mmc: atmel: Add atmel sdhci support

The SDHCI is introduced by sama5d2, named as Secure Digital Multimedia
Card Controller(SDMMC). It supports the embedded MultiMedia Card (e.MMC)
Specification V4.41, the SD Memory Card Specification V3.0, and the SDIO
V3.0 specification. It is compliant with the SD Host Controller Standard
V3.0 specification.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/arch/arm/mach-at91/include/mach/atmel_sdhci.h b/arch/arm/mach-at91/include/mach/atmel_sdhci.h
new file mode 100644
index 0000000..9652bc2
--- /dev/null
+++ b/arch/arm/mach-at91/include/mach/atmel_sdhci.h
@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2015 Atmel Corporation
+ *		      Wenyou.Yang <wenyou.yang@atmel.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __ATMEL_SDHCI_H
+#define __ATMEL_SDHCI_H
+
+int atmel_sdhci_init(void *regbase, u32 id);
+
+#endif