drivers: add designware emmc driver

Support Designware eMMC driver. It's based on both IO block
and eMMC driver.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
diff --git a/include/drivers/synopsys/dw_mmc.h b/include/drivers/synopsys/dw_mmc.h
new file mode 100644
index 0000000..22192f8
--- /dev/null
+++ b/include/drivers/synopsys/dw_mmc.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __DW_MMC_H__
+#define __DW_MMC_H__
+
+typedef struct dw_mmc_params {
+	uintptr_t	reg_base;
+	uintptr_t	desc_base;
+	size_t		desc_size;
+	int		clk_rate;
+	int		bus_width;
+	unsigned int	flags;
+} dw_mmc_params_t;
+
+void dw_mmc_init(dw_mmc_params_t *params);
+
+#endif	/* __DW_MMC_H__ */