepo:
  subdir:   "stratosphere/libstratosphere"
  merged:   "0c5dab80"
upstream:
  origin:   "https://github.com/Atmosphere-NX/libstratosphere"
  branch:   "master"
  commit:   "0c5dab80"
git-subrepo:
  version:  "0.4.0"
  origin:   "https://github.com/ingydotnet/git-subrepo"
  commit:   "5d6aba9"

stratosphere/libstratosphere/source/cfg/cfg_sd_card.cpp

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2018-2019 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <switch.h>
+#include <stratosphere.hpp>
+#include <stratosphere/cfg.hpp>
+#include <stratosphere/sm.hpp>
+
+namespace sts::cfg {
+
+    namespace {
+
+        /* Convenience definitions. */
+        constexpr sm::ServiceName RequiredServicesForSdCardAccess[] = {
+            sm::ServiceName::Encode("pcv"),
+            sm::ServiceName::Encode("gpio"),
+            sm::ServiceName::Encode("pinmux"),
+            sm::ServiceName::Encode("psc:c")
+        };
+        constexpr size_t NumRequiredServicesForSdCardAccess = util::size(RequiredServicesForSdCardAccess);
+
+        /* SD card globals. */
+        HosMutex g_sd_card_lock;
+        bool g_sd_card_initialized = false;
+        FsFileSystem g_sd_card_filesystem = {};
+
+        /* SD card helpers. */
+        Result TryInitializeSdCard() {
+            for (size_t i = 0; i < NumRequiredServicesForSdCardAccess; i++) {
+                bool service_present = false;
+                R_TRY(sm::HasService(&service_present, RequiredServicesForSdCardAccess[i]));
+                if (!service_present) {
+                    return ResultFsSdCardNotPresent;
+                }
+            }
+            R_ASSERT(fsMountSdcard(&g_sd_card_filesystem));
+            g_sd_card_initialized = true;
+            return ResultSuccess;
+        }
+
+        void InitializeSdCard() {
+            for (size_t i = 0; i < NumRequiredServicesForSdCardAccess; i++) {
+                R_ASSERT(sm::WaitService(RequiredServicesForSdCardAccess[i]));
+            }
+            R_ASSERT(fsMountSdcard(&g_sd_card_filesystem));
+            g_sd_card_initialized = true;
+        }
+
+    }
+
+    /* SD card utilities. */
+    bool IsSdCardInitialized() {
+        std::scoped_lock<HosMutex> lk(g_sd_card_lock);
+
+        if (!g_sd_card_initialized) {
+            if (R_SUCCEEDED(TryInitializeSdCard())) {
+                g_sd_card_initialized = true;
+            }
+        }
+        return g_sd_card_initialized;
+    }
+
+    void WaitSdCardInitialized() {
+        std::scoped_lock<HosMutex> lk(g_sd_card_lock);
+
+        InitializeSdCard();
+    }
+
+}