IOS LLE: emulate SD CMD6 and document Wii conformance run

Source/Core/Core/IOS/Starlet/StarletMemory.cpp

@@ -274,6 +274,7 @@ constexpr u16 SDHC_ERROR_DATA_TIMEOUT = 1U << 4;
 constexpr u32 SD_CARD_GO_IDLE = 0;
 constexpr u32 SD_CARD_ALL_SEND_CID = 2;
 constexpr u32 SD_CARD_SEND_RELATIVE_ADDRESS = 3;
+constexpr u32 SD_CARD_SWITCH_FUNCTION = 6;
 constexpr u32 SD_CARD_SELECT = 7;
 constexpr u32 SD_CARD_SEND_IF_CONDITION = 8;
 constexpr u32 SD_CARD_SEND_CSD = 9;
@@ -608,6 +609,7 @@ void StarletMemory::InitSDCard()
   m_sd_card.Close();
   m_sd_card_inserted = false;
   m_sd_card_high_capacity = false;
+  m_sd_high_speed = false;
   m_sd_block_length = 512;
   if (!Config::Get(Config::MAIN_WII_SD_CARD))
     return;
@@ -673,6 +675,7 @@ void StarletMemory::Reset()
   m_seeprom_write_all = false;
   m_sd_app_command = false;
   m_sd_card_selected = false;
+  m_sd_high_speed = false;
   m_sd_block_length = 512;
   m_sdhc_status_before_write = 0;
   m_wifi_sdio_status_before_write = 0;
@@ -748,6 +751,7 @@ void StarletMemory::DoState(PointerWrap& p)
   p.Do(m_sd_card_high_capacity);
   p.Do(m_sd_app_command);
   p.Do(m_sd_card_selected);
+  p.Do(m_sd_high_speed);
   p.Do(m_sd_block_length);
   p.Do(m_sdhc_status_before_write);
   p.Do(m_wifi_sdio_status_before_write);
@@ -3204,8 +3208,49 @@ void StarletMemory::ExecuteSDHCCommand(u32 command_and_mode)
     {
     case SD_CARD_GO_IDLE:
       m_sd_card_selected = false;
+      m_sd_high_speed = false;
       m_sd_block_length = 512;
       break;
+    case SD_CARD_SWITCH_FUNCTION:
+    {
+      // CMD6 returns a 512-bit status block, distinct from ACMD6 (bus width).
+      // Offer default and high-speed access modes in function group 1. The
+      // other groups have only their mandatory default and no-change functions.
+      if (!data_command || (transfer_mode & SDHC_TRANSFER_DMA_ENABLE) == 0 || block_size < 64)
+      {
+        succeeded = false;
+        break;
+      }
+
+      std::array<u8, 64> status{};
+      status[1] = 64;  // Maximum current consumption: 64 mA.
+      bool function_error = false;
+      for (u32 group = 0; group < 6; ++group)
+      {
+        const u16 supported = group == 0 ? 0x8003 : 0x8001;
+        status[2 + (5 - group) * 2] = static_cast<u8>(supported >> 8);
+        status[3 + (5 - group) * 2] = static_cast<u8>(supported);
+
+        const u32 requested = (argument >> (group * 4)) & 0xf;
+        u8 selected = group == 0 && m_sd_high_speed ? 1 : 0;
+        if (requested != 0xf)
+          selected = requested == 0 || (group == 0 && requested == 1) ?
+                         static_cast<u8>(requested) :
+                         0xf;
+        function_error |= selected == 0xf;
+        const u32 status_byte = 16 - group / 2;
+        status[status_byte] |= static_cast<u8>(selected << ((group & 1) * 4));
+      }
+      status[17] = 1;  // Busy-status fields are defined and all functions are ready.
+      for (u32 i = 0; i < status.size(); ++i)
+        WriteDMA8(dma_address + i, status[i]);
+      WriteRegister(SDHC_DMA_ADDRESS, dma_address + static_cast<u32>(status.size()));
+      WriteRegister(SDHC_RESPONSE, 0x900);
+      transfer_complete = true;
+      if ((argument & 0x80000000) != 0 && !function_error && (argument & 0xf) <= 1)
+        m_sd_high_speed = (argument & 0xf) == 1;
+      break;
+    }
     case SD_CARD_ALL_SEND_CID:
     case SD_CARD_SEND_CID:
     {

Source/Core/Core/IOS/Starlet/StarletMemory.h

@@ -250,6 +250,7 @@ private:
   bool m_sd_card_high_capacity = false;
   bool m_sd_app_command = false;
   bool m_sd_card_selected = false;
+  bool m_sd_high_speed = false;
   u32 m_sd_block_length = 512;
   u32 m_sdhc_status_before_write = 0;
   u32 m_wifi_sdio_status_before_write = 0;