Add MMC/SecureDigital device support. Not yet used because of

a bad implementation of SEND_CSD and SEND_CID commands (TODO).

DiscImageChef.Devices/Linux/Structs.cs

@@ -65,5 +65,62 @@ namespace DiscImageChef.Devices.Linux
         public uint duration;      /* [o] */
         public SgInfo info;          /* [o] */
     }
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct mmc_ioc_cmd
+    {
+        /// <summary>
+        /// Implies direction of data. true = write, false = read
+        /// </summary>
+        public bool write_flag;
+        /// <summary>
+        /// Application-specific command. true = precede with CMD55
+        /// </summary>
+        public bool is_ascmd;
+        public uint opcode;
+        public uint arg;
+        /// <summary>
+        /// CMD response
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
+        public uint[] response;
+        public MmcFlags flags;
+        public uint blksz;
+        public uint blocks;
+        /// <summary>
+        /// Sleep at least <see cref="postsleep_min_us"/> useconds, and at most
+        /// <see cref="postsleep_max_us"/> useconds *after* issuing command.Needed for
+        /// some read commands for which cards have no other way of indicating
+        /// they're ready for the next command (i.e. there is no equivalent of
+        /// a "busy" indicator for read operations).
+        /// </summary>
+        public uint postsleep_min_us;
+        /// <summary>
+        /// Sleep at least <see cref="postsleep_min_us"/> useconds, and at most
+        /// <see cref="postsleep_max_us"/> useconds *after* issuing command.Needed for
+        /// some read commands for which cards have no other way of indicating
+        /// they're ready for the next command (i.e. there is no equivalent of
+        /// a "busy" indicator for read operations).
+        /// </summary>
+        public uint postsleep_max_us;
+        /// <summary>
+        /// Override driver-computed timeouts.
+        /// </summary>
+        public uint data_timeout_ns;
+        /// <summary>
+        /// Override driver-computed timeouts.
+        /// </summary>
+        public uint cmd_timeout_ms;
+        /// <summary>
+        /// For 64-bit machines <see cref="data_ptr"/> , wants to
+        /// be 8-byte aligned.Make sure this struct is the same size when
+        /// built for 32-bit.
+        /// </summary>
+        public uint __pad;
+        /// <summary>
+        /// DAT buffer
+        /// </summary>
+        public ulong data_ptr;
+    }
 }